Brake bias valve?

[richlaz]

Got my T25 back from the garage today... it passed the MOT, with only a steering rack boot to replace, so I'm well happy with that!

One of the mechanics mentioned that there is a slight problem with the rear brakes, that they are "too effective" and can even "lock on" which is slightly worrying, I've never actually noticed this.

He said that the rear brakes should be doing about 20% of the braking, but it's more like 40%. He said that he couldn't fail it because the brakes physically work really well, apart from this.

Apparently there is a "brake bias valve" which I believe "shares" the braking between the front and rear. He said this could be sticking/jammed etc. and may need cleaning out.

Has anyone had any experience on these brake bias valves? I don't even know where to start on this job... not even sure where it is sutuated, suppose I'd have to just follow the brake lines?

Any help/advice would be appreciated

Cheers, Richard

[leebo]

above the rear axle somewhere it will have a small spring system with brake pipes going in and out when the rear has more weight in it put more power to the rear brakes give it a good clean with wd and a good wiggle should start to move freely then give it a good dose with spray grease should be ok for a few years then without worrying about it

[Hacksawbob]

Heres a replacement.
http://www.brickwerks.co.uk/index.php?p ... t&Itemid=3

we had a bit of a discussion a while back about it, I think someone was going to dismantle one (Billy numbers?) anyway its just a metal ball in a cylinder installed at a 30 degree angle. when you brake harshly the ball moves forward blocking the REAR brake pipes and sending the braking force to the FRONTS. It's all in the Bentley manual. section 47.8
https://club8090.co.uk/forum/viewtopic.php?f=42&t=99764

There is a pressure test where you tilt it forward and test the standard test is 50psi to both brakes with the tilt (harsh braking) pressure should be 100psi to front and 55-65 PSI to the back. But the disks are more efficient than the rear drums so they will be handling the majority of the braking anyway. The rears could maybe do with a service to make sure they shoes are returning away from the drums perhaps.

[Hacksawbob]

above the rear axle somewhere

No it's not. It is at the front end of the van Offside on a LHD. I am guessing it is NS on a RHD.