TR2/3/3A Caliper problemI have spent hours researching all of my manuals

Getting my TR3a ready for the road this spring by working on the brakes. Purchased the auto one year ago from a guy who gave up on the restoration but had completed much a the heavy ugly work. Going over most of his work I noticed the front Girling caliper was leaking fluid. The fluid was coming out of the big plug behind the piston not out the front seal. Ordered a rebuild kit from TRF which was manufactured by TRW. My question is what kind of seal is used behind the big steel plug on the back?

The plug came out with no problem and a mangled o ring was behind this plug which was not doing any good to stop the brake fluid from leaking out the back of the caliper. The rebuild kit only had the two dust covers and four of the flat sealing rings. I have spent hours researching all of my manuals and searching the forums and kind no info on how to seal the back side of this caliper. Any advice on this problem would be appreciated. THANK YOU

You are the first I have heard of having removed the big plug! The manual says not to. No kit comes with that o-ring, so your best bet is to take the old one you pulled out to ACE, or another decent industrial supply and match it. I'm interested to hear your results...and from anyone else who had the courage to remove the plug!

I think you need to check the opposing surfaces for whatever pulled the old o-ring, smooth them thoroughly, and use a brake cylinder rebuild lube on the o-ring on reassembly. There may not be any burrs on the mating surfaces but the old o-ring was pulled by friction from dry assembly.
Bob

That plug is in there to facilitate the machining of the bores since the casting is one piece. The later castings are made in two pieces so no plug is required. I've taken those plugs out often and just replaced the O-rings. I don't remember the size offhand, but they are readily available. Just get something compatible with brake fluid like an EPDM material.

Excerpt from the manual..."No attempt should be made to remove the end plug retainer, as this is screwed in tightly by mechanical means." Glad to hear they can be R&R'd. Randy, when you find a replacement o ring let us know the source.

Thanks for the replays to my leaking end plug problem. I had no choice other than removing the end plug which came out with no problem because it was leaking fluid. I think the PDO had been messing with this caliper. He gave up on the restoration and I am now going over most of his work but I will make a nice TR3 out it when I finish it. I will try and replace the "O" ring and see what happens and report back the results.

CJD said:

"...this is screwed in tightly by mechanical means."

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Really. Could they have possibly been any vaguer?

Sooner or later anything that can be undone will be undone so good to know some have refit them successfully.

Geo Hahn said:

Really. Could they have possibly been any vaguer?

Sooner or later anything that can be undone will be undone so good to know some have refit them successfully.

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Use Rrrruussian. BIG like HOUSE!

I have undone many an item that could not be redone! Many assembly processes are one way. The key is to figure out what can be redone, and what cannot before you waste your time on it.

Sorry this is a little late, but just for the record: O rings are standard sizes, and if you look a bit on line, you can find dealers who sell them with tables of part no. vs. dimensions. The last time I did this, I had to get a bag of 1000 (!!) but it only cost $20. It was for a common application, so I was able to distribute them to my pals, and I became a minor hero in the process. All you need is the dimensions and you can find the part. If the O-ring is mangled, you can still measure the groove it fits into.