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MG MGA - Help with Brake cyl. Identification

Need some advice here. I put new brake wheel cylinders all the way around, (1500 4 wheel drum brakes). What I didnt realize is that there is a difference in L/H and R/H parts up front. I dunno if I put them in the right positions. They all went in with no issues. I checked MGAGURU, but couldn't find anything on this topic.

After install and bleeding, I have very little stopping power, but it improves a little if I pump the pedal. Could this be from wrong cylinders in the wrong position?
Here's my question. How can I tell which is which?

Your expertise is appreciated.
Judd Irland

Did you adjust the brake shoes after replacing the cylinders. If you are sure there is no air in the system, show adjustment should be the next step.
dominic clancy

The brake backing plates are handed and must be installed on correct side of the car. See pictures here:
Barney Gaylord

I did adjust the shoes after and bled the brakes. I think I mis spoke. What I need to know is this:

I bought new brake cyclinders

MM Part 180-656 quantity 2
MM part 180-641 quantity 2

Two lefts and two rights.

Does the left drum get one L and one R or both lefts.

The rears are the same piston so no worries there.
Judd Irland


This thread is in danger of dying without giving you an answer, so here goes!

On the left-hand side of the car you put both LH cylinders and on the right-hand side of the car you put both RH cylinders. As always, LHS & RHS are defined by facing in the same direction as the car.

As far as identifying the cylinders is concerned, do they have any numbers in the casting? If so, you could ask the supplier to confirm which is which by comparing their boxed stock.

New brake shoes are never up to much until they have bedded in but at the front you have twin leading shoes, which means they ought to be biting fairly soon. If your drums have worn oversize, their radius is bigger than the shoes, which means they lose efficiency.Did you use a spray brake cleaner before doing the work? I normally use it on the inside of the drum then wipe with a very clean cloth to make sure there's no contamination.

After fitting new shoes I always give the pedal a few good shoves to centre the shoes in the drum. Then I readjust again to take up any resulting slack. Wind the adjuster up until the wheel is locked, then back it one click. The wheel should free up.

I'm a bit worried about the pumping. That suggests your real problem may be air in the system. I swear by the one-man bleeding kits that use tyre air pressure (e.g. Eezibleed) otherwise its a PITA to get the air out the "old-fashioned" way.

Malcolm Eades

Thanks Malcolm,
Turns out that due to the design, (offset bolt-hole), you cannot put a RH cyl on a LH plate and vice versa.

I have bled the system twice now (the old way)and still "feel" like there is air in there. I pulled the Master cylinder today. Rebuilding it tomorrow.

I did put new shoes on the front. Had to click the adjusters 4 or 5 clicks to lock the drum, I brought them back one click. This left them dragging more than a little, so I backed em off another click. Maybe I should have left them dragging?

All of this makes me think my drums might be too worn.
Judd Irland

This thread was discussed between 31/01/2011 and 07/02/2011

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