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brake compensator

lads went for the nct today and they failed me on rear brake compensator (think thats whats it called)would anybody no where i get one of these or does anybody have a good secondhand one car has to be back in in a couple of weeks for retest thank in advance.
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You don't need another one, what you need to do is unseize it.

If you get under the car & have a look you will see it on the rear subframe on the passenger side. It has 4 brake lines going into the top of it & a swinging arm attached at the rear with a spring. What you need to do is get someone to work the brake & watch for movement. Most likely your spring has seized & is no longer bringing the arm close enough to keep the pistons from opening.

You can either unseize the spring & adjust the arm so it's closed or you can change the spring for a shorter stronger one.

If you take the plastic cover off you will see what looks like a big washer with something in the middle, pull that off & give it a bit of lube. Behind that are the 2 pistons that push out. Should be about 2-3mm of travel. You want these to move as little as possible when it's all attached. The further out they come the less rear brake pressure is applied.
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Yep , what he said ^^

The compensator gets coated in all the road crud and just seizes up , normally .
Top tip - if you're going to do the work tomorrow , dive unerneath and give it a proper see-ing to with Duck oil or similar tonight .

To re-adjust the arm when its all free and lovely , the wheels are supposed to be level & the arm loaded with 5kg - around the same weight as 5 litres of oil .
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cheers mate was just about to go on to evilbay and try sort one thanks
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thanks mate be under first thing in the morning .cheers
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Don't worry too much about the 5kg, the proper way to set it up is a pita, if you want to do it the easy way, just back it onto ramps & key it sitting hard on it, then push the brake, about 1-2mm of movement from the arm is about right.
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unquestioned. took the washer of the compensator last night and soaked it with wd4o. got underneath the car the morning put washer back on doesnt look like its unseized as their is no movement atall but their is plently of slack between the little washer shaft and arm.what do you men by key it thank for info
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It took about 30 mins of levering to get the arm moving freely on mine..
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It isn't the washer that seizes, it is the swinging arm. That washer is just there to keep the pressure between the pistons in the compensator even when the brakes are applied. If you remove the washer bit with the shaft you'll see 2 black nubs behind, these are the actual pistons. The more they come out, the less power to the rear brakes, they only come out when brake pressure is applied. Get someone to push the brakes & look for them to be moving, they don't move much mind. Now what you want is the swing arm to be up against that washer holding it tight to the compensator. The spring also needs to be a bit tighter. The reason they go wrong is the spring gets too weak & doesn't apply enough pressure.

A guy on .org says a good replacement spring is one off of an old bed with the springs on the bottom.
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Last edited by romeo1967; 13-06-12 at 21:22. Reason: wrong post
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Quote:
Originally Posted by unquestioned View Post
It isn't the washer that seizes, it is the swinging arm. That washer is just there to keep the pressure between the pistons in the compensator even when the brakes are applied. If you remove the washer bit with the shaft you'll see 2 black nubs behind, these are the actual pistons. The more they come out, the less power to the rear brakes, they only come out when brake pressure is applied. Get someone to push the brakes & look for them to be moving, they don't move much mind. Now what you want is the swing arm to be up against that washer holding it tight to the compensator. The spring also needs to be a bit tighter. The reason they go wrong is the spring gets too weak & doesn't apply enough pressure.

A guy on .org says a good replacement spring is one off of an old bed with the springs on the bottom.
cheers mate i no were i going now wiil have another battle at it tommorow
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Quote:
Originally Posted by unquestioned View Post
Don't worry too much about the 5kg, the proper way to set it up is a pita,
Yeh but it makes it look like you know what youre doing ....

Easiest way I've found is to run the N/S wheels up the kerb , then if the camber of the road is enough , you can slide underneath along the gutter .

Happy days !
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If it comes to getting another valve the one from the Fiat Tipo/Tempra is the same - either a second hand one or if you need new I find a Fiat blue bag is a lot cheaper than an Alfa red one containing the same part.
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Or do what I'm doing & remove it because meh. Is going to involve me putting good pads & discs on the rear but since it's in bits already, why not.
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Quote:
Originally Posted by mcalinney View Post
lads went for the nct today and they failed me on rear brake compensator (think thats whats it called)would anybody no where i get one of these or does anybody have a good secondhand one car has to be back in in a couple of weeks for retest thank in advance.
hi what i did to fix my compensator is i used a phase 2 gtv cause ive just replaced all my rear brake lines and seems to work fine.
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Here's a close up of the compensator showing which parts need to move.

thel ever is in 2 parts, both should move freely, independant of each other, when the nut is undone.

compensator.JPG
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Resurrecting this old thread as I think I may have a seized compensator.
One of my calipers is sticking on. I put a spare on today and this too is sticking hence why I think the compensator may be stuck.
Anyway... I had a look underneath... passenger side around the subframe... but can't see it. The brake pipes disappear behind the exhaust heat shield.
Can someone point me to exactly where it is mounted please. Thanks in advance.
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My apologies Only just realised...this thread is for a 155.... I have a 156! Numpty!
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If your caliper is seizing "on"... then the problem may be in the rubber brake hose to it, breaking down internally causing a fluid "lock" rather than the compensator.

If the compensator is seized, the caliper would get very little pressure. The brake won't stick on... it's more likely to be "weak" since the caliper isn't getting worked enough. Eventually that under-used/"inactive" caliper piston may stick/seize in its "weak/off" position.. so that the rear brakes don't get enough braking force, even if you correct the compensator so it is pushing more bias (i.e. fluid) to the rear brakes.


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