> Date: Mon, 26 Jul 93 13:02:57 -0500
> From: email@example.com (Brad Richards)
> Received: by bamba.cs.wisc.edu; Mon, 26 Jul 93 13:02:57 -0500
> To: firstname.lastname@example.org
> Subject: Questions on Two-Piece Brake Calipers
> My service manual uses a pretty frightening tone when warning about
> disassembling the calipers. It says that one should never part the
> halves. Torque figures are given for the "bridge bolts" in case
> one needs to part and reassemble them for some reason, but it says
> that the rejoined parts should be returned to the factory as soon
> as possible thereafter for servicing.
I've parted my snake calipers both times I've rebuilt them; once in 1968
and again about two years ago. So far both the calipers and I have
survived. I'd be more concerned about having the bores honed. That's
not recommended for calipers because of the very tight tolerances. Use
of crocus cloth to remove rust is okay, however. Are the seals in the
bores or on the pistons? If they're in the bores you may be okay,
though I'm not absolutely sure about this.
I asked a British car mechanic I know if it was okay to re-using the old
bolts and was told that it was; but I opted for new ones anyway. The
consensus was that the original bolts were grade 8, which is what I
used. I used a very thin layer of high temp silicone sealer on the
mating surfaces but you might want to see if the original type sealer is
available form the rubber seal supplier (see below).
> Second, there's a small round rubber seal where the fluid passages
Don't re-use the old seals or substitute O-rings. I ordered new seals
from Dave Bean Engineering and discovered that the new ones were about
twice as thick as the old ones. These seals do not recover their
original shape after being under compression for several years. They
are quite cheap so don't scrimp. BTW, according to Dave Bean, Girling
used the same size seal for all calipers.
> Finally, they specify that the bridge bolts should be clean and dry
> before reassembly, but I'd always been told to lightly oil fasteners
> that needed to be set to precise torque settings to make sure that
> the torque was really a measure of the fastening force instead of
> just resistance due to thread friction. Should I oil these bolts
Torque specs are different for dry and lubricated threads. I don't
think putting oil on the threads is a problem as long as you use the
correct torquing specs and you don't get any oil inside the calipers.