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MG Midget and Sprite Technical - Front Brakes Seized

Decide to check my brake linings prior to MOT next month and as usual just before I began this work I started to get a squeal from the front brakes once they got hot.

I have pulled the drivers side pads to check their condition and inspect the piston to see if they were sticking. Found no serious corrosion or pitting but a built of of 'black stuff' which I cleaned off with a rag where I could reach. Then pressed down on the brake pedal a couple of times to see if they would move - which they did. However they wont push back using a piece of wood so I can get the pad back in!

How can I get the pad back in to see if I have freed them up or is it now time to pull the Caliper off and fit new seals/pistons. The Car is a 1275 RWA (1974). By the way there are no anti-squeal shims in the caliper either so I am going to buy a set tomorrow from Moss and fit these as well. Thanks for any help. Andy
Andy Davies

Have you tried disconnecting the brake hose, and then using a small G-Clamp.
K Harris

Rather than disturb the brake hose, slacken the bleed nipple a 1/4 turn. You were probably going to bleed the brakes anyway. Then use a tyre lever, pry bar or large flat bladed screwdriver to lever the brake piston back in.

Guy
Guy Weller

You wiped a bunch of black stuff off...what does that mean, what was it and from where?

Having been down this road, your probably looking at a rebuild. its not hard, just aggravating, look for a kit with a stainless steel or chrome piston, those high carbon pistons love to rust...for as cheap as pads are buy new...but I warn you, once you start, it rarely ever end with a simple rebuild, theres always something else to refurbash

"black stuff" in my experiance is rubber seal deterioation OR oil from the engine leaking and other multiple fluid leaks.

Prop
Prop

release the master cylinder cap, squeeze the caliper pistons back with a crowbar, tyre lever or large screwdriver. If you push back too far watch for fluid spillage at the master...
David (davidDOTsmithAT stonesDOTcom)


I've got a pair of 3" g-clamps that I use for squeezing the pistons back. I find it less stressful than crowbaring.

I would imagine the black stuff you're referring to is brake dust? Obviously that would be nothing to worry about. If there's liquid leaking, the piston seals will need replacing, which is not a massive job.

Oh, and it's probably best if you get new split-pins as well as anti-squeal shims. Always worth replacing them since they're pretty much all that hold the pads in place...

HTH
Mark
MarkH1

Thanks for all the advice. Unfortunately, none of the suggested methods appears to be allowing me to move the pistons back! A mechanic advised me to get the caliper off and put it into a vice. I am going to take the caliper off and use some G Clamps first to see if the better access helps before I disconnect the hydraulic hose. On the assumption that this still doesn't work. Are exchange calipers the best solution or will new seals and pistons do. Is this easy? My skill set doesn't go very far I'm afraid when it comes to brakes. Thanks again .Andy
Andy Davies

personally I never rebuild calipers, for the price of exchange ones at around 40 quid a side it really isn't worth it IMO.
David (davidDOTsmithAT stonesDOTcom)

It is staggering to think you can not push the pistons back. Never had that happen when they have at least moved out. Are you sure you have not allowed them to come too far out of the caliper and they have subsequently toppled sideways and locked themselves?

If however they are faulty it makes far more sense as David states to simply buy exchange calipers from most good suppliers.
Robert (Bob) Midget Turbo

Andy,

Unless you just like pain, or are really broke,,,I got to agree...exchages are cheap....Ive been close to where your at...most likely its a god awful lot of rust...it dossnt take long and it dosnt take much esp. with of all things a "HIGH CARBON non-treated piston" I never did understand that concept...born to rust!

I rebuilt mine, and within several weeks the drivers side was sticking closed whenever I put on the brake..I never did solve it.., an exchange was my best friend...no problem scence

If you can, get a set with a stainless steel or chrome piston they will resist rusting

also look for a "Loaded" set...most of the time its a good value..."Loaded" is everything....pads, bleeders, pins, shims, squeelers, everything. bolt and go.

Prop
Prop

It just acured to me...how old are your brake hoses, if you got those rubber ones, they can look okay on the outside but be completely broke down and collapsed on the inside...causing it to act as a one way valve

Prop
Prop

This thread was discussed between 14/06/2009 and 20/06/2009

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