Lockheed caliper

chopped850 · Nov 11, 2009

So I fab'd up a brake bracket and that's all good. I started to take the caliper apart to replace the seals and the piston under the cap is frozen in place. It will not move. The inside blind piston does move. I'm wondering what kind of tricks have been used to free the pistons in these calipers. I did put it in my carb soaker to eat at the seal and what ever grim is holding it in place. The caliper leaked when I got it and I'm just now getting to it.

debby · Nov 11, 2009

I've got one with a stuck inner piston. :?

Have you tried blowing it out with compressed air?

Debby

chopped850 · Nov 11, 2009

I did but the cap was off and blew all this nasty swag all over the place. But the air passages are clean! :mrgreen: I even put my grease gun on the air bleed fitting and forgot to open the screw like a retard. But now the bleed screw is stuck in my grease gun tip. I'm gonna let it soak in the good stuff for a few days.

B+Bogus · Nov 11, 2009

If you're not concerned about scrapping the piston you could drill and tap it and use a bolt to draw it out (maybe screw it against a plate inserted across the disc aperture?).

I've also found a good blow-torch to be a great asset in these situations!

Chris · Nov 11, 2009

Hi
if its the cast iron road caliper try & prise out the seal holder rings. I also try & press the piston in & try & clean up the corrosion in front of the lip before using the air line. I also tried a grease gun & ended up with the nipple stuck to the gun! I wrap the caliper in a towel as they can come out with some force.
I dont know of a chemical that will eat the seals without damaging the metal (alloy)
Chris

79x100 · Nov 11, 2009

They're not normally so badly stuck that they can't be freed, the biggest problem is that the inside one is so inaccessible.

If the outer piston won't move when being tapped from behind then it is well and truely corroded. How hard have you been hitting it ?

chopped850 · Nov 11, 2009

I haven't hit it that hard yet. I'm waiting a few days of soaking before I apply heat or stick it under the press. Keep the ideas coming.

79x100 · Nov 11, 2009

chopped850 said:
I haven't hit it that hard yet.

This is a Norton we're talking about here ! If it won't move, go and get a bigger hammer !

...It is worthwhile inserting a close-fitting bar into the disc opening to make sure that the outer side is properly supported if you have to drift it inwards to get it moving.

The piston is likely to need replacement so the most important thing is to save the caliper body.

grandpaul · Nov 11, 2009

I've got a Lockheed caliper that I'm not sure where it came from, but it has a tapped hole drilled in the backside to drive both pistons out with a thin screwdriver or long screw.

daveparry · Nov 11, 2009

a tapped hole drilled in the backside
---------------------
I was just about to suggest that Paul, never seen it done but I reckon it could work, copper washer under the bolt head when done,
Dave.

Cookie · Nov 11, 2009

It's way too late for the simple expedient of boiling it in water and pumping it out with the master I'm sure.

Bazz · Nov 11, 2009

The Old Brits website has a tech article on overhauling brake calipers. There are a couple of hints on removing the hard to get at inside piston.

HTH

Bazz

chopped850 · Nov 11, 2009

http://www.oldbritts.com/caliper_rebuild.html

THANKS!

I just read the entire thread and see it's okay to hit the top piston with a drift and dead blow. I will give it a shot tonight when I get home from work and see what happens.

montelatici · Nov 11, 2009

Why don't you soak it in clean DOT 3 brake fluid for two or three days . Usually works.

chopped850 · Nov 11, 2009

Well I pulled it from the tank and what do you know the drift and deadblow hammer knocked it right out. Pulled the seal and the piston came out without any issues. Then the back one came out with some compressed air. The B12-Chemtool carb cleaner in a gallon can softened the seals right up. The pistons are fine and the bores are clean. Seals removed and put all the parts back in the bucket till Friday night. Reassemble on Sat and mount on the bike. Thanks for the insight gents. :mrgreen:

Chris · Nov 12, 2009

Hi Grandpaul

The Lockheed calipers with the threaded hole in the back. Most of mine that are like that cam from sidecar crews, although quite a few solos did this in the early days. Straight forward thinking, ie universal steel hose & banjos, easier repairs & easier to fit inside wheel hubs.

Ps Sorry to hear you did not race this season. Cant bare the thought of not having a run around the track.

All the best Chris

Lockheed caliper

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