Brake Question.

greyhoundjake · Dec 24, 2010

Happy Christmas to all! Having some trouble getting my 2001 TD5 Defender 90 through its DOE test (3rd time!). Basically its failing on insuffecient braking pressure, theres new pads on rear and a new calliper so i suspect the problem is in the hydraulics. When I tested it originally it scored 54/55% for braking effort. An ex-Land Rover mechanic suggested weighting it may improve the figure so I put over 300kg on it to bring it to the legal gvw weight of 2400kg, tested it again but then scored 47.5/55%! The test technician claims that the jeep is not "sensing" the load and therefore not adjusting the braking efforts accordingly, otherwise the overall effort should have improved. My question is, does the Defender have any type of load sensing valve or equilisng valve that pressure to either front or rear depending on load? If so, where is it?

Thanks in advance.

wiltshire landyman · Dec 24, 2010

i think the problem lies with the tester calling the defender a "JEEP"..its just ****ed of with him

greyhoundjake · Dec 24, 2010

Just to set the record straight I call it my landy, and was merely quoting the tester when said landy was refered to as the 'jeep'!!

wiltshire landyman · Dec 24, 2010

try shifty on ere hes yr man who is the all knowing about the td5

jamesmartin · Dec 26, 2010

calipers should really only bee changed in pairs like discs and pads ,is your brakes system abs ,on alot of vehicles pressure to rear brakes is reduced through a valve as during braking the back brakes would lock up as weight goes forward, with some vans this reduction can be self adjusted depending on load ,you dont have one of these you need to check pipes especially flexi,s as these can swell up inside restricting fluid , your master cylinder works front and rear brakes seperatley with part closest to servo working front brakes and forward part operating rear , but if one of these fails both brakes will operate with reduced effeciveness ,how have your brakes been tested

greyhoundjake · Dec 26, 2010

yeah only changed the one calliper as it was seized, then changed all the pads on that axle so should be ok. And its not an abs model. Well all the pipes and fittings appear to be ok, no leaks or weaps, theres fresh brake fluid in it, its been bled and thers a good stiff pedal and thats what made me think it could be the hydraulics itself. I was told that there is an 'equalising valve' in some Defenders and that they are prone to fail but can't find any refeerence to such a thing anywhere! In any manuals or forum etc.!
Thanks.

jamesmartin · Dec 26, 2010

its all done in the master cylinder ,how did he test your brakes ,do they feel normal,does pedal feel to hard to press

greyhoundjake · Dec 31, 2010

jamesmartin said:
its all done in the master cylinder ,how did he test your brakes ,do they feel normal,does pedal feel to hard to press

They were tested on a single axle roller rig (probably should get them to do it a different way). As for the brakes they feel fine, have a good firm pedal but not too hard or too soft and perform fine.

jamesmartin · Dec 31, 2010

did they remove props as permanent 4wd shouldnt be done this way ,they should know better thats probably why results were poor do they feel good can you lock wheels but not too easily, it can cause serious damage to your drive train

sypher · Dec 31, 2010

jamesmartin said:
did they remove props as permanent 4wd shouldnt be done this way ,they should know better thats probably why results were poor do they feel good can you lock wheels but not too easily, it can cause serious damage to your drive train

It depends on the type of rollers , some are designed for 4x4s by running the other side in the opposite direction and vise-versa .

Failing that type they should use a TAPLEY meter .

greyhoundjake · Jan 4, 2011

sypher said:
It depends on the type of rollers , some are designed for 4x4s by running the other side in the opposite direction and vise-versa .

Failing that type they should use a TAPLEY meter .

Rang the test center a few minutes ago and was talking to one of the testers. Apparently they use a contra-rotating single axle roller rig and he assured me that it won't cause any damage to the transmission and its suitable for Defenders (says he has tested many a Defender on that same rig.) Rang my local dealer as well, apparently there is a load sensing valve somewhere around the back axle so am just gonna get under and investigate!

Bromsgrove Defender · Jan 4, 2011

greyhoundjake said:
Rang my local dealer as well, apparently there is a load sensing valve somewhere around the back axle so am just gonna get under and investigate!

When you find it take a photo of it and post it on here........

Along with a photo of the Diff lock adjuster

tottot · Jan 4, 2011

Single roller testers are fine just so long as the test is done at low speed [less than 20 on speedo].

greyhoundjake · Jan 4, 2011

Bromsgrove Defender said:
When you find it take a photo of it and post it on here........

Along with a photo of the Diff lock adjuster

Managed a few photos, sorry they're not great!

Pic 1: Is this some kind of Bias valve that sends unequal pressure to front or rear?? Its below and to the right of the servo (when looking from engine bay).

Pic 2: View of same valve from underneath.

Pic 3: View of another valve above rear axle. Not sure if this would likely give trouble? Is it a two pressure 'and valve'??

Any positive ID would be much appreciated!!

Bromsgrove Defender · Jan 4, 2011

greyhoundjake said:
Managed a few photos, sorry they're not great!

Pic 1: Is this some kind of Bias valve that sends unequal pressure to front or rear?? Its below and to the right of the servo (when looking from engine bay).

Pic 2: View of same valve from underneath.

Pic 3: View of another valve above rear axle. Not sure if this would likely give trouble? Is it a two pressure 'and valve'??

Any positive ID would be much appreciated!!

Yr right about the bias valve.

Yr Landy has ABS doesn't it? thats what that other "valve " is there are sensors on the hubs and on the brake lines front and back, left an right .

I'm still not convinced they're load sensors tho.

andy mcd · Jan 4, 2011

The 3rd one is a spliter or Y piece, the 1st one is the bias valve between front and back. I had a problem with a compensator valve on my van a few years ago (adjusts for load) when that failed the brakes at the rear didnt work,

I dont know much about TD5's but on any other braking system i would be curious about the master cylinder thats what generates the pressure, When you press the pedal down does it after a few seconds let you push it further ?? If so could be worn seals in the master cylinder allowing fluid back into the reservoir. Or if thats ok it could be the bias valve, it might be resticting the pressure to much and not letting enough through.

greyhoundjake · Jan 5, 2011

Thanks for the response. Nearly sure theres no ABS, no sign of any sensors or wiring on the hubs. Not on my spec sheet either. Besides if I did im sure it would have given me trouble by now!! Pedal seems fine, its firm and not spongy at all. So I'd say the bias valve is probably the culprit?

Bromsgrove Defender · Jan 6, 2011

greyhoundjake said:
Thanks for the response. Nearly sure theres no ABS, no sign of any sensors or wiring on the hubs. Not on my spec sheet either. Besides if I did im sure it would have given me trouble by now!! Pedal seems fine, its firm and not spongy at all. So I'd say the bias valve is probably the culprit?

With no ABS then as has been said before that other "valve" is just a connector.
IMHO like you say, the Bias valve is the most likely culprit.

Landy-Pilot · Jan 6, 2011

My 300tdi 90 vans brakes seem to require a lot of effort from me compared to what I remember my dads 200tdi 110 needed. Am I likely to have a similar problem? I am replacing all my discs and pads all round at the weekend as there now pretty knackered but they seemed to require pressure even when they were fine.

Bromsgrove Defender · Jan 7, 2011

Landy-Pilot said:
My 300tdi 90 vans brakes seem to require a lot of effort from me compared to what I remember my dads 200tdi 110 needed. Am I likely to have a similar problem? I am replacing all my discs and pads all round at the weekend as there now pretty knackered but they seemed to require pressure even when they were fine.

How much weight you got in the back ??

Could be the bias valve but is your servo working properly ?

I'm fairly sure there's a thread on here of how to test if your servo's working or not.

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