I bought new rear brake calipers for my 1995 Barchetta and when they arrived i was like a kid with a new toy and played with them checking them out.
Then I notice on the side of the box that it states
DO NOT TOUCH
as the handbrake is pre set.
So I fit them anyway with fingers crossed.
At the MOT the guys says there is an imbalance but it did not matter.
That was last year and this year i thought id try ad fix that imbalance problema.
So I take both calipers off and play with them !!! releasing the handbrake spring and pushing the piston back into the caliper.
So i do the same to both sides and put it all back together again and go for the MOT.
ehhh now he says there is an imbalance between sides even with the foot brake which is an mot fail !!!
So ive balls it up completley now.


Can anyone advise how I re set the calipers ??
thanx Dave

arnietwo said:

I bought new rear brake calipers for my 1995 Barchetta and when they arrived i was like a kid with a new toy and played with them checking them out.
Then I notice on the side of the box that it states
DO NOT TOUCH
as the handbrake is pre set.
So I fit them anyway with fingers crossed.
At the MOT the guys says there is an imbalance but it did not matter.
That was last year and this year i thought id try ad fix that imbalance problema.
So I take both calipers off and play with them !!! releasing the handbrake spring and pushing the piston back into the caliper.
So i do the same to both sides and put it all back together again and go for the MOT.
ehhh now he says there is an imbalance between sides even with the foot brake which is an mot fail !!!
So ive balls it up completley now.


Can anyone advise how I re set the calipers ??
thanx Dave

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further to above i went down this afternoon for the re test and it failed again but at least this time i found out that the handbrake is fine, just the foot brake thats faulty.


So if the handbrake is mechanical and is ok does that mean the calipers are ok an the faults somewhere else.


When i came back i took the caliper off and depressed the foot brake and the piston moved out no probs.


So i have no idea now whats the problema with my limited knowledge !

arnietwo said:

further to above i went down this afternoon for the re test and it failed again but at least this time i found out that the handbrake is fine, just the foot brake thats faulty.


So if the handbrake is mechanical and is ok does that mean the calipers are ok an the faults somewhere else.


When i came back i took the caliper off and depressed the foot brake and the piston moved out no probs.


So i have no idea now whats the problema with my limited knowledge !

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May be check the brake balance valves on the rear anti roll bar, not to sure if this is your problem, but they do sieze up if the car is left standing. They usualy just need some WD 40 and work the lever back and too to get them freed up.
Regards Dave.

Dave-M said:

May be check the brake balance valves on the rear anti roll bar, not to sure if this is your problem, but they do sieze up if the car is left standing. They usualy just need some WD 40 and work the lever back and too to get them freed up.
Regards Dave.

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Thanx Dave-M, yes i know what you are talking about, i believe they are meant to equalise brake pressure front and aft under heavy braking but on looking at them the spring is slack and as far as i can see will never actívate ??? Ive actually removed the spring cause it was annoying me !!! hahaha.
OK i will look at them on both sides !! and report back. Only prob now is that ive just had to fit a new standard exhaust cause the ITV (MOT) guys here in Spain didnt like my straight throoooo sports exhaust, and the end box is now right infront of where i need to look !!!

Yep you are correct they are to control front to rear braking under load, but I am sure that your springs should have had some load on them I would check to see that the levers have free movement, incidentally in the UK removing the springs would be a fail, the wording is something like " Reason for fail" "If evidence of load sensing valve has been removed or disconnected from the vehicle, where it is known to be fitted as standard".

Dave-M said:

Yep you are correct they are to control front to rear braking under load, but I am sure that your springs should have had some load on them I would check to see that the levers have free movement, incidentally in the UK removing the springs would be a fail, the wording is something like " Reason for fail" "If evidence of load sensing valve has been removed or disconnected from the vehicle, where it is known to be fitted as standard".

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Saga continues, bought and fitted new compensators, regulators on both sides and find that there is no lever on these and no way of taking lever off old ones omto new. So now def no springs.


I bleed everything and take it to local garaje and have guy check balance !!
and surprise surprise still have the same imbalance with left side drivers side less tan other. in Spain need less tan 30% imbalance and i think it touched 47.
Back to my garaje and Jack back of car up and find that the left side Wheel spins freely, like i think it should, whilst right side the Wheel is pretty stiff to turn.
So is it that i have been thinking faults on left side when infact it might be the right side.
Would that cause the imbalance if right side is tighter on the disc at rest ????
Hope someone can help me ??? as im running out of ideas on where to look bext !!

arnietwo said:

Saga continues, bought and fitted new compensators, regulators on both sides and find that there is no lever on these and no way of taking lever off old ones omto new. So now def no springs.


I bleed everything and take it to local garaje and have guy check balance !!
and surprise surprise still have the same imbalance with left side drivers side less tan other. in Spain need less tan 30% imbalance and i think it touched 47.
Back to my garaje and Jack back of car up and find that the left side Wheel spins freely, like i think it should, whilst right side the Wheel is pretty stiff to turn.
So is it that i have been thinking faults on left side when infact it might be the right side.
Would that cause the imbalance if right side is tighter on the disc at rest ????
Hope someone can help me ??? as im running out of ideas on where to look bext !!

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Meant to say I had also fitted new rear discs, so could it just be that pads have not bedded in, and inbalance has been caused??
Ive taken all pads out and put 2 thickest on 1 side and 2 thinner on right side. Not much diff really, they are comparitively new. I will drive it the next few days and take it back to garaje on Tuesday and see if teres a differance !!

I feel your pain - I also have some rear brake imbalance, but not bad enough to fail the MOT.

The new discs shouldn't make a difference, but you do need to give them time to bed in. It's definitely not wise to reuse old pads with new discs, as inevitably you won't get 100% contact between disc and pad.

Have you ensured that the pads are properly seated? A few years ago on mine, I found that one of the inner rear pads had worn very unevenly, and the disc was badly corroded on its outer half, indicating that the pad was only pressing on the disc for about half of its surface area. The only explanation I could come up with was that when the pads were fitted, one of the lugs on the face of the piston was positioned directly on the lug on the back of the pad, so that in effect all the force of the piston was on just one point, causing the pad to twist slightly as the brake was applied.

So you may need to rotate the piston very slightly when fitting the pads, to ensure that the lug on the back of the pad isn't preventing a good contact between piston and pad.

Having said that, mine got through its MOT twice (and two routine services ) with that defect, and I only discovered it when stripping the brakes down to try & improve the wretched handbrake. (It was the inner pad, so the defect wasn't obvious from a quick external inspection - I've now learned the importance of taking all the wheels off at least once a year and checking the pads and discs properly, as you can't be sure that those tasks will be done on a routine service )

Not sure what to advise. Seems strange that you should have this problem.If I had this problem, I would remove the hand brake cables from the calliper's, remove pads, wind back the pistons. Then refit pads checking that they are not binding. It might be good to just bleed the brakes again, sometimes with new components you can have oil contamination inside making it difficult to get good compression. I wouldn't at this point reconnect the hand brake,
Then take the car for a spin applying the brakes and generally just bedding the brakes in. Then jack up car and spin the rear wheels check the resistance from side to side, perhaps have someone applying the foot brake also.

Just re-read your post, I would buy new pads, they could be contaminated.
The rear brakes are a duel line system, could your master cylinder be at fault,

Dave-M said:

Not sure what to advise. Seems strange that you should have this problem.If I had this problem, I would remove the hand brake cables from the calliper's, remove pads, wind back the pistons. Then refit pads checking that they are not binding. It might be good to just bleed the brakes again, sometimes with new components you can have oil contamination inside making it difficult to get good compression. I wouldn't at this point reconnect the hand brake,
Then take the car for a spin applying the brakes and generally just bedding the brakes in. Then jack up car and spin the rear wheels check the resistance from side to side, perhaps have someone applying the foot brake also.

Just re-read your post, I would buy new pads, they could be contaminated.
The rear brakes are a duel line system, could your master cylinder be at fault,

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Possibly the fault is with the caliper mounting bracket ???


The pins in the bracket are slughtly loose, ie it allows the caliper to move laterally when pressure is applied.
So im now thinking that this causes the uneven application of the pads onto the disc !!
So ive bought new mounting brackets, so we will son see if that solves the problema.

ive tried to buy the mounting brackets from 2 companies in Spain without success. I cant even find ant in the UK, ive found a site selling the guide pins but not the bracket !


Does anyone have any suggestions ??

thanx folks, just a quick update to say Barchetta passed ITV (MOT) here in Spain. Seems new pads once bedded into new discs done the trick !!!
So Im free for open top driving again this summer.

:woot::woot:

Great news - just shows that perseverance sometimes does pay off!