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Gareth

Brake proportioning Valve

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i'm currently reading a book called Volkswagen Sport Tunning for street and competition.

This has mentioned the affects on the Brake proportioning Valve after lowering the car.

saying that, Quote: You fool the the system into thinking that it has a lot of weight in the trunk/boot of the car, making the rear brakes lock up too soon.......

Has any1 had these symptons happen to them :?: or is this mis-infomation :?:

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It's not mis-information, that's true. That's a description of what *can* happen, but it's pretty rare.

You *should* get the valve adjusted for the new suspension drop when you lower it though...

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You only need to tamper with the brake valve if you go over the top with lowering. Moderate lowering won't affect the rear brakes at all.

 

K

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It's correct.... After lowering the car, you need to re-set the bias valve else you'll end up with too much brake bias to the rear of the car making it unstable (rear end locks up before the front)....

 

It's the same on most VW cars... It's easy to do, but you do need either a pit, or a set of 4 post lifts so you can get under the car while it's on it's wheels... IIRC you just undo one nut, move the adjuster valve to it's upper position and then tighten the nut again... 8) Job done...

 

It makes one hell of a difference if you've lowered your car a lot and have to hit the brakes hard... :|

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Anything lower than about 25mm and you should adjust the rear brake compensator.

 

The normal reason people don't find problems with locking rear brakes is that the rear callipers are usually that caked in crap thet they are partially seized!

 

With nice and free callipers and decent discs and pads, you can quite easily lock the rear end if you brake too deeply into a corner.

 

I don't believe the ABS equipped cars have this valve though, do they?

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I don't believe the ABS equipped cars have this valve though, do they?

 

ABS G60s do, dunno about the rest of 'em, but I can't see why not... 8)

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As do VR6s....

 

Hmm...odd.

My last Golf had one...an early 8v with no ABS...

Can't ever remember seeing it on the current Golf and it's got ABS...

Must have another look.

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Definitely has got one mate......the valve and spring system + distribution block are in the usual place in front of the nearside rear wheel.

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G60's definately got one too... I''ve still got the scar on my wrist where it fought back as I was trying to free it off when it seized up... :roll: :oops:

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Read Kevhaywire's post.

 

To get the adjustment about right, set it so that if you stomp on the brakes in a straight line on a dry road (difficult at the moment I know) the rear end is on the point of skidding, but doesn't actually get out of line.

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Oh - btw.

 

To do this, you need the abs switched off. Disconnect the plug for one of the front wheel sensors where the cable passes over the top of the front strut mounting.

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Thanx 2 every1'nz responce to my post :)

 

in the book im reading it says to do the car park braking test :wink: and in the bentley manual it has a stand with 2 pressure gauges connected to left front and right rear brake calipers. in the manual with brake pedal pressed it gives the value of the pressure that should be obtained on the gauges...... there is a little more to it but thats the long n short of it...... oh BTW thats on cars without ABS.....

 

So i would think that the latter method is more accurate.

 

What do u guys think is the first method just as affective as the second...... or is it worth paying some1 with the equipment to ajust the valve after lowering :?: ..... after all brakes are very important especially at high speed braking :mrgreen:

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The way I've always set 'em is to measure how far the valve is moved when there's no weight in the car... Lower the car and take it around the block so the suspension levels out a bit, then put the car on ramps (or over a pit) so the weight is always on the wheels and reset the valve back the same measurement it was on before it was lowered...

 

The way to work out how to measure it is while it's on the ramps, get someone else to get into the boot while you watch for which way the valve moves... 8)

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