load sensing brake bias valve? edit: how do i reset it?

[leigha 0]

when i bought my corrado, it was lowered by 40mm on a brank new weitec (sp?) suspension kit.

 

earlier while having a familiarising thrash, i noticed the brakes seem rather rear biased. is there a load sensing valve on these beasts that needs resetting?

[dr_mat 0]

Yes. It's attached to the rear axle beam.

[leigha 0]

thought that might be the case!

 

how can i reset it? is it adjustable?

[dr_mat 0]

Yeah, there's a special tool you can use from VW, or you can do it by eye ..

I think there's some bolts one side of the valve's arm that will slide when you release them.

You should set this when the car is standing on it's wheels, obviously, so an inspection pit would be handy ..

[double-6s 0]

Could you briefly explain this please? I don't get the general concept? Which load affects the brake bias?

 

Sorry to be stupid :)

[leigha 0]

the height of the suspension is changed by the load on it.

 

the idea is that if you have a full tank of fuel, a boot full of shopping and 2 lardy mates in the back, the suspension drops. this drop moves the linkage of the bias valve which increases the line pressure on the rear brakes, keeping the bias correctly in proportion with the weight distribution of the car.

 

the problem being when a car is lowered and the valve isn't reset, the valve 'thinks' there is 40mm worth of weight in the rear of the car and increases the pressure. the nett result being me locking the rear up very easily. resetting the valve should cure it.

hth!

[double-6s 0]

Hmmm.....

 

Can you un-reset it?

 

Locking up rear sounds good to me! :)

 

 

BTW - the height of my suspension is hardly effected at all by load - it's so fekin hard there is almost zero travel :)

[dr_mat 0]

BTW - the height of my suspension is hardly effected at all by load - it's so fekin hard there is almost zero travel :)

 

.. which is something you can't account for with the standard load proportioning valve. Ideally you'd have a more sensitive setup that detects the smaller changes in ride height ..

[leigha 0]

mine is fooking hard now too!

 

it can be adjusted i suspect but to be honest, a handbrake turn is not the best way of doing an emergency stop!

[double-6s 0]

BTW - the height of my suspension is hardly effected at all by load - it's so fekin hard there is almost zero travel :)

 

.. which is something you can't account for with the standard load proportioning valve. Ideally you'd have a more sensitive setup that detects the smaller changes in ride height ..[/quote:4bca2]

 

Is that something that is or might be available as a replacement mate?

[leigha 0]

i'll have a look at mine later or tomorrow. maybe it could be modified to work at a proportionally higher (30%) ratio?

[double-6s 0]

i'll have a look at mine later or tomorrow. maybe it could be modified to work at a proportionally higher (30%) ratio?

 

Cheers. Let us know :)

[leigha 0]

just found this thread i'd forgotten about!!!

 

still not had a proper look either!!! is the compensator mounted just in front of the rear wheel? is there one on each side? it keeps raining so i've not played under the rear of the car yet!!!!

[bcstudent 0]

No, there's just the one on the near-side.

[mgbv8mike 0]

I had a look at this valve when I fitted the rear suspension, it appears to be load sensitive rather than height sensitive, surely the momentum of the car braking determines how far it restricts pressure to the rear cylinders ?

 

A couple of tests on a straight road should determine if I have dramatically altered the bias , my MG locks its rear for Britain when I slam the anchors on, even fitting (old) mini cylinders did little good....you just have to make sure that you are pointing straight ahead when you hit the anchors in anger !!!!

[leigha 0]

i had a good look yesterday eve. i suspect it could be modified to change the rate of increase but its not going to be a quick or easy mod. for now i reckon i'll leave it!

 

which brings me to my next question...

 

how do i readjust the valve? it looks like the arm could be adjusted but the haynes jokebook (golf) says to take it to VW where they set the spring tension by adjusting the spring itself...?

 

i assume i'm really looking to effectively slacken it off but need an idea of how much...

[dr_mat 0]

I think the bit where it attaches to the chassis moves, if you release the bolts (the bolts fasten into slots, rather than holes). I can't remember exactly though ..

[leigha 0]

any ideas on how much it needs adjusting?

[dr_mat 0]

That's what the special tool from VW is for - it provides the correct alignment.. I've never seen one, unfortunately.

[leigha 0]

i wonder what vw will charge for setting mine up?

[mgbv8mike 0]

What makes you think that it needs changing ? Are your rear brakes locking up on heavy braking ?

[leigha 0]

yes!

 

driving in the wet especially is scary.

 

i lowered the ride height at the rear by another 10mm at the weekend to get it stitting level and now it's a lot worse. the rears will lock first in any situation though the fronts aren't a long way behind

 

probably doesn't help that the rear brakes are in tip top condition with new calipers and pads etc.

[mgbv8mike 0]

So what state are your tyres in.?.......they are often the problem.

[leigha 0]

they're fine. it's definately a heavy rear bias, that can be felt when braking at any speed

 

it must reckon there's about 1/4 of a tonne in the boot!

[leigha 0]

right, i've not got this sorted yet but hope to over christmas (been driving very gingerly and often sideways since my last post!!!!)

 

does anyone have a measurement from the centre of the rear hub to the highest part of the arch on a standard suspension setup? i can then use a jack to lift the rear to this height and see exactly how the valve is set. then i can try and replicate this at my new ride height.

 

i can't just assume it's 40mm as the weitec kit is rear ride height adjustable!