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Re: Caliper rebuilding

Subject: Re: Caliper rebuilding
Date: Sat, 2 Jun 2001 07:41:02 EDT
In a message dated 06/01/2001 11:41:38 PM Eastern Daylight Time, writes:

> >Re-building calipers WITHOUT replacing the inner "o" ring is a plain waste
> >of time and money (and AIN'T safe).
> So, what is the solution?
> a. buy all NOS calipers instead of rebuilding
> b. buy rebuilt from _____________
> c. junk the car

- - - - - - - - - - - - -

According to my manuals and the Moss catalog, you are not supposed to 
separate the halves of the calipers (probably for this reason).  I did not 
when I rebuilt my calipers and they work fine.  If you do separate the 
halves, Moss sells the gasket.  I'm not sure about the o-ring, but a new 
nitrile o-ring should be easy to find.  New grade 8 bolts would probably be 

I'm sure my buddy Ed will correct me, but I am going to take a stab at what 
the o-ring does.  Brake fluid has to get across the halves of the caliper to 
get to the other piston, so there must be a hole matched to a hole in the 
other side.  I would think that the o-ring is a seal around the holes to 
prevent brake fluid from soaking the gasket.  I can't see how this o-ring 
could get damaged from normal use.  I guess it could break down after many 
years, but I don't know the half-life of nitrile rubber.  The o-ring has to 
be the correct size, too big and it will close the hole when you reassemble 
the halves, too small and it won't do anything at all.  It also must be 
resistant to brake fluid, which I believe is nitrile rubber.  (?)

So if you don't have brake fluid seeping out between the halves of the 
caliper, don't take it completely apart and you will probably be fine.

A word of warning here - If you are not sure of what you are doing with brake 
work, send your calipers out to a reliable rebuilder like White Post 
Restorations.  Even if your car doesn't go real fast, you want it to stop!!!

Safety Fast!

Allen Hefner
Philly Region SCCA Rally Steward
'77 Midget
'92 Mitsubishi Expo LRV Sport

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