Brakes out of balance

[JMS1947]

Passed last year's MOT but advised that disc brakes were 22% out of balance. After new disks and pads this year they were 29% out of balance and failed MOT, although problem is not apparent while driving. Changed calipers on both sides and out of balance reduced to 22% and just passed MOT.

Question is why are brakes still out of balance with new discs, new calipers and relatively new pads. MOT station said the flexible pipes may be restricted but find this hard to believe and would cost another £30 or so which could be wasted. Could the ABS be at fault?

[Crasher]

Flexible pie blockage is extremely rare and the ABS system could not cause this unless there was contamination in the system. Does the car pulse to a stop during braking almost as if you are pressing and releasing the brake pedal or give steering judder when braking from high speed?

[mluton]

Welcome mate, Wish I could help, but I havent a clue

[Bora me Golf]

With all new bits and no apparent braking problems i would be dubious of the mot stations brake test rollers.. But as you say the brakes were outa balance last year so it be a strange one.... I would tho, get a second oppinion from another mot station, dont think they would charge much or even anything for testing brakes..

[JMS1947]

In response to Crasher, there is nothing unusual at all in the operation of the brakes, they don't pull to one side and there are is no pulsing unless they are working in a skid situation, which thankfully has not happened for some time.

Boro me Golf makes a good point about trying another test station, although it was the same place last year when it also came up with 22% error and it is difficult to believe that an inherent fault in the test gear has gone unoticed for a whole year. I don't know for sure but I would imagine that the test equipment has to be calibrated at least once a year. Anyway I will make enquiries and at least I will go to another test station next year if I still have the car.

Thanks for your time.

[smokey0123]

Different tyre pressures (1 side lower than the other) affect reading and if the car is not pulled sqaurely into the RBT it will read an inbalance.