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MG MGB Technical - stuck brake piston

Okay guys - here's the scenario. Just taken on a 'new' car and not had time to check the brakes. This morning it started making grinding noises and so in the car park at work I took the pads out to find the outer one down to the backing. I have a new set being delivered tomorrow but in the meantime I can't push the piston back into the caliper. Any advice? It's being really stubborn and I know I'm not going to get the new pad in there at the moment...
Thanks
Martin
Martin Port

Martin,

I used a big G clamp, followed by a small G Clamp and a suitable socket to wind the pistons in on my car. Have a look at my web page http://www.mymgb.co.uk/Projects/Brake_Pads.htm for pictures of what I mean. I couldn't get them to budge any other way.

Iain
67 BGT
I D Cameron

Martin, if you have an imbalance in the wear then it may be time to do a caliper rebuild with new seals and new pistons if they are pitted on the sealing surface.
David Witham

Since only the outer pad was worn down to the metal you likely have a sticking caliper that needs replacement or rebuilding.
John H

Martin. As the others have said, if only one pad is badly worn, you need to do some experimentation before simply installing new front pads. It is possible that three new pads were installed along with one old pad and the old pad wore out more quickly than the new ones, resulting in your problem. But, I consider that to be unlikely.

More probable is the scenario that the others have mentioned--some form of malfunction of the caliper resulting in increased wear of the outer pad. This could be either the caliper piston not retracting properly after the brake pedal is released, or it could be the inner caliper piston is not functioning.

As the others have mentioned, consider a rebuild of the calipers. A poorly operating caliper is less safe than a properly operating caliper. A dragging pad reduces power and cuts down on fuel mileage. This is not something to consider anything other than a first class repair to.

Les
Les Bengtson

Hi Martin,

If you can get both pads out, proceed as follows - first check there is space in the master cylinder for the fluid you are going to displace then, on the thin side lever the piston back till you can get the thicker pad in on that side and swap the thin pad to the thick side, doesn't matter if it flops over as long as it is in there.

Then go and stamp on the brake pedal till the pistons hit the pads, then lever back and repeat a couple of times till the thin side piston moves easily.

Now fit the new pads.
Chris at Octarine Services

Thanks Chris - I'll try that in the morning and see if I get anywhere. I should probably at this point own up and admit that this isn't actually a problem on my MGB, but that it is actually on my new project - a Porsche 912! I'd quite happily take the caliper off of the disc assembly on the MGB but the Porsche doesn't have the advantage of flexible brake pipes!
Martin
Martin Port

This thread was discussed on 17/04/2007

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