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Brakes
Aug 1, 2011 20:33:19 GMT
Post by Penguin45 on Aug 1, 2011 20:33:19 GMT
Problems...... Need some help rather urgently.
This started off as trying to cure a "long pedal" on the car. The upshot is that I now have new cunifer lines and flexies to the front calipers, one of which also has new seals in it. Bled it off, pedal still "long". Bled the entire system - got some air out of the longest run to the rear. Fluid absolutely filthy, so we've put a lot through to try and clean things up.
Now: engine off - good, stable, short pedal. Engine on and the pedal lengthens and will ultimately drop to the floor. There is no evidence of fluid leakage anywhere and the level in the master cylinder appears stable. Turn engine off, pedal is lower than before, but will pump up.
I suspect the servo (Which is typical - the one major component I haven't got a spare for) but know little about them or their workings.
Supposed to be heading for Cornwall on Friday, so need a speedy resolution.
Any ideas welcome.
Chris,
P45.
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Brakes
Aug 1, 2011 21:18:26 GMT
Post by tommydp on Aug 1, 2011 21:18:26 GMT
Hi, Chris! Do you have the Powerstop or the Super- vac, which has the master cylinder mounted on the servo? It seems most UK cars has the Powerstop. All Crabs here had the Supervac, from about 68.
I once had some real trouble with a Powerstop unit, that car had been stood for some years, however. I seem to recall it suffered from a low pedal too, and I finally made it by bleeding all brakes while engine was running and servo connected, a lot of filth came out. Could be worth a try.
Good luck!
Regards, Tommy
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Brakes
Aug 2, 2011 0:09:06 GMT
Post by dave1800 on Aug 2, 2011 0:09:06 GMT
Hi Chris
Do what Tommy suggests; also sometimes the ball in the pressure regulating valve can stick and cause odd effects when bleeding which can benefit from bouncing the car to release it. As you have had a lot of dirt in your system it does sound as though there have been rubber seals and hoses deteriorating for a while. I would be tempted to change the rear hoses as well - if they are contaminating the fluid it can only cause more trouble.
Unfortunately if you bleed a system that hasn't been bled for a long time, or in which the seals are deteriorating then the bleeding allows further piston travel than normally encountered and can causes a seal to fail. If you canot get a firm pedal with the engine on after all the bleeding, I would suggest that it is an internal servo fault with a seal.
If you have a Mk2B servo there may still be an overhaul kit available, you need to cut the outside crimped banjo clip and the kit includes a replacement with a worm drive screw like a large jubilee clip. It's a fit fiddly but just like rebuilding a master cylinder but with a large rubber diaphragm and needs to be partially reassembled with the engine running if I recall. It's a long time since I did one but it wasn't too bad. If you do rebuild I would modify the short rubber right angled vaccum pipe that comes out of the servo to join the steel pipe which often splits as designed but can only be properly replaced from inside the servo.
A a last resort as you need to get to Cornwall this week, you could take the servo out of the system. As long as your calipers are good and your right leg is strong then this would be the safest option. But try it first to see how you feel. I have driven a car for about 100 miles like this, it wasn't too bad but I guess you will probably have a laden car.
Good luck
regards
David
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Brakes
Aug 3, 2011 8:48:22 GMT
Post by Penguin45 on Aug 3, 2011 8:48:22 GMT
Managed to aquire a MkIIB servo yesterday - it's loosely mounted and new pipework has been made up and fitted.
I've done an intitial bleed through - my mate Ady is coming down this evening and we'll finish it all off and test it.
Fingers crossed.......
Chris.
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Brakes
Aug 3, 2011 8:58:01 GMT
Post by tommydp on Aug 3, 2011 8:58:01 GMT
Managed to aquire a MkIIB servo yesterday - it's loosely mounted and new pipework has been made up and fitted. I've done an intitial bleed through - my mate Ady is coming down this evening and we'll finish it all off and test it. Fingers crossed....... Chris. Great, fingers crossed here too:-) Good luck:-) Regards, Tommy |
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Brakes
Aug 3, 2011 23:54:40 GMT
Post by Penguin45 on Aug 3, 2011 23:54:40 GMT
'Tis done and a titanic struggle it became..... Bolted everything up properly, did a basic bleed of the system and went for a spin. Good to start with, then the pedal dropped. It has taken three lots of bleeding and the help of my friend Ady to get it right. I've now got a nice high, quite sharp pedal and the replacement servo is doing its job.  Servo in place with new pipework. Ady came down with Teri (Mrs Ady) - I suspect that she lost interest in our activities quite quickly. This is my noticeboard in the garage:  All good fun. Anyway, no compromises with the brakes - safety first. Chris. |
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