Souster Posted April 23, 2015 Share Posted April 23, 2015 Hi all Yes unfortunately its a thread on the dreaded brakes again. Just a brief overview of the work done on the brakes over the last year. Everything has been replaced except the vacuum pump on my 1995 300tdi defender. And by everything I mean literally everything. Also, all wheel bearings have no play, new TRW Lucas discs and mintex/ferodo pads. And totally free of any leaks. The latest work I've had done about 2 months ago was the pressure relief valve by a good land rover specialist. And once I had the vehicle back I was very pleased. In fact the brakes felt the best they had ever felt. I had that replaced due to the rear discs going rusty. Which seems to be now solved. And I haven't touched the brakes since! The reason for me making this thread is due to an inconsistent feel with the brake pedal. Which didn't occur for a good few weeks after coming back from the land rover specialist. One day the brake pedal will feel great, firm and high. The next day it could feel soft and lower to the floor. Spongy in a way. But not always. It seems to be worse when reversing, usually off my drive. Has anyone got any ideas on this? I'm totally lost now, I can't understand why it's intermittent. Especially differing on days, despite some of them being short journeys (5 to 10 miles). I have been advised to try adjusting the servo pushrod, but still can't work out why that would help the intermittency?! Is there anything else I could try? Or shall I just shut up and drive the bl**dy thing. I do like things right though I must admit. Thankyou all for reading Quote Link to comment Share on other sites More sharing options...
Boydie Posted April 24, 2015 Share Posted April 24, 2015 What distance have you driven on your new discs and brake shoes ? Have you given them time to properly bed in ? If the discs and pads aren't glazed then they haven't had chance to bed in and this will give you an intermittent feel. I would recommend at least 100 miles of normal brake operation to bed them in properly, the alternative is to drive on the nearest motorway for about 1 mile with your foot just on the brake pedal, so that you can just feel the brakes gripping, let the brake off or a further mile or so to let them cool down and apply again and do this for about 4-5 rotations. Quote Link to comment Share on other sites More sharing options...
deep Posted April 24, 2015 Share Posted April 24, 2015 One possibility is inconsistency with your booster. If the booster isn't working, the pedal will feel firmer than if the booster is working. You could be losing vacuum quicker than the vacuum pump is producing it, so the brakes feel firmer the more you use them, even though the retardation is less. You'd work that one out pretty quickly if you just went up a quiet road in, say, second gear and accelerated a little, then braked hard, then accelerated and braked hard again, repeating a few times. If the vacuum pump isn't supplying enough, the pedal will feel harder but the amount of effort you need to apply will increase each time. When you say everything has been replaced, does that really mean all new cylinders, pistons and seals? Because it is possible there is a slightly sticky cylinder somewhere. They can drive you nuts! Easy to check on disk brakes by taking the wheels off and levering each piston back into the cylinder with a large, flat screwdriver - it should be smooth but with some weight to overcome, not sticky. A gentle push on the pedal should get them back out very smoothly, or they could even creep back out as you watch. With drums, you take off the wheel and drum, then get an assistant to gently and progressively push the pedal down. If only one shoe moves, try pushing against it while it's out and the other should then move easily. Don't push too far or they will pop out and make you VERY grumpy! Disc brakes don't "know" if you are reversing or going backwards, unlike drums (front drums have more bite going forwards), so the reversing thing suggests that another possibility is a loss of pedal when parked, the pedal then comeing back with use. So that could be some slight internal weeping in your master cylinder, though it seems unlikely. Quote Link to comment Share on other sites More sharing options...
pete3000 Posted April 24, 2015 Share Posted April 24, 2015 well I had not that long ago fitted an "aftermarket master cylinder " which I was never happy with, now I have a genuine girling/trw the feel of the pedal and the brakes are much better. So yes basically I too have replaced the entire system and uprated the components as I went along. Just goes to show you pays your money......... Pete Quote Link to comment Share on other sites More sharing options...
Souster Posted April 24, 2015 Author Share Posted April 24, 2015 What distance have you driven on your new discs and brake shoes ? Have you given them time to properly bed in ? If the discs and pads aren't glazed then they haven't had chance to bed in and this will give you an intermittent feel. I would recommend at least 100 miles of normal brake operation to bed them in properly, the alternative is to drive on the nearest motorway for about 1 mile with your foot just on the brake pedal, so that you can just feel the brakes gripping, let the brake off or a further mile or so to let them cool down and apply again and do this for about 4-5 rotations. well I had not that long ago fitted an "aftermarket master cylinder " which I was never happy with, now I have a genuine girling/trw the feel of the pedal and the brakes are much better. So yes basically I too have replaced the entire system and uprated the components as I went along. Just goes to show you pays your money......... Pete Thanks for the replys guys. I'm useless at multi quotes so bare with me. There's about 1500 mile on the front discs and pass, and about 500 mile on the rear. So they should be good to go. The master cylinder and servo is new TRW/Lucas parts. Only a few months ago Quote Link to comment Share on other sites More sharing options...
Souster Posted April 24, 2015 Author Share Posted April 24, 2015 One possibility is inconsistency with your booster. If the booster isn't working, the pedal will feel firmer than if the booster is working. You could be losing vacuum quicker than the vacuum pump is producing it, so the brakes feel firmer the more you use them, even though the retardation is less. You'd work that one out pretty quickly if you just went up a quiet road in, say, second gear and accelerated a little, then braked hard, then accelerated and braked hard again, repeating a few times. If the vacuum pump isn't supplying enough, the pedal will feel harder but the amount of effort you need to apply will increase each time. When you say everything has been replaced, does that really mean all new cylinders, pistons and seals? Because it is possible there is a slightly sticky cylinder somewhere. They can drive you nuts! Easy to check on disk brakes by taking the wheels off and levering each piston back into the cylinder with a large, flat screwdriver - it should be smooth but with some weight to overcome, not sticky. A gentle push on the pedal should get them back out very smoothly, or they could even creep back out as you watch. With drums, you take off the wheel and drum, then get an assistant to gently and progressively push the pedal down. If only one shoe moves, try pushing against it while it's out and the other should then move easily. Don't push too far or they will pop out and make you VERY grumpy! Disc brakes don't "know" if you are reversing or going backwards, unlike drums (front drums have more bite going forwards), so the reversing thing suggests that another possibility is a loss of pedal when parked, the pedal then comeing back with use. So that could be some slight internal weeping in your master cylinder, though it seems unlikely. Thankyou deep. Appreciate the detailed response. I've been thinking on exactly the same lines as you. Granted I'm no mechanic, but I've began to learn a fair amount about the land rover brake system. But this has got me! Anyway... In regard to the servo assistance, the servo is new. However, the pedal doesn't sink on start up, or sometimes it does but not immediately and it just creeps down slightly. Not quickly like a modern vehicle. So I was also thinking along the lines of brake boosting fault. Despite it being a new servo, it doesn't seem to hold its pressure for that long after the vehicle has been switched off. I replaced the servo due to the pedal not sinking, and it was exactly the same on the brand new one (trw Lucas with MC o ring fitted correctly). I do prefer when the pedal feels higher though I must admit... but if it is down to poor vacuum pressure and i replace the pump could I adjust that through servo pushrod? Lastly, yes discs all round for me. New calipers about 8 months ago now which are great and free. Quote Link to comment Share on other sites More sharing options...
deep Posted April 24, 2015 Share Posted April 24, 2015 If you are really worried (with brakes, you certainly don't want to be too casual), getting an opinion from a professional could be a good investment. Who that professional is, sadly, seems to vary from place to place around the world. Land Rover brakes being fairly simple, an ordinary garage with a good reputation can be a good start. A Land Rover approved dealer should also be good but it's not a given. Or a specialist brake workshop should be ideal. We have them in New Zealand, not sure where you are. All they do is brakes and clutches and they tend to get to the guts of the problem pretty quickly. An opinion is usually cheap enough - you don't have to pay for the repair there and then! Quote Link to comment Share on other sites More sharing options...
Souster Posted April 25, 2015 Author Share Posted April 25, 2015 I'm not really worried. And know if i took them too a specialist they would probs work perfectly on the day. Just wondered what the reason for intermittency and if it could be solved. Looks like it's one of those things to live with Quote Link to comment Share on other sites More sharing options...
cackshifter Posted April 25, 2015 Share Posted April 25, 2015 Before assuming the vac pump is faulty, try swapping the non return valve on the servo. They are relatively cheap, and as you have replaced so much there are limits as to what it could be. I have used Bearmach ones and they seem fine. Quote Link to comment Share on other sites More sharing options...
Tanuki Posted April 25, 2015 Share Posted April 25, 2015 You could still have a few bubbles of 'trapped wind' in your brake pipes. My trick to solve this is park up, then push the brake pedal down as hard as you can, and wedge it down with a piece of wood between the pedal and the seat-box. Leave it overnight with the pedal wedged down then re-bleed all the brakes as usual. Put a couple of pints of fresh brake-fluid through the system. Why? Well, if there's a trapped bubble of air in a 'high point' of the brake hydraulics, normal bleeding can't always shift this. Wedging the pedal down under load for 12 hours or so - these trapped bubbles are forced to dissolve themselves into the brake-fluid [air-solubility in liquids increases markedly under pressure - this is why divers get 'the bends' when they come to the surface and the pressure's released so the air turns back to bubbles]. Next day, you bleed-out the brake fluid with the air dissolved in it, and replace it with fresh, non-air-containing fluid. Try it - it's an easy fix and will at most only cost you a couple of pints of fluid. Quote Link to comment Share on other sites More sharing options...
Souster Posted April 26, 2015 Author Share Posted April 26, 2015 Thanks cackshifter. I have tried blowing into the non return valve and it seemed to be working. But I will replace. Thanks Tanuki. They have been bled that many times by me from changing out different parts, and then the garage also doing it everytime leaving the same results. So unless air is getting in and fluid not getting out. I'm pretty certain it can't be air now. Quote Link to comment Share on other sites More sharing options...
Souster Posted May 10, 2015 Author Share Posted May 10, 2015 Hi guys. Sorry for digging this one out again. But I have a feeling I might finally be near the end of this problem. This weekend I set out to replace a couple of brake pipes that weren't too good in terms of nearly kinked. So I decided to replace them and bleed the system. I got them air free, both manually and with the eezi bleed. But when I road tested it, had this intermittent brake pedal feel again. So I had another go at bleeding the system, manually after using the eezi bleed. Pedal felt great with engine off, firm, solid no creep or pumping higher. Perfect! I took it for a road test and the same happened again. Pedal would feel good sometimes, and not others. So I decided to investigate the vacuum pump and pipe work. Even though the inconsistency seemed worse after replacing the brake pipes. So I went onto a private road, and pulled the vacuum pipe from the servo. Up and Down in a straight line forward and reverse they were consistent. Untill I TURNED. Then the pedal travel would suddenly increase. Immediately after turning. Now logically that would imply that it's wheel bearings. But there isn't any play in them, or at least I can't feel it. All along I've thought It was when I was reversing (backing off my drive) but it appears it's turning and rough roads (off road ) that the pedal travel increases?! Am I on the right lines? Sorry for the long winded post Quote Link to comment Share on other sites More sharing options...
Maverik Posted May 11, 2015 Share Posted May 11, 2015 The only thing that comes to mind that can effect the brakes when steering is engine rev's, especially when reversing... which would point to poor vacuum pump... especially as you've already said your wheel bearings are all ok - but to me your symptoms aren't reminiscent of a servo/vacuum failure... The only other thing that's screaming at me is that the master cylinder is bi-passing (intermittently)... that's the only component that you can't prove really, if its bi-passing there's no way to check it... I know its a new TRW unit, but I've replaced a lot of brake masters as they don't seem to have a very good life span, and its usually damage to the cylinder bores too that causes it. This is a tricky one as the problem has persisted after changing to nice new parts, but to me I'd suspect the master cylinder is dodgy... Now thinking further before I hit post... Does this truck have a G- valve? if this was maybe not working properly I wonder if it could cause you pedal issues... especially after you suggest its irritated by movement... maybe thinking there's muck interfering with the ball bearing in it..? Quote Link to comment Share on other sites More sharing options...
Souster Posted May 11, 2015 Author Share Posted May 11, 2015 Cheers Maverick If the pedal is proving totally solid when the engine off, would that mean the master cylinder is okay. Why when going in a straight line forward and reverse with the vacuum pump disconnected... The brakes are solid and good. The minute I turn the vehicle, the pedal travel is increased. Is this pointing to something to do with the wheels, knocking the pads back in the calipers when turning? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted May 11, 2015 Share Posted May 11, 2015 Sorry for ignorance, but what is the vacuum pump driven by on these engines? Quote Link to comment Share on other sites More sharing options...
Retroanaconda Posted May 11, 2015 Share Posted May 11, 2015 How sure are you the wheel bearings are OK? Just a test by hand, or something more substantial? Jacking the vehicle up 1/2" and using a prybar between the floor and the tyre will show the play better than by hand if there is any, you may need to have someone else monitor the back of the hub for the play, either by hand or by 'feel'. It may be worth stripping the hubs down and checking the individual condition of the bearings if all else fails. Quote Link to comment Share on other sites More sharing options...
pete3000 Posted May 11, 2015 Share Posted May 11, 2015 Two ideas, could the rough roads have settled out any small air bubbles, may be worth a mini bleed? once it's settled down. Or if it is worse after cornering then you may have a leak on a flexible pipe or a leak from the casting on the caliper. I had a leak from my NSF caliper out of the box new. Look for spray round the wheel/tyre in dry weather. If the wheel bearing is a worry and you can get it checked it's worth doing, you may notice one wheel hub outside by nuts is hotter than the other after a few miles without hammering the brakes. Don't check after hammering the brakes as you'll get burned fingers. P.S Read RA's thread after posting, usually tighten my bearing's up by over tightening a bit to "settle" the race and pull in any final clearances then, back off by 1 nut flat, before lock washering. Check again after 1000 miles. Quote Link to comment Share on other sites More sharing options...
pete3000 Posted May 11, 2015 Share Posted May 11, 2015 Sorry for ignorance, but what is the vacuum pump driven by on these engines? mechanical plunger pump driven off cam on engine crankcase, so low revs affects vacuum build up? Quote Link to comment Share on other sites More sharing options...
Souster Posted May 11, 2015 Author Share Posted May 11, 2015 How sure are you the wheel bearings are OK? Just a test by hand, or something more substantial? Jacking the vehicle up 1/2" and using a prybar between the floor and the tyre will show the play better than by hand if there is any, you may need to have someone else monitor the back of the hub for the play, either by hand or by 'feel'. It may be worth stripping the hubs down and checking the individual condition of the bearings if all else fails. Well when the wheels are jacked up. I can't feel any play at 12 and 6. However, when the vehicle is on the ground, I can rock the vehicle and feel movement. But I didn't think it was wheel bearings, so to isolate this I got someone to press the brakes and feel for any movement. I could hardly rock the vehicle at the top of the wheel. On a private road with servo pipe disconnected... driving forward and reverse in a straight line applying the brakes. Perfect no issues. As soon as I turn round and turn the steering wheel. The pedal travel increases. I removed servo pipe to try and rule out vacuum pump intermittency. Quote Link to comment Share on other sites More sharing options...
Souster Posted May 11, 2015 Author Share Posted May 11, 2015 Two ideas, could the rough roads have settled out any small air bubbles, may be worth a mini bleed? once it's settled down. Or if it is worse after cornering then you may have a leak on a flexible pipe or a leak from the casting on the caliper. I had a leak from my NSF caliper out of the box new. Look for spray round the wheel/tyre in dry weather. If the wheel bearing is a worry and you can get it checked it's worth doing, you may notice one wheel hub outside by nuts is hotter than the other after a few miles without hammering the brakes. Don't check after hammering the brakes as you'll get burned fingers. P.S Read RA's thread after posting, usually tighten my bearing's up by over tightening a bit to "settle" the race and pull in any final clearances then, back off by 1 nut flat, before lock washering. Check again after 1000 miles. Cheers Pete. There are no leaks anywhere, unions dry. New stainless flexis too. Zero creep in the brake pedal when engine off too. High pedal etc. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted May 11, 2015 Share Posted May 11, 2015 Thanks, was wondering if it was powered by a slipping PAS belt, but clearly not. I know you say you have no play, but have you stripped them down? It can be hard to detect if the caliper is still attached, more so if it is partially seized, grabbing the disc. Quote Link to comment Share on other sites More sharing options...
Souster Posted May 11, 2015 Author Share Posted May 11, 2015 Thanks, was wondering if it was powered by a slipping PAS belt, but clearly not. I know you say you have no play, but have you stripped them down? It can be hard to detect if the caliper is still attached, more so if it is partially seized, grabbing the disc. I have stripped them all down and I know the bearings are in good condition. However I don't think I have preloaded them correct. Just done some research and I haven't been doing it right. I've just purchased a 52mm impact socket online, so going to set them up as per the Rave manual. The difference between rocking any of the four wheels normally and then with someone pressing on the brake pedal is quite considerable. Despite feeling no play when jacking up the wheels and rocking them at 12 and 6. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted May 11, 2015 Share Posted May 11, 2015 How have you done it up til now? Quote Link to comment Share on other sites More sharing options...
Souster Posted May 11, 2015 Author Share Posted May 11, 2015 How have you done it up til now? I just nipped the bearings up untill no play was felt from rocking the disc. And that was it quite literally. Should I get my coat and hide in embarrassment haha? I've had this problem for god knows how long now though. But after doing some brake system work the weekend it seems to have become more noticeable. Or probs because I'm inspecting how the pedal feels to see if I bled it correct. I'm guessing it's the latter Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted May 11, 2015 Share Posted May 11, 2015 Is that a yes ? Mo Quote Link to comment Share on other sites More sharing options...
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