MOT with an LSD
Discussion
What’s the latest on this? I have read lots of posts of people saying that a car with an LSD should not be tested on brake rollers, but can't find the applicable guidance online from VOSA. As I understand it, the alternative is for the tester to test brakes on a road test, using a decelerometer.
I called the MOT place and they said that they only road test 4x4 vehicles.
I called the MOT place and they said that they only road test 4x4 vehicles.
My Landrover has a limited slip centre diff and the advice from the manufacturer (Ashcroft Transmissions) is; Note : Due to the nature of the AATB diff we do not recommend the vehicle is brake tested on rollers, ask for a decelerometer to be used instead.
Probably more critical in the case of a centre diff though as it means the front to rear drive is 'locked' rather than just cross axle, also means it shouldn't be towed with 2 wheels off the ground, though that's probably also the case for the open diff?
Luckily it's MOT exempt due to age so not an issue.
Probably more critical in the case of a centre diff though as it means the front to rear drive is 'locked' rather than just cross axle, also means it shouldn't be towed with 2 wheels off the ground, though that's probably also the case for the open diff?
Luckily it's MOT exempt due to age so not an issue.
Cats_pyjamas said:
Let the garage know it has a LSD, post it note on the steering wheel for the tester.
A LSD will lock on the brake tester and could throw the car off and/or damage the diff.
Never had an issue with my MOT tester, I'd advise going to a tester who understands what a LSD is.
No it wont, a spool diff would but the rollers dont go fast enough to trouble a lsd.A LSD will lock on the brake tester and could throw the car off and/or damage the diff.
Never had an issue with my MOT tester, I'd advise going to a tester who understands what a LSD is.
A centre diff might be a problem tho.
Cats_pyjamas said:
Let the garage know it has a LSD, post it note on the steering wheel for the tester.
A LSD will lock on the brake tester and could throw the car off and/or damage the diff.
Never had an issue with my MOT tester, I'd advise going to a tester who understands what a LSD is.
Have you got a link to the guidance?A LSD will lock on the brake tester and could throw the car off and/or damage the diff.
Never had an issue with my MOT tester, I'd advise going to a tester who understands what a LSD is.
Testers in the know/testers who care will do the road test instead of rollers but I get the impression that lots just don’t.
I test a lot of Land Rovers, and we always do a decelerometer test on these due to the centre diff.
On cars with LSD's we can set our rollers to brake both wheels together, which at the speed the rollers turn will not upset the LSD.
If the roller set brakes the wheels individually, then the tester must use the decelometer.
When you take your car for test be sure to mention it to the tester as he may not realise otherwise.
On cars with LSD's we can set our rollers to brake both wheels together, which at the speed the rollers turn will not upset the LSD.
If the roller set brakes the wheels individually, then the tester must use the decelometer.
When you take your car for test be sure to mention it to the tester as he may not realise otherwise.
P100 said:
I test a lot of Land Rovers, and we always do a decelerometer test on these due to the centre diff.
On cars with LSD's we can set our rollers to brake both wheels together, which at the speed the rollers turn will not upset the LSD.
If the roller set brakes the wheels individually, then the tester must use the decelometer.
When you take your car for test be sure to mention it to the tester as he may not realise otherwise.
Thanks for this.On cars with LSD's we can set our rollers to brake both wheels together, which at the speed the rollers turn will not upset the LSD.
If the roller set brakes the wheels individually, then the tester must use the decelometer.
When you take your car for test be sure to mention it to the tester as he may not realise otherwise.
So there is a chance that the rollers brake wheels together? I have a feeling that it doesn’t. Proper old school place.
I've always advised the tester it's got a plated lsd so can't go on the tester. He's never grumbled at it. I'm not sure if a helical diff would be any different, when I had one of those you could make it spin 1 wheel pretty easily out of junctions etc so in theory could potentially go on a brake tester
I own an MOT garage. As per DVSA instructions or our database we do not test LSD cars on the brake test rollers but use a de-accelerometre as we don't want to damage a customers car. The car MOT pre test instructions advise u on this matter mostly! I would advise anyone with an LSD car to advise the station before the test.
We get a lot of high end cars and classics for test because of the extra care we take and because we encourage owners to watch the test. I am not sure we should encourage this as there is no money to be made testing cars.
We get a lot of high end cars and classics for test because of the extra care we take and because we encourage owners to watch the test. I am not sure we should encourage this as there is no money to be made testing cars.
orangeLP400 said:
I own an MOT garage. As per DVSA instructions or our database we do not test LSD cars on the brake test rollers but use a de-accelerometre as we don't want to damage a customers car. The car MOT pre test instructions advise u on this matter mostly! I would advise anyone with an LSD car to advise the station before the test.
We get a lot of high end cars and classics for test because of the extra care we take and because we encourage owners to watch the test. I am not sure we should encourage this as there is no money to be made testing cars.
Really appreciate this.We get a lot of high end cars and classics for test because of the extra care we take and because we encourage owners to watch the test. I am not sure we should encourage this as there is no money to be made testing cars.
Any chance you could share a link? I’ve been digging.
To be honest, I’m wondering whether it would just be easier to go elsewhere. If they are adamant that the will put it on the rollers I am not sure it is worth the debate.
You may find a tester with experience of slippy diffs here - https://www.pistonheads.com/gassing/topic.asp?h=0&...
Tommie38 said:
The place I am getting tested doesn’t do anything different for LSDs. I asked. The two testers have been doing MOTs for years so they tell me.
It’s a standard MOT garage basically.
My MoT guy knows his stuff, races, has tested a few of my cars on the rollers without a problemIt’s a standard MOT garage basically.
Tommie38 said:
What’s the latest on this? I have read lots of posts of people saying that a car with an LSD should not be tested on brake rollers, but can't find the applicable guidance online from VOSA. As I understand it, the alternative is for the tester to test brakes on a road test, using a decelerometer.
I called the MOT place and they said that they only road test 4x4 vehicles.
All 2wd cars go in the brake rollers, some 4wd do, so need a deceleration test, teslas tend to go in the brake rollers but not quite as straight forward.I called the MOT place and they said that they only road test 4x4 vehicles.
We have a kit car that we test, the customer mentioned it had a lsd and would prefer if it wasn’t put in the rollers so we just carry out a decel test. If you not sure always mention it when dropping it off, the same applies to sports cats.
A brake tester isnt going to kill a lsd. Different on centre locking diffs with 4wd cars but anything else will happily go in a brake testers. The speeds it runs at isnt going to affect a lsd in the slightest. As for dvsa they give instructions on what cars should be decceled over a rolling road and apart from a few most should be used in the rolling brake tester. Most new equipment will run both wheels together now over doing individual specially fully connected systems.
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