Discussion of Quaife and other Torsen type LSDs

Paul_S

Paul_S

Club Member
I think that's because the brake testing machine can cause them damage. They'll need to go old skool and take it out on the road.
 
Huw

Huw

Club Member
Found this on the internet from VOSA

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/205905/11_107.pdf

Extract:
Vehicles not to be tested on a roller brake tester
Certain vehicles should not be tested on a roller brake tester, e.g. vehicles with
· More than one driving axle permanently engaged
· Limited-slip differential
· Belt-driven transmission
· Brakes for which the servo operates only when the vehicle is moving
These vehicles should be tested using a properly calibrated and maintained decelerometer or a plate brake tester designated as acceptable for the statutory tests. A roller brake test is also not appropriate for vehicles with damaged, under-inflated or studded tyres.


 
Rob Gaskin

Rob Gaskin

Treasurer
Staff member
Site Administrator
jonbills said:
why Rob?
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During brake testing they try to stop one wheel which they can't do.
Huw said:
Found this on the internet from VOSA

https://assets.publishing.service.g...ploads/attachment_data/file/205905/11_107.pdf

Extract:
Vehicles not to be tested on a roller brake tester
Certain vehicles should not be tested on a roller brake tester, e.g. vehicles with
· More than one driving axle permanently engaged
· Limited-slip differential
· Belt-driven transmission
· Brakes for which the servo operates only when the vehicle is moving
These vehicles should be tested using a properly calibrated and maintained decelerometer or a plate brake tester designated as acceptable for the statutory tests. A roller brake test is also not appropriate for vehicles with damaged, under-inflated or studded tyres.
Click to expand...

Good find Huw. My tester wouldn't put my car on the rollers.
 
jonbills

jonbills

Membership Secretary
Site Administrator
I can just about imagine some LSD setups making it hard to measure inneficient braking on one side, maybe that's why VOSA say that they shouldn't be tested.
They don't try to stop one wheel. The car is in neutral and the rollers drive the wheels and they measure the load put on the rollers by braking. If one wheel stops, its because the brakes on the other side aren't working properly.
I just can't see how it could do any harm to the diff. esp the Quaife- there's no applied torque to balance with the car in neutral.
 
AliK

AliK

Vehicle Dating Officer
Staff member
Club Member
You’re right Jon. Being a one way LSD, with no applied torque and on the overrun, as you say, it effectively becomes an open diff. They don’t even need to drop into neutral.

But Rob’s point is very valid on 1.5 and two way LSDs.
 
Huw

Huw

Club Member
jonbills said:
I can just about imagine some LSD setups making it hard to measure inneficient braking on one side, maybe that's why VOSA say that they shouldn't be tested.
They don't try to stop one wheel. The car is in neutral and the rollers drive the wheels and they measure the load put on the rollers by braking. If one wheel stops, its because the brakes on the other side aren't working properly.
I just can't see how it could do any harm to the diff. esp the Quaife- there's no applied torque to balance with the car in neutral.
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Just to follow up on this, I contacted Quaife on this matter and have received a response.

They state that an MOT can be carried out as normal with one of their ATB diffs and the brake test will not damage the diff.

Straight from the horse mouth, so all good come MOT time.:thumbs:
 
atomman

atomman

Club Member
Huw said:
Just to follow up on this, I contacted Quaife on this matter and have received a response.

They state that an MOT can be carried out as normal with one of their ATB diffs and the brake test will not damage the diff.

Straight from the horse mouth, so all good come MOT time.:thumbs:
Click to expand...

that will be because its a 'Torsen' diff , if one wheel loses traction , it acts just like a open diff,
 
Rob Gaskin

Rob Gaskin

Treasurer
Staff member
Site Administrator
A Quaife is an Automatic Torque Biasing (ATB) diff. They work fine unless one wheel is in the air.
 
peter_s

peter_s

Club Member
Rob Gaskin said:
? waste of money then.

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No, that happens very seldom. And you can feel and drive around that problem. It basically only happen around some curbs on the track. Almost never on the street, unless you are rallying.

I personally prefer clutch based LSDs, but will probably get the quaife myself. It's not a deal breaker
 
atomman

atomman

Club Member
Rob Gaskin said:
A Quaife is an Automatic Torque Biasing (ATB) diff. They work fine unless one wheel is in the air.
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I'm not saying it's a waste of money Rob, I've got one to try in my Z

But like you said if you get one wheel in the air/lose traction it's goes open , they are good for road cars as it's fit and forget unlike plate lsd's and don't need special oil either, that's why they have been fitting them in subaru's for years
 
Alphabettispaghetti

Alphabettispaghetti

Club Member
atomman said:
I'm not saying it's a waste of money Rob, I've got one to try in my Z

But like you said if you get one wheel in the air/lose traction it's goes open , they are good for road cars as it's fit and forget unlike plate lsd's and don't need special oil either, that's why they have been fitting them in subaru's for years
Click to expand...

I had a kit car with a torsen diff, on tight linconshire country roads where a wheel might drop the camber or hit loose gravel, it could cause a few interesting moments. From that point on I'd always have plated diffs as for mortals, they're more predictable.
 
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