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MG Midget and Sprite Technical - Rear Brake Cylinders - Junk

My beautiful assistant and I were bleeding the brakes today. We were reaching the last section, the front right caliper and all was going swimmingly.

Kate was pumping the pedal and said that it was starting to go hard. Great!

A wee bit more bleeding for good measure, then she says it's going soft again. Hmmm... "Hang on, just pump it a little... no? nothing? erm..."

Oh crap! There was a huge puddle of brake fluid under one of the back wheels. The (new) rear cylinder had blown it's seals and all the fluid had been spurting out at high pressure into the drum and out onto the floor.

WTF?!? This is a new cylinder and couldn't even survive being bled! How can people be selling such junk. Slightly fear of ever taking the car on the road if the brakes are going to explode by the end of the street!

Are all rear cylinders and junk as each other?

Urgh... hacked off.

Malcolm
M Le Chevalier

Nicely written allegory, Malcolm.
Nick and Cherry Scoop

Not all Malc, I had two last year from Sussex and aOK. Done 6500 miles with them. No problems.

Keep at it, can't be far to go now then?

Cheers, Dave
Dave Squire

Take them back, it could be a faulty batch that could be traced.
j hall

It may not be a faulty cylinder. If you attempt to bleed them before adjusting the brakes it is possible that there is so much free travel in the cylinder, that the piston pops out the end and twists enough in the bore to let the fluid out. Once the fluid is out, it is quite usual for your Attractive Assistant to find that however much she goes on pumping, it will go soft.
Guy Weller

One problem I've noticed with repo cylinders is that the bleed screw threads are not always machined deep enough, sometimes with only a couple of threads engaged. Same goes for MGBs, Minis etc with the same style cylinders.
I have found the genuine ones (now made by Caparo) to be properly machined in this respect
R.J Mogford

Hey... Maybe you are right Guy (as ever) and it is my fault and I have jumped to the wrong conclusion. The brakes were adjusted to some degree but it was a while back and by no means a "finished" job...

Will investigate tomorrow morning. Would I have badgered the cylinder do you think?

Losing my enthusiasm for all things MG and it's showing up as more and more frustrating cock ups. Ho hum... Just keep swimming!!

Malcolm
M Le Chevalier

Wasn't being critical of your mechanical prowess, Malcom. But it is a possibility - I know 'cos I bin there don that! Mind you, they have to be pretty far out of adjustment for it to happen!
Guy Weller

Its OK Guy, understand you weren't being critical. Just kicking myself a bit, because you might be right. (Well, I will see tomorrow).

As I said, just getting a bit frustrated and it is leading to mistakes and more work! Feeling slightly pressured to get the thing moving!

Malc.
M Le Chevalier

And what mechanical prowess?! Ha ha. Massive leap into the unknown! Stripping everything was so much easier :-D

Mal
M Le Chevalier

Actually I think I probably meant to say Engineering prowess. Mechanical prowess would be something different and would imply that you were some sort of Cyborg.
Guy Weller

Mal,

Unless you're under pressure to save money on the storage, shut the door and walk away for another few weeks! Come back with a clear head. I know you've just had a couple of weeks off and want it finished for the summer week in Aberdeen (have you missed it yet ;) ) but I have learnt from bitter experience that you can get too wrapped up in pushing on and it's easy to forget things which end up biting back.

Take a break, think about what you're doing and all the things that could possibly impact on it and check them all again.... (that's easy for me to say from a distance!!)

You've got until the 13th July when I expect to see you at the Glamis Classic event ;)

Best of....

MGmike

M McAndrew

Here's a big surprise... Guy was right! My cock up! I withdraw my rantings and I'm off for a hearty brunch of humble pie. Mmmm pie!

Malcolm
M Le Chevalier

I hope you're both having custard with that pie Malcolm


I bet most of us have had some of that pie ourselves

It's good news if that is all it is

Usually the pistons will slide back in without damaging the sealing faces*, fingers crossed mate.

*the most likely thing to damage a piston seal that slides out is old dirt and/or rust

shouldn't be a problem with new ones
bill l

FWIW,

My AHS failed it's MOT on rear brake imbalance, the nearside brake cylinder was leaking fluid.

I purchased a new cylinder from AHSpares in Southam and it came with "AP' on the bleed screw cover and was distinctly better quality than the one that came off, the new cylinder had a 5/16 hex on the bleed screw whereas the old cylinder had a 7mm hex.

I think the old cylinders came from Ron Hopkinson in Derby in 1992.

Just for reference really
Malc Gilliver

This thread was discussed between 01/06/2014 and 03/06/2014

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.