My 2000 Opel Agila 1.2 has an advisory on it's MOT saying:

Front Brake imbalance [sic] high at 23%

What does this mean?

What's wrong with my brakes?

What does the 29% mean?

How can I fix it?

NOTE: I am asking what it is, unlike this question which asks for tips on how to fix them, and I don't find the answer very useful. I am asking what it is

Here is all the info that I can find on the front brakes:

  • Floating Calliper (Disc) brakes

  • 247mm Diameter

  • 12mm Thickness

  • NO ABS


I have a few more questions:

  1. Will it affect the braking of the car?

  2. Will it be okay if I just leave it?

  • Was the actual percentage 23% or 29%? I see both in the question. Just curious as now there is a difference from what I saw when I originally answered the question. Commented Jul 30, 2015 at 10:34

1 Answer 1


What does this mean?

Brake imbalance is caused because one side of the braking pair (front or back axle) is not applying as much power as the other side.

What's wrong with my brakes?

There are too many answers for this forum. It could be any number of things like a sticking caliper, or a worn pad, or air in the lines.

What does the 23% mean?

When the braking force for each side is measured, one side has 23% more stopping power than the other. I believe for the MOT it must be within 25% in order to pass.

How can I fix it?

It all depends on what the problem is and what type of brakes are being used. Without more information, like your brake type and what mechanically has been done recently, it would be hard to give you a good answer here.


Will it affect the braking of the car?

Yes it does affect the braking of your car. At 23% you can probably feel it pull to which ever side is stronger, but not bad enough you'd lose control of the vehicle. If you have disk brakes there is little you can do about it but check to ensure the calipers are working correctly, you have good and even pads, the rotors aren't worn out, and that the calipers slide correctly.

Will it be okay if I just leave it?

If you are happy and don't feel there is any issue, you can leave it. MOT says it's just an advisory, so no worries there (this year). Personally, I'd want the bias down below 10%, so would try to figure out what the issue might be.

  • Thanks. I'll just have a look on the service info and pull up all the info I can find on the brakes
    – George
    Commented Jul 29, 2015 at 20:37
  • Thanks for the good answer :) Would you mind taking a look at my other two questions I asked?
    – George
    Commented Jul 30, 2015 at 22:42
  • @George - Send me a note in The Pitstop as to which ones you are talking about exactly. Just preface my username with an "@" symbol in the body of the text and I'll get it. Commented Jul 31, 2015 at 0:07
  • I meant my other two sub-questions that I write in this question! Sorry...
    – George
    Commented Jul 31, 2015 at 21:24
  • 1
    @George - Please see edit. Commented Jul 31, 2015 at 22:16

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