Brake pressure
Turbo Mini Forums

Okay, I know it doesn't really have to do with turbo or efi, but I'm hoping someone on here can help. I had some work done on my mini(I didn't have the tools) and the shop I took it to was supposed to bleed my brakes to give me pressure back. As is I have to pump the pedal to get pressure. The master cylinder is new, but it was installed before I bought the car. Is it possible that it's the wrong master cylinder? I have a 1978 Mini 850, if that helps. Any input would be aprreciated!

-James

I think it's safe to say that if it 'fits' the bolts, then the master cylinder is close enough that you shouldn't have to pump the brakes. Basically all masters that will fit the bolts are of bore sizes that will 'function' without pumping.

IE it sounds like you need the brakes bleeding. If you have to pump brakes, you have air in the system (or a faulty component) - not a 'wrong' sized master cylinder.

Edited by turbodave16v on 28th Jul, 2009.

Okay. So there wasn't a check valve or some such for the disc brake minis? That's the only thing that made any sense.

-James

First thing i'd check in this case would be Rear wheel cylinders.

Get the drums off, and with a small screw driver just lift one part of the rubber boot up. If there is fluid in either of the boots on the wheel cylinders then they need replacing.

In my experience that is the most common fault under these symptoms.

I checked that, thinking the same thing, and there's no fluid in them. They're pretty much brand new too, maybe 1 year old... But no fluid either way.

-James

Are the brakes adjusted correctly? If not they will require pumping up as the piston in the cylinder has to travel further than one push of the pedal.

Paul

I seriously doubt it!

I'll have to check. These are the things that made sense to me, as I cannot recall a change in the actual cylinder itself other than bore as far as construction.

-James

check what paul has suggested then bleed them and be confident you have all the air out. if that doesnt make any difference then get some pipe clamps (proper pipe clamps not vice grips) and clamp the brakes off one by one to see if pedal improves, maybe try and clamp both rear pipes at the same time etc. if you clamp all 4 off and pedal still reqs pumping then there either air in there still or a knackered master cylinder. oh or a leak.

no longer a series, but still 1.3 turbo.

you could also try a long pice of 3 or 4mm transparent tubing from the bleed nipple back to the resovoir, with the nipple open a full turn pump the pedal fairly quickly, you will be able to see the fluid travel in the pipe,

Were the brakes ok before?

Have you build disk brakes on your car?
If yes, (probably too obvious, but..)
Are the front calipers on the correct side; as in does it have the bleeding nipples at the top?

Ask me how I know this can result in same issue... :$

Dazed and Confused....

I'll have to try you're guys suggestions. I don't have disc brakes yet though. It's still drum all around. It might be a week or so, but I'll let you know how it goes. I do need to ask you how you know about having the calipers on the wrong side....

Ehm, err, blush..

Maybe I shouldn't, got laughed at too many times already for this..

Dazed and Confused....

Being drums all round, Im sure its adjustment.

Have you ever had them adjusted?

Paul

I seriously doubt it!

They were supposedly just adjusted, and bled multiple times, supposedly I say again. I bled them last year when I put in new hub bearings, and got solid pressure out of them.

you could try adjusting them right up tight, prob one at a time, to see if you then get a solid pedal. just to see if it is infact possible to get a pedal at all.
my old drums backed themselves off under pressure, resulting in lots of head scratching (read screaming and shouting)

Okay, now, not to sound daft, but I don't have a manual to look at, but is the adjustment outside? It's that little square little adjuster on the outside right? Which direction do I turn it to tighten, which to loosen?

-James

thats the one,

righty tighty..
lefty loosey...

regards
colin

awesome. Now, only if I didn't have my cylinder head to worry about...

-James