My 98 Turbo went in for it's MOT this morning, and despite me calling in earlier in the week to check they could do the brake test (with the 4wd and all) "yes we have a decelerometer (sp?) that we can use". What's the first thing I see when walking back from the newsagents to get something to pass the time??

Yep, car's on the rollers and back wheels are spinning up whilst front are stationary

Now what I need to know please is will this have damaged the centre diff in any way?? The wheels were spinning very slowly (about 5mph at a guess) and not for long, and driving back at slow & high speeds it seems fine, no funny noises or whines.

Am I just being paranoid, or do I need to be worried???

Advice appriciated please!!!!

Cheers,

Matt

 

OMG do some people not listen! hopefully nothing to worry about if no strange noises! i didnt leave my car for an mot anywhere for just that reason!

 

I've had numerous 4 wheel drive cars and because of the center diff you should have no problem with an MOT I've owned 4x4's from 97 'til october last year and every MOT has been fine

 

Mmm...another classic case of the tester not reading the testers manual and CORRECTLY using right procedures and equipment.
Did it pass or fail?
If it passed then(after collecting your new certificate) tell them that you will be reporting them for the incorrect method of testing your brakes to the VI and you will be getting an independant report for possible damage caused by this.
If it fails then get them to give you an appeal form and tell them again that you will be informing the VI about incorrect testing methods used and possible damage caused to your diff/gearbox.

steve

 

No it passed fine, do you think there is any chance of some damage or am I just being overly protective of my pride & joy

Matt

 

I would say something just in case......after all if damage has accured albeit minimal and it doesn't show up for 6months or so you will be gutted if you didn't say something and register the complaint with them.

steve

 

Read my post again That is the way they MOT 4 wheel drives.

 

BUT the book says the contary (the testers manual),you have just been lucky.

 

If the rollers were only for 2 wheels then IT SHOULD NOT BE MOT'd on the rollers. Make it known to the garage that you saw them do it, and that they have tested the vehicle incorrectly which could cause damge to the rear diff, front diff or transmission. They know that it should be done with a tapley metre - it's in their basic training!

If it fails and then you complain then you can't do a thing, they just write it off as coincidental.

They have a tapley metre for permanent 4wd cars, they should use it.

It's testers like this that cause so much distrust with MOT stations and garages

The centre diff is not the problem, it's the viscous coupling that causes the problem, as it's forced to work in the wrong direction.

 

My centre diff is knackered!!! First noticed it a day after an MOT! I wonder if the daft buggers have done damage to it!

 

Paul, I read your post as in "no problem with mot" meaning that you had no problem passing an mot with a 4x4, not that there were no technical issues with the diff being put on 2wd rollers! Does your local station not use the in-car meter then

Matt

 

I asked a few stations about the diff issue because I certainly have never found a garage that has a 4 wheel brake testing set-up and they all assured me that the diff would be fine because of the low speeds. If you think of it the center diff should be able to cope this quite easily because it's just like spinning one wheel on a 2 wheel drive car when it's jacked up. That's my theory any way.

In the years that I had MOT tests done this way I didn't have any diff damage that I ever knew about.

 

Totally agree with you..

steve (Mot tester and Authorised Examiner)

 

All MOT testing stations MUST have the facilities to brake test 4x4's...

steve (MOT tester and Authorised Examiner)

 

If this is any help.....I questioned the very same thing with an engineer...His reply was....Thay are more likely to damage their equipment than damage the diffs...As these are very well engineered items.....Kev.

 

My baby scoob (non turbo) was mot,d.. (wow)

first question he asked was is it 4wd... answer yes...

MOT MAN...

we will have to do a driven brake assesment, is that ok with you sir..


lil ol me.. no probs....


and it passed....

you thinks yours is bad,,,


i heard of a happy testers apprentice on the rollers with a rangey!!!

giving it plenty of welly, and pulled the handbrake !!!!!!!!!!!!!!

suffice to say the clang and violent leap to one side scared him sh**less and caused a few bobs woth of damage!!!

Mart

 

If its any help I had an MOT back in May and they put mine on the rollers and all was fine, I asked the inspector and he said it would be no problem, if the car didnt like it then it would launch itself off the rollers or show drag, mine showed neither and I "will" take it back there next year too, but if you look at worst case cenario then you wouldn't smoke, drink or **** too often

 

My disco went on the roller four years running no problems

 

How are they supposed to test it then? Ive never seen a 4x4 being tested

 

MOT MAN...

we will have to do a driven brake assesment, is that ok with you sir..


lil ol me.. no probs....

My local MOT tester did a driven brake test also.Rather than put it on the two rollers.
Although his dad previously tested it using the rollers the year before.Ummmm.

 

i thoguht was under the impression all 4WD vehicles had to be tested on a road rather than the rollers! this was the way it was always done in any of the garages i ever worked at!

I'd complain just incase you get any damage 6 months down the line!

Tam

 

Your disco has a standard centre diff...NO VISCOUS COUPLING, so it will be pretty much ok. Do the same with a Freelander or a Range Rover fitted with a Borg Warner transfer Box and you'll have a different story

But it should STILL be tested with a tapley metre, as thats what is the MOT test guidelines.

Permanent 4wd = Tapley metre, no excuses, if it's done on the rollers, they are doing it wrong - simple as that!

I think, IIRC that Re-Bitten hero can give you information on what happens to a scoob brake tested on a 2 wheel roller

 

Cannot agree more with you Tams...i really cannot understand why people are quite prepared to have their pride and joy incorrectly tested and have the attitude 'well it didn't damage mine'.
The MOT guidelines state 'Under NO circumstances must a vehicle equipped with permanent four wheel drive,Limited Slip differentials or belt driven transmissions be brake roller tested'.

It has been put in there for a reason !!!

So would the engineer expert who said the rollers would not damage your car cough up for the repair bill if it did?? ..........somehow i think not.

Rest assured that my garage test all vehicles CORRECTLY and 4x4/AWD transmissions are never brake roller tested.


steve.

 

you can not test a scooby on one roller.My cousin owns a garage and every 4wd car that they mot they have to go out on the road to test it.I had my own car on the roller two years ago to see if the discs had warped again and i was driver when he set the rollers away.I emediately stopped the roller due to the diffs locking up in a matter of seconds (you can here them).We could not do the test, full stop! It sounds like I am not the only one on the bbs telling you this so it is time to speak to the garage,just incase.


ps just look at these cars getting rolling roaded,they dont do it on one set of rollers do they?

Good luck mate

 

Totally correct

Dipster

 

DO NOT LET A MOT TESTER CHECK YOUR BRAKES ON A 2WD SET OF ROLLERS
anybody who says otherwise is full of **** and does not know what there on about

complain NOW

big thread about this last year after sumbodys car fooked up after a test
the garages need to do a roadtest to tell weather the brakes work properlly or not

 

A road test! Dont like the idea of muppets driving the car for a *test drive*.

So what does this Tapley meter look like/ do?

 

If this is *so* important then why dont subaru make any mention of it in the handbook

 

Look in the section on "towing the vehicle in the event of a breakdown" for all the does and don't, IIRC it says tow with all four wheels on the floor or on a flatbed truck, I think it states not to tow by lifting just the front or the rear wheels as this will damage the viscous coupling.

 

The meter they used to test my car is a wooden box with a window on the top.

They drive down the road at a set speed and stand on the brakes, the meter then gives a value between 0-100% (Think mine was in the high 90's?)

They then repeat the test with the handbrake?

I think I would rather a muppet take it for an "Insured" test drive than have the centre/front/rear diff fail and be faced with a big bill, that I would have to pay myself?