Brake imbalance issue!!! - SkyMan
Hi there,

My wife's Toyota Carib ( a 4WD 1.8 Corolla Jap Import) failed its WOF (like the MOT) the other day, due to brake imbalance. The deal is is that the rear RH brake is 36% down on the rear LH brake.

I had a mechanic take the drums off and clean the brakes, but on re-testing the RH brake was still 33% down.

Toyota have the car right now, but haven't yet found the problem. They've checked the slave cylinders but no leaks there....

The car was built in 1995 and has ABS with discs at the front and drums at the back.

Any ideas/suggestions I can pass onto to Toyota?

I thought that maybe the brake pipe MIGHT be bulging on that side, but haven't yet told Toyota this.
Brake imbalance issue!!! - Robin the Technician
It's with the dealer now- let them look at it.

These are the views of Robin the Technician with 35 years in the trade. I fix, therefore I am...
Brake imbalance issue!!! - SkyMan
Err, Thanks very much for that, really helps.

My wife needs the car as shes disabled and so I'm hoping to get it fixed very quickly, which is why I was hoping for any ideas/comments from people who have experienced similar.
Brake imbalance issue!!! - Mark (RLBS)
nice one Robin; got anything more constructive to say from your years of experience ?
Brake imbalance issue!!! - Dynamic Dave
Is your wife a light braker? The rear shoes could have glazed though light braking and might just need roughing up a bit by rubbing a wire brush over the surfaces of the shoes. Be careful and do this in a well ventalated area though - you don't want to be breathing in nasty asbestos dust, etc. You might also want to give the brake drum surfaces a rub over with some coarse emery paper as well.
Brake imbalance issue!!! - SkyMan
Hi Dave,

I had a local mechanic look at the brakes and he gave them a good clean up - he's a top notch bloke so I reckon he'd have done as good as he could. Even after this the RH brake was still down by 33%

The problem is is that the handbrake worked fine (i.e. both brakes performed well, and also equally) therefore it looks like a problem with the hydraulic system.

Brake imbalance issue!!! - greaser pv
Had a 60% brake imbalance on a Nissan Serena the other day. I was expecting the worst i.e. leaking cylinder new shoes etc. However could find nothing obvious. Cleaned out dust, roughened shoes and drums,re-adjusted shoes , greased backplates and bled cylinders. Took it back for re-test- no further problems.Try seeing if there is any air locally in the system by bleeding through fluid on both sides.
Brake imbalance issue!!! - Peter D
Do you know the service history of the vehicle. Has a slave cylinder been changed and the wrong one fitted i.e. different bore diameter, this will cause the problem especially as even after the mechanical checked it all out it only made a 1% difference. Check all flexible hoses as this could be where the loss is occuring particularly as the hand brake operation dose not identifty a shoe/drum problem. Check if your model has pair of brake balance regulators, one made have failed safe and is braking unregulated. After that is is a master cylinder problem although the front brakes are no I assume imbalanced. It could be air in the system assumming it is a dual braking system. Regards Peter.
Brake imbalance issue!!! - SkyMan
Hi Peter,

The car is a Jap import, imported by Toyota under their Signature class (which means that Toyota trusted the car enough to give it a 2 year unlimited mileage warranty). Not sure of the Jap service history, unfortunately.

The Toyota mechanic now thinks its the back brake proportional valve, and is fitting a new one today. They did re-bleed the brakes but no difference. Also all the rear brake assembly was cleaned up, but that only made a small difference. No leaks from the slave cylinders either.

Will keep you posted...

Brake imbalance issue!!! - SkyMan
Got the car back, and it passed its Warrant :)

Toyota replaced the rear proportioning valve, which fixed most of the problem. They then fitted new rear pads because the old ones were "contaminated". Result - braking is now balanced across the back brakes !!

Pads are not covered by the warranty, but they haven't charged me for them, so I suspect that they were contaminated by the mechanic when they were trying to fix the problem...

Anyway, the car's all legal now for another 6 months (Warrants only last 6 months in NZ).

BTW - they must have had the ABS unit out, because they'd un-plumbed the washer bottle to get to it. I know this because the washer jets for the front and rear were swapped over by mistake.


Value my car