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MG TD TF 1500 - Master Cylinder Install

I installed the new mc and I used the clevis rod from the old mc still attached to the brake arm. I noted I had to depress the cylinder slightly to move the new mc forward enough for the side bolt holes to line up with the frame. This means there is always some depression of the cylinder when bolted in place. Is this normal, or is the old rod too long for the new mc? Or, does it matter if the cylinder is depressed slightly with the brake pedal at rest?

TIA

Larry
L Karpman

Shouldn't matter Larry. That's exactly the way I install them. To double check, put the car on jack stands and make sure eash wheel is free. While on the stands you can adjust the brakes.

warmly,
dave
Dave Braun

Larry.
You must have pedal free movement. I suggest adjusting the rod until you have about 1/2" free pedal before you feel the take-up. If you do not have free play you most likely will have brakes that stay locked on.This is because the piston and cup do not clear the small holes (2) in the reservoir to cylinder and allow the brake fluid to return to the reservoir.
Sandy
SANDY SANDERS

Thanks Dave/Sandy. I have free pedal and good brakes. Although I do have more bleeding to do today.

Cheers

Larry
L Karpman

While I do have free play, the brakes are quite stiff. Much stiffer than with the old leaking mc. The total pedal travel before stopping is only about 1 -1 1/2". After that the pedal stops. I don't think this is normal, but I don't have anything to compare to and I can't find anything in the WSM to address this. Any info appreciated.

Larry
L Karpman

Larry, are you describing the 1 and 1/2 inches of pedal when you press it down by hand, or when driving and getting full braking?

Dallas
D C Congleton

Full braking Dallas. I have about 3/8 - 1/2 " free play with my fingers.

Larry
L Karpman

Assuming the replacement brake master cylinder is the same bore and stroke as the original (you mentioned some difference?)then I would re-check the brake adjustments. You may have to back off a click- if you can't tell by the amount of drag, then a good method is to use one of the now cheap infra red heat guns and check all your drums before, and after a drive with no (or very little) braking. If the drums heat up it will tell you if you have dragging brakes. Repeat after some braking and the comparison of each drum will tell you if they are relatively equally adjusted.

I don't remember if you had replaced the brake shoes, but if you did and only have moderate drag , then just let them "run in " for a few miles and they will wear them selves to the shape of the drum, and your pedal will increase.


ALSO I will remind you to recheck that the emergency brake is fully released ;^)

Dallas


D C Congleton

Thanks Dallas. So what is a "normal amount" range of pedal movement to full lock? I assume by your answer that 1 1/2" is too little. The old mc was aftermarket, and the new one is AP-Lockheed.

I did adjust the brakes today. 3 of the wheels adjusted normally, but the left front would not lock with the adjusters full clockwise. The wheel would drag, but that's all. I had suspected a sticking wheel cylinder in the right front before, as the car will sometimes pull left while braking. I was surprised that the left front had the problem. I did back off an extra click on each wheel, but it made no difference on any wheel.

I assume, as I am out of adjustment on the left front, that the brake drum is worn too large. I know the O'Connor adjusters with the shims welded on are for the rear brakes only. So, what are your thoughts here.

TIA

Larry
L Karpman

Thanks Dallas. So what is a "normal amount" range of pedal movement to full lock? I assume by your answer that 1 1/2" is too little. The old mc was aftermarket, and the new one is AP-Lockheed.

I did adjust the brakes today. 3 of the wheels adjusted normally, but the left front would not lock with the adjusters full clockwise. The wheel would drag, but that's all. I had suspected a sticking wheel cylinder in the right front before, as the car will sometimes pull left while braking. I was surprised that the left front had the problem. I did back off an extra click on each wheel

I assume, as I am out of adjustment on the left front, that the brake drum is worn too large. I know the O'Connor adjusters with the shims welded on are for the rear brakes only. So, what are your thoughts here.

TIA

Larry
L Karpman

Larry, I'm not sure what ''normal" travel is, but it was you stating a concern about having only 1 1/2 inch.

I was replying to your question in the light that if you have the brakes too tight already, the pedal travel will be less, and if the brakes are worn and too loose, the pedal travel will be excessive.

I would say that your reported pedal travel of 3/8 to 1/2 inch is not "normal" and as Sandy pointed out, you need 1/2 inch free play to allow the piston to clear the return holes. You may be still blocking these partially.

My brakes are generally full on by 1/2 pedal travel. If much more than that, I adjust the brakes.

D C Congleton

Thanks Dallas. You may be correct. Just to be clear, I have 3/8" "free play," and now after driving a bit about 2" of total pedal travel.

I tried, to no avail, to adjust the mc piston rod with the mc still in place, I was able to get a wrench on the locking nut and loosen it a bit, but no luck getting a wrench on the larger nut to screw the rod further forward. Of course working through the side of the pedal box is no joy anyway. Say, what is the little stop at the rear inboard side of the pedal box? It is held in by a nut on the bottom outside of the box. If I remove this temporarily, I may have success in grabbing the larger nut. Although I have a Datsun 5-speed which I believe is wider at this point than the standard gearbox, which in turn restricts the wrench.

In any case, if I have to remove and reinstall the mc to do this, I will.

Thanks for the info.

Larry
L Karpman

"Say, what is the little stop at the rear inboard side of the pedal box? It is held in by a nut on the bottom outside of the box."

That is a stop for the clutch to prevent it from going too far and damaging the throw out bearing. Cheers - Dave
David DuBois

I fixed my problem today. I was able to adjust the pushrod forward giving a minimum of 1/2" free play. I now have more pedal movement when braking, and the car stops well. I'm going to readjust the brakes "again" today with the new pushrod position. I still have a slight pulling left on hard stops, so I'm hoping to solve that. If readjustment doesn't help, than as some have said, I have either worn brake shoes on that side, a worn brake drum, or defective piston(s).

Thanks again to all.

Larry
L Karpman

Larry, if you have one of the brake masks with the piece welded on, try it on the left front brake. Start with one on the front adjuster. If you don't have one, do the old penny or dime trick.
D C Congleton

I've read about the old penny trick, but never having fooled with wheel cylinders before, I'm unsure how to put the penny between the mask and piston. Can you depress the piston by hand while installed and slide the penny in? A description otherwise would be great.

Thanks again

Larry
L Karpman

This thread was discussed between 19/09/2009 and 20/09/2009

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.