Brake inefficiency

[bluequattro]

Took car for test
Failed on rear brakes (caliper dragging and worn pad)
Freed caliper off. Fitted new pads
Inefficiency 44% now.
Fail
Could it be lack of bedding in?
Or more likely big calipers on the front? (BMW Brembos)
Retest up by Friday.
Tester said drive home with handbrake on a little.
Couldn't jiggle the numbers for me.thats all its failed on now.
Anyone know what numbers rear brakes should pull? ( just in case I can persuade him do a a road test on the brakes)

[RichLV]

Bleed the whole brake system for starters. Starting with the farthest wheel from the master brake cylinder and move to the closest one by one. Did the handbrake test succeed (if it was done)?

[bluequattro]

It was parking brake that failed. Sorry didn't mention that first
Fronts were fine

[mike74]

I occasionally drive with the handbrake on to improve it as your mechanic suggested. I don't know if its just the relevant surfaces glazing or getting crud on them but driving with the handbrake on definitely improves its performance...just don't do it for too long in one go obviously...

[AndyP]

How many miles had you done on the new pads before re-testing?

[rynaqui]

What sorted out my handbrake issue wasn't new handbrake cables, but new calipers unfortunately. Bloody thing grips though now!

[bluequattro]

How many miles had you done on the new pads before re-testing?

About 10! Mostly dual carriageway too.
Car had no test so difficult to bed in pads without doing a few rebel runs.
Just put handbrake on and tried to push the car. Three of us couldn't shift it.
I think I'll just have to do a few SAS manouvers and go out after dark to bed them in a bit more.
Can't think of anything else bar new calipers, but they work on foot brake.
This is what comes of buying cars that have stood for a while.
It defo goes better than it stops though.

[AndyP]

I'd say do more miles, especially if you've put in new pads and not discs, the pads will have to wear to the grooves on the old discs

[bluequattro]

Discs look virtually new with no lip or scoring.
I think it's due to lack of miles still.
May have to go the very long way round to test centre.
Any excuse lol

[Error404]

Sounds reasonable. "I'm on my way to the test centre **** stubble"

[bluequattro]

And another thing.
D other people have their quattros tested on 2wd brake rollers ?
I thought it wasn't supposed to be done that way?
Spoke to mate who is a tester and he said he uses a decelerometer to test 4wd cars (and he told me off for not taking it to him- if it fails after bedding in ill go there)
On road brake efficiency seems better than my other cars, yet it failed test
Results were
Front 240 and 200
Rear 80 and 90
Park brake 100 and 141

[Greg_S]

Yes needs to be tested on a 4 wheel or use the decelerometer methd

[bluequattro]

Yep. Just looked at online MOT manual and screen shot it to show tester to ask for the road test
If he says no ill ring the ministry to complain

[Error404]

Give him a kicking for raping your centre diff

[bluequattro]

Woo hoo!
25 miles worth of braking and it passed.
Cheers for advice guys
Just have to pay tax now and it's legal