MOT advisory

[southerly95]

We had an MOT advisory on our 65 convertible which said the front brakes were almost at the limit of being out of balance (in my words - pulling to one side). Does anyone know how they measure this? I havn't noticed any pulling to one side whatsoever. Thanks, John

[charlie_morris_minor]

they will put it on two different sets of rollers, get the rollers up to a set speed and then apply your brakes.. they should then be able to see the difference on each side.. i think if you had been able to tell that it had been pulling to one side you would have failed not been given an advisory

[bmcecosse]

Well worth having the drums off and checking to see if there are any leaks - causing fluid contamination of the linings. Otherwise - it's likely to be a sticking cylinder - which may 'cure' itself if you use the brakes good and hard a few times! Otherwise - it's likely to get worse.

[Chris Morley]

When I go for my MOT I always watch as the brakes are tested, there is a dial for each side of the roller (one for each wheel). They look like a set of clocks on a white board and the tester holds what looks like a remote control to start & stop the rollers. It's not uncommon to see a slight difference in performance between sides but this can be acceptable within set limits. Obviously one of yours was worse than the other, I assume they told you which side?

BMC has mentioned the likely causes, however old/warped drums, cracked or badly worn brake shoe linings and mismatched cylinders can also cause an imbalance. Also ensure that both the snailcams are properly adjusted (one click back from locked up), if the shoes are too far from the drum this will reduce the braking performance.

[rayofleamington]

non-matching brake shoes will cause an imbalance.
The new ones (Asbestos free) do not have the same coefficient (i.e. they aren't as good). If you had new on one side and good old ones on the other I expect it would give enough bias to fail the MOT.

I've had brake balance problems in the past - the car just needed to be driven a few dozen miles to get rid of the pulling. It had been off the road for 5 months and without an MOT it wasn't easy to get the cobwebs blown off!

[bmcecosse]

As above - lining imbalance - I have had to mix and match linings (ie swop one lining from left to right) to get good balance.