[s-cars] Rear brake saga - will the questions *never* end?

[Richard Tanimura]

I gotta admit, with me anything is possible. But I am a scrawny 160
lbs project manager using regular length hand tools. I didn't use a
torque wrench though. That much is true. Another thought that struck
me when I thought about it was that the bolt might have been too
loose. The sheer face was right at the interface between the carrier
and the hub.

But think about this. First, the threads on these standard bolts are
cut, not rolled. Cut threads are stress risers. Second, the bolts are
threaded the whole length of the bold rather than just in the section
that goes into the hub. That gives you maybe 6 complete turns of
stress risers that are un-engaged just waiting to snap.

I am in no way saying I was not culpable. But the design of the whole
thing seems to beg for caution and margins of safety.

While we are at it, anybody know what the torque on these puppies is
supposed to be?

RIchard

On 1/24/06, mtgadbois at aol.com <mtgadbois at aol.com> wrote:
>
> Richard wrote:
>
> "I had a catastrophic failure 6 months ago when one of the bolts I
> reused broke. These were stock Audi bolts used to attach the caliper
> holder to the hub. I had a picture showing how the bolt was shorn
> exatly at the interface between the holder and the hub. It was a
> classic mechanical illustration of sheering failure.
>
> Now imagine this. Only one bolt failed. This cause the caliper and
> holder to rotate around the remaining bolt and self lock on the inside
> of my expensive alloy wheels. The rear front wheel locked in the
> middle of an intersection. Luckily, I was in town and only going about
> 10 mph. But it was enough to gouge a hole in my wheel. If I had been
> driving at speed, the locking of the rear wheel would have put me in a
> spin. I probably wouldn't be writing this.
>
> The cost was a new wheel, new caliper and holder, new bolts, new brake
> line, new tire since the other one was flat spotted.
>
> Since then, I gladly cough the few bucks for new bolts."
>
>
> My question
>
> Any chance that this bolt could have been over torqued?
>
> Mark
>