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MG MGB Technical - Caliper Rebuilding

Attempting rebuild of front brake calipers. Trying to avoid spiltting the two halves. I'm having trouble installing the wiping seal retainer. Is there a special tool? Is splitting the halves better? I've already wrecked two of these things. Any ideas welcome.
Steve M

Steve; I split the calipers, it is much easier, you'll need to replace the O ring between the caliper
halves, the O rings are available from most major MG parts suppliers. Clifton
Clifton Gordon

I have the O-rings and I have spilt one caliper. Installation of the retainer is still difficult. Related question: What about the caliper half bolts? Torqe? Must they be replaced? Manuals all say do NOT spilt the halves.
Steve M

Steve,

I've split calipers before to make up V8 ones using half MGB & half Triumph P2500. I did however get them pressure tested for leaks prior to fitting.
Nick Ashmore

The problem with splitting the caliper halves is that the bolts are high tensile strength bolts (I don't know what level) and should be replaced rather than reused. They also need to be torqued to a specific value so that they are neither too tight or too loose. To great a torque can cause the bolts to fracture and to loose can cause them to fatigue over time and break. If the grade of the bolt can be determined and the torque value found, then one can safely brake the calipers apart and reassemble them. Without the proper bolts and torque value, it becomes a crap shoot with a critical safety item on the cars - not a real good idea. I am sure that there are those who have disassembled the calipers and reassembled them using the same bolts and using their "calibrated arm" to torque them in place and have lived to tell about it - so far - but I really would rather not ride in their cars with them.
Safety Fast - Dave
David DuBois

Steve M,

Yes, there is technically a special BMC/BL tool to install the metal retainer. However, I purchased a brake seal/retainer installation kit a my local pep boys/advance (whichever...) It consisted of six pieces of variyng sizes, each the appropiate size for a seal retainer, depending on the size of the piston. I then use a C-Clamp with the correct piece from the kit to gently compress the seal into place.

Hope this helps...And yes, I split the calipers.

-Mike
Mike

I rebuilt calipers once and never again. It was a bear trying to get the seals back into the bores without bending them, although I found that a different distributor (might have been Beck-Arnley) had seals that slipped in easier. Then I found out I can get already rebuilt, lifetime warranty calipers from Kragen (Schucks/Checker if you live somewhere else) for the price of the rebuild kits.
Paul K

Well, I tried Sears Automotive late Sunday for retainer tool. Guy at the counter gave the typical dumbfounded shrug. I'll try an auto parts store today. I'm seriously consiering reusing the old bolts and using the highly calibrated "feels about right" reassembly approach.

This whole thing got started when I noticed the front hubs seemed unusally warm (the KO was hot and smoke was rising from the wheels) after replacing the front pads and rotors. I was concerned it might be the front bearings, replaced them (no real problems seen). Replaced the brake hoses, no improvement.

The caliper bores do no appear to be rusted or scored. The old pistons are clean and shiny. I had a tough time getting the new pads installed and now I'm wondering if the new rotors and pads together and just too thick to allow the pads to fully release. Can (should?) the pads be ground or sanded to provide more room for the pistons and pads to move off the rotor?
Steve M

Steve M:
Could be your brake flex lines. Over time they get can mushy inside and act like a one-way valve, not completely releasing pressure on the caliper.

Regards,
Jerry
Jerry Causey

The caliper bolts should be torqued between 35.5 and 37 lb. ft. Reference MGB Shop manual Section
M page M.8. Moss sells the seals, but bolts are not listed. All this leads me to believe that you will
not get new bolts when you buy a rebuild. That said I recently did four and also had problems getting
seal retainers in even with the calipers split. I'll admit I used old bolts, I checked that the were not
rusted or pitted. I have as much or more faith in an old bolt in good condition as I do most of the
replacement bolts we are getting that may have been made in who knows where. The cost to do a rebuild
is about the same as getting a rebuild from Advance or Cragen and others, plus I received some chrome and some black pistons. One black piston was defective and had to be returned. Why did I do it, I
guess a bridge was there and I had to cross it. I'll go for rebuilds the next time just as I will with the
MGB master brake cylinder. I do not suggest doing the caliper yourself if you are not comfortable
doing so. I'm just relating my experience, not suggesting how to do it. Clifton
Clifton Gordon

This thread was discussed on 29/07/2002

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.