ldtopham Posted August 31, 2009 Share Posted August 31, 2009 Following my original post http://forums.lr4x4.com/index.php?app=forums&module=post§ion=post&do=reply_post&f=9&t=46210&qpid=424593 I have further diagnosed the fault. From cold the brake pedal feels good. After approx 2 miles of steady driving on applying the brakes the pedal feels a little firmer, after a good few miles on a couple of occasions it becomes so firm that the brakes start to grab without any pedal effort and the pedal is right at the top. It appears to be the rear brakes that are causing the problem. If it is a wet day then the symptoms occur much earlier and I can actually hear the pads starting to contact the discs followed by high resonance screeching. Here is what I have done prior to the fault: 1. All calipers removed and cleaned up. 2. All discs and pads replaced for new Mintex items. 2. Replaced all the caliper pistons for a stainless set inc new seals 3. Bled the system/ replaced the manky fluid. 4. Wheel bearings were replaced too. Adjusted correctly with a dti. I went to my local motor factors this weekend and noted that there are 2 different Mintex pads for the Landrover Defender. Both share the same mounting pad dimensions but the pad is 14.5mm on one set and 18mm on the other. The set listed on my receipt are the correct number for my model and year but I'll physically check the dims tonight in case the box set I used was incorrectly sent. This is my next check to see if I have the thicker pad fitted. After that I'm stabbing in the dark. The servo test is fine (ie deplete vacuum start up pedal drops a little) and the vacuum pump has a healthy draw on the feed line. The NRV works ok and the hoses are in good condition between the servo and v pump. Any pointers? I'm wondering if the master cylinder has a fault which is not letting fluid return correctly and slowly allowing the pressure to build up with each application of the pedal and driving distance? Anyone had anything similar or ideas? After the above works we did approx 800 miles with no problems, only the morning after the return motorway journey did this fault appear?? Thnaks in advance. Quote Link to comment Share on other sites More sharing options...
errol209 Posted August 31, 2009 Share Posted August 31, 2009 Any pointers? I'm wondering if the master cylinder has a fault which is not letting fluid return correctly and slowly allowing the pressure to build up with each application of the pedal and driving distance? Anyone had anything similar or ideas? That does seem to fit the symptoms. I'm guessing you're still on the original master cylinder? They have numerous rubber seals, all of which age. Could be worth the few quid to overhaul it. Off chance - is the vent on the reservoir cap clear? it could be holder the pressure on. The closest experience I have is mananging to adjust the servo pushrod badly, so that it held the MS partly operatedf even with the pedal at the top. A dozen operations and the brakes were half on and smoking! Quote Link to comment Share on other sites More sharing options...
ldtopham Posted August 31, 2009 Author Share Posted August 31, 2009 AFAIK it is the original MC. There are still what appear to be factory witness marks on the brake fittings to it. I'll check the cap too in fact I may have a new spare one that I can swap out. I re-flushed and bled the system again on Friday. I also checked that the rear pistons were free to compress back in to the calipers. The idea there was that maybe I had fitted the wiper seal retaining rings a little to deep and causing stiction to the piston. It wasn't the case and all is well there. I really need to study some schematics of the MC and servo operation to decide where to start after the cap vent check. The servo or pedal have not been adjusted in anyway. It may be some carp got pulled through the MC when pulling the new fluid around. I did the clutch fluid on Friday, it was 'as black as the fire back' Quote Link to comment Share on other sites More sharing options...
errol209 Posted August 31, 2009 Share Posted August 31, 2009 I did the clutch fluid on Friday, it was 'as black as the fire back' Reet champion! Sorry, I'm from Buckinghamshire - no idea what came over me . Anyway, I'd go for MC seals, as it's about the only thing left! Good luck! ps. I know I said MS, its to earley inn thee mourning four write spleling! Quote Link to comment Share on other sites More sharing options...
ldtopham Posted August 31, 2009 Author Share Posted August 31, 2009 Reet champion! Sorry, I'm from Buckinghamshire - no idea what came over me . Anyway, I'd go for MC seals, as it's about the only thing left! Good luck! ps. I know I said MS, its to earley inn thee mourning four write spleling! Reet then, after tha's teckin whippet ahht in them there fields al get a seal kit sorted tha naas and hopefully Bob's your fathers brother Quote Link to comment Share on other sites More sharing options...
errol209 Posted August 31, 2009 Share Posted August 31, 2009 Reet then, after tha's teckin whippet ahht in them there fields al get a seal kit sorted tha naas and hopefully Bob's your fathers brother I'm sorry, I am of the south and do not understand your quaint local patois Am I to undersatnd that your response is in 't affirmative? (damn damn damn) Quote Link to comment Share on other sites More sharing options...
ldtopham Posted August 31, 2009 Author Share Posted August 31, 2009 I'm sorry, I am of the south and do not understand your quaint local patois Am I to undersatnd that your response is in 't affirmative? (damn damn damn) Ay, summet like that Quote Link to comment Share on other sites More sharing options...
ldtopham Posted October 2, 2009 Author Share Posted October 2, 2009 In case it is of help to anyone else I have now sorted this problem. It was the the seals within the master cylinder. I put a genuine seal and primary piston kit in the original master cylinder as the bore was good. A 1 hr job. It now drives great again. Thanks for you assistance. Lee Quote Link to comment Share on other sites More sharing options...
errol209 Posted October 3, 2009 Share Posted October 3, 2009 In case it is of help to anyone else I have now sorted this problem. It was the the seals within the master cylinder. I put a genuine seal and primary piston kit in the original master cylinder as the bore was good. A 1 hr job. It now drives great again. Thanks for you assistance. Lee No problem, HTH. Quote Link to comment Share on other sites More sharing options...
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