MOT Puzzle.

[realscot]

I'm bored, so I thought i'd test the knowledge of the motors crew a little. I expect any testers or mechanics here to get this one relatively easily, and I also expect a few trollers adding pointless views on whatever.

A EP3 Civic Type R and a BMW E46 M3 are both presented for an MOT with the same fault, the BMW pass's with and advisory and the Civic fails. The part on both cars is defective in exactly the same way and to the same degree.

Why did the BMW pass but the Civic failed? Can you guess the failure?

*note the civic did not fail because it didn't have the torque to climb back out of the brake rollers*

Will check back in the morning.

 

[realscot]

Handbrake, as the BMW has to be tested using a handheld device due it it's LSD?

But must still be 16% efficient just like the civic. Be much easier to get 16% on the handheld mind u. So no..

 

[realscot]

Rear CV gaiter split on the BMW, a front one on the EP3. Front fails as it's part of the steering assembly.

Dogbreath wins.
Only front outer drive shaft gaiters come into an MOT.
Some LSD have enough slip to allow for testing on rollers (civic type r - focus st etc) even some 4wd systems are ok on rollers (discoverys for example)

 

[realscot]

The grease usually doesn't get onto the brake discs because of the backing plates. The main reason for CV boots being split failling means the CV joint is no longer lubricated well enough and will wear out quickly. If you've ever drive a car with a badly worn CV joint you will know just how dangerous and sometimes undrivable it is.

Mike, those were just cars off the top of my head that can have LSD's fitted.

Rich, you don't check just the handbrake on brake rollers

 

[realscot]

I wasn't aware that the Type R didn't have an LSD, my Civic has, I just assumed that all the type r's did.
My point was that most LSD's are ok on brake rollers, only a few like the M3 don't have enough slip to allow for the 2-3mph that the rollers spin.
All of that is completely irrelevant as the brakes or diff weren't the reason for the failure on the civic vs the bmw.