bmwe21.net forums

I would be interested to receive any advice on brake booster replacement and/ or refurbishment. I assume that the booster is the same across all models for a given year ? Also most economic way of getting from a broken booster to a working booster.

Yea they are all the same.

What are the symptoms of your problem? Could be your master is due a replacement?

I've been trying to assess the brake problem today and can only conclude that the brake pedal is really heavy to operate and the pedal also fades out ( pedal slowly hits the deck) within a couple of seconds, which renders the braking ability in the atrocious section. I initially thought it was the booster, beleiving the brakes were just heavy to operate but I also have now noticed the fading pedal as well. Could this combination of symptoms point to the master cylinder, I have never experienced a heavy brake due to a master cylinder fault, although I really am no expert in these matters and would appreciate any thoughts. Gary

Heavy brake pedal could be a leaky vacuum line or one way valve to the booster. I've never heard of anyone breaking a booster before. The master is ridiculously expensive. Buy the rebuild kit first it's defo worth a shot before you dump 150 quid on a new one.

You are not pumping the brake with the engine off are you?

No, whilst using the brakes, moving and with engine running, also a good vacuum at the booster and the one way valve is also doing its job. I think I have two faults, I think the booster is not providing much or any assistance to the hydraulic system and I also think that the master cylinders piston/ seals are failing, causing the pedal to drop after operating the pedal for a few seconds. The car has refurbished calipers on the front, which leads me to believe there was a problem with the brakes before I bought it ?

Could very well be. I think I'd remove the brake master, quite a chance it is leaking, inside the booster. Clean it up, give the master an overhaul and you might be fine again.

Jeroen wrote:Could very well be. I think I'd remove the brake master, quite a chance it is leaking, inside the booster. Clean it up, give the master an overhaul and you might be fine again.

Do you know what Jeroen, that's a damn good idea, I have wasted time thinking about the problem, when I could have removed the master cylinder and either identified or eliminated a problem with it. Will do exactly that and see what happens. Cheers, Gary

Another question, where is the best place to get a brake master cylinder repair kit from, tried Gsf and euro parts and neither do them for the e21.

see here

http://brakeparts.co.uk/#page=parts&pag ... 20+%26+323

crap just noticed they don't do the rebuild kit on the online store - try calling them..
failing that - its the BMW dealer?

Thanks for your input and help guys. I have now spoken to Fritzbits in Taunton and they are going to refurbish the master cylinder for me with a stainless bore/ sleeve and new rubbers etc. Needless to say, I have removed the master cylinder this evening and it is currently packaged up, ready for dispatch to Fritzbits. I'm thinking, get the master cylinder sorted and see how the brakes perform when it's reinstalled, I should be able to tell whether the booster is performing correctly, once I can rely on the master cylinder. Plan !

Good to hear. Was the MC leaking indeed?

No, I'm afraid it wasn't Jeroen, all as dry as a bone and no loss of fluid either. I spoke to Richard at Fritzbits and explained that I felt that I had two problems, a fading pedal and also a heavy pedal. I figured that if I get a master cylinder refurb then I can eliminate that from any potential problem that still exists with the brakes, once It is reinstalled. To be honest, I don't mind refurbishing everything on the braking system, if I have to, piece of mind.

Funny!

Just wondering how much it's costing for a m/c recondition?

Max, I haven't had the bill yet, but Fritzbits said it would be about a hundred quid'ish. I will post the final cost and result for any interested members. Do you need a refurb mate ?