From digest.v7.n1448 Sat Apr 4 14:40:50 1998
From: Steven J Bernstein <stevenb_at_garageboy.com>
Date: Sat, 4 Apr 1998 13:44:21 -0500 (EST)
Subject: RE: <ALL> Caliper Guide Bolts
Steve D'G clarifies:
>>Pete is correct...there is generally no need to replace these. They
>>should be cleaned when removed and a bit of high temp anti-seize put on
>>them prior to reinstallation. I have had people cross thread & break
>>them or use a worn allen key and round them out. I sell them for $10.00
>>each (a little cheaper than the dealer) and it's probably not a bad idea
>>to keep 2 spares in your tool box at the track or in your garage. Fixed
>>and Girling calipers do not use this part. SD
>>Steve D'Gerolamo - The Ultimate Garage
Yes, sorry, folks for the previous bit of misinformation. Thanks, both
Pete and Steve D'G. I'm now looking at the shop manual, and indeed, it
says "renew if necessary" but it doesn't say what "necessary" means. I
don't recall where I thought I read "renew every time" (perhaps on the
instructions from ATE in the factory brake pads box? - I'll have to
check). So how do YOU define necessary? Every 100k? Every 5
re-torquings? In MY opinion, as long as they're not rusting, and clean up
fine every time, re-use them. On my old E28, some are original with 289k
miles. But they're clean. 8^)
Some rabid type piped in with something like "I musta removed these 40
times in the past year and I've never had a problem...".
So, clearly, his experience falls outside the category of what 90% of BMW
owners go through. While he may be correct, his experience may not be as
relevant to the rest of us. The accumulation of brake dust is the most
damaging factor in your brakes, and when you're taking them apart only
once a year (ok, even up to 5 or 6 times for non-rabid track-goers),
you're dealing with a different set of factors.
The most important point here, regarding your brakes, is cleanliness.
Steve D'G reiterated that in his post. Clean, clean, clean. My friends
make fun of me because while I can theoretically do a pad replacement in
about 5 minutes per wheel (7 minutes with my eyes closed), I put the car
up in the air and putter and clean all the brake components carefully
before reassembly. It takes awhile.
I remember snapping one, yes, even with a torque wrench, because on my old
E28 after 240k miles, one of them was simply ready to go. It happened on
a Sunday afternoon a couple years ago, and I frantically found a small
parts store that had a "replacement part". It cost $6. I used it, but I
bought one at a dealer the following Monday and swapped it in that
evening. The quality of the aftermarket bolt was unbelievably poor.
There were noticably fewer threads (shorter) and there was so much play in
the head with the 7mm driver that I knew I could never get an accurate
torque reading. It scares me to think that they're allowed to sell such a
low-quality brake part. I trust Steve D'G's bolts are factory.
Now the BMW factory shop manual clearly states "don't lubricate". But, we
all have opinions (what's that expression?? 8^)), and I tend to agree with
Steve D'G's opinion to use a bit of hi-temp anti-seize. When I had to use
an easy-out on the remaining portion of the bolt left in the caliper
bracket, it was cake. Because I anal-retentively clean the bolts (and
threads) to perfection (and use anti-seize) each time I reassemble my
brakes, the easy-out grabbed immediately and the remainder of the bolt
spun right out.
It's situations like these that proper mechanic techniques make all the
difference to your automotive Zen repairs...
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