Member Since: 07 Jun 2021
Location: France
Posts: 8
Intermittent brake drag
Hi, I would like to ask for input please on what might be causing intermittent brake drag on my auto 2.7 disco 3 2005.
Background
Purchased the car 2 months ago, 209000 miles on clock
I proceeded to address any issues and start preventative maintenance
Cam, fuel and all other belts changed + water pump
Upper rear suspension arms changed
All lower suspension arms changed
Auto gearbox double flushed, new pan cover
Diff oils changed
All filters changed, engine oil changed
Rear propshaft changed
New tires all round 265/70R17 115T GRABBER AT3
Alignment done on hunter equipment in tight tolerance mode
At this point the car drove fine, until on a long gently downhill straight road towing a trailer, when I applied the brakes, the pedal went very firm and it was very difficult to stop, a two feet on the pedal job.
After researching what the issue might be (at the side of the road) I found the 'oil in vacuum' issue, checked my vacuum line and yes there were traces of oil.
I could have approached LR about the recall fix, but the car is in France (RHD) on French plates and I couldn't face the drama I expected I would get from LR over a 2005 car originally purchased by someone else in the UK, yes I know they should still cover it, but I wanted it fixed.
So I purchased new vacuum pump, master cylinder, RRS upgrade servo and I also got new front hubs and I asked the mechanics (indie mechs, English working in France) that were going to do the work to supply new front disks and pads while they were doing the work if the car needed them. The disks and pads were getting low, so they changed them as well.
Now the fun really started
Driving the 30 miles home from the garage the car felt sluggish at times, but it didn't click something was wrong.
The next day I drove it 7 miles and the brakes started to progressively increase in drag to the point the car was too dangerous to drive.
The front wheels were hot, stupidly I didn't check the rear wheel, I was focused on the smoking front ones.
I had the car trailer-ed to the mechanics, they could not find fault, they re-bleed the brakes, took it for a short run and it drove fine, they suggested they take it for a longer run and sure enough after around 6/7 miles the brakes started to really lock on.
The mechs felt that there was a building up of pressure in the braking system, potentially being a faulty new master cylinder not allowing fluid to return.
Luckily, me being the idiot I am, I ordered two master cylinders by mistake and so I had a spare.
BTW all parts were ordered through the site sponsors Advanced Factors and all parts used are OEM the brakes being TRW.
A new master cylinder was fitted, same issue as before, pressure build up, brakes drag getting increasingly worse.
It was discussed that possibly the old flexi brake hoses can cause issues, so to avoid any doubt and due to the hoses age all were replaced, front and rear. This made no difference, but at least the hoses are confirmed new and all good for a few years again.
The mechs then considered the new servo upgrade from the RRS, and tried placing a 2mm spacing washer between the master cylinder and the servo, to test if the servo rod was set wrong, whilst this did ease the brakes binding, it was found that the brakes were still being applied, just without as much servo assistance.
So the washers were removed.
The mechanics are good 'normal' mechanics, but are indies and have no LR dealer experience, they have the electronic tools and are good guys. There is no alternative where the car is, no LR dealer etc it is in very rural France, 300 miles to closest LR dealer and I do not hold much hope that the French LR dealer would be too interested in trying to help apart from trying to get me to trade it in..
So while the mechanics were discussing and researching I asked to drive the car again as I wanted to try and gain as much insight as I could before posting here, I tried driving with my left foot under the brake pedal forcing it up (laugh sure, but try anything and then eliminate I say) anyway, the pedal didn't feel like it moved much more than a mil or 2, but there was no brake drag while driving like that!
Now having had the issue for a while I felt that I might be dreaming and clutching at anything that might be a fix, so to be sure I was right and the brakes were no longer binding I drove around for 15 miles watching the av MPG, and not only did the car feel normal (with my foot under the brake pedal forcing it up) but the MPG increased by 3 mpg over the 15 miles and was rising.
Before the brake issue the MPG was steady at 30, after the issued appeared it dropped to 21.9
In an attempt to eliminate as many factors as possible, I have ordered new OEM calipers, carriers, slider kits and a new brake light switch.
These parts should arrive next week and will be fitted in the order of brake light switch first, then test and see if any change, then if the issue is still there the calipers, carriers and sliders changed.
So after my marathon of background information, has anyone experienced this type of brake issue?
Could the issue be related to a faulty brake light switch?
Does the brake light switch communicate with the ECM in a way that could apply the brakes electronically in anyway?
I realise this is a big ask to try and diagnose like this, but please remember the location of the car and what's available there.
I want to say that Advanced Factors have been a good supplier, I have been in contact with them to discuss any potential problems that they are aware of, their response has been very rapid and they have also contacted TRW, so I cannot fault AF. The chap I have been in contact with at AF did say it was like trying to solve a murder without having a body, but that's life sometimes, if owning a LR was easy, everyone would have one
Any input would be appreciated.
Thanks
Last edited by Lumberjackinfrance on 15th Jun 2021 4:22 pm. Edited 1 time in total
Could the issue be related to a faulty brake light switch?
Does the brake light switch communicate with the ECM in a way that could apply the brakes electronically in anyway?
I think the brakeswitch could be part of the problem, not sure about "all" of the problem.
The brakeswitch has two circuits, one normally-open and one normally-closed. Either can go faulty. On mine it occasionally meant braking did not kill the revs, so the car just fought the brakes and moved slowly forwards ... not good when you've stopped to let oncoming traffic get through a tight gap.
The car DOES apply the brakes for you ... Hill Decent Control and some of the Special Programs. But certainly on mine, you know it's using HDC as it's noisy - like driving down a cobbled road at speed kind of noise.
Before throwing all your money at it, the brakeswitch is worth a go ... as is the notion of only changing one thing at a time so you know what fixed it !.
Dean
====================================
2011 D4 XS - OBD port protection, RLD spare wheel protector, All LED interiors lights, Timed Climate enabled, iiD tool paired.
2011 D4 Landmark - Stolen from same dealer before I paid for it
2011 D4 GS - Stolen whilst at dealer ... All LED interiors lights, DRLs, Spare Wheel protector.
1996 300Tdi - Eaten by tin worms
15th Jun 2021 11:12 am
Lumberjackinfrance
Member Since: 07 Jun 2021
Location: France
Posts: 8
Thanks Dean, I was of the same opinion, that the brakeswitch is a cheap and easy swap, do that next, see what happens before doing anything else.
It does feel like the brake drag is cycling when it does it, but it could be warped disks or something making the brakes pulse, I have requested the mechanics check the brake disks to see if they are still true or if they are warped.
One step at a time.
I will report back on this thread regardless what happens.
Thanks
Lumber
15th Jun 2021 1:03 pm
aja4x4
Member Since: 14 Apr 2019
Location: Westbury
Posts: 2459
You also need to check your servo for oil contamination, if oil gets into the valve assembly it can cause the brakes to stick onAndrew
D3 2.7tdv6 2005
D4 3.0 SDV6 Commercial died and gone to LR heaven
D5 3.0 SDV6 HSE
15th Jun 2021 1:28 pm
rrhool
Member Since: 28 Aug 2014
Location: Norfolk
Posts: 4405
Warped discs are not uncommon.
Flexi brake hoses have been known to collapse internally, allowing the braking pressure to flow through to the caliper, but not to return so easily. Might be worth a check.Richard
D3 SE 2007. Triumph 2.5Pi 1973. Ferguson TEA20 1948.
Discovery 2 4.0 ES 2001- Gone
Discovery 1 300Tdi ES '95 - Gone
Range Rover Classic '79 - Gone
15th Jun 2021 1:30 pm
Lumberjackinfrance
Member Since: 07 Jun 2021
Location: France
Posts: 8
Thanks for the input so far.
I forgot to add that all flexi brake hoses were changed. I will edit my original post to show these were changed.
The servo is brand new, as is the vacuum pump and the vacuum pipes, I will have it checked for oil though just to be safe.
Will update if the disks are worn.
Thanks
Lumber
15th Jun 2021 4:14 pm
Lumberjackinfrance
Member Since: 07 Jun 2021
Location: France
Posts: 8
Latest with the intermittent brake drag on my disco 3.
New brakeswitch has been fitted - brake pedal was not moved during the installation, seemed simple enough, old one was turned until it clicked loose from the bracket, new one was inserted and twist locked into place.
The car was driven with the electronic diagnostics running live data to a mechanic in the passenger seat.
The brake pressure readings were either 14psi ish or 19psi ish when we started driving, with a firm push on the pedal for a sharp full stop bringing the pressure up to around 1000psi, when the pedal was released the pressure stayed at around 24psi and did not drop, the car felt like it was suffering brake drag and the mpg display showed increased fuel usage.
While the mechanic was watching the live data I put my left foot under the brake pedal and 'lifted' the brake pedal, the brake pedal does not actually move upwards like it is moving the servo rod, it just feels like the pedal or pivot point is flexing, it is a tiny amount and need a firm foot to do it. The result of 'lifting' the brake pedal on the live data is the brake fluid pressure drops instantly to the 14/19 psi range and the car instantly feels like it drives free of any brake drag.
The brake fluid pressure does not increase as you drive (after the pedal lift) and even after applying the brakes it is only on occasion that the fluid pressure starts to stay higher than the 14/19 range and if the pressure does stay high, then a slight bump up on the brake pedal results in the pressure reverting to the normal 14/19 psi.
So, the issue is getting closer to being resolved, but it's still miles away.
Could it be the pedal is not close enough to the brakeswitch and therefore the pedal is not quite allowing the switch to make a proper regular contact when there is not foot on the brake pedal?
Does anyone have information on how far in the switch should sit on a normal set up?
Is the switch usually fully depressed when the brake pedal is in its usual position?
Could it be a faulty connection that is corrected when I am lifting the brake pedal, the brakeswitch bracket does seem to be a flimsy item that does flex.
I am open to ANY suggestion to try.
I have a full set of front calipers and slider kits etc ready to fit, in case that may be the issue, but at this stage it is looking more like an issue in the pedal area.
Remember that a new OEM RRS brake servo was fitted as part of the brake system repair / recall issue, could the RRS brake servo be preventing the brake pedal to return to normal height, thus triggering the switch issue? Anyone had any issue with that before? Although when you try and lift the pedal, it does not feel like its actually moving the brake servo rod, surely it could not be so finely tuned that a fraction of a mill movement on the rod would have such an effect.
I have read of intermittent disco 3 brake issues previously, yet no one has written about a solution, all of them were traded in for new LRs, so the problem was passed to a dealer, who clearly do not share the information publicly, if they found a fix at all.
I will keep going, I will share what I find, I hope I can help others that may come up with the same issue.
I am no expert, assume I know nothing and explain if you feel something has been done wrong on my car please?
Can you see the pivot for the brake pedal? Has it worn and changed the angle of the arm so it's not freely returning to top of it's travel?.
Dean
====================================
2011 D4 XS - OBD port protection, RLD spare wheel protector, All LED interiors lights, Timed Climate enabled, iiD tool paired.
2011 D4 Landmark - Stolen from same dealer before I paid for it
2011 D4 GS - Stolen whilst at dealer ... All LED interiors lights, DRLs, Spare Wheel protector.
1996 300Tdi - Eaten by tin worms
19th Jun 2021 1:20 pm
jenseneverest
Member Since: 12 Jun 2017
Location: somewhere
Posts: 769
before changing other parts, i would concentrate on what you have changed already.
Your pressure readings are interesting, in that you can see there is a difference when you feel the brakes binding, all be it a relatively very small difference. And you can make the pressure return to "normal" with your foot trick. indeed it points to the pedal or related parts.....
Don't suppose you have the old master cylinder to try ??
May be worth jacking up all 4 corners and seeing if all 4 wheels bind or if it is just one / both fronts / rears. ?
I will see if i can get the pressures up on my diag later today just for comparison.
19th Jun 2021 1:52 pm
Flapper
Member Since: 04 Feb 2015
Location: Gloucester
Posts: 329
I had a similar issue short trips no problem go a few miles further car seems get slower.
If I walked round the car after a long trip you can feel the heat on your legs.
My dragging brake was rear drivers side I changed the calliper and noticed when bleeding the new calliper that no air went up the pipe when the pedal was released even though the pipe was out of the jar.
I replaced the short metal pipe on the arm and both flexi hoses the one on the calliper and the one at the back where it joins the metal brake pipe.
The issue was the one at the back. It was like a one way valve.
All sorted no goes like rocked and no burning brake pads.
Last edited by Flapper on 21st Jun 2021 10:04 am. Edited 1 time in total
20th Jun 2021 10:09 am
ronnie12342003
Member Since: 20 Jun 2016
Location: london
Posts: 55
could be the flexi pipes are collapsing internally when hot
20th Jun 2021 11:34 am
jenseneverest
Member Since: 12 Jun 2017
Location: somewhere
Posts: 769
just to add the live data values of the pressures look similar to yours, so no help there....
The brakeswitch is also visible with live data.... not sure that is of any help either
20th Jun 2021 1:13 pm
Lumberjackinfrance
Member Since: 07 Jun 2021
Location: France
Posts: 8
Thanks to everyone for all the effort in replying and the advice.
I didn't do anything with the disco today, I needed to take a day away from it....
To cover the replies
My plan is tomorrow to inspect the brake pedal, pivot, how the brake pedal meets the brakeswitch and to hopefully take some clear photos to post here for comparison.
A new master cylinder was fitted as part of the recall fix, then when the issue of brake drag / pressure build up was spotted on the test drive another new master cylinder was fitted, but the result was the same. Both master cylinders were new OEM TRW from Advanced Factors, it is highly doubtful that two new OEM cylinders are faulty, I do not have the old master cylinder to try.
After I inspect the pedal area tomorrow, I will take the disco for a drive, if the brake problem appears I will stop the car and check each brake disk and caliper with a temp gun and record the temps and report back if it is all four or which brakes are dragging.
All flexi hoses have been changed for OEM, it is def the front calipers that drag as they get very hot quickly, uncertain about the rears, will confirm tomorrow.
I will use the live data to try and monitor the brakeswitch while its being driven and report back here tomorrow.
With the brake fluid pressure build up (and the effect being the brake drag) being able to be dropped to "normal" pressures by "lifting" the brake pedal a fraction, I am considering a few possibles:-
1. Either the pedal simply is not high enough to allow the brakeswitch to either make or break contact when the brake pedal is supposed to be in the not used position.
2. The brake pedal is so close to being in the right spot in relation to the brakeswitch but not quite, that the contact made (or broken) is intermittently either making or not making contact?
3. There is a break or loose connection in a wire somewhere along the switch connection cables, which when I lift the brake pedal corrects itself enough to trigger the ECM into thinking the brakes are off and pressure should be released.
4. The servo rod is being prevented by some means in properly returning, thus keeping the pressure on, and my lifting the brake pedal jerks the rod enough to release the pressure.
If I was not certain that the foot under the brake pedal, lifting it, made an immediate reduction in brake fluid pressure, then I would be considering other areas - but as witnessed by two people studying the live data, when the brake fluid pressure builds after braking, or doesn't release - as soon as the brake pedal is lifted a fraction, it is instant and the brake fluid pressure drops to "normal".
It makes sense to continue to look at the brake pedal area for ether mechanical or electrical issues ?
If anyone has the time could you please have a look at the disco 3 brake light switch, where it meets the brake pedal, when the brake pedal is in the off position, how far in is the brake light switch plunger depressed? Is it pushed in all the way by the brake pedal when your foot is not on the pedal, or how much of the plunger is showing please?
I cannot remember if the brake pedal is sitting lower than it was before the new servo was fitted, so cannot tell if the pedal height is correct or not.
I do appreciate the help and input from this forum and I am trying to document everything as clearly as possible in case others encounter a similar issue - assuming I find a solution
20th Jun 2021 5:31 pm
Flapper
Member Since: 04 Feb 2015
Location: Gloucester
Posts: 329
LR-Time Youtube channel
If you go on youtube and look for LR-time a German man does this video all abut the brake light switch. He explains how it works how to remove it and how to install it and something about how to set it up.
I think he even takes it apart to show you how it works.
He speaks English better than us Brits..... he has loads of videos on how to change/check and fix everything.
21st Jun 2021 10:01 am
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10368
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... not good when you've stopped to let oncoming traffic get through a tight gap.
... All LED interiors lights, DRLs, Spare Wheel protector.
