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Tuesday, April 23, 2024

Doug's Domain

Doug Vetter, ATP/CFI

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Sunday, March 3, 2013

Wiper Blade Update

A reader chimed in shortly after I posted my last update concerning the wiper blade part change. He said that he found the Bosch 347S to be an adequate aftermarket replacement blade set for the E36. A google search for "Bosch 347S" revealed parts that looked almost identical to the BMW parts. While a check of the Bosch US website failed to find a match, the same reader suggested I look at the Excel+. That blade has the same multi-component rubber as the 347S.

The problem is that while the driver side blade in the 347S set appears to be equipped with the spoiler attached to the frame, none of the blades on the Bosch website including the Excel+ appear to provide that feature. I realize it's probably only useful at extremely high speeds we can't utilize here in the brain-damaged US, at least without a trip to the house of many doors, but I find it hard to believe they've been able to figure out how to engineer the blade not to lift at high speed without the spoiler. The upside is, at $25 a set, they're a little more than half the cost of the BMW parts, which are still available.

(Image: Set of OE wiper blades)I was at the dealer last weekend and decided to price a new set of blade assemblies for giggles. They're "only" $40 my cost per set. That's highway robbery, of course, but at least they're not $100 like some of the newer vehicles. Hey BMW....while I appreciate browsing all the new car brochures you've been sending me lately, keep replacing $10 parts with $40 parts and I'll continue to throw those brochures in the circular file.

And speaking of new vehicles, I read an article online recently citing Consumer Reports best and worst vehicles of every major auto manufacturer. BMW's best: the 135i. Worst: the X5 35i Premium, whatever the hell that is. It's not hard to conclude why: the 135i is a relatively simple car. I hope somone at BMW is starting to get the message. Cut out all the stupid technology, or at least make it all optional. I don't want iDrive, I don't want powered seats, and I doubt I'll willingly buy a sunroof ever again. As we say in aviation, if it ain't installed, it can't break.

Pirelli Update

Some experimentation has revealed that simply turning off traction control (ASC) allows me to accelerate almost normally. The tires still slip excessively in that mode, but I can actually put my foot down and accelerate. I have a theory as to what is happening.

All winter tires today seem to integrate "sipes" which are cuts through large tread blocks that create additional edges as required to improve traction. Looking closely at old pictures of the Winter Sport M3 I noticed that the sipes were shaped in a sort of "zig zag" pattern, which I imagine helped interlock the individual tread blocks. I also noticed that the sipes didn't cut through the edges of all the tread blocks either, which no doubt contributed to the overall tread stability, and hence performance.

Pirelli's implementation, on the other hand, cuts a straight line through the tread block to create several smaller tread blocks. Unfortunately, due to the soft rubber compound they used these tread blocks can be pushed over by hand -- i.e. with only a few pounds of force. Imagine, then, what happens under load, i.e. acceleration. My guess is that the tread blocks are being pushed over so far that two things happen: 1) this exposes the side of the tread blocks rather than the edge, and that reduces friction and therefore traction, and 2) it reduces the overall diameter of the tire. Taken together, this causes ASC to fire prematurely and erratically, and this leaves me with my foot down and no acceleration when I need it.

In short, it appears that the tread of the Winter Carving Edge is not designed for vehicles with traction control, and for that reason they don't belong on a BMW. My plan is is to run them one more season simply to get my money out of them and then retire the E36 from winter duty. I think she deserves the rest.

Oil Service

(Image: Comparison of OBD I and II 20 pin diagnostic connector cap)Despite the recent airbag warning light and my absolute displeasure with the winter tires the E36 has been running well. Last weekend I pulled up my maintenance schedule worksheet and realized it was in need of an oil service. With temperatures still in the 30's I wasn't particularly interested in crawling under the car, but as they say...duty calls.

Fortunately, some duties in life are enjoyable. During the holidays I brought a batch of my world-famous homemade chocolate chip cookies to the cute dealer service receptionist. The recipe is a variation of a family standard and includes turbinado and dark brown sugars, blended dark and semi-sweet chips, real vanilla extract, and organic walnuts, butter, and flour. They were a big it so it didn't exactly surprise me when she insisted I bring her another batch for her upcoming birthday. Never one to say no to a beautiful girl, I fulfilled my obligation shortly after picking up a oil service kit from the parts desk.

After 4600 miles in service I completed the oil service today without issue, but when I pulled the 20 pin connector off to reset the service indicator the plastic retaining strap split in half, no doubt due to age and temperature. The strap isn't required, but it certainly assures that I'll never misplace that cap. I found the part depicted in section 12 but discovered it was not applicable to the E36 for some reason. I searched online and found part number 12521724690. I'm planning to pick up the cap and two sets of wiper blades this week.

[Edit 3/9/2013]: The part number for the cap turned out to be incorrect, as it is for OBD I vehicles. So I did what I should have done in the first place -- I pulled the cap off the car and used the partial part number silkscreened onto the PCB to come up with the correct OBD II part number: 12521703202. In addition to the part number, the OBD I cap may be distinguished from the OBD II version by the number of pins: the OBD I part has 4 and the OBD II part has 5. I also discovered the OBD II part number depicted in the E39 and E46 vehicles.

Mileage: 232700, Parts: $53