brake proportioning valve

My car had the SVA test earlier this month. It failed on a few points, one of which was incorrect brake bias(too much to the rear). I have not adjusted the brake bias valve since I have had the car and so had left the valve in its locked position. It is my understanding that clockwise turning equates to more rear bias.This would mean at the time of the teat the valve was at its least rear bias position. This is a little worying, as now I have to adjust the bias (need more at the front). The knob on the valve can only go clockwise as it is fully out. This would mean more rear bias!. Is my bias valve faulty?.

Clockwise turning on my valve results in less rear bias.

The other thing to keep in mind is that in the main, a bias valve does not adjust the front rear ratio as such. These valves actually have two fixed ratios and adjustment merely changes the point at which one ratio kicks out and the other kicks in. Effectively, you are selecting the pedal position where you want the ratio to change.

See figure C Here

Thanks Chris. I will take the car to a car park and adjust the brake bias valve until the front wheels lock up just before the rears.

I have heard that if you set your brakes so that the front lock first and drill and split pin the setting (Through the shaft) this will then pass SVA as not adjustable.

If the pin happens to fall out afterwards then who at the SVA center will know?

Ian

Ian,my examiner did not ask about any brake bias adjusting devices and I did not volunteer the information either. He may have choosen to ignore the bias valve.

Please check your email, you have my 2c worth Good luck with the SVA.

Cheers