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MG TD TF 1500 - Brake Cyliinder

With the cold weather on I have been going over my TD. I removed the front wheels drums. With someone gently pressing on the brakes I observed that the front wheel brake cylinders. The rear cylinder on each wheel pushes out on the brake shoe but the fronts do not move. The cylinders do not appear rusted. Should I see movement in both cylinders? If the cylinders are frozen can they be rebuilt?

Thanks so much to readers for your help on past issues. This has been a most valuable site.

J.F.
J FLESHMAN

My guess would be that either the gentle pressure is not enough to move both cylinders (the easiest one moves), the cylinders are frozen, or there is no brake fluid in the cylinders. bleeding the brakes doesn't necessarily get brake fluid into the cylinders as the bleeding port is before the cylinders.

Try locking down the cylinder that moves and see if the one that doesn't will move. If not, try disconnecting the brake line at the wheel, injecting the cylinder with fluid, and then bleeding. If it works, it was a lack of fluid. If not, you will have to remove the cylinder and inspect.

dave
Dave Braun

JF - I don't know how many miles you have on your brake cylinders or what kind of brake fluid you are using, but the cylinders can form a sticky, rust filled film inside the cylinders over time if you are using DOT 3 or 4 fluid. This film will cause the pistons to stick and not actuate and in accute cases not actuate at all when braking, causing a need for heavy pedal pressure to stop the car. Dave's suggestion of clamping the cylinders that are moving and seeing if the non moving ones move at all is a good starting point. If you have been driving the car and not had a problem with a spongy pedal, then I doubt that air in the cylinders is the problem, althoughdave is correct about bleeding the system does not necessarily get the air out of the cylinders. If the car is drivable, another check you can make for sticky cylinders is to drive about 10 or 15 mph on a gravel road and stomp on the brakes hard enough to lock them up, then check to see if all 4 corners are locking up at the ssame time. Good luck - Dave
David DuBois

Thanks guys. I locked down the cylinders with small c-clamps and had my wife gently press the brakes. Dave B was correct in that the added clamp made the front cylinder work. I did discover that a cylinder on one wheel was frozen. Dave B... I have been using DOT 3 but I dont know what the P.O. used. The frozen cylinder is so bound that I am going to have to spring for a new one.

Thanks for the help. It is greatly appreciated.
J FLESHMAN

J F
Go for it, you have done the difficult bit by removing the front drums. Now strip off all the front cylinders, don't forget to plug the hydraulic lines, then strip down each cylinder, clean out the crud - sometimes it's possible to recover the inner face of the cylinder with 00 grade steel wool - fit new seals- reassemble with a smear of red rubber grease on the piston.
When fitting the shoes adjust the snail cam till the shoes just rub - and after a few runs adjust the cams again.
On that frozen cylinder, be a bit brutal with it., you should be able to persuade it to open up. I've even known some folks attack them with a blowlamp, cos your gonna fit new seals anyway. Chances are it will be past it with pitted corosion.
Good Luck
Graham
TD/C 7822
G.D. Smith

And it is much easier to work/remove/install the front cylinders "after" the backing plate is removed...
gordon lawson - TD 27667

You could fabricate a tubing out of some old parts that allows you to pump in grease to hydraulic it apart.
D Clark

First of all, clamp all of the other cylinders, then really hammer the prake pedal standing on it with all your weight. This may push the piston out. If that doesn't work, use a 3/8 BSF bolt about 1/2 inch long, drill a hole through it lengthwise and install a zerk fitting at the head end. Install the bolt in the cylinder, heat the cylinder up with a heat gun or even a torch, then attach a greas gun as Dave C. (there are entirely too many Daves on this board) suggestes and pump away - the piston should pop right out.

This is a very common problem when using DOT 3 or 4 fluid. A small amount gets past the seals and on the piston. Because it will draw moisture, the piston starts to rust and the rust particles mix with the film of brake fluid and it gets sticky, causing the pistons to stick. Chances are the piston that did finally move, is just begining this process and should be cleaned, honed and new seals installed. This problem does not happen with silicone fluid because it doesn't draw moisture. That said, don't try to put silicone fluid into the system until you can disassemble everything and flush all the old fluid out with something like Brake Kleen, making sure all the brake lines are blown free of old fluid and the Brake Kleen and are completely dry. Replace all o f the seals and the flex hoses (any software that has been in contact with the old fluid). Only then can you put silicone fluid in the system. Good luck - Dave
David DuBois

Apple Hydraulics says they can resleeve the cylinders. I seem to remember reading about that in an old "Sacred Octagon". Is that a worthwhile option?

Terry
Terry Jacobs

I have just replaced all slave cylinders and also the Master. Master and the Front ones I managed to obtain resleaved ones with S/S sleaves on an exchange basis here in Sydney cost wise fronts A$36 each and the master was A$70 ....Rear cylinders not on an exchange basis cost A$50 each.
Good Luck
Richard
Richard Hyde

J.F. --- Resleeving is the way go. However the wheel cylinders are cast aluminum and Apple resleeves with brass. To me this is a recipe for disaster due to electrolytic corrosion. Brass and aluminum just don't get along together. Find a shop that resleeves with stainless steel! I can provide the address of a shop in Massachusits(sp) that does them in SS. if you need it.
Think Spring,

Bob
R. K. (Bob) Jeffers

I used White Post a couple of months ago to re- sleeve with stainless the master and all brake cylinders. They actually do the whole thing. You get them back ready to install. Lifetime warranty. Pricey at $650 but after checking those who just re- sleeve and adding parts "kits" cost it was reasonable.
D (too many Dave's) Clark
D Clark

New Repro Moss rear cylinders are around $44, so I would just get new ones for the back. My brass sleeved front cylinders have been working fine for at least 10 years. George
George Butz

This thread was discussed between 18/01/2006 and 19/01/2006

MG TD TF 1500 index

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