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Calipers (was gearbox mount)

To: triumphs@autox.team.net (Triumphs List), tr3driver@comcast.net
Subject: Calipers (was gearbox mount)
From: spamiam@comcast.net
Date: Thu, 29 Dec 2005 21:31:43 +0000
>So tell us, Jim, what pressure have you tested your calipers to ?  And what
>temperature ?
>
>Let's see, if we assume the driver can put 300 pounds on the brake pedal
>(when his/her life depends on it), times about 7:1 mechanical advantage,
>divided by about .4 sq in for the MC piston, that's about 5000 psi hydraulic
>pressure ...
>
>Randall

And what?  3 square inches for the caliper's piston = 15,000 lb tension on the 
bolts?

I have eard here that the bolts are tensioned to create a certain degree of 
elongation of the bolt itself.  Re-using the bolts does not replicate the 
pre-load of the bolts in a reproducible way.  

Therefore the bolt might fail, or allow too much stretching.  Both outcomes 
could result in catastrophic failure.

The answer is to have new bolts, but no one knows where to get them.  I THINK 
that new versions of these calipers are being made, so I would have thought 
that one could either get new bolts or get exact specifications for the bolts 
to find a source of a good replacement.  Unfortunately, I have seen neither new 
bolts, nor the specifications.

Also, I have heard of NO, ZERO, ZIP reports of failures of split and rebuilt 
units.  Of course there may be no reports because dead men tell no tales....

-Tony


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