View Full Version : OK - pulled the calipers off - now what?

01-24-2010, 11:57 PM
The '68 TR4a brake MC was shot so I've never tried to run any fluid into these, but after sitting for 20+ years I am assuming they need to be either rebuild or replaced.

Am I just looking to see the condition of the pistons since all the seals etc would be replaced anyway?

01-25-2010, 11:21 AM
The only way to know for sure is to pull the pistons and take a look at them and the bore. You will need to do this regardless, as the seals should be replaced.

01-25-2010, 11:24 AM

And be prepared for pitted pistons.

01-25-2010, 11:27 AM
Once you get the pistons out you will be able to see if there is corrosion in the caliper. Mine cleaned up nicely with Mother's Billet polish (there's another Mother's polish that's a bit cheaper, too). When I was satisfied that there was no corrosion in the seal area I blew out & flushed the passageways and put it back together. I did not split the caliper. I also used that opportunity to switch to silicone fluid having also replaced all the flex hoses & wheel cylinders and rebuilding the MC.

01-25-2010, 11:32 AM
Thanks guys - I'll dig into them this afternoon. I am expecting the pistions to be toast.

Wouldn't I need to split the caliper to replace all the seals?

01-25-2010, 11:48 AM
Wouldn't I need to split the caliper to replace all the seals?

No you don't. I pushed out my pistons with a bike tire pump. You probably have a compressor. Just don't ruin your haircut. Put something between them so they both come out. I also got bad seals from the guys in Kansas, all that work and leaks because no seal was the same. Repainted wheels and got a new supplier.

01-25-2010, 12:08 PM
I think there a small seal/gasket for the passageway transition between the caliper halfs. I didn't change that. That was about 8 years ago, and no problems since.

01-25-2010, 12:43 PM
Personally, I would split them anyway and get them cleaned up. Easier to work on getting the new pistons out/in etc. Also, easier to paint that way.

Just my two cents.

M. Pied Lourd

01-25-2010, 12:46 PM
I think there a small seal/gasket for the passageway transition between the caliper halfs. That's right, but the 'official' recommendation from Girling was to never split the calipers. So that seal is not included in the rebuild kit.

So if you do elect to split them, you'll want to source the seal separately. Should be available at Moss, TRF, etc.

BTW, my cars have the early Girling calipers that were one piece. It is definitely possible to R&R the pistons & their seals without splitting the calipers!

01-25-2010, 01:30 PM
FWIW, I did split the calipers and replaced the seals. My hydraulics were completely dry after a 28 year barn nap (must have leaked away) and I was changing to silicone fluid, so I wanted to replace all seals no matter what.

No leaks after 3 driving seasons (that's jinxed it).

01-25-2010, 01:51 PM
Thanks guys,

The pistions are really stuck - OK to use Pblaster or similar to help loosen them up? Everything is going to need to be rebuilt anyway right?

01-25-2010, 06:24 PM
You can still probably blow them out with an air compressor. Just put something between the pistons (thick rag will do) and put the nozzle into the brake line hole. They should pop out. BE CAREFUL!!!

01-25-2010, 06:26 PM
IMO, using PBB or equivalent makes it mandatory to split the calipers and replace the seal between the halves. Which I guess is what you wanted to do anyway <<GRAEMLIN_URL>>/grin.gif Point being that the solvent/oil may attack and soften the seal, allowing it to leak later on. Plus anything that you don't get thoroughly cleaned out may do the same to the new seals.

One way around this is to use the car's brake system to force the pistons out. It will generate pressures much higher than your shop air. One piston will come out first, of course, so clean it up, put it back in, and use a big C-clamp to hold it in place while you eject the other one.

01-25-2010, 07:27 PM
Well <span style="font-weight: bold">that</span> was exciting! Man then they let go they really let go! I had a thick towel stuffed in the middle so no new hairstyle needed.

Only one side came out on each of the calipers. Clamp trick time?

01-25-2010, 07:37 PM
Yup. If you don't have a single clamp that will fit in there, use a flat strip of metal and clamp it on both sides.

01-25-2010, 08:13 PM
That worked great Randall - thanks!

01-26-2010, 12:17 PM
mehheh... POP!!! Dangerous to th' phalanges! Any who attempt this be aware.

We use a small piece of quarter-inch plywood as a shock absorber instead of a rag. An old brake pad and clamps for retainer.
Glad ya got 'em out sans trauma, Tom. :thumbsup: