Jim58 Posted January 5, 2012 Report Share Posted January 5, 2012 Hi Guys, Some advice on brakes would be appreciated. I've just replaced the entire brakes system on my 1971 CP. This included servo, master cylinder, calipers, disks and all pipework. I've bled the system a few times which appears to be air free but the brakes are still very spongy with not a lot of stopping power. There is a lot of travel in the brake pedal. Any pointers would be great. Cheers, Jim Quote Link to post Share on other sites
SteveF Posted January 5, 2012 Report Share Posted January 5, 2012 A trick I`ve used when everything is new; you will need an assistant standing by to crack open the bleed valve. With the bleed valve shut and the system full of fluid pump the brake pedal like crazy 6-10 times, on the last stroke hold it down and get your assistant to crack open the valve whilst catching the resultant fluid ejection in a suitable container, the pedal will sink to the floor and your assistant should retighten the bleed valve. Check there is sufficient fluid in the master cylinder, top up if required and try the brakes. If at first it doesn`t work try again, sometimes it takes two or three attempts to expel all the air bubbles. I presume you are using new fluid? it`s the one thing you didn`t mention! Effectively you are pressurising the whole system whilst pumping the brake pedal, be warned the fluid can (and will) come out with some force! Hope this helps, Steve. Quote Link to post Share on other sites
DOG_MORGAN Posted January 5, 2012 Report Share Posted January 5, 2012 jim whats your tele no thanks billy Quote Link to post Share on other sites
Jim58 Posted January 5, 2012 Author Report Share Posted January 5, 2012 Hi Steve that's something I haven't tried. BTW I am using new DOT 4 fluid. Do you do this per bleed nipple or is only required once on any nipple? Billy I've sent you a message with my number. Thanks Guys Quote Link to post Share on other sites
Rob72CP Posted January 5, 2012 Report Share Posted January 5, 2012 (edited) Hi, I presume that you have adjusted the rear drum brakes as if the adjusters are not set correctly this will create a lot of "slack" in the system. Cheers, Rob Edited January 5, 2012 by Rob72CP Quote Link to post Share on other sites
Jim58 Posted January 5, 2012 Author Report Share Posted January 5, 2012 Hi Rob yep new brakes on the back. I've tightened up so I can feel a bind on the wheel when turning by hand. Cheers, Jim Quote Link to post Share on other sites
Jersey Royal Posted January 5, 2012 Report Share Posted January 5, 2012 Another tip you could try is to force down the brake pedal with a length of wood off the seat, and leave it overnight, This is one of Stuarts ideas and has worked for me in the past. If you have new discs and pads you will need to bed them in, until they are bedded in they will not have the stopping power. The manufacture of the discs and pads should have a bedding in procedure for their products. Hope this is of help Guy Quote Link to post Share on other sites
Rorr1971 Posted January 6, 2012 Report Share Posted January 6, 2012 Hi Jim I had a similar problem recently after changing out the master cylinder and rear wheel cylinders. When opening the rear nipples a had fluid coming out, however I was not happy with the volume and could not get a firm peddle. After reading some other post it was recommended to bench bleed the master cylinder. I actually did this in the car with some well placed rags and the assistance of a helper to apply pressure to the peddle. Basically attached a tube to an old brake connector at the front master outlet and feed this back into the master tank. After a few pumps had a really good flow. hooked up the system again, bleed the brakes and firm peddle. Might not be your problem, but it go me back in the road. Thanks Rob Quote Link to post Share on other sites
CDT Posted January 6, 2012 Report Share Posted January 6, 2012 Hi Jim, I'll second Guy's post. I've used this method of wedging the brake peddle down over night on numerous cars and it's always worked for me. Cheers Chris Quote Link to post Share on other sites
stuart Posted January 6, 2012 Report Share Posted January 6, 2012 Reference the jam the pedal down method. Pump the pedal a few times until it is at the highest and firmest you can get before wedging it down with a bit of wood between the seat and pedal. Then leave overnight. Stuart. Quote Link to post Share on other sites
Jim58 Posted January 6, 2012 Author Report Share Posted January 6, 2012 Thanks for the advice Guys. Once left overnight do you then bleed again or should that be it? Jim Quote Link to post Share on other sites
Guest ntc Posted January 6, 2012 Report Share Posted January 6, 2012 Jim Post 2 is the way to do it Quote Link to post Share on other sites
stuart Posted January 6, 2012 Report Share Posted January 6, 2012 Thanks for the advice Guys. Once left overnight do you then bleed again or should that be it? Jim That should do it. Stuart. Quote Link to post Share on other sites
Jim58 Posted January 6, 2012 Author Report Share Posted January 6, 2012 Out of interest Guys what's the theory? Quote Link to post Share on other sites
Jim58 Posted January 7, 2012 Author Report Share Posted January 7, 2012 Well I tried the pumping the brake pedal method and locking down overnight and it has def made a difference. Anyone explain why this should make a difference ........ Thanks Quote Link to post Share on other sites
Guest ntc Posted January 7, 2012 Report Share Posted January 7, 2012 Well I tried the pumping the brake pedal method and locking down overnight and it has def made a difference. Anyone explain why this should make a difference ........ Thanks Guess it leaves the seal's under pressure so they do seal? never had to do it myself Quote Link to post Share on other sites
PJM Posted January 7, 2012 Report Share Posted January 7, 2012 Any air trapped in the system slowly works its way back up the pipework to the master cylinder, escaping past the seals. Quote Link to post Share on other sites
stuart Posted January 7, 2012 Report Share Posted January 7, 2012 Never really understood how it works myself but I think its that with the pedal down any trapped air can find its way back up to the master cylinder as the system is effectively "open" from pedal to cylinders and when you release the pedal any air that was present is trapped in the part of the master that returns the fluid back to the reservoir effectively dumping it back into the reservoir. Stuart. Quote Link to post Share on other sites
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