My 03 passed its MOT today a the 1st attempt yay!

But the guy said that they didnt perform the rolling road brake test because it could break the diff.

Is this true ? And if so then how are the brakes usually tested as an alternative ?

It passed so it's not critical I was just curious.

Thanks :-)

 

Yes this is true on some cars fitted with lsd or on 4x4. When the mot tester logs on to do your test it will warn him that the brake rollers may cause damage. There is a machine that place on the passenger floor with a gauge on this measures brake force.He will also check each wheel aint sticking on when jacked up.

 

We do this at work, a full on brake application at 20mph using foot and hand brake to get an efficiency reading.
Got a rolling road session booked soon, will this be a problem, never considered this.

 

i've been at the testers when he has done a few diffed cars, he allways tests the wheels as a pair as you would on the road, mines booked in for 29th feb i'll see what he says

 

It's called a decelerometer

 

As long as both wheels are rotating the diff will be happy. Fully spinning one wheel up for any period of time isn't healthy for the diff.

The diff is a limited slip, so it is always compensating for one wheel attempting to rotate at a different speed to the other.

 

Cheers nice to be reassured.