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MG MGA - Master cylinder rubber replacement question

I'm replacing the rubbers in my master cylinder and perplexed as to how to remove the secondary cup from the piston to replace it. See photo attached. Can someone who has done this before please enlighten me? Many thanks. Tim MGA Coupe 1600 Mk 1


TJ Prime

2 methods
If you want to re-use it, make a small tube adapter to your vacuum and suck it out.
If its trash, glue a self tapper to a stick and spear it.
3 methods!
you could M/T the reservoir and blow with air from the discharge.
Art Pearse

If they don't pull off easily I just cut them. Lots of lubricant on the replacements to ease them on. If it's not brake fluid you use then make sure they are thoroughly rinsed when in place.

Steve
Steve Gyles

Just roll them over the end of the piston with your thumbs and then settle it in the groove. It will stretch enough and not be damaged
Dominic Clancy

Thanks all. I've managed to remove the rubber from one and it seems that putting the new one on is more challenging! I'll persevere using brake fluid to hopefully make the rubber pliable. You need very strong fingers! Tim
TJ Prime

Make sure you have the AP Caparo seals. Some suppliers of seals don't fit the groove in the piston properly and bulge making the piston a tight fit in the bore. Barney's site mentions this and I did some investigation in 2014 with different seals when I had a problem. Its in the archive under master cylinder holding pressure.
John Francis

OOps I misread the question! Thought you had the main washer stuck in the cylinder
Art Pearse

It happened to me when I inserted the cup before the spring! Duh.
Art Pearse

Thanks John. I'll check. No problem Art. I was a bit perplexed by your response! Cheers. Tim
TJ Prime

Thanks to this forum I have replaced the rubbers in the master cylinder. Took the M/C off the car to do it in the end. Put it back on the car this morning and hooked up the Ezibleed to bleed brakes and clutch (I've done it several times before) and frustrated to find that I couldn't get a flow from first the rear nearside nipple or the rear offside nipple. An initial dribble from each one but that was all. I ran out of time and so have put all the wheels back on to sort out another day. Any thoughts on what the issue might be please? Blocked brake line beyond the M/C or a M/C issue? In hindsight I should probably have pushed compressed air down the M/C brake port when I had it off the car and empty.
TJ Prime

Same as TJ I had the same problem with the Eziybleed. I had used it a few times before with no issue. The fluid just flows out nicely, and no dribbling at all. I tried another bleed using the E/Zeebleed again and, as what happened to TJ, only a dribble came out of the nipples.I have now decided to bleed the entire system again but using the conventional method of having someone pushing the pedal and opening the nipples.
Since I have installed a brake servo on the car, my pedal goes down a little more than half way down its travel when braking. I suspect that a lot of air is still in the system, and a good conventional bleed will push all the air out completely. I shall wait and see. BTW no fluid leaks in sight.

Frank
F. Camilleri

Frank, how effective is the servo vs standard?
Art
Art Pearse

No difference at all in braking capacity, just less pedal force required. And of course some possible additional maintenance issues in the future.
barneymg

This thread was discussed between 07/03/2018 and 15/03/2018

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This thread is from the archive. The Live MG MGA BBS is active now.