Rear Brake Imbalance - Mot Fail Help

[gwyn_mi16 7]

Im after some help please Gents.

 

Took the 205 for an MOT last week and it failed on an imbalance of the rear brakes.

 

Apparently each wheel on the same axle has to be within 30% of each other.... mine are at 56%.

 

Ive had a look, the discs and pads are in great nic with plenty of meat. Ive only owned the car 2 months but each rear caliper looks relatively fresh as do the brake hoses and brake lines to them.

 

The calipers are sliding freely so Im a bit baffled really.

 

Could it be the compensators to blame? Anyone experienced anything similar?

 

Any help greatly appreciated.

 

Thanks, Gwyn

[Tom Fenton 1,524]

Compensator failed would be my guess, usually they fail open meaning that the side with lowest effort is working correctly and the other side with high effort has a faulty compensator.

[gwyn_mi16 7]

Ok thanks. Im I right in saying there's 2 on these? Take it there's no way of testing them? Lastly if it's failed best/ cheapest place to buy another?

 

Sorry for all the questions, thanks

[Tom Fenton 1,524]

I suppose in theory you could test them with a suitable pressure gauge and fittings. But unless you already have suitable high pressure test equipment, it's probably more sensible to spend the money on a replacement.

[welshpug 1,621]

if it was a 1.6 originally then it'll have a single unit in the engine bay on the left hand chassis leg behind the battery tray, a 1.9 with discs would have a diagonally split system with a pressure limiter in each line.

 

it is advisable to replace in pairs, the spec changed from early to late cars, last 205/309 ones I bought were £30 each for Bosch items at GSF, the zx 16v specific ones I sourced through a bosch stockist came from German stock and cost £50 each.

[Anthony 1,000]

Were the readings from the handbrake test broadly equal across the rear axle?

 

If so, you can assume that the friction side of things is OK and certainly I'd be suspecting a failed compensator if it was originally a 1.9 model. You normally know if a 1.9 compensator has failed open as you'll lock a rear wheel before the fronts under heavy braking, and if it's failed closed then you'll have almost no brake effort and get minimal fluid through on the failed when trying to bleed the brakes.

 

The 1.6 compensator setup doesn't tend to cause differences side to side (as each side should always see the same line pressure) and is in my experience very reliable and you almost never hear of them failing, unlike the 1.9 setup which do seem to commonly give issues for some reason.

[welshpug 1,621]

commonly, as in once in the lifetime of a vehicle that's at the very least 21 years old

[Anthony 1,000]

I don't know about that - one of my previous cars had several replaced over its life judging by the comprehensive history file.

 

Either way, you regularly hear of 1.9's suffering failed compensators but you almost never hear of 1.6's failing, and that matches my experience having replaced several 1.9 items over the years on various cars but never a 1.6

[gwyn_mi16 7]

Yes it's an original 1.9. The handbrake test raised no issues Anthony so as you've suggested the friction element is probably ok.

 

So it sounds like a need a pair of compensators then.. great another £100 down the drain! lol

 

With mine being a 1990 on a G would it be fair to assume it's the earlier type Im after? Or are they interchangable?

 

Thanks for all the advice

[scbond 15 1 Cars]

My recent imbalance was caused by seizing pins apparently...just required taking apart, cleaning and new grease.

 

Worth checking before forking out for compensators.

[gwyn_mi16 7]

The pins are all greased and slide freely mate, good shout though! Thanks

[commievid 8]

I think the compensators aren't interchangeable in the sense that one old and one new can be used, they need to have a matching letter or something like that. As you're buying a pair (or should be?) it should be fine to use, i.e. Phase 2 or Phase 1 doesn't matter.

[welshpug 1,621]

the pressure was changed afaik, later ones have an E stamped on them.

[scbond 15 1 Cars]

The pins are all greased and slide freely mate, good shout though! Thanks

Ah yea, sorry. Just read back through the first post and saw that!

[gwyn_mi16 7]

Right so got a pair of Bosch compensators on order, should be here on Thurs and fit them Friday ready for re-test. Finger crossed she passes this time.

 

Big thanks to Craig (Farmer) for helping me source the parts at a great price.

[Tom Fenton 1,524]

Bosch compensators are available from Mister Auto online, £34 each.

[gwyn_mi16 7]

Yes that's where I got them from mate, Farmer pointed me in the right direction as they seemed to be £50-£60 each everywhere else and no longer available at pug. Thanks