cluffy Posted January 4, 2012 Share Posted January 4, 2012 Just finished rebuilding my 1989 90, relaised the brake pedal was going to the floor, so fitted new master, problem carried on and put brand new servo on. I have put new pistons etc in callipers bled the brakes what seems like a hundred times. Yesterday I tried the brakes again - engine off, pump brakes the pedal goes hard! Thought I had cracked it, start engine Press the brake pedal and it goes straight to the floor with rear brakes locking up! If pump while engine running it again goes hard but then wait a moment and will go straight to the floor again. At a shot in the dark I took a box off the chassis dthat goes from master to rear brakes, called a g valve I think? Striped this down and gave it all a good out. Now the pedal does the same but the front brakes seem to work abit rather than the back brakes just locking up! I've asked around and everyone is stumed. Any ideas greatly appreciated thanks Ben Quote Link to comment Share on other sites More sharing options...
minimaquinas Posted January 4, 2012 Share Posted January 4, 2012 hi try clamping your flexy pipes in turn and it will show where the problem lies hth brian Quote Link to comment Share on other sites More sharing options...
cluffy Posted January 4, 2012 Author Share Posted January 4, 2012 Yes ok, I'll try that, another idea I was that the flexi hoses are expanding under Pressure? What's the chances of this? Quote Link to comment Share on other sites More sharing options...
stuck Posted January 4, 2012 Share Posted January 4, 2012 Yes ok, I'll try that, another idea I was that the flexi hoses are expanding under Pressure? What's the chances of this? Slim. Are you trying to bleed them manually? Have you tried something like a Gunson Eazibleed? Had a similar prob on a RRC once, took 5 mins with the Eazibleed. HTH's Mick. Quote Link to comment Share on other sites More sharing options...
Phillis Posted January 4, 2012 Share Posted January 4, 2012 get some braided hoses so much better than the rubber ones, also are the seals ok on the calipers that you refurbed? Quote Link to comment Share on other sites More sharing options...
cluffy Posted January 4, 2012 Author Share Posted January 4, 2012 Thanks for ideas however I have bleed them in every way under the sun even took the truck to the local garage and had it power bled with their machine and still no luck, wouldn't I be able to feel/see the hose expand? Quote Link to comment Share on other sites More sharing options...
verminhunter Posted January 5, 2012 Share Posted January 5, 2012 Had a similar problem on a car at work, it turned out that one flexi had broken up inside and one of the copper pipes had been trapped by someone jacking the car up without looking where the jack was hitting the chasis. I never worked out why it would cause the problem it did but once all flexes were replaced with braided and copper pipe replaced all was good. Quote Link to comment Share on other sites More sharing options...
cluffy Posted January 5, 2012 Author Share Posted January 5, 2012 Ok thanks all! Looks like I will have to try new hoses all round and see if that gets me anywhere Cheers Quote Link to comment Share on other sites More sharing options...
kinbelieveit Posted January 9, 2012 Share Posted January 9, 2012 I have got the same problem with my 90. I have got braided all round and it is still the same! I have got discs all round (Disco rear diff) and have been told it could be the fact that the master servo can't cope as it is the original ie. for drums. Was told if i put a more recent one on that accomidates rear discs it MAY solve the problem. Anyone think this could work?? Quote Link to comment Share on other sites More sharing options...
Frax Posted January 9, 2012 Share Posted January 9, 2012 Make sure all the bleed nipples are at the top of the calipers as you can fit them the wrong way up (wrong side) - ask me how I know Quote Link to comment Share on other sites More sharing options...
cluffy Posted January 9, 2012 Author Share Posted January 9, 2012 Well, I have done that funnily enough but have swapped them haha, not sure about all discs, I hope not, got a brand new master for mine with drums on and have got disco rear discs to put on in a few months when I get round to it, don't want to have to get another master cylinder? Let me no how you do Quote Link to comment Share on other sites More sharing options...
Tom1809 Posted January 10, 2012 Share Posted January 10, 2012 Try and clamp the rear flexi and see how the pedal goes, I had really carp bakes on the 90, replaced rear drum cylinders, new shoes, adjusted all up, still carp. Clamped it off, pedal felt good, and the front brakes worked. With discs on the back apparently it makes it night and day difference, can vouch for that yet myself as its still just a chassis. Quote Link to comment Share on other sites More sharing options...
kinbelieveit Posted January 10, 2012 Share Posted January 10, 2012 Well it looks like its another afternoon under it again!! I said i had braided on the rear but looked today and it's a rubber hose so gonna change that tomorrow and bleed the whole system. If that don't work then i will look at changing the master. I have also got a shudder from the front wheels at slow speed!!! Somethin else to worry about, so it's back up on axle stands to try and find that problem........ Ideas anyone?? Not enough day light to get anythin done at the mo!! Quote Link to comment Share on other sites More sharing options...
cluffy Posted January 10, 2012 Author Share Posted January 10, 2012 Shudder could be a warped discs or possibly the slides on your calliper seized, that would be my guess anyway. Quote Link to comment Share on other sites More sharing options...
kinbelieveit Posted January 10, 2012 Share Posted January 10, 2012 K thanx for your posts. That may be the problem as she was standing for a few months and with the sea air and wild winds thing's have taken a battering!! I will get it all stripped and check it out tomorrow. Fingers crossed it will solve it. Steve. Quote Link to comment Share on other sites More sharing options...
Eightpot Posted January 11, 2012 Share Posted January 11, 2012 Sounds like you might have a big air lock in the front brake circuit, or maybe a problem with the G-valve? Presume your front brake calipers just have the single bleed nipple? My rangie has three, and if you don't bleed them in the right way you get a lot of air in the system. When you changed the master cylinder, was it packed in grease? I've fitted one in the past and didn't get all the packing grease out, and ended up with a block in the brake lines which meant they wouldn't bleed properly. Also when you changed the caliper pistons, have you checked they can move freely and aren't stiff or stuck in the bores? Quote Link to comment Share on other sites More sharing options...
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