bombx3 Posted August 31, 2017 Share Posted August 31, 2017 (edited) Hi im pulling my hair out with my brake problem As i work away for long periods i have not used my landy since last winter I had a couple of seized calipers so i thought i would treat it to 4 new discs,calipers/master cylinder and a couple of rear pipes as the nipples were rounded I have used a snap on power bleeder set at 10psi and the pedal is solid , but when i drive it the pedal is spongy but if you give it one pump it is ok for a while, on tick over in traffic with your foot on the brake it slowly goes to the floor When parked up engine off the pedal is solid I just put 4 liters of fluid trough it tonight no air Could a servo cause this problem? Regards Ray Edited August 31, 2017 by bombx3 Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted August 31, 2017 Share Posted August 31, 2017 Servo? No, sounds like a leak or air in the system still. Try clamping the hoses and see if it still happens. If not, remove a clamp one at a time and when the sponginess returns that is your corner that is affected. If it still happens then check your master.... It is not unheard of for these to be faulty out of the box, especially if the box was blue... Quote Link to comment Share on other sites More sharing options...
bombx3 Posted August 31, 2017 Author Share Posted August 31, 2017 Thanks mate , I will get some clamps this morning and let you know the findings Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted August 31, 2017 Share Posted August 31, 2017 If it only happens when you drive you could also check your wheel bearings for play. If they have play in them then they can knock the pads back as they wobble resulting in a spongy feeling pedal. HTH Mo 1 Quote Link to comment Share on other sites More sharing options...
bombx3 Posted August 31, 2017 Author Share Posted August 31, 2017 I just clamped the pipes and took it for a little spin and the pedal was high and hard then suddenly went soft , I have changed the master cylinder twice so I'm sure I can rule that out i checked the wheel bearings that's all good Stuck Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted August 31, 2017 Share Posted August 31, 2017 If you clamped the lines and then drove it, they weren't clamped, as if clamps you won't get any braking effort! The idea is to test the calipers/hoses for leaks while stationary, driving with clamped lines is a little dangerous The idea is to stop the fluid going to all four wheels, thereby eliminating them as problems -if you solve the problem by clamping the lines, then your problem is definitely one of the wheel corners, unclamp each until you re-enable the issue, and there you have your problem location. If you have stainless lines then you can't clamp them anyways....! Quote Link to comment Share on other sites More sharing options...
cackshifter Posted August 31, 2017 Share Posted August 31, 2017 Is it a 90 by any chance? I ask because on mine I occasionally lost a lot of fluid - it was dribbling out of the end of the G valve on the bulkhead. It was not obvious when parked up, but a slight moistness on the end that points outward was the clue. I was looking round all the calipers for leaks - no sign. Bled up fine. A new valve fixed it. Just a thought. Nigel Quote Link to comment Share on other sites More sharing options...
bombx3 Posted August 31, 2017 Author Share Posted August 31, 2017 Thanks I have to pop out but when I get back I will pinch them up and do it again "stationary " Quote Link to comment Share on other sites More sharing options...
Peaklander Posted August 31, 2017 Share Posted August 31, 2017 7 hours ago, bombx3 said: I just put 4 liters of fluid trough it tonight no air Just a point that moving fluid through 'the system' doesn't mean there's no air in there. It's quite easy to leave a bubble or two, with the fluid moving past. This is especially true in the slave cylinders just behind the pistons. Quote Link to comment Share on other sites More sharing options...
bombx3 Posted August 31, 2017 Author Share Posted August 31, 2017 Thanks guys but rain stopped play today what is a g valve? with engine off if I put my foot on the brake it's nice and hard then a few seconds or so whoosh it goes soft do it again exactly the same Tomorrow I will try the clamps again Quote Link to comment Share on other sites More sharing options...
western Posted August 31, 2017 Share Posted August 31, 2017 G valve prevents rear brakes locking up before the front brakes, its bolted to a bracket on top of right chassis rail at bottom of the bulkhead, just follow the brake pipe down from the master cylinder. Quote Link to comment Share on other sites More sharing options...
bombx3 Posted September 2, 2017 Author Share Posted September 2, 2017 What is the nut on top for ? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted September 2, 2017 Share Posted September 2, 2017 Without a wider angle shot, I'd say it is a plug ? Quote Link to comment Share on other sites More sharing options...
Snagger Posted September 2, 2017 Share Posted September 2, 2017 It's a blanking plug. The fluid paths inside the calipers are drilled after casting, and you can't drill around corners, so the paths are a grid of intersecting straight lines, some of which are capped by the union with the pipe, some with bleed nipples and some with these plugs. Quote Link to comment Share on other sites More sharing options...
bombx3 Posted September 2, 2017 Author Share Posted September 2, 2017 Thanks for that info Todays session clamped all lines Engine off pedal rock hard if you keep pedal pressure on it suddenly hits the floor after 15secs , do it again same thing happens im I correct that it's drawing in air from the master cylinder? Quote Link to comment Share on other sites More sharing options...
Snagger Posted September 2, 2017 Share Posted September 2, 2017 Sounds like a failed master cylinder. Quote Link to comment Share on other sites More sharing options...
bombx3 Posted September 2, 2017 Author Share Posted September 2, 2017 Only thing is I have changed it twice now , first one I took back said it's leaking they give me another cheapy one Should I fit a genuine part? Quote Link to comment Share on other sites More sharing options...
Snagger Posted September 2, 2017 Share Posted September 2, 2017 YES! Never go for cheap parts on safety critical parts - your life is worth more than a few quid saved in the short term (and so are those of other road users)! Besides, pattern parts more often than not fail early or don't work at all, so cost more in down time, collection/delivery and labour plus repeating the job with the genuine parts you should have bought first time. TRW is the latest incarnation of the Lucas brand. But even they can be fault from new, just much less likely than Britpart - stay well away from their brake and steering parts, bearings and seals. Quote Link to comment Share on other sites More sharing options...
bombx3 Posted September 2, 2017 Author Share Posted September 2, 2017 Is TRW my only option apart from britpart? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted September 2, 2017 Share Posted September 2, 2017 Yes, master, or a fluid leak elsewhere... Quote Link to comment Share on other sites More sharing options...
Snagger Posted September 3, 2017 Share Posted September 3, 2017 13 hours ago, bombx3 said: Is TRW my only option apart from britpart? No, but it's far better. It'll actually work. Quote Link to comment Share on other sites More sharing options...
bombx3 Posted September 3, 2017 Author Share Posted September 3, 2017 Are you saying a new Britpart master cylinder has a high chance of being useless? If so that's so wrong Quote Link to comment Share on other sites More sharing options...
Snagger Posted September 3, 2017 Share Posted September 3, 2017 Try a search on this and other forums for discussion about their quality, especially their brake components. There was a reason the MoD terminated their contract so quickly, and things have to be pretty bad to lose a contract with them. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted September 3, 2017 Share Posted September 3, 2017 Err, britpart master cylinder, bought, fitted, bled up, testing brakes while stationary giving it some, and the pedal collapsed with no braking effort to the wheels. If I had been moving and simulating an emergency it could have been quite different. High chance? Maybe not, but with brakes I would rather not take the chance.... Quote Link to comment Share on other sites More sharing options...
bombx3 Posted September 3, 2017 Author Share Posted September 3, 2017 Surely they can't sell this stuff if it don't work, I always buy pattern parts for my peugout Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.