Rear brake question/problem

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GeoffBob
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Mon Feb 08, 2010 8:23 am

bumhole wrote:I assume the m/c pistons have seals around them? so what I am pressuming is that the rear piston seal is leaking slightly. Looking at geoffbob's animation it seems feasible for that to be the case???
Yes, they do have seals around them. Replacing the seals is always a cheap and useful place to start.

Most importantly, while you have the M/C apart you will have the opportunity to inspect the condition of the primary and secondary pistons and the bore of the M/C (can corrode due to the fact that brake fluid absorbs moisture), as well as inspect the condition of the springs (whose job it is to keep the secondary piston centered between the primary piston and end of the M/C while your foot is off the pedal). If these springs rust through and snap you can land yourself up in all kinds of trouble.
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"It is amazing how many drivers, even at the Formula-1 level, think that brakes are for slowing the car down." - Mario Andretti
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bumhole
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Mon Feb 08, 2010 7:39 pm

Are they reasonably easy to take apart Geoffbob? And safe to do so? bearing in mind I am a bit of a ham fisted plumber! Thanks
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GeoffBob
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Tue Feb 09, 2010 7:16 am

bumhole wrote:Are they reasonably easy to take apart Geoffbob? And safe to do so? bearing in mind I am a bit of a ham fisted plumber! Thanks
Oh yes, very easy. More annoying than anything else as you have to drain all the fluid from the reservoir and M/C before you can remove it, else it spills fluid everywhere. Chances are you'll have fluid everywhere when you disconnect the brake lines from the M/C anyway. Be sure to clean it up or it will eat your paintwork.

Be sure to keep all the parts in the correct order when you disassemble the M/C. Have a complete new set of seals handy before you start the job, available from you nearest motorfactor.

If in doubt on how to do the job, Haynes do a very nice book in their "TechBook" series that covers the A-Z of braking systems. The book is manufactured with all the quality of a telephone directory, so shouldn't be that expensive.

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"It is amazing how many drivers, even at the Formula-1 level, think that brakes are for slowing the car down." - Mario Andretti
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bumhole
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Tue Feb 09, 2010 9:21 am

:cool: Thanks
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bumhole
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Tue Feb 09, 2010 9:49 pm

Had a busy evening! I bought a new master cylinder today (sorry Geoffbob but it was a convienience thing and i'm fed up with pratting with the brakes now) Slapped it on and bled the brakes using my eezibleed thing. First off had no rear brakes at all, which nearly led me to find the nearest bit of rope and tree. Then decided to bleed the brakes the proper way with the missus! Got a cracking pedal now, tried my 1st gear in the air thing and bingo it stalls it easy. Took it for a drive and the brakes are ridiculous, considering aswell that they need bedding in. Thanks for all the help and comments! :cool:
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keri-WMS
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Wed Feb 10, 2010 12:47 am

Good stuff! Well done to both you and Geoffbob on this one - glad they are sorted (just wait until they are bedded in and warmed up)... :D
WMS E30 brake kits! (4-pot 280mm & 300mm front / 2-pot 290mm rear)

www.wms-brakes.co.uk / http://www.e30zone.net/modules.php?name ... c&t=209737
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GeoffBob
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Wed Feb 10, 2010 7:30 am

Fantastic stuff Bumhole! Well done to you. You must feel well chuffed now that you have that one sorted. :thumb:
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"It is amazing how many drivers, even at the Formula-1 level, think that brakes are for slowing the car down." - Mario Andretti
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Brianmoooore
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Wed Feb 10, 2010 8:56 am

bumhole wrote: Then decided to bleed the brakes the proper way with the missus!
See! They DO have their uses!
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daimlerman
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Wed Feb 10, 2010 2:17 pm

Brianmoooore wrote:
bumhole wrote: Then decided to bleed the brakes the proper way with the missus!
See! They DO have their uses!
Last time I bleeded brakes this way she chose to wear a very short skirt,the instuction...
'Get out of the seat and top up the master cylinder',kept both myself and the the guy next door very happy...
Youth is wasted on the young.
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keri-WMS
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Wed Feb 10, 2010 2:26 pm

daimlerman wrote:
Brianmoooore wrote:
bumhole wrote: Then decided to bleed the brakes the proper way with the missus!
See! They DO have their uses!
Last time I bleeded brakes this way she chose to wear a very short skirt,the instuction...
'Get out of the seat and top up the master cylinder',kept both myself and the the guy next door very happy...
:rolling:
WMS E30 brake kits! (4-pot 280mm & 300mm front / 2-pot 290mm rear)

www.wms-brakes.co.uk / http://www.e30zone.net/modules.php?name ... c&t=209737
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bumhole
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Wed Feb 10, 2010 9:43 pm

So..... Your missus was pumping the brakes and you were bleeding them, what was the neighbour doing other than glegging!!!! :D :D
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