Took wife's car for MOT and they had two tracks they drove the car on and braked sharply. Split tracks on each side to do front/rear wheels - they set the vehicle weight and the computer did the rest.
No more worries about the rollers driving just the front or rear wheels and any suspected damage to diffs this may cause on the scoob. But did h/brake test - applied from 5-10 mph - so still possible damage there.
Are rollers likely to cause less damage or these track gizmos ?
Or is there no risk of damage to diffs anyway ?
Stan

[Edited by StanS - 6/5/2002 7:49:15 PM]

my XR4x4 has been tested like that for last 6 years with no problems at all

Neil

Cheers Neil - its just that I had heard that handbrake turns were a quick way to ruin the centre diff (or was it the rear drum assemblies ?), and only driving one pair of wheels (front or back) was damaging to th ecentre diff.
Hope someone who knows for sure (re Scoobs rather than Fords) will reply.
Stan

according to ford manual for car, it states the car can be run on each axle for no more than 30 secs with a max speed of 5 miles per hour

driving only the front or rear axels will cause serious DAMAGE!!!! to the diffs.DO NOT let any mot center tell you different
and the damage could be immediate.
if they dont have the rolling equipment to do all wheel drive vehicles then they can do the test with a (velocimetre/accelerometer)
basicly they imput the weight and speed in to the meter then drive the car (on the road)to the set speed and then brake. The metre then does its thing and tells them the overall braking force used to stop. do this 2 or 3 times and get the average once you over the required % you pass.

hope this helps
john.

my center diff has a viscous coupling inside the box, can turn the front prop on its own but with a lot of effort

neil

Thanks guys - but you see the problem - so many conflicting views. When I get my scoob MOTed using Pete C's little helper and his local MOT garage, Pete says not to worry about only one axle being tested at a time. Yet the commonly held view is that it is bad for the diff - and especially bad to do handbrake turns or to use the handbrake to correct massive understeer. I also read on this BBS people saying they had done h/b turns for "years" with no ill effects on the car ("std" diff turbos). :confused:
Stan

The MOT station I used for my MY97 a couple of years back said they would never put my car on the 2WD rollers and used a "tap meter" sitting in the foot well of the passenger side. Whether old wives tails or not they recountered several reasons why 4WD vehicles shouldn't be brake tested upon a 2WD tester. As well as knackering viscous diffs, it has interesting results on cars with locked diffs as the inertia winds the diff. up and then fires the car off into the wall when the brakes are released.

Steve

I can confirm that subarus are on the list in mot stations that should not be done on two wheel rollers along with lots of other awd vehicles.

my local mot station said they only had imports listed as not to be tested on there standard rollers, because of the diff wind up,
If in doubt get the mot guy to test it the old way, take him up the road at 30mph (with a hot cup off coffe in his hands) and brake as hard as poss, :D if he does'nt spill any- you fail :)

So it seems that the track type tester in my local garage is fine for testing the foot brake rather than use the 2 wheel rolling road tester (which still seems to have a split opinion as to its damage to diffs).
BUT what about running the car onto these MOT testing tracks at 5-10mph and applying the handbrake to test that ??????????
Exit handbrake ? /diff ?? or no problem ??
Stan

4X4

The Ministry of Transport provides guidelines for the testing of 4wd vehicles, it is not up to each MOT centre to decide whether it is appropriate to to test a 4wd vehicle on 2wd rollers.

Guidelines to testers are as follows (see section headed 'Vehicles not to be tested on a roller brake tester'):

http://www.motuk.co.uk/manual_370.htm

Any MOT centre that decides otherwise should be reported to the Ministry of Transport.

At the end of the day it is your car they are testing incorrectly and it is unlikely that you will be able to prove that the incorrect brake test has destroyed the centre diff of the car.

Nigel

Thanks Nigel + all who replied.
Stan

[Edited by StanS - 6/9/2002 3:38:04 PM]