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MG TD TF 1500 - Rear Brake Cylinder

Good morning, I am replacing the rear brake cylinder on my 54 TF. Do they come pre-oilied or do I need to take it a part and oil it w/brake fluid? It looks pre-oiled.
Thanks
TRH Hammond

Todd,
I always use silicone fluid, and I always soak the cups in fluid before I install them. I also coat the pistons in synthetic brake caliper crease. Moss sells a red Rubber brake parts grease, I’ve had a tub for years. I’ve used that too.
Be well,
David
D. Sander

As always, I appreciate your knowledge an guidance! Thanks David.
TRH Hammond

By silicone fluid.... Do you mean silicone brake fluid??? Can you mix silicone with Dot 4 brake fluid????
How do you coat the pistons.... take new cylinder apart???
I am also doing my 54 TF and this info is very timely... THANKS.
I was planning to fill the new cylinders before install, however was waiting for it to arrive...so I can see how to do that.
Charles Branick

If you have dismantled or are fitting new wheel cylinders it is a very good idea to push the pistons in fully with the bleed screw removed. You should then adjust the shoes so they are locked solid before bleeding. Even better is to clamp the pistons fully home with G clamps.if you don't do this there will be a bubble of air behind the piston. As you bleed the brakes the fluid can compress the bubble and fluid will flow over this from the inlet to the nipple without purging the air.

Jan T
J Targosz


I am presently replacing my TD rear brake cylinders. I don't believe I have ever fully gotten the air out of them. I would bleed all the brakes, get a high hard pedal and come back in a few days and have a low soft pedal. The brakes were installed 36 years ago but only have 500 miles on they. They have only see DOT-5 fluid.
I have replaced the MC, which was leaking, and I have Discs on the front.

I THINK one of the rears may have been leaking around the emergency brake lever. The boot seemed to be wet, but that might have come from a (potential) wheel seal leak.

Before Installing, this time, I injected some DOT-5 into the cylinder using a 1 ml syringe, many times. I pumped the E-Brake lever and kept filling until I believed all the air was expelled, and I could see the fluid rise and fall as I operated the E-Brake lever. The brake is off the car and the springs are keeping the cylinder closed.

Just a suggestion.

Jim B.
JA Benjamin

Hi Jim,

Since you have discs fitted to the front it is even more important that you push all the hydraulic pistons fully home, with nipples open, before starting to bleed. The caliper bores are large and can hold a large bubble of air. Often the fluid inlet and bleed nipple are next to each other and the fluid simply goes from one to the other without purging the air. If you buy new calipers or cylinders the pistons will normally be fully pushed in, the problem arises if you rebuild them yourself and only insert them far enough to get the shoes or pads fitted. I woul try bleeding with all pistons firmly clamped home.

Jan T
J Targosz

This thread was discussed between 09/05/2020 and 15/05/2020

MG TD TF 1500 index

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