SLROC Forum

Vehicle is a Defender 90 TD5 (2003), with disc brakes all round but without ABS.

The possible problem (as I've been told it is normal), is that I am unable to get the rear brakes to lockup the wheels when driving normally and breaking hard, even on very slippery surfaces.

I have had the brakes tested on a VOSA brake testing rolling road with the rear prop disconnected and got the results as follows:

Max Force
Front N/S 336 kgf
Front O/S 288 kgf

Rear N/S 143 kgf
Rear O/S 141 kgf

The brake tester center told me that this would be a FAIL for an MOT if the vehicle was tested that way (The Defender is tested using a footwell meter normally and passes).
The rear wheels never locked up on the rollers. (The fronts did and pulled the car off the rollers).

I know the front brakes should by design lock up before the rears for safety, but I am unable to get the rears to lock up at all, even on wet grass when they should lock up very easily (I would think).

The pads seem fine (plenty thickness left), and the rear calipers also seem fine - pistons move freely in and out. I think the discs are OK too. The system has been fully bled and the pedal feels fine.

Can anyone give any advice on this, or just confirm for me that under extreme braking on slippery surfaces I should be able to get the rear wheels to lockup.

Thanks in advance
Marcus

Do the defenders have a load sensing valve for the rear brakes? if so and this was disconected or seized then there would be very little pressure going to the rears. Just a thought.
Drew.

Check to see if there is a bias valve for the back brakes. This is to put more pressure on the fronts where it is needed, it may be sticking or faulty.

Check all the flexis too, if one is expanding a lot that will waste pressure.

Thanks for the replies so far.
In answer, yes it does have a brake bias valve, fitted to the bulkhead drivers side. This was my thought too - the lack of pressure getting to the rear cylinders.
The hoses are fairly new (1 year old) braided Goodridge hoses so I think they are OK - the brake pedal pressure feels fine - when engine off pedal goes rock hard after two pumps and does not sink.

The "problem" I have is some people seem to just say "that is normal" or "its a Land Rover thing", but I dont really accept that, surely I should be able to lock the wheels in an unladen 90 on a very slippy surface when I stand on the brakes.

Isn't that supposed to be the point of load sensing and bias valves - to prevent lock up    Whe the vehicle is unladen, pressure to the rear is restricted to prevent overbraking, and as the weight is piled on, more fluid is allowed through to increase braking.   When I served my time as a mechanic we were always told that if the back brakes locked it could spin the vehicle.

I can't really relate the brake readings you gave to how efficient your braking is - but they all seem low to me - perhaps someone who has knowledge of readings off brake testers might be able to help

When you have went to the length of removing the rear prop to have the roller test - do you feel the brakes are rubbish or just think they're not right because the rears don't lock

Its also a fairly newish vehicle - shouldn't it have abs?

Duncan

Duncan - on Defenders at that time ABS/Traction Control was an option. Sandy.

Sandy

That's interesting to know as a I genuinly didn't know  Education - another benefit of the forum!

Duncan

I can confirm the lack of ABS etc. on some vehicles.

My 03 90 did not have ABS or traction control, however it does show up as not functioning if you plug in a Nanocom.

Tommy

I have a set of braided hoses fitted and had to return one of the fronts as 10 months the internal wall closed up and stopped the fluid passing thru.
Drew.