NCT Fail - Rear Brake Imbalance

[Viper]

Failed the NCT on the above in the FTO, the probalem though is that no garage can find the problem. The one suggestion I have got is that the 'equaliser valve'(?) supplying the brake pressure to the rear wheels may be shot and need replacing. Anyone ever heard of the above item??

[kevinod]

Hmmm thats normal brakes, not the handbrake, right?

Not aware of any equalizer valve on the FTO for the back brakes... there's 4 lines coming out of the brake master cylinder iirc, one for each wheel.

Whats the difference? maybe we could compare what you're getting with other NCT test results... are they both definately braking, there isn't a seized cylinder in one of the calipers? After a drive, not necessarily spirited, take a look at your rear discs, see are they both cleaned off, should both be fairly shiny.

[Viper]

Yep, normal brakes...
Both are braking, but there's a 50% difference between their stopping power. There's no noticable difference between the disks, and new pads put in about four months ago.
All I can think of is there's a warped disk which is giving an unbalanced reading, or brake fluid pressure is different between the two brakes, maybe an air lock or something.. Other than that it's going to have to be new calipers etc !

someone up above doesn't want me to get my new car !

[CJ]

Viper, change the brake fluid if ithat hasn't been done already, have the brake lines checked, worst case scenario, change the master brake cylinder - it has to be something reasonably straightforward.

CJ

[Viper]

Cheers CJ, I think thats the way to go alright... if it was caliper surely something would have been spotted seizing up by now.
I'll keep you all posted on the latest results !

[AL]

viper, the transfer valves in the master cylinder, get clogged etc, this happened to me old cyborg years ago, was cheap to rectify, got a secondhand replacement for nct. but not too sure how much fto part will cost

[Viper]

Pricey enough according to the camskill website !
One more question though about this, am I right in saying that only one pipe runs from this to the back brakes? If so it couldn't cause the imbalance... it must be whereever the pipe splits into two...

[kevinod]

I could be wrong but I'm nearly sure there are separate pipes going to each of the 4 wheels for the brakes.

[AL]

yeh, im not 100% sure ..... but i thought that a seperate pipe going to each break would make sense, but if only one pipe goes to the rear brakes try the calipers for sticking or wearing etc

[RiceRocketUk]

if I`m not mistaken there is a brake balancing valve on the bulkhead as well, this can sometimes go faulty as Ive had to supply a few to fto members, not saying this is the fault but a possibility

[Viper]

That might be what the garage was referring to when he mentioned that 'equaliser valve'! He reckoned it was 80% likely to be that fault. I think you've just made a sale... !

[Viper]

All sorted, thanks to RiceRocket for brilliant service and parts suggestions as always !

Now to try sell my baby....