Saturday, June 5, 2010
Axle Remanufacturing Options
For the past week I had been going back and forth about the need to regrease the CV joints in the rear axles during the rear suspension overhaul. I would have preferred to do the job myself and save a ton of money, but given the scope and logistical headaches of this job, my schedule, and the cost of my time to rework them, I ultimately decided to go with a pair of "remanufactured" BMW output shafts.
Of course, "remanufactured" is a somewhat disingenuous term as applied to those parts. Normally, the term "remanufactured" refers to a part that has had all wear components replaced with new parts. The unfortunate reality is that BMW does not replace the CV joints on their "remanufactured" output shafts. The better word to describe what BMW does is "overhaul" the joints, which amounts to disassembly (where possible), cleaning, inspection for damage, regrinding, and then regreasing and installing new boots and clamps. Basically, this is the same kind of thing a pro technician or DIYer can do (sans grinding), only a hell of a lot more expensive.
I looked into having a professional remanufacturer overhaul my axles but the one I spoke to (raxles.com) said they couldn't touch BMW axles anymore because they were no longer able to source new CV joints from Germany. Both raxles.com and Mike Miller of the BMWCCA confirmed that due to a "bear claw" design of the outer joint, few if any remanufacturers can disassemble the joint in the same way an average DIYer can disassemble the inner joint. It was not always this way but BMW changed the design for some stupid reason, so now all we have are more or less throw-away parts. The best thing to do, therefore, is make sure your axles don't fail.
As Mike Miller commented, however, he has yet to see a failure of a CV joint on the back of a BMW that wasn't due to failure of the boots (which causes the grease to leak out and moisture and dirt to get in and destroy the joint in short order). So it's safe to say that if you are so inclined and have the time to invest in the process. you can clean them in a bucket of solvent, regrease them and install new boots for considerably less than I paid for each of the BMW "remanufactured" units. Of course, do that job wrong and you'll be buying BMW remanufactured shafts in any case. I could not take that risk, and with a nearly 25% discount on the parts from my dealer (a total of $750 without the core charge), buying OE up front seemed like the best thing to do.
Rear Suspension Overhaul - Disassembly Day One
I had hoped to begin the suspension overhaul last weekend but I wound up committed to other things for the holiday. It was probably just as well, since I was still busy sourcing parts and dealing with the logistical headaches associated with a project of this magnitude. And as it turns out, my technician went on vacation this week so while I didn't expect to need his counsel to dismantle everything and get the parts out for overhaul, I knew full well it would be preferable to have him a mere phone call away before I started tearing into this.
The vast majority of the parts came in from Tischer and my local dealer yesterday and I spent a couple hours inventorying everything last night. This was a very big and tedious process largely because I ordered virtually all new hardware to replace rusted or otherwise damaged parts. As it turned out, they shorted me a few parts, including a wheel bearing. That shouldn't delay me as long as the parts arrive before mid-week.
I set the goal for today to disassemble the entire rear. Needless to say, I didn't get that far. This is what I did manage to accomplish:
- Remove the interior panels from the trunk.
- Remove the wheel nuts.
- Remove the sway bar.
- Partially disassemble the brakes and disconnect the wear sensors
- Remove the nuts holding the driveshaft to the differential.
- Remove the external torx bolts holding the axles to the differential.
- Push the driver's side output shaft out of the hub.
The first snag of the day came when I attempted to use my 36MM socket to remove the axle nuts. Too bad I got my signals crossed and bought the wrong socket. The E36 uses 30MM nuts on the rear. So, I jumped in the E46 and ran over to Eppy's to buy a 30MM impact socket. Fortunately that only ran me $11, but I naturally saw some other sockets I needed to the total bill jumped to $125. This deviation blew about an hour of my day.
I quit for the day after about 5 hours of work when I realized I was not able to press the passenger side output shaft out of the hub using an air hammer or the old fashioned hand-operated kind. This will require a two arm puller, something I plan to buy tomorrow. I figured I could probably leave the output shaft in the trailing arm and let my local indy tech press it out when they press out all the bushings for me Monday, but I have to go the tool store anyway to pick up a set of impact sockets to remove the subframe. There is no way those rusted bolts and nuts will come out using breaker bars. I had a hell of a time just removing the output shaft bolts (yea, even the ones my tech removed a couple years back when he did the left rear wheel bearing, and yea, after I coated them earlier in the day with some PB Blaster penetrating oil), so I'm convinced I'll need air tools and appropriate sockets to make that happen.
The good news is that there is nothing to stop me from removing the differential first thing tomorrow, which is absolutely necessary for me to fly it up to diffsonline on Monday morning. I'm doubtful at this point whether I will be able to reassemble everything by next weekend simply because I don't believe my parts will be back from powdercoat until late in the week and I still have to schedule my indy tech at that point to press all the new parts in. Worst case is the car will be down for two weeks and I'll spend next weekend taking a well-deserved break. We'll have to wait and see.
Mileage: 193332, Parts: $1572, Tools: $125, Supplies: $30, Parts Saved: $400
Sunday, June 6, 2010
Rear Suspension Overhaul - Disassembly Day Two
I'm not a factory trained BMW technician, but I play one on the Internet. :-)
I began the day with a stop at Eppys to pick up some tools. Specifically, I bought an OTC front hub puller to press the passenger side axle out of the drive flange, and a nice set of SK impact sockets simply because I didn't have any and knew I would need to leverage my air tools in a big way today.
I arrived at the garage and did the following, in order:
- Press the passenger-side axle out of the drive flange.
- Break loose the differential fill and drain plugs and then drain the oil.
- Remove the differential.
- Remove the brakes and parking brake assemblies.
- Disconnect the shock from the trailing arm.
- Disconnect the upper and lower control arm from the trailing arm.
- Disconnect the trailing arm from the body at the RTAB.
- Destroy perfectly good speed sensors while attempting to remove them from the trailing arm.
- Curse the speed sensor design.
- Remove the parking brake cable assembly from the trailing arm.
- Curse the parking brake cable assembly design.
- Disconnect the control arms from the subframe.
- Remove the subframe.
- Jump for joy (mentally, not physically...as my body was too tired to stand, let alone jump, at this point).
In short, I completed the disassembly process and the vehicle now stands in the condition shown in the picture. This was a solid four hours of work, which brings the total disassembly time to nine hours.
I spent a few moments examining the old CV joints. I found all the joints very loose and the outers with some play. I think if I had chosen to regrease them in the field, the new, thicker, grease would have taken up some of the wear tolerance and no doubt tightened up the joints somewhat, but my guess is they would not be as tight as the axles I received from BMW. And there's a very good reason for that -- most remanufacturers replace the balls with parts one or two thousandths oversize to compensate for the wear in the carrier. The result is a joint with the proper tolerances.
I was pleasantly surprised to find the differential gear oil almost like new. That was certainly not the case when I changed it last time, but I think that was the result of the fill at that time effectively cleaning the inside of the differential following my error of leaving the original differential oil in the unit for over 120K miles.
When I disconnected the control arms from the trailing arm the cause of that squirrely feeling in turns became obvious as the trailing arm, now hanging from the RTAB, sort of bounced around in all axes -- something it is clearly not supposed to do. And in fact, a close look at both bushings revealed that the metal core had separated from the rubber. Note to self -- change these blasted things more often than every 193K miles.
I knew before I started this overhaul that replacement of the trailing arm bushings would likely have solved perhaps 80% of the crummy handling, but I also noticed that the upper outer ball joints were quite loose. If you've never tried to move a new ball joint, let's just say it takes some effort. These ball joints flopped around with a flick of a finger. The remaining control arm bushings were reasonably tight, but it doesn't take a lot of give in all the individual bushings to translate into that 20% sloppiness, which I'm sure would have annoyed me no end had I not taken the obsessive-compulsive approach to the repair.
Unfortunately, I had to destroy the speed sensors to remove them from the trailing arms. In spite of the sensor body being plastic (you know that stuff that doesn't rust or otherwise react with nearby metals) it somehow managed to bond itself to the bore in the trailing arm. I tried to be careful with it. When that didn't work, I used a universal alignment tool (UAT) and a socket as a drift to remove it with prejudice. Looks like I'll be buying new sensors. Oh well. That's life in the big city. By the way -- BMW makes a stink about coating the bore with a special German-sourced grease during reassembly. My tech said he sparingly uses a common lithium-base grease, so that's what I will use as well.
The speed sensors must have been shacking up with the parking brake cable assembly, as that too bonded with the bore in the arm and really gave me fits. Fortunately, because the end of the cable that mates with the arm is metal, it was able to take a bit more abuse from the UAT. That in combination with a small screwdriver as a pry bar and a bit of tugging on the cable in all directions pulled it from its corroded confines. Of course, I won't bore you with the disassembly procedure of the parking brakes which made this all possible. That will be covered in an upcoming DIY, should I wish to relive the horror at some point for the benefit of my readers.
I found removing the differential to be reasonably easy in spite of its weight (80 pounds or so...about the weight of a bag of concrete). The jack certainly came in handy. I'm not looking forward to reinstalling it, however, as everything is easier when Sir Newton is helping. Maybe I can flip the car upside down for that part. ;-)
In spite of being a huge hunk of metal, I found the subframe to be reasonably light, and that's a good thing because it fits very tightly to its mounting studs and bolts. I really had to jimmy it back and forth to get it to come off the front studs. Of course, that may have had more to do with the rear pivoting down somewhat under its own weight, but we'll see.
As for the subframe bushings, I'd call the differential mount bushing toast, which isn't exactly a surprise -- the forces on that bolt even on the street are pretty substantial, and on the track with manual transmission they're high enough to break a grade 10 bolt (or rip the entire bushing carrier from the subframe). The two front bushings and one of the rear bushings had noticeable cracks in them. Whether the cracks were merely a surface phenomenon or indicative of impending failure, I'll never know. And I don't really care, since they'll all be replaced. The rears are slated to receive the stronger M3 parts as well.
Tomorrow I'm taking a vacation day as planned and have several things to accomplish:
- Return the drive axles to the dealer for a core credit. It's only $100, but I'm not in the business of giving interest free loans, so I want it back.
- Drop all the parts off at my local tech to have him press everything out in prep for powdercoating. He said he knows a good fabricator, so I'll have him weld on the swaybar tab reinforcement kit. That will cost more, but will make the mobile welder's job a bit easier and hopefully simplify the logistics a bit, as the part will then be ready for a full sandblast and powdercoating.
- Fly the differential up to Dan at diffsonline so he can get busy with the overhaul and (hopefully) have it back to me by the end of the week.
The remainder of the week will amount to shuttling the parts back and forth, something I hope to do with a minimum number of vacation days. I do have a bunch to do at my real job and it's not getting done while I'm wrenching, that's for sure.
Mileage: 193332, Tools: $240
Wednesday, June 9, 2010
Rear Suspension Overhaul Update - Parts Sent Out for Disassembly
On Monday I managed to get up reasonably early so I could run over to the dealer and get the core credit on the axles and then run the suspension parts over to my local indy technician, Mr. M Car, which just so happens to be located at one of my old stomping grounds, and the location of my first skydive, Monmouth Executive Airport. I arrived to find Don, the owner, in a nondescript hangar filled with an assortment of nice cars, most of which were BMWs.
I told him that I wanted all the bushings, ball joints and bearings removed from the parts in prep for refinishing. I also mentioned the need to MIG weld the swaybar tab reinforcement kit to the subframe and he told me that he knew a fabricator on the airport grounds that could do a fine job. He even read my mind when he told me that the kit needs to be installed properly or else it would interfere with the swaybar mounting tab or the hardware used to fasten it. My instincts told me this wasn't Don's first rodeo and I figured I'd found the right guy for the job.
As I looked around the shop I saw a couple engines in various states of assembly as well as some tasteful memories of money-shfts gone by and the proverbial light bulb illuminated in the dark chasm that often masquerades for my brain. I asked him whether he could install new bearings and seals in my differential and help prep it for refinishing. He quickly admitted to his share of knowledge of BMW differentials, including his insistence to use German bearings (SKF or FAG) rather than cheap Chinese crap. So, rather than haul that 80 lb bag of concrete up to Massachusetts and back, and pay Dan a cool grand for what is just this side of a spray paint overhaul (no gear changes or LSD upgrade), I told Don I'd bring my differential to him later in the day, and that's exactly what I did.
Since there wasn't much for me to do on the car while I waited for Don to prep the parts I went back to the salt mine on Tuesday. Last night I managed to place yet another order with Tischer to cover a few miscellaneous parts I'll need for reassembly. First and foremost was a replacement for the ABS sensor ($110!) I broke during disassembly. While under the car I could not overlook the rubber hose that connects the fuel filler tube with the fuel tank. It looked so heat damaged and brittle that I considered that an essential replacement for safety reasons. The only problem? That simple hose is $66. I also ordered four (4) new large retaining washers for the subframe simply because the old ones were rusty and some simple math convinced me it would cost more to prep and paint the old parts than it would to buy new. I expect that order to be here Friday or Monday at the latest.
I also noticed that during disassembly the electrical plug that connects the body harness to the brake wear sensor practically disintegrated in my hands (12 years of exposure to countless heat cycles will do that to plastic). I failed to find the plug in the ETK so I went to the dealer. The parts guy couldn't find it either so he called the BMW tech line and they gave him what we both hoped was the correct part number. It's on order and I expect to see that later this week as well.
And if you're wondering about the picture, that's a closeup of the new "split" style trailing arm bushings that were reportedly originally developed for the Z4 M Coupe. The TIS recommends replacement of flange-type bushings with the new split type, so this is not exactly an out-of-the-box upgrade. I can't wait to get the car back on the road to try them out.
Mileage: 193332, Parts: $245, Parts Saved: $80
Friday, June 11, 2010
Rear Suspension Overhaul Update - Parts Returned
Yesterday I exchanged some email with Don.
First of all, he let me know that he would have the parts ready to go shortly but said he was unable to remove the inner bushing from the lower control arms. The arm is actually split into two pieces in that area and he said he would likely crush or bend the arm trying to remove the bushing. My dealer tech told me much the same thing but I figured that he was saying that simply because the cost of his labor usually requires him to buy new arms vs. new bushings. Guess not. So last night I placed an order with Pelican Parts for Lemforder (OEM) rear lower control arms with bushings pre-installed. The damage? $50 each or about $50 cheaper than the OE versions. The perk? I won't have to paint the lower control arms to get the "like new" look I'm trying to achieve.
Don also offered to do the differential overhaul consisting of new bearings and seals, resetting the lash and a rattle can paint job for $750. We discussed the idea of replacing the mounting bushings and he said that he would do those for the cost of parts. I did a couple quick part lookups on realoem.com and realized that the bushings retailed for about $15 each so I figured I'd go ahead with that option. In for a penny, in for a pound, right?
A few thoughts then ran through my head. Would it make sense to press new bushings into the existing cover? Perhaps not because...
- Don would have to waste his time swapping the bushings. Not a cost to me, per se, but a cost to him that I'll ultimately pay for in some way. There ain't no such thing as a free lunch.
- I'd have to waste my time running the cover over to the only person I knew with a blasting cabinet -- my aircraft mechanic -- in order to dress the part up enough so it would look at home on the newly repainted case.
- There is a reason why BMW does not advocate pressing new ball joints into front lower control arms made of aluminum (a la E46). I won't belabor the point here, but think metal fatigue.
- A brand new cover with pre-installed bushings is only $100.
If you've read this far you already know what I did. A new cover and related hardware as well as a speed sensor for good measure is on the way from Tischer (getbmwparts.com). As I placed the fifth order with in them in the last couple of weeks I added a comment to the order form I knew Jason and Evan would read: "How much more do I need to buy before you guys increase my discount level?" :-) I'll spare you the details of the response, but apparently I'll need to buy a BMW dealership if I want a higher discount. Hmmm...if only I had a spare $15 million burning a hole in my pocket.
Today I made some follow up calls to a couple powder coaters. One never returned my call from yesterday and didn't answer today either. The second guy called back but told me that it would take him a bit more than a week to get the parts back to me. That meant if I delivered them Monday I'd waste the following weekend waiting for the parts rather than beginning reassembly as planned. I quickly realized that powder coating just wasn't going to work out, and I would be forced to prep and paint the parts myself using rattle cans. This isn't all bad news. It removes the question of whether the powder coat would interfere with reinstalling the brake guards on the control arms (it's a tight fit as is...can't imagine how would work with 3-4 mils of powder coat). It also will save me anywhere from $300 to $500. And given how I've been bleeding money lately, that's a welcome change of pace.
This afternoon I picked up the control arms and trailing arms from Don. He charged me 2.5 hours and that's not bad considering how long it would have likely taken me to do the job. I paid the bill and took a few minutes to shoot the shit, as it were.
He asked me to confirm I was planning to use the new split type RTAB and of course I answered in the affirmative. He said that was a good choice because the new bushings use a higher durometer rubber than the prior version and the outer diameter of the bushing (uncompressed) is somewhat larger than the opening in the arm. Installing it in the arm compresses the rubber further which helps keep that center metal bushing where it should be. Unfortunately, he mentioned that he has seen cases of the bushings "walking" slightly out of the arm so he said he'll drill a small hole in the arm in an inconspicuous place and install a screw to lock the bushing to the arm. Easy enough to do with a minimum of consequences, given that the arm is steel rather than aluminum.
This eventually led to a discussion of the body / subframe reinforcement plates I had planned to install. He and one of his staff quickly retorted that the chance of the E36 body failing in that way was so remote as to make it not worth the hassle, particularly on a street car, and one with an automatic transmission to boot. This wasn't exactly news, but it was interesting to hear it from guys that race these cars. Don said that the three cars he'd seen damaged were all driven by the "younger element" who tended to slam the throttle around, dump the clutch, accelerate rapidly over potholes and generally abuse the cars on the street or the track. This advice combined with my desire to get the car back in service AND reduce the bleeding coming from my wallet has convinced me to NOT install the reinforcement plates after all. That should save me at least $300 for the mobile welder plus the usual risk of fire that comes along with welding a car with the fuel tank installed. I haven't decided yet whether I'll sell the plates as I may use them eventually, but contact me if interested in a small discount off retail.
Fortunately, welding the AKG Motorsport swaybar tab reinforcement kit on the subframe was easy to do with the subframe removed from the vehicle. As you can see in the picture, Don had his fabricator install the kit and the the work is beautiful. It is better than the Turner kit, in my opinion, by the virtue that it includes an extra piece that is used to box in the structure, thus significantly enhancing the strength of the modification. Truth be told, the kit is overkill for a street car equipped with the stock rear swaybar, but you really didn't think I was going to keep that on there forever, did you? After all, there is a method to my madness.
This weekend I plan to:
- Install the new brake wear sensor wiring I picked up from the dealer this morning (pictured)
- Scrub the underside of the car's body while I have the opportunity
- Prepare, prime, and paint all the parts I'll take back to Don on Monday morning
Mileage: 193332, Parts: $205, Parts Saved: $80, Labor $235
Sunday, June 13, 2010
Rear Suspension Overhaul - Parts Prep and Body Cleanup
The first step to any paint prep is to degrease the parts. This presented a question -- what degreaser to use? Traditionally, I've used mineral spirits shot through a spray wand attached to shop air to degrease the airplane's engine and cowl area. It strips grease and oil very well and then dries quickly with little or no residue. And, in fact, most enamel (think rattle-can) paints suggest stripping the surface of the area to be painted with mineral spirits, so I know they are compatible. The problem, of course, is that mineral spirits is a petroleum product and as a consequence, not particularly environmentally friendly. It's also flammable as hell.
Based on some research online I've found that the age of bio-friendly citrus-based degreasers has arrived, and guess what -- unlike most "environmentally friendly" chemicals, they actually work. So while at Home Depot yesterday I bought a gallon jug of Zep Heavy Duty Citrus Degreaser, a pair of black nitrile rubber gloves to protect my hands, and a sturdy nylon brush. I also picked up several rattle cans of automotive primer and some satin black finish coat, as well as a gallon can of mineral spirits that I figured I'd use to remove whatever residue the citrus degreaser might leave behind just prior to painting.
Back home, I got to work and poured about 1/4 gallon of the degreasing fluid into a stainless steel bucket and used the brush to transfer the degreasing fluid to the parts at full strength. I scrubbed the parts and then rinsed them with water and was pleasantly surprised at how effective the process was at cleaning all the penetrating oil, brake dust, and other grime from the parts. I'm sold on citrus degreasers and can wholeheartedly recommend them if you want to be environmentally correct AND come out smelling as sweet an orange grove rather than the butt end of a refinery.
I then set up the compressor, equipped my die grinder with a medium grit abrasive disc, and sat down with the parts to begin the tedious process of cleaning off the rust and scuffing the existing paint to give it a "tooth" appropriate for painting. I spent a solid hour doing this and managed to clean up the parts pretty well, but ultimately realized that the damage due to rust on the subframe was a bit deeper than originally thought. I knew I could not fully clear the surface of rust or smooth out the surface in preparation for paint with anything but an electric grinder equipped with a hard-abrasive wheel -- something I did not have at the moment. At that point I realized I'd simply have to bite the bullet, accept a delay in the reassembly process, and get the parts professionally sandblasted. I left the garage for the day somewhat disappointed, but still satisfied that I gave it the old college try.
Today, after washing and applying some paint sealant to the E46 to protect it from the elements it now braves on a daily basis, I got to work on the E36. First, I managed to replace the connector on the body harness of the E36 for the rear brake sensor. Although I expected to have to solder in the pig tails purchased this week along with the new connector, I managed to remove the existing pin sockets from the broken connector and insert them, unmodified, into the new connector.
As it turns out, that connector is equipped with a locking tab and that, in combination with small barbs on the pin sockets, locks the sockets into the connector. I tried to gracefully pry the locking tab up to slide it back and out of the way, but it broke. What a surprise. So I used a micro screwdriver to pull the remainder of the locking tab away from the connector and then pushed the barbs in far enough to release the sockets from the connector. To install the new connector, I simply reversed the process and snapped the locking tab closed. Done!
Since the brake wear sensor is just a switch of sorts I doubt the polarity of the wiring matters, but for future reference I noted the following wiring convention:
- Pin 1 = brown wire of the body harness
- Pin 2 = yellow wire of the body harness
I put the unused pigtails for the sensor wiring in my spare parts drawer before moving on to the messiest part of the day. Using some of the degreasing liquid diluted 50/50 with water, I got under the bottom of the car and used the nylon brush to scrub everything in sight, particularly the areas that would be inaccessible once the subframe was reinstalled. I let the liquid soak in a bit and then rinsed it with water. The color of the water I rinsed off the garage floor was a black as night, so I knew the degreaser had done its job. I then looked up at the body and confirmed it -- the cleaning process exposed body color and gray primer that likely hadn't seen the light of day for many years. I'm now comfortable that the body won't clash with the freshly painted suspension parts.
This week I have to get the parts sandblasted, painted, and then back to Don so he can install all the new bushings, bearings, and ball joints. At this point I am uncertain as to whether I will be able to do any reassembly this weekend, but if I can get the subframe installed in order to get my rear jack point back I'll be happy.
Mileage: 193332, Supplies, $120
Friday, June 18, 2010
Rear Suspension Overhaul - Parts Return from Powder Coating
Yes, you read that entry title correctly. After a lot of back and forth on the subject, I managed to get the suspension parts powder coated with a turnaround of four days. I picked them up from Mike at Shore Powdercoat today around Noon and immediately drove them over to Don at Mr. M Car along with a box of parts he'll press into them over the next few days.
Overall, I'm very happy with the finish. While the subframe in particular still shows the deep scars of the rust damage (click on the pictures to see what I mean), I think I can rest assured that the sandblasting removed what remained of the rust and the powder coating effectively sealed the steel so it should no longer be an issue for the remaining life of the car.
I asked the powder coater to avoid sandblasting the smooth bushing surfaces on the parts but they did anyway. Fortunately, according to Don, that should not be an issue, and at least in the case of the RTAB the extra friction might be a good thing.
I also asked them to sandblast the parking brake attachment assemblies to clean them of a ton of crud that refused to come off with the degreasing agents and solvents I had on hand but I requested they not paint them because clearances can be an issue with those parts. They painted them anyway, and when Don saw that he expressed some concern about it, but I noticed that the parts seemed to actuate without any binding and they do look a hell of a lot better than they did. I guess I'll find out how they work when I attempt to install the parking brakes.
And speaking of brakes, I bent one of the brake shields trying to remove it from the rusted trailing arm last weekend so I ordered new brake shields at $15 each. Since they must be put on before the drive flange is pressed into the bearing, now is the time to do that. And, of course, I ordered all new hardware to go along with that because nothing looks more half-ass than new parts put together with old, rusty fasteners. And if you're wondering why I didn't just paint the fasteners, it's because the ratchet would likely mar the paint and the rust would soon return. The new fasteners are zinc plated and that should help prevent rust from forming for some time.
Before I left to go back to the office, Don mentioned he was still waiting for bearings for the differential but he expects to see them Monday. He also suggested the parts would be ready by the middle of next week. If he sticks to that schedule I should be able to begin reassembly Thursday or Friday. In the meantime, this weekend I plan to install the new fuel tank hose and a new muffler heat shield I bought to replace the original part that was damaged a long time ago when one of the muffler mounts failed. The heat shield is largely a cosmetic fix, but I've become very good at justifying such things lately.
Mileage: 193332, Labor: $295
Sunday, June 20, 2010
Rear Suspension Overhaul - Miscellaneous Preassembly Tasks
Earlier in the week I spoke to my technician about two issues:
- How to press the axle shafts into the drive flanges. Specifically, I asked him whether it was possible to press them in most of the way by hand and then use the nut along with an air wrench to pull the axle in. He smiled and said "sure, you can do it that way if you want to ruin the axles!" He quickly retorted that the proper way to do that is to use the BMW special tool or an equivalent that bolts to the hub and threads into the axle shaft to pull the axle into the flange. Fortunately, he agreed to loan me the necessary tool. All I have to do is bring him one of the axles to make sure he gives me the correct threaded component. Have I said lately how important it is to maintain a good relationship with your local BMW technician? :-)
- How to align the trailing arm bushing carrier (what BMW calls the "console") for zero preload at ride height. I knew there was a special tool for this task but he said that he no longer had the tool in the shop because it broke and it really wasn't necessary in the first place. He said he uses a similar technique that involves a generic straight edge. I've known about that technique for some time but had hoped that I could use the tool because it takes the place of the extra hands that will no doubt come in handy while I hold a couple box end wrenches and torque the bolt to 110Nm (81 ft*lbs). If that doesn't sound challenging, consider that the torque is just shy of that required for a wheel lug bolt. Yea, that will be a piece of cake. Riiiiight.
Yesterday I did a bit of minor preassembly work while I waited for parts to come back from Don.
To start things off I picked up the new muffler heat shield from the dealer in the morning. While I was there, I asked the parts guys for three wheel lug bolts to replace the ones whose threads were damaged when I used them with the special tool to press the axle shaft out of the drive flange. Always willing to help, my "alternate" tech, K, overheard my quandry and responded with a gesture of three near-new lug bolts from his spare parts bin...free of charge, of course. Cool guy, eh? He also mentioned that he was looking forward to seeing the results of my efforts and I told him he'd see it soon for an alignment to wrestle the rear toe and camber back into spec.
Back at the garage, while pulling the old heat shield out, I realized that the heat shield actually comes in two separate pieces and I had only ordered the larger of the two ($55). A quick call to the parts department solved that problem. The smaller part ($35) is on order and should be here by Wednesday. As it turns out, one of the heat shield retaining nuts was also missing in action (it probably fell off some time ago since I certainly did not remove it during this project) so I ordered more. They were only available in a package of ten, but rather than something like 45 cents each retail the parts guy took pity on me again and gave them to me for one penny over cost, or 25 cents ($2.50). Those will be here Wednesday too.
I then installed the new fuel hose that connects the filler neck with the tank. The hose attached to the filler neck side easily but the end that attaches to the barbed nipple molded into the tank gave me fits as there was essentially little to no clearance between the nipple and the body of the vehicle. I finally managed to wiggle it on but I had even more difficulty trying to fit the clamp to far enough down the tank nipple. It's definitely on there now and it looks great, but what a needless pain in the ass. You'd think BMW had never built a car before this one. All they had to do was mold the tank to push the nipple a 1/4" farther down and this would be a non-issue. The perk of this task was that I realized I had picked the right time to do this. I can't imagine replacing the hose with the upper control arms, etc. in place as there is simply no clearance to get in there.
Next up was pre-assembly of the shocks. First of all, I discovered that I could not remove the top nut that secures the mount to the rod from the existing shock assemblies because I couldn't securely grab the shock rod and prevent it from rotating. This prevented me from reusing the top cup washer that I originally chose not to order because it seemed to be in great shape. This also highlighted the fact that if I couldn't remove the nut, there was a pretty good chance I wouldn't be able to tighten it on the new assemblies either. I also discovered that I neglected to order a very small washer that fits inconspicuously below the bottom cup plate, presumably to add strength to the cup plate where it rests on a small ridge machined into the rod. I thought briefly of reusing the washer from the old assemblies but closer examination revealed they were both badly rusted and unusable. A quick call to the parts department fixed the problem and new washers are on order.
I then reviewed the first task of reassembly – installation of the subframe. The subframe attaches to the body with two studs in the front and two bolts in the rear. Per the TIS, the studs must be torqued to 120 Nm (88 ft*lbs), while the two nuts that hold the subframe to these studs as well as the two rear bolts must be torqued to 140 Nm (103 ft*lbs). I soon wondered how to secure the studs to the body. While they have a hex nut cast into them, the stud shafts are too long for even the deepest of sockets so I concluded I'd need a 24 mm crow's foot socket to first torque the stud to the body and then a regular socket to torque the large grade 10 nut that would hold the subframe to the stud.
The last task of the day involved prep and paint of the fittings that mate the parking brake cable assemblies to the trailing arms. I used emory cloth to remove all the rust from the fittings but made a point of not painting the portion that mates with the bore in the trailing arm for fear that the close tolerances would prevent installation. You can see the results in the foreground of the heat shield picture, above.
Today I did some Googling to find out if there was a better solution for R&R'ing the shock mounts than a set of vice grips. Ultimately, the terms "oval shock socket" revealed what I needed to know, including the fact that Lisle makes a “universal” kit of oval sockets (Lisle Part number 20400). That led to the realization that my local tool shop, Eppy's, carried the kit. I ran over there today with one of the old shock assemblies and confirmed that one of the tools in the kit fit the BMW application before I plunked down the whopping $10 for the set. While there, I also picked up a set of metric crow's foot sockets ranging from 8 to 24 MM (Astro Pneumatic Tool Part number 7115) for $36 and considered it money well spent.
Mileage: 193332, Parts: $90, Parts Saved: $20, Tools: $50
Thursday, June 24, 2010
Rear Suspension Overhaul - Assembly Day One
Yesterday I picked up the parts from Don and paid him for a job well done. He managed to get all of the bushings, bearings, and ball joints installed without scratching any of the parts. And as it turned out, he did not have to drill the trailing arm to secure the RTAB because he was able to press it in without using any lubricant. That in combination with the sandblasted surface and Vorshlag shims should keep the RTAB well positioned. He also finished the differential earlier than expected, complete with new bearings, seals, cover, speed sensor, and all new hardware along with a fresh paint job. It looks brand new.
Today I began the day by visiting Eppy's to pick up a small set of 1/2" drive extensions because I knew I'd need them today in several places. I tried to buy SK to match the bulk of my ratchets but they only had a set of wobble extensions in stock. So I was forced to buy a small set of three extensions (3, 5, and 8") from an offshore vendor. I also stopped by Home Depot and picked up a couple three foot pieces of 1/8" thick aluminum angle to help with the RTAB console alignment and a future task involved in the front suspension I expect to tackle in a few months.
By the end of a five hour work session in 95 degree heat I had managed to install a bulk of the suspension. It went largely as expected with a few exceptions:
- As I started to install the subframe I noticed that the inner diameter of the rear bushings were significantly (1mm+) larger than the bolts used to secure them. In my haste during disassembly I never noticed that so I called Don and he was kind enough to confirm it is normal. With that knowledge in hand, I installed the subframe in short order.
- When it came time to mount the RTAB and the shims into the console, the aluminum angle did an admirable job of taking the place of the special BMW tool, but I found it rather difficult to apply the required 81 ft*lbs of torque to the bolt. I quickly realized that the small box-end wrench I was using as a counter-holder was the problem and replaced it with my largest breaker bar. I then used careful pressure with my foot to prevent the console from rotating as I held the breaker bar with one hand, the torque wrench with the other, and finally managed to get the "click" from the torque wrench I expected. Then it was just a matter of wrestling the trailing arm up to the body and securing the console to the body with three new bolts.
- I also could not manage to torque the nut that secures the mount to the top of the shock rod, but I know pretty well what 10 foot pounds feels like so I just used the special Lisle tool I bought in combination with a 16 mm box end wrench and tightened it down until I was satisfied.
I managed to dial in both the camber and toe settings pretty well based on pictures I took prior to disassembly and applied the final torque on the control arm outer bolts. I could do this because they are ball joints and will naturally rotate as I lower the suspension down to normal ride height. I can't apply final torque to the inner bolts that secure the control arm bushings to the subframe because the preload on those bushings must be set at normal ride height and I can't achieve that until the wheels are reinstalled and they are lowered down onto a set of ramps for clearance purposes.
The remaining components to be installed include the parking brakes, wheel brakes, axle shafts, differential, swaybar and muffler. Tomorrow I'll install and adjust the parking brake and wheel brakes first because I'll need those functioning to prevent the drive flanges from rotating while I use a tool provided by my technician to pull the output shafts into each drive flange. Once that is done, I'll use my jack to lift and install the differential. The swaybar will be next next because it is easier to install without the muffler in place. Then I'll finish up by installing the muffler with new sealing rings and hardware. At that point, I expect to take it on a brief test drive around the block before I take it for an alignment sometime in the next few days.
Mileage: 193332, Labor: $950, Tools: $30
Friday, June 25, 2010
Rear Suspension Overhaul - Assembly Day Two
When I arrived at the garage I got right to work because I knew I had a very long day ahead. I started with something easy -- securing the shocks to the trailing arm. That uncovered a small wrinkle. As I jacked up the right side trailing arm I noticed that the spring didn't look right. It turned out the lower spring seat on the right side had popped out of the upper control arm and caused the spring to sit crooked. If you look back at yesterday's post you can clearly see that in one of the pictures. Once that was fixed I secured the shocks to the arms and moved on to more pressing (and annoying) things.
When I told my technician about this project initially he smiled and said "Don't curse too much". In spite of dealing with stubborn fasteners, banging my head on various protrusions under the vehicle, and wrestling very heavy objects half way around the state of New Jersey I have managed to maintain my composure throughout the project. In fact, this was a zero curse job...right up the point I started work on the $!#@!$! parking brakes. These infernal things caused me to curse (loudly) several times as I wrestled with the return springs. They were damn near impossible to stretch as required to reach the hole in the adjacent brake shoe. I almost broke one of my hook tools and then decided to try a pair of long nose pliers. With nearly half of my body weight on the pliers I still had a hell of time securing the springs. I managed to get the work done, naturally, but it was the most annoying aspect of the entire project.
The only upside of dealing with the parking brakes -- that is to say, other than the obvious fact that they look great now -- is that I now know how to adjust them. BMW insists that they be adjusted such that the clamping force is matched to within 30% and since they are completely independent of one another that is most certainly a trial and error process. I spent probably 20 minutes just going back and forth between each rear wheel with the parking brake lever in the various states advocated by the TIS to make sure that it was adjusted correctly. I will likely have to tighten them up further after I go through the break-in process but that should be easy enough to do now.
With that nightmare over, I took one of my axle shafts over to my technician so he could assemble the correct components from his wide array of BMW special tools required to pull the axle shafts into the drive flanges. Back home I screwed the shaft onto the end of the axle, inserted the axle into the drive flange, mounted the base to the rotor with a couple wheel bolts, threaded the bearing-equipped nut on the shaft and then used a huge adjustable wrench (also courtesy of my technician) to tighten the nut and pull each axle shaft smartly into its flange.
The right side axle slipped almost all the way into the drive flange by hand but the left side axle barely fit into the flange so the tool was absolutely essential to this task. The lesson learned? Don't think for a second it's possible to just press these things in by hand even with new flanges and remanufactured axles with nice clean splines. The parts are designed to mate with a press fit and special tools are consequently required for the job. Baum Tools makes a tool that should do the job, but it's not as slick (or as expensive, I'm sure) as the BMW toolset. Once both axles were pressed in I returned the tools before anyone missed them and drove back to the garage once again to install the differential.
Due to the angle at which the differential must be inserted into the subframe I found the jack only slightly useful for the task. I wound up hulking the thing up there with my bare hands, and burning out the muscles in my arms in the process. That thing is HEAVY. Once it was in position I mated the input shaft with the driveshaft and then secured the differential with new hardware. I had to use the old nuts to connect the driveshaft to the differential because I forgot to buy new nuts. No matter, really. I have new nuts on order and I have tightened and torque sealed the existing nuts so I can inspect them in the interim to make sure they don't walk before I'm able to replace them with the new parts.
What's torque seal, you ask? It's a colored gel that is used to bridge the gap between a fastener and its mating surface. When torque seal dries it becomes brittle and will crack if the fastener moves. This provides a clear visual indication that the fastener is no longer secure. It can also be used simply to mark fasteners that have been properly torqued and it came in very handy in that sense when I began to secure the axle shafts to the differential. Securing those bolts requires multiple trips between the underside of the vehicle and the interior to alternately secure and release the parking brakes or gear shift so the output shafts can be rotated to provide access to all of the bolts and then secured as required to apply the necessary torque. So my output shafts now look like they belong on an airplane. I can't wait to see if the car lifts off at rotation speed. :)
After about six hours of unrelenting work, I said "uncle" and went home short of my goals for the day. I have eleven hours in the assembly process so far and expect to spend another 2-3 hours tomorrow installing the wheel brakes, swaybar, and muffler. I spoke with the dealer today and they said an alignment might be possible tomorrow but it would be tight. I'm not holding my breath. At this point I think it is more likely to happen early next week.
Saturday, June 26, 2010
Rear Suspension Overhaul - Assembly Day Three
The last day of major assembly began with a minor repair to one of the fasteners on the heat shield that protects the driveshaft. The heat shield had broken free of the fastener so I bought some galvanized fender washers and sandwiched the shield material between them before reinstalling the screw.
Brakes were up next, and it was at this point that I felt most comfortable, since I had done this several times before. Still, installing the brakes took a solid hour and I almost freaked when I couldn't find the little spring clip that holds the brake wear sensor to the inboard pad. A few seconds of deductive reasoning led me to find it left behind on the old brake pad.
I decided to clean the swaybar of a bunch of old, dried cosmoline using some of the Zep degreasing fluid before installing it with new self-locking nuts. That took only a few minutes because I had done that recently too. Interestingly, I found the rubber in the swaybar links riddled with small cracks after only a few years in service. There was nothing I could do about it now, but I may wind up replacing those links again soon.
The muffler turned out to be relatively easy to install in spite of its weight, but I needed to leverage the jack to hold the heavy end of the muffler up so I could mate the pipes with the mid-section smoothly. As per BMW requirements, I used two new sealing rings and new hardware including copper self-locking nuts. There's no getting a torque wrench between the pipes so I fastened them with two box end wrenches (the bolt head is 13mm and the nuts are 12mm...which is a good thing since I don't have two of either size wrenches). They snugged up suddenly and I took that as a sign to stop tightening. Easy enough.
Removing the old (larger) sealing ring left behind on the pipe was as simple as placing a screwdriver on it and hitting the screwdriver with a hammer. The sealing ring is made of some kind of composite material and breaks easily. Graphite appears to be one of the ingredients because my finger tips were a nice shade of dark gray after handling it for only a few moments.
I installed the wheels temporarily (meaning, I did not torque the bolts) lowered the car to the ground and then torqued the axle nuts to 250 Nm (184 ft*lbs). Everyone complains about that torque but I had no problems applying it with my largest torque wrench and my 30mm impact socket. I couldn't stake the wheel nuts with the wheels on because the hub of the wheel got in the way so I jacked the rear up again, removed the wheels, and then staked the nuts before I reinstalled the wheels a final time.
I then lowered the vehicle down on a set of ramps to achieve the normal normal ride height as required to apply a final torque to several fasteners including the bolts that attach the control arms to the subframe and the shocks to the trailing arms. I could not use a torque wrench on the control arm bolts due to clearance issues so I just torqued it by feel. I had sufficient clearance to swing the torque wrench on the shock fasteners, however, so those were torqued to specs without any problems.
With that out of the way, I conducted a last minute inspection before I lowered the vehicle down to solid earth and went to grab the key. The M52 engine can be somewhat finicky when it is started after being dormant but aside from a bit of stumbling on the first few cylinders it fired right up and settled into a smooth idle. And better yet, I saw no warning lights in the gauge cluster. I took this as a sign that it was ready for a test drive and I carefully pulled the car out of the garage for the first time in three weeks.
I got out of the car to conduct another inspection and immediately noticed the rear ride height was a bit higher than before but I expected that given that the new springs hadn't settled yet. I grabbed my cell phone (with my local wrecker's number in the address book just in case) and took the car around the block at normal residential speeds with the windows open to listen for any undue creaks or groans.
At about 25 MPH I conducted some shallow and then progressively more aggressive turns to get the body to roll a bit in an effort to help settle the springs. I also used the emergency brake to stop the vehicle a few times and thus completed the break-in process. Back at the garage I re-checked the ride height and saw it had settled down enough to call it "near normal". I also took into account the fact that the old springs may very well have been sagging a bit. In short, it looks great, and it drives well in spite of not being "officially" aligned yet.
After cleaning up the garage I called it a day after another five hours of work. Tomorrow I'll reinstall the interior and detail it. Then I'll bring it for alignment first thing Monday morning before I call the project complete.
Mileage: 193332, Parts: $5
Monday, June 28, 2010
Rear Suspension Overhaul - Complete
Yesterday I wrapped up the project by installing the interior trunk components, giving it a bath and taking it to the local deli to grab lunch. I tried to arrange for an alignment at the dealer today but as usual they were swamped and without loaners until next Monday so the car returned to duty today anyway. While some might balk at driving a vehicle without an alignment, the reality is the rear isn't as critical as the front and my alignment estimate could hardly be worse than the trailing arms flopping in the breeze as they were prior to the overhaul.
After driving the vehicle over 100 miles since the overhaul the most prominent thing I've noticed about it so far is that I no longer have to constantly countersteer to correct deviations in track caused by the sloppy rear end. The rear end is also more subdued over bumps; it doesn't "bounce" around as much as it used to. And, not surprisingly, the subtle clunks that were caused by the trailing arms hitting the consoles due to the failed trailing arm bushings are gone as well. In short, the rear end hasn't felt this good in years.
If there is any downside to the rear suspension overhaul, it's that the front end now feels sloppy in comparison.
I paid a total of $2922 in parts, farmed out work worth $1480 in parts and labor, bought $445 in new tools, and paid $150 in miscellaneous supplies, for a total of...well, I'll spare you the nickels and dimes and just round it up to $5000. I also saved $800 sourcing parts myself by negotiating higher than normal discounts with my dealer and buying from online vendors.
Research and parts ordering took a good six hours, disassembly required nine hours and reassembly took a solid 15 hours, or a total of 30 hours. I don't know exactly how long it would have taken a professional to do this work, but in all the time I've worked on this vehicle I've typically been within 10% of the book labor figures. If I chop five hours off for good measure and then multiply the remaining 25 hours by the labor rate, I'm looking at a labor "savings" of $2000 for an independent technician (assuming $80/hr) and a cool $3000 if I paid the dealer to do it ($120/hr). I think I'll average those numbers and suggest I saved $2500 in labor. That works out to $100/hr, which is, coincidentally, the number I typically need in order to justify working on the car myself.
In summary, the project cost almost twice what I expected and took three times as long to complete, although much of that time was spent waiting for subs to complete their work. I'm very happy with the result, not only from the perspective of vehicle performance, but also in how much I learned during the process. If you're wondering whether I'd do it all over again, I'd say yes -- but I'd make damn sure I had a lift and, preferably, a nice climate controlled garage in which to work.