Vauxhall Corsa SXI 1.4 07 - Uneven brake pressure

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Mon 1 Jun 2015 14:41
Vauxhall Corsa SXI 1.4 07 - Uneven brake pressure - Corsaowner81
Hi there,

I'm not a car expert at all and having moved house, have taken my car to a new garage (masterfit) for a service and MOT. Things seem to be taking a long time and I'm concerned that I may be being taken for a ride.

The car didn't show any obvious problems when being driven prior to the service. I was told that there was uneven pressure being applied through the brakes and that it had failed the MOT because of this. They checked the friction of the various components in the system - this didn't solve the problem. They have now replaced the master cylinder which still hasn't fully solved the issue and they are now considering other options (valves and modulators have been mentioned). Does this seem reasonable? If the master cylinder hasn't solved the problem, I don't see that I should pay for it.

I'm concerned that they will suggest that the ABS unit is to blame - I don't see how this wouldn't show up on the diagnostics. Any advice would be really appreciated!!

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Mon 1 Jun 2015 15:54
Vauxhall Corsa SXI 1.4 07 - Uneven brake pressure - old-school-tech

Brakes often fail the MOT on inbalance which is measured on each axle, IE left rear compared to right rear brake.

Inbalance is usually a result of a partially sticking or siezed brake caliper or wheel cylinder, or something that causes one side to be applied with more braking effort than the other side, sometimes air in the system can cause that side of the braking system to become spongy and not as effective but unless there is a leak somewhere that tends to be rarer thesedays,

rarely is inbalance caued by the friction side of things (pads,discs, shoes, or drums) so there wasn't much point in looking there other than to make sure they were i good order, It won't be the ABS pump (very unlikely), It wouldn't have thought it would be the master cylinder, modern braking systems are split via the master cylinder (dual systems) which means the left front brake works with the right rear, and the right front works with the left rear, this would mean if one of the 2 seals in the master cylinder had failed it would cause an inbalance on the front and rear axles together. (assuming it only failed on one axle?)

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Mon 1 Jun 2015 16:20
Vauxhall Corsa SXI 1.4 07 - Uneven brake pressure - gordonbennet

I agree with old-school-tech, the first thing i would have done is to check the free movement of all caliper pistons, and their sliding mechanisms, and slave cyls if rear drums, that automatically means removing the friction materials or in the case of drum brakes removing the drums so all is revealed...to be fair you cannot examine brake pads properly without removing them so they *should* have checked calipers at the same time.

Whether they did so is another thing entirely, hope you haven't found one of these places that throw new parts at the problem till they happenstance upon a cure.

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Mon 1 Jun 2015 16:33
Vauxhall Corsa SXI 1.4 07 - Uneven brake pressure - Corsaowner81

Thanks again - It's a registered Masterfit garage - who knows if it's a serious outfit :( Is it worth asking for my old parts back and to have the documentation to show that the old master cylinder was failing? I want to be able to argue the toss if they identify another problem which 'solves' the issue.

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Mon 1 Jun 2015 16:30
Vauxhall Corsa SXI 1.4 07 - Uneven brake pressure - Corsaowner81

Thanks so much for this - the imbalance is on the front axle, so given what you have said, that suggests that the master cylinder replacement was a red herring. I'm awating a call back from the garage, this will give me some information that I can throw at them if they suggest something else.

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Mon 1 Jun 2015 17:00
Vauxhall Corsa SXI 1.4 07 - Uneven brake pressure - old-school-tech

that narrows it own a bit, inbalance on the front only will either be a sticking/partially siezed caliper or sliders, or maybe one of the brake pads was really tight in the brake pad carrier, either way should have been relatively simple fix...maybe they had a spare master cylinder they wanted to get rid of...hmmmmmm.

good luck :)

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Mon 1 Jun 2015 17:43
Vauxhall Corsa SXI 1.4 07 - Uneven brake pressure - Corsaowner81
Well they've now said that it's the ABS modulator pump and have said that 'it's not cheap' I'm due a call at 5.30 to confirm. Is this even a possibility?
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Mon 1 Jun 2015 17:49
Vauxhall Corsa SXI 1.4 07 - Uneven brake pressure - old-school-tech

Its a very slim possibility....but I think I would ask for a quote (in writing), tell them you want to think about it, and get a 2nd opinion...steer clear of the large franchises..not saying they are all bad (that would be wrong) but a small independant friendly garage might be a better bet...

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Mon 1 Jun 2015 18:03
Vauxhall Corsa SXI 1.4 07 - Uneven brake pressure - galileo

Its a very slim possibility....but I think I would ask for a quote (in writing), tell them you want to think about it, and get a 2nd opinion...steer clear of the large franchises..not saying they are all bad (that would be wrong) but a small independant friendly garage might be a better bet...

I'd second that advice, I would doubt either master cylinder or ABS would be most likely cause of brake unbalance (even if there was unbalance anyway - my local indy is happy to let me watch the brake test and see the readings on the meters; if you didn't see the test, you don't know what the results were)

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Tue 29 Mar 2016 23:18
Vauxhall Corsa SXI 1.4 07 - Uneven brake pressure - madhouse1968

hi did you ever cure problem got same problem on mine car tries to pull to the centre of road ,as if theres no pressure on one wheel until you press brake again

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