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MG TD TF 1500 - TD Brake problem

I have a problem that has me baffled. When I adjust the rear brakes on my TD they will work fine untill I apply the emergency brake. Then they seem to self tighten and drag badly there after. This doesn't happen when using the foot brake but only when the emergency lever is used. If I back the adjuster off enough to prevent this the back brakes become ineffective when using the brake pedal. What am I missing here?
P.W. Lester

P.W.

There is a sequence of adjustments in the Work Shop Manuel, under the "brake adjustment" section, that describes what you should try, to overcome your problem with the emergency brake lever. The insructions are easy to follow and should solve the problem unless you have other issues with the brakes.

George Raham
TD 4224
G. L. Raham

are the brake cables free? if they don't slide freely in the conduit they won't release. regards, tp
tom peterson

Have someone reply and release the handbrake whilst you are watching the movement of the levers at the backing plates. They should move and then fully return. If not, you will have to investigate the cables as suggested by Tom. Regards, Richard.
R Payne

Sticky cable most likely. You can remove the clevis pin, and with an assistant inside the car move the handbrake lever up and down, push/pulling on the cable end to see if it is free.
George Butz

I followed the adjusting procedure for the brake cables. Someone had put bolts through the clevis pins so they could not swivel. I made new pins and installed them according to the manual. The levers appear to be dropping back down properly. In spite of this the brakes remain tight after the first use of the hand brake as if the adjuster had been tightened. The brakes seem to be in otherwise good condition with good thick linings and the drums are not worn. I thought maybe an application of the brake pedal might "recenter" them but it does not. They just stay tight. I am beginning to think the piston on the mechanical side of the wheel cylinder is hanging up for some reason. Paul.
P.W. Lester

Unlike the front brakes, the rear brake cylinders float in a slot in the brake back plate. The rubber boot protects both the clevis and lever and the cylinder to back plate interface (the slot). If the loop in the rear brake line is too tight, or there is excessive friction in the slot that the brake cylinder floats in, after handbrake application the cylinder can be stuck in the 'up' or 'top' of the slot, dragging the top shoe. The slots need to be greased (lightly) and the brake cylinders moving fairly freely. Finally, make sure the 'light' brake shoe pull off spring is located away from the wheel cylinder. The piston on the mechanical side of the wheel cylinder also moves with the hydraulic piston, so it is unlikely that it is hanging up if the hydraulic system is working, unless it moves farther with the mechancal system than with the mechanical... which I've never checked for. But if it does, it might be hanging up there instead of in the slot, AND you would probably have more pedal travel then previously, because the hydraulic piston would have to travel further to hit the mechanical piston.


warmly,
dave
Dave Braun

Dave, thanks for pointing out that the brake cylinders are supposed to "float". That seems to be the thing I was missing(though it should have been obvious to anyone else). They were not rusted. The automatic undercarriage oiling system precludes any rusting problems. :-) However, they were pretty gummy and would not travel freely. A little solvent freed them up considerably and they seem to be working much better. Also one side had the "lighter"spring on the wheel cylinder side and I put that right also. Thanks for the tip and thanks to everyone who took the time to reply. You guys are the best! Paul.
P.W. Lester

This thread was discussed on 22/03/2009

MG TD TF 1500 index

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