Souster Posted January 1, 2015 Author Share Posted January 1, 2015 if you get pulses in the readings it can indicate disk or caliper issues, if you get a very low reading that improves over time that could be a bias valve issue if you get one wheel much better than the other that reverses sides on retest that could again be bias issues. the list goes on but a experienced tester can tell you what's most likely wrong just by looking at the results. Right I'm with you. Thank you. I'll have to find a garage that can test this then Quote Link to comment Share on other sites More sharing options...
Lewis Posted January 1, 2015 Share Posted January 1, 2015 Personally I would ignore it. I'll get you a picture of my disks, then you can decide if yours is a problem Quote Link to comment Share on other sites More sharing options...
Lewis Posted January 3, 2015 Share Posted January 3, 2015 Still worried about yours? Quote Link to comment Share on other sites More sharing options...
Souster Posted January 3, 2015 Author Share Posted January 3, 2015 Still worried about yours? I would say mine are the same after the recent bad weather rusting the, and the pads not clearing it. Isn't that funny that they are both similar, yet a friends TD5 that is unladen all the time, the rear discs are polished perfectly. Thank you Quote Link to comment Share on other sites More sharing options...
Nigelw Posted January 4, 2015 Share Posted January 4, 2015 My Disco has perfectly polished rear discs too and no bias valve thingy either after looking at the system today,(1992 200Tdi Disco 1 if you're wondering). If you have one you could remove it and see how it goes? Quote Link to comment Share on other sites More sharing options...
Souster Posted January 4, 2015 Author Share Posted January 4, 2015 My Disco has perfectly polished rear discs too and no bias valve thingy either after looking at the system today,(1992 200Tdi Disco 1 if you're wondering). If you have one you could remove it and see how it goes? If it's possible to remove it, would certainly be worth a try. Will that affect the balance of the brake system though? Quote Link to comment Share on other sites More sharing options...
Lewis Posted January 4, 2015 Share Posted January 4, 2015 My Disco has perfectly polished rear discs too and no bias valve thingy either after looking at the system today,(1992 200Tdi Disco 1 if you're wondering). If you have one you could remove it and see how it goes? Yes but you've got a great big fat heavy disco with a massive rear overhang and vastly different weight distribution. A 90 has much less weight over the rear axle, especially unladen, hence the need for a bias valve Quote Link to comment Share on other sites More sharing options...
Souster Posted January 11, 2015 Author Share Posted January 11, 2015 Guys the last few days I've done about 100 miles in the vehicle. Checked the rear discs to see what the situation was. And the outside of the discs closest to the wheels on both sides are wearing fine and braking as they should. On the inside however, lines and ridges of rust are present. The discs on the inside also feel rough. Which I believe maybe from previous rust. They just aren't clearing the discs as they should. Next job is to get it on the rollers as you've suggested. I just haven't had time while the garages have been open. What's are the chances of sticky pistons on 2 calipers that are six months old on the pistons nearest the diff. Very odd. Just thought I would let you know. Maybe I should just drive the bloody thing and take no notice. But if you've spent hard earned on new parts, you want it to be as good as new. Cheers all Quote Link to comment Share on other sites More sharing options...
qwakers Posted January 11, 2015 Share Posted January 11, 2015 maybe the calipers arent bled properly.? Quote Link to comment Share on other sites More sharing options...
Souster Posted January 11, 2015 Author Share Posted January 11, 2015 maybe the calipers arent bled properly.? They've been bled repeatedly mate. I originally thought that too. But after replacing the Master cylinder after rebuilding it. I would have thought the air has escaped by now. Bled with eezi bleed and the day after manual bleeding Quote Link to comment Share on other sites More sharing options...
qwakers Posted January 11, 2015 Share Posted January 11, 2015 might be worth bleeding it then with a non return valve attached to the bleed nipple open it and push the inside piston all the way back in. Quote Link to comment Share on other sites More sharing options...
bushwhacker Posted January 11, 2015 Share Posted January 11, 2015 You could remove the pads on the suspect pistons (do them one at a time) put a pry bar or the like in place of the pad have someone press lightly on the pedal while you watch if the piston is moving out, use the bar to push the piston in. If the piston is sticking put some good penetrative oil around it and work it in and out with the pedal and bar until free. I hope this makes sense. Quote Link to comment Share on other sites More sharing options...
Souster Posted January 14, 2015 Author Share Posted January 14, 2015 I replaced the master cylinder just in case I had messed that up. As it turns out no real improvements. I originally thought there was improvements, but no luck. Both outsides of the rear discs nearest the wheels seems a fair bit better. Not great though, insides are poor. Looks like I'll have to get it on the rollers to see what's going on. Or live with it and replace discs when needed Quote Link to comment Share on other sites More sharing options...
Boydie Posted January 15, 2015 Share Posted January 15, 2015 I'm assuming here that your LR doesn't have such things as anti-lock breaking (ABS) or rear axle load-limiting devices. If this is the case and it's a simple dual circuit system then I think it can only be one of three things, and one has been discounted by the fitting of your new master cylinder. The second culprit could be the pressure limiting valve, this reacts to front brake pressure to prevent the rears from locking up and causing a sidewards skid, on our rally cars we did just that as we generally wanted a rear wheel bias to assist in high speed cornering. This pressure limiting valve can normally be serviced with new valves, springs and seals. The last thing is the rear callipers, the inner pistons could be sticking as they are more prone to getting crud over them, this would result in the outers giving more breaking force. Take them off the disc, (one at a time) put a block of wood between the pistons - say 30mm wider than the disc and with someone else applying the brake see if both pistons come out at the same rate, if they don't dismantle clean the pistons and problem should be solved, its very unusual for both rears to have the same side piston sticking but you do own a Land Rover and anything and everything is therefore possible. Quote Link to comment Share on other sites More sharing options...
Les Henson Posted January 15, 2015 Share Posted January 15, 2015 Next job is to get it on the rollers as you've suggested. You can't put it on a normal single axle rolling road - it'll damage the transmission. MOT stations either use a taplow meter, or just drive it to test the brakes. I believe that in order to do an individual wheel test or single axle only, you have to remove the rear prop. There may be a way round it - such as transfer lever in neutral perhaps, but I'm not sure. Les 1 Quote Link to comment Share on other sites More sharing options...
Souster Posted January 15, 2015 Author Share Posted January 15, 2015 Thanks boydie ane Les for your replies. Yep its a 1995 defender 90 so no ABS. I Loaded the vehicle up today with what I had in the garage to try and get some weight over the rear to see if it would make any difference. I got 6 land rover steel wheels and tyres in along with a heavy jack. Some decent weight and by far exceeds other 90 hard tops that are unladen with no rear brake issues. I then had to go and collect something so used the vehicle for 15 miles with these items in the load space. And there was no difference to how the rear discs looked at the end of the journey. They still don't look like they are wearing correctly. I'm happy to live with it if it's normal, however a friends vehicle of the same year isn't the same. And a TD5 90 isn't either. Would the amount of servo assistance play a role in this? It's a new servo, but the pedal still doesn't sink on start up. It does on the second press though. Just wondering if that had anything to do with it. I took a picture of the rear discs to see what you guys thought after carrying those items in the load bay. They were cheap mintex discs of Amazon. I'm not sure if that has any factors? http://s905.photobucket.com/user/souster4/media/Mobile%20Uploads/20150115_114353.jpg.html?filters[user]=109140969&filters[recent]=1&sort=1&o=0 Quote Link to comment Share on other sites More sharing options...
pete3000 Posted January 15, 2015 Share Posted January 15, 2015 Don't know if it's been mentioned at all, but have you clamped the rear braided hose at all? they don't like it as the pipe doesn't truly return to its original shape. I didn't get on with the braided hose at the back of my 110 so changed it back for a standard £2.50 rubber job, the diameter of the pipe used seems to be larger on the standard rubber pipe than on the braided. Other thing is do you have a pic of your master cylinder type and servo type? there are various setups with some having 2 outlets for the front and 1 for the rear, and some having 1 for each with a T piece on the chassis rail and so on. Pete Quote Link to comment Share on other sites More sharing options...
Souster Posted January 15, 2015 Author Share Posted January 15, 2015 Don't know if it's been mentioned at all, but have you clamped the rear braided hose at all? they don't like it as the pipe doesn't truly return to its original shape. I didn't get on with the braided hose at the back of my 110 so changed it back for a standard £2.50 rubber job, the diameter of the pipe used seems to be larger on the standard rubber pipe than on the braided. Other thing is do you have a pic of your master cylinder type and servo type? there are various setups with some having 2 outlets for the front and 1 for the rear, and some having 1 for each with a T piece on the chassis rail and so on. Pete Thanks Pete. I haven't clamped the new flexi no. They are terrifirma braided, not sure if they are any good. I'll try and get a pic of the brake system later Quote Link to comment Share on other sites More sharing options...
Souster Posted January 15, 2015 Author Share Posted January 15, 2015 Don't know if it's been mentioned at all, but have you clamped the rear braided hose at all? they don't like it as the pipe doesn't truly return to its original shape. I didn't get on with the braided hose at the back of my 110 so changed it back for a standard £2.50 rubber job, the diameter of the pipe used seems to be larger on the standard rubber pipe than on the braided. Other thing is do you have a pic of your master cylinder type and servo type? there are various setups with some having 2 outlets for the front and 1 for the rear, and some having 1 for each with a T piece on the chassis rail and so on. Pete I've just had a look Pete. And there's 3 pipes coming off the master cylinder. Pretty sure there's no T piece for the rear other than the back axle. Do you guys think I should Book it in to my local land rover specialist to have the bias valve changed? Not sure if the pedal not sinking on start up is anything to do with it? Quote Link to comment Share on other sites More sharing options...
steve b Posted January 15, 2015 Share Posted January 15, 2015 If the servo has held it's vacuum you will still have servo assistance doing that . you have to empty the servo with a few pumps until it goes hard , then hold it down and start - as the servo gains vac the pedal will then go down a bit . I thought the brake rollers were fine on a t/box with a lockable diff Les ? and it's the viscous diff ones that can't be roller tested ? ....If you are unsure just whip the front prop off and run it in t/box difflock for the roller test . I suspect you will find the brake effort is up to spec , my suspect is cast quality being a bit towards the low end of acceptable - the spotting visible in the pic's suggests inclusions in the cast staining the surface? ....what does the collective think? cheers Steveb Quote Link to comment Share on other sites More sharing options...
Souster Posted January 15, 2015 Author Share Posted January 15, 2015 If the servo has held it's vacuum you will still have servo assistance doing that . you have to empty the servo with a few pumps until it goes hard , then hold it down and start - as the servo gains vac the pedal will then go down a bit . I thought the brake rollers were fine on a t/box with a lockable diff Les ? and it's the viscous diff ones that can't be roller tested ? ....If you are unsure just whip the front prop off and run it in t/box difflock for the roller test . I suspect you will find the brake effort is up to spec , my suspect is cast quality being a bit towards the low end of acceptable - the spotting visible in the pic's suggests inclusions in the cast staining the surface? ....what does the collective think? cheers Steveb Cheers Steve. The pedal doesn't sink on start up when the vacuum is expelled, but does on the second pump when vacuum has built up. I think the vacuum pump is a bit worn. Would that have any impact on the rear brakes? That's interesting About the disc casting. I thought I was pitting as a result of them not being used? But maybe not. They were mintex from amazon. But how genuine they are I don't know. I need to get it on rollers if I can. Nobody think it's the bias valve then? Quote Link to comment Share on other sites More sharing options...
dailysleaze Posted January 15, 2015 Share Posted January 15, 2015 I had this exact problem, and unfortunately never got to the bottom of it. (I replaced the axle before I worked it out) The previous discs: The new discs: I rebuilt the calipers with new stainless pistons and used new pads, but it was starting to happen again after 4 months: My brakes were never that good, and since the new axle they're still the same. The only bit of the braking system that now hasn't been replaced is the master cylinder. I do have stainless flexi hoses on the rear. Quote Link to comment Share on other sites More sharing options...
Souster Posted January 15, 2015 Author Share Posted January 15, 2015 I had this exact problem, and unfortunately never got to the bottom of it. (I replaced the axle before I worked it out) The previous discs: Imgp3531_web.jpg The new discs: web1.jpg I rebuilt the calipers with new stainless pistons and used new pads, but it was starting to happen again after 4 months: web2.jpg My brakes were never that good, and since the new axle they're still the same. The only bit of the braking system that now hasn't been replaced is the master cylinder. I do have stainless flexi hoses on the rear. That's exactly how my rear discs look on a good day. Interesting that you've replaced everything also with no luck. Has yours got a bias valve? It wouldn't be these braided rear hoses would it? Mine are new though. When I was bleeding the brakes, the flow to the rear was less than the fronts. They still aren't right though. I wouldn't mind if I hadn't spent a small fortune on them. The only thing left for me to replace is the bias valve and vacuum pump. So its one of the two haha Quote Link to comment Share on other sites More sharing options...
dailysleaze Posted January 15, 2015 Share Posted January 15, 2015 No bias valve. The replacement axle doesn't have this problem. It has about 70k on the discs and calipers, and everything else in the system is the same as with the previous axle. I did wonder that it was the calipers Quote Link to comment Share on other sites More sharing options...
Souster Posted January 15, 2015 Author Share Posted January 15, 2015 No bias valve. The replacement axle doesn't have this problem. It has about 70k on the discs and calipers, and everything else in the system is the same as with the previous axle. I did wonder that it was the calipers Now that's interesting. My calipers are new 6 months ago, bearmach branded. Looks like I might have to live with it Quote Link to comment Share on other sites More sharing options...
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