in an mot test will their brake test damage anything on a 4 wheel drive car like the scooby???

I wondered that too but the wheels are not locked together so i wouldnt think so

they dont spin them for long anyway

could be a problem on some though

When the garage tried to test my EVO, they failed, the LSD's mucked up the readings. They let it go as they said the Brembo's would proabably 'brake ok'.

As to damage, at the low speed the tester rotates at, no problem

Everything I have read, including the MOT procedure, says they shouldn't be tested on the 2 roller testers.

When mine has been in for it's MOT, the guy always goes for a run with his decelerometer in the car to test the brakes.

This link shows the procedure and specifically mentions not testing any car with "more than one driving axle permanently engaged"

I said it before and i'll say it again...
'four wheel drive vehicles and cars fitted with limited slip diffs or belt driven transmissions MUST NOT be brake roller tested'...this is in black n white in the MOT testers manual'...

any damage caused to the vehicle whilst in the custody of the tester due to incorrect testing methods makes them liable for the damage!!!

If in doubt ask your tester when you take the car in for it's MOT !!


steve (mot tester/authorised examiner)

Maybe this will help.

http://www.scoobynet.co.uk/bbs/threa...hreadID=275197

It's already been said above, but do not test a 4wd vehicle on a 2 wheel brake testing device. It can knacker your diffs.

The only test that I know as valid for 4WD is a dynamometer strapped to the seat, but I'm not in the trade at all.

You are correct....we test them correctly BTW !!!

steve

Our guy has a dolly that sits in the passenger footwell, you then brake from 30 mph or 20mph, the dial moves round & shows what force deacceleration has been applied.

Depending on the needle's position will then indicate if the car has safe brakes,

All very easy stuff

All MOT testing stations should have a Tapley meter for checking the brakes on four wheel drive vehicles.

It is definitely bad for the limited slip diff unit in the gearbox to put the car on the rollers. Insist they they don't do it but use the Tapley meter which they should have.

Les

yes but i forgot to say my car is a uk my99 - do they have front or rear lsd-i dont think they do??

It doesn't matter because it's still permanent four wheel drive and must NOT be brake roller tested.

quicksprint you sound like a true pro to me why cant there be more like you!! merry xmas

Cheers mate,only doing my job.

steve.

OK now I'm worried. When my car was MOT about 4 months ago they put it on a two wheel Brake roller, when I questioned this they said it's OK because the centre diff allows the front and rear wheels to be turned independently. Do you think they have reduced the centre diff's life? :(

[Edited by DreXeL - 12/12/2003 10:32:52 PM]

I think if any damage was done then it would of shown up by now.
What model is yours?
All testing stations should carry out the test to the same standards using the correct equipment and procedures...

but this apparently is not always the case.

steve.

It's a UK MY97.

[Edited by DreXeL - 12/12/2003 10:35:40 PM]

As long as there isn't any unusual noises from the gearbox you should be ok.

[Edited by quicksprint - 12/13/2003 9:05:39 AM]

They've all got a centre diffs, just a different type on the STI type R/RA.

[Edited by DreXeL - 12/12/2003 10:51:31 PM]

Ive got a MY96 GL, my MOT stn used a taplow meter,,, as he aked my various questions about the car as he was carring out the test..

suffice to say it passed


mart

If its AWD it has a centre diff, be it electro-mechanical or the basic viscous coupled. They should be tested with a decelerometer as previously said though at the speeds of a rolling road brake tester the stress on the center diff is not a lot. The big no no is towing with one set of wheels off the ground, tow it flat or put it on a trailer. MOT people usually know the score, recovery may not and they can do much more damage.

According to the AA's 'technical Info' , Subaru's should not be towed flat for more than about 4-5 miles and at no greater speed than about 20MPH ..... They told me that a full lift was the only way they would recover my car. I was very happy with this , as they were putting themselves to more work arranging the proper transporter and not the towing dolly. Well done AA.

Nate.

When I had my EVO towed by the AA, they used a solid tow, ie all four wheels on the ground and turning. I think this is ok as its no different from normal driving.

Just been for an MOT this morning. Saw the thread before I went and I mentioned it to the testers. They said they knew about the AWD thing so didn't test it on the roller thing. Fair enough but I'm pleased I asked cos you never know with these places that aren't specialist. Needless to say it passed with no problems.

Steve :cool:

good news mate and i'm glad you asked them first before they carried out the test.

It does not matter about the front and rear diffs, limited slip or not. It is the centre diff in the gearbox which is limited slip, which can be damaged.

Les

can anyone tell me if a my 99 uk scoob has front or back lsd??
glad this thread helped someone anyway myself included.