Unusually long brake pedal

[crazybiker]

I recently got myself a vr commodore and it freaked me out a little with how long the brake pedal travels before it does anything. The brakes still work effectively once youve used some of the pedal.

It feels like there's a huge amount of air in the line, but there's not. I bled and flushed the system last weekend. Dad says it could be a faulty master cylinder.

Any ideas?

[Not_An_Abba_Fan]

Nice sig quote

A faulty master cylinder can usually be tested by pumping the brakes a couple of times and holding the pedal down, if it slowly goes down, it is bypassing.

A test I do is to clamp each flexible line to the calipers one at a time starting from the rear and pushing the pedal down each time to see if the pedal travel improves. The one that improves the most is usually the culprit. If it improves the same amount each time, your calipers and hoses are fine.

If the pedal is still low after clamping all the lines, then there is still air in the system.

[crazybiker]

How do you bleed the ABS system on a VR?

That wasn't done. Hoping that's the problem...

[Brett_jjj]

You can activate the ABS with a suitable scantool to let any trapped air through the ABS modulator. Or, you could find a safe area where its grassy or gravel/sandy and lock up the brakes a heap of times to activate the ABS, this should let any trapped air get through to the brake calipers where it can be bled out, so, obviously you will have to rebleed them again after locking them up. At this stage, its best to have someone keep a continuous eye on the brake master cylinder fluid level, because if it gets low, it can suck in more air, which then means you will have to start all over from scratch with the bleeding process etc.

[hako]

Or, you could find a safe area where its grassy or gravel/sandy and lock up the brakes a heap of times to activate the ABS, this should let any trapped air get through to the brake calipers where it can be bled out, so, obviously you will have to rebleed them again after locking them up..

I don't think this would work Brett, it would only push the air out of the ABS pump part way along the brake line and as soon as it stopped pumping it would return to the ABS unit....but I could be wrong.