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Brake problem on 924-advice please......
https://forums.tipec.net/viewtopic.php?f=25&t=17153		 Page 1 of 1
Author:  John W [ Sun Mar 02, 2014 2:35 pm ]
Post subject:  Brake problem on 924-advice please......
Guys

I have replaced the rebuilt/resealed front calipers on my 924 auto, new hoses etc. Bleeding the brakes this morning but cannot get a pedal. There doesn't seem to be air in the fluid, there are no leaks and pumping the pedal repeatedly produces feel, but as soon as I stop pumping, all pressure is lost.

I got Mrs W to pump the pedal whilst watching the master cylinder reservoir. Nothing happens during the pumping to build pressure, but as soon as she stopped, fluid shot upwards from the bottom of the front of the reservoir hitting the top, then pressure is lost.

Am I right in thinking this is master cylinder seals? :(

Thanks
Author:  tr7v8 [ Sun Mar 02, 2014 3:07 pm ]
Post subject:  Re: Brake problem on 924-advice please......
Yup the master is knackered! Sometimes when this happens you get bubbles make into the reservoir.
One thing I keep repeating is that if you're manually bleeding brakes or clutch. A. suck out fluid from the reservoir BEFORE you start bleeding, it reduces the amount of old fluid you pump through the seals, which is probably 60% crud!
B. And very important never pump the full stroke of the pedal when bleeding. The master only uses around 30-45% of its travel in normal use. By pumping full stroke you push the seals over rough areas that they never run over in normal use.
This is why perfectly good masters die after brake fluid changes.
Author:  Althejazzman [ Sun Mar 02, 2014 3:09 pm ]
Post subject:  Re: Brake problem on 924-advice please......
John W wrote:
Am I right in thinking this is master cylinder seals? :(


Logically I would assume the same. Having just refurbished all 4 corners of the brakes on my 924, I had no such trouble, and the master cylinder is the only thing I didn't touch.

Additionally, I use the Gunson Eezibleed kit, which purely by chance, means that I didn't risk the problems that Jim describes.
Author:  John W [ Sun Mar 02, 2014 3:44 pm ]
Post subject:  Re: Brake problem on 924-advice please......
Thanks guys-I think you've confirmed my suspicions.
Next question, can I get one from anywhere other than Porsche? (Approx cost £220)
Author:  tr7v8 [ Sun Mar 02, 2014 3:50 pm ]
Post subject:  Re: Brake problem on 924-advice please......
I must get a recording done of this! I'd shop around JMG, Berlyn, ProMax, Euro car parts, German Swedish & French etc.
Author:  John W [ Sun Mar 02, 2014 3:57 pm ]
Post subject:  Re: Brake problem on 924-advice please......
tr7v8 wrote:
I must get a recording done of this! I'd shop around JMG, Berlyn, ProMax, Euro car parts, German Swedish & French etc.


Exactly what I was intending to do-just wondering if anyone had a specific recommendation..... :?
Author:  John W [ Tue Mar 04, 2014 4:51 pm ]
Post subject:  Re: Brake problem on 924-advice please......
Seems that they are Porsche only. Luckily, I was sitting down when they told me it will cost £220 and take a week to get from Germany..... :shock:
Author:  timmyturtle [ Tue Mar 04, 2014 10:57 pm ]
Post subject:  Re: Brake problem on 924-advice please......
Not sure about autos spec but there are loads on ebay
Author:  jmgarage [ Wed Mar 05, 2014 12:25 am ]
Post subject:  Re: Brake problem on 924-advice please......
Hmmm.. I should be able to get one, it could be ATE have been told to stop supplying them in the aftermarket by Porsche, but I should be able to make a call and get the same one as you get in a Porsche box, but without the Porsche box if you are still looking for an alternative to Porsche.
Author:  AlpineTurbo [ Wed Mar 05, 2014 7:25 am ]
Post subject:  Re: Brake problem on 924-advice please......
Hopefully you may find a cheaper supplier. That price is a little cheaper than the 944 cylinders for sure!
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