Quaife ATB Diff ?

[stratos]

Has anyone got an opinion on the Quaife ATB diff or any experience of using one for for competition ( race )?

[GeoffBob]

Has anyone got an opinion on the Quaife ATB diff or any experience of using one for for competition ( race )?

Yes. Much better than the clutch type ZF LSD due to the way the torque is transferred from the wheel losing traction to the one with traction.

See my earlier thread on LSD's here

Third post down includes a link to the most recent Quaife patent that explains how the Quaife ATB mechanism works.

What is important to understand is that a clutch type LSD will effectively lock (hard and fast) your two drive wheels together when one or the other wheel loses a certain amount of traction.

A Quaife on the other hand will progressively transfer torque in direct proportion to the amount of traction lost at one drive wheel, over to the other wheel. It is, to a certain degree, a form of traction control. And since it is a progressive thing it won't catch you out like a clutch type LSD will on the track.

On the down side - a Quaife is lousy on ice or any surface with limited traction (but then it was never designed for that).

[martinpallot]

Useless for competition purposes, mainly because if one wheel lifts then it will act just like an open diff. would agree that its better than a strandard 25% lock bmw item.

[GeoffBob]

Useless for competition purposes, mainly because if one wheel lifts then it will act just like an open diff.

Sorry Martin, but I am afraid I have to disagree with you on that one (just a comment, I really don't mean to start an argument).

While it is true that lifting a wheel with a Quaife will result in wheel-spin, if a car is lifting a drive-wheel then its either over an obstacle, or the suspension is setup incorrectly. In my opinion, the benefits of a Quaife outweigh any cost incurred in the unlikely event of either the above.

To the best of my understanding, the Quaife ATB diff has been well received by the motorsport fraternity. To quote No Limit Motorsport, "The Quaife ATB Differential has been proven in everything from SCCA Rally to Formula 1. The Quaife ATB Differential provides autocrossers with such an advantage, it has become "required" equipment for a winning effort."

A further example is Nick Leason who uses a Quaife on his BTCC BMW.

[agent006]

Excellent example with a picture of Nick being lapped.... again. Do we know what diff the RAC and Airwaves BMWs use?

[kimbo]

Useless for competition purposes, mainly because if one wheel lifts then it will act just like an open diff.

Sorry Martin, but I am afraid I have to disagree with you on that one (just a comment, I really don't mean to start an argument).

While it is true that lifting a wheel with a Quaife will result in wheel-spin, if a car is lifting a drive-wheel then its either over an obstacle, or the suspension is setup incorrectly. In my opinion, the benefits of a Quaife outweigh any cost incurred in the unlikely event of either the above.

Err - kerbs?
In my experience, the Quaife requires a softer setup with more 'droop' on the wheels to maintain traction. Not ideal if you're using rear ARB.
For race use I'd stick with a plate diff and play with the settings until a compromise is found. Each to their own, though.

Kim.

p.s. The team that bought our old race car off of us blew up the diff (Gemini plate) and replaced it with a Quaife and have suffered with excessive wheelspin and tyre wear since.
Luckily I've got a spare Gemini in stock, so they have that option if they wish to spend the money. FWD car, but the morals the same, in my view.

[Jon_Bmw]

Kimbo it is much easier to lift an driven wheel in a a FWD car though... I use a plate diff on a FWD and it is great, but crap on the road(thankfully it only drives to and from events).

I am pretty sure plate diffs are universily preferred(and presumably better?) than a quaife type diff for competition.

[GeoffBob]

Play fair gents. It goes without saying that the intended application is a RWD e30. FWD is a totally different kettle of fish.

Spend much time on the kerb do we Kimbo?

[Cook318IS]

My mate has a citreon saxo... (not quite the same i know) but its about 190bhp (with nos) and he has a quaife lsd and internals in his gearbox. The internals are very well made i'd say... he's cracked 3 gearboxes so far but all the internals appear to take the power well.

[mt1104]

I thought quailfe solved the whole 'loosing drive if one wheel gets in the air' thing with its latest designs?

[GeoffBob]

I receivd the following response from Kevin Bird at Birds Auto, from whom I bought my Quaife, when I raised the issue of lifting a wheel:

Nick Leason had us convert the BMW Motorsport diff which was misbehaving with the Drexler diff, making the car unstable and difficult to drive out of slow corners. We installed the Quaife ATB, and he reported that he could use all the power driving out of slow corners after that. Regrettably, lack of sponsorship didn't allow him to finish the 2009 series, and prove the installation properly.

James Thorpe ran his Quaife ATB diff equipped 130i to a brilliant 15th place agains Moslers, M3 GTs and the like. 3rd in his class. See http://www.astonmartinracing.com/eng/re ... tcar24hour

BBC Top gear ran their 24hour race with Quaife installed. See http://www.topgear.com/uk/tv-show/series-10/episode-9

Mike Salmon converted his E36 M3 race car, removing the modified ZF diff and replacing with Quaife during his 2007 campaign. Can't find any relevant links. He was recommended to do this by Dave Ellis, who had already converted a similar car with strong results. I believe this is the car/driver here http://www.serverware-racing.co.uk/page ... ar0407.asp

On the subject of "lifting wheels", I would comment that there would have to be something seriously wrong with a RWD suspension setup car if the car lifted a rear wheel. That's not a problem you would ever see in practice. I have tested my own track prepared M3 with both ZF clutches LSD and the Quaife. The ZF would always lock up suddenly and loose all rear grip on tight, slippery corners, completely destabilising the car and required me to completely get off the throttle. With the Quaife installed, that eliminated that problem, and I could then easily modulate the throttle depending on the level of grip.

With every solution for any technical issue, there will always be advantages and disadvantages. This hypothetical loss of performance due to wheel lifting would only ever be disadvantageous if the car suspension was deliberately set up without consideration to the whole dynamic characteristic of the chassis and driveline.

I also noticed that the rear end became much more stable under braking. With the ZF, I often used to get rear ABS activation under hard braking on slippery surfaces. With the Quaife, the problem never appeared again, and on those slippery conditions, both front and rear brakes had similar amounts of ABS intervention.

And before anyone asks, no, I do not own shares in either Quaife of Birds Auto . I did, however, do a lot of homework into the various aftermarket diffs for the e30. I even went as far as to download patent documents to see how the different types of diff work. I firmly believe that the new design (2003) Quaife will progressively earn the respect of both professional and amateur drivers alike. But this is only my opinion.

[N00b]

Does anyone have an approximate price for the Quaife part?

[N00b]

^^^
Scratch that, I found it.

[kimbo]

Play fair gents. It goes without saying that the intended application is a RWD e30. FWD is a totally different kettle of fish.

Spend much time on the kerb do we Kimbo?

Its the only way to get a time round some tracks. Not relevant for trackday, I know. Above is at Thruxton, Snet is the same - got to ride the kerbs leading on to the start / finish straight to carry the speed, or you lose out for the first half of the lap.

In another life, I spend a lot of time marshalling at hillclimbs and it isn't at all unusual to see a rwd car pick up it's inside rear wheel on the tighter corners - particularly Ashes at Gurston Down, an uphill (obviously) left hander which the camber drops away from on the exit.

Anyhow, as I said earlier, each to their own, but we'll stick with our plate diff.

Kim

edit - not trying to pretend thats me, by the way, just illustrating that its not unusual for wheels to be in the air!!

[GeoffBob]

Excellent picture Kimbo! Point well taken, thanks for that.

I had in mind however that the advantage provided by a Quaife (in particular its ability to power out of slippery corners, due to the way it distributes torque) would more than offset the resultant loss of traction on the outside (edit, sorry, I mean inside) drive wheel during an event such as that shown above. Looking at that pic I am not so sure (not that I would ever have the balls to drive like that, so that's definitely not me in that car either )

I currently have a ZF clutch type diff on the rear of my car (what you call a plate diff?) but plan to swap it for my new Quaife before I put her back on the track (have been finishing off some paint and GRP work during our winter months). Based upon the mechanics of the two types of diff I am, however, convinced at this time that the Quaife is superior, but the proof of the pudding, as they say, is in the eating - which could produce and altogther different result. I'll be sure to report back on how I feel the two compare to each other. Will only be my opinion though (as a function of my own driving skills) and whether that amounts to a hill of beans is another story .

[mt1104]

I was under the impression a rear wheel drive car should ideally raise its inside front wheel in hard cornering and a front wheel drive car should raise its inside rear wheel (like the clio does) if the suspension is set up correctly.

In either case, if a driven wheel is raised under power, your going to get into trouble no matter what diff is in the transmission.

[stratos]

Thank you for your replys - very interesting. So far I am on the side of the Quaife which sounds like it should be used with a decent set up and vehicle dynamics. The car currently weighs 850 kg ( without fuel or driver ) but is relativly front end heavy. I ran the car at a sprint at Llandow (as a bit of a systems check)with an open diff and of course it had very little traction - very entertaining !

[GeoffBob]

Hi Stratos,

I am in the process of fitting my new Quaife ATB diff to a spare "medium case" final drive. I am documenting everything as I go along, which may be of some help to you. You can see my car here. There's a pic of the Quaife on page 3. The car has a similar weight to yours and I experienced similar problems to yourself with an open diff. I currently have a clutch type ZF diff fitted, which is a big improvement, but will soon replace it with the new Quaife. I am keen to do an objective comparison of the ZF to the Quaife once I get my Quaife fitted.

BTW, I have studied the patent document of John Quaife in minute detail and for the life of me I cannot see how it is possible for the diff to become "open" with one wheel raised off the ground - at least not while a substantial torque is applied to the diff input shaft.

Certainly, with the vehicle stationary and one drive-wheel raised off the ground it will seem to behave like an open diff, but I challenge anyone to blip the throttle and see if it doesn't try to jump its axle-stand. I could be wrong about this (and this is certainly a test that I plan to try once my Quaife ATB diff is fitted), but I do believe that the current Quaife design (as detailed in Michael Quaife's most recent patent) has addressed the above much debated issue. This is basically as mt1104 said in his earlier post.

If anyone has deeper insight into this matter, or "actual experience" of a Quaife ATB diff in a RWD car, please post it up. I have e-mailed John Quaife to try and get his response but I am not holding my breath for a reply. He has already had enough problems with people copying his invention that I doubt he wants to answer questions on how it works.

[e21Jason]

I aways thought quaife and most diffs all have some form of preload to stop the issue with 1 wheel being frictionless

Jason

[GeoffBob]

Yes. In fact, the preload on the current Quaife design is adjustable by means of set-screws. This is the improvement to the original Quaife design that is at the heart of the 2003 patent. In the patent document the adjustment is defined for the purposes of a mild to aggressive setup. With the set-screws all the way in (and stiffer Bellville springs) the diff comes very close to being fully locked (and likely results in excessive tyre wear) and is recommended only for very slippery conditions. Winding the setscrews out reduces the pre-load and is recommended for a daily driver.

Adjusting the set-screws can only be done with the diff removed from the casing. 'Would be nice to have a knob on the dash (similar to the brake bias adjuster) to adjust the diff. Off course, with a hydraulic (viscous) diff, this is possible.

[Jon_Bmw]

I wonder if the problem with quaifes spinning the inside wheel up is the fact the engine easily overcomes that preload torque-thus spinning the wheel.

On a friends metro VVTI with a quaife he was definately complaining of spinning the inside wheel(FWD) and that is on a corner weighted car. This was tight turns on a tarmac rally stages. I suspect the issue is less profound with RWD due to physics.

It is horses for courses, all I know is that I look a right prat when manouevering my 205. BANG BANG BANG

[Jhonno]

all I know is that I look a right prat when driving my 205

[GeoffBob]

I wonder if the problem with quaifes spinning the inside wheel up is the fact the engine easily overcomes that preload torque-thus spinning the wheel.

Jon, from what I understand (from the patent) a Quaife ATB diff won't stop you from spinning an inside wheel if the torque at that wheel exceeds the tyres available traction. To prevent the inside drive-wheel slipping your friend needs to fit stickier tyres or adjust his ARB's so that less weight shifts to the outside while cornering.

What the Quaife ATB diff will do, however, is to redistribute a percentage of the torque from the slipping wheel back to the outside wheel. it doesn't elimate slip, but it does optimise the amount of power the engine can put to the ground. Unfortunately, you pay for this (if you use it) in the form of tyre wear.

A plate/clutch type diff, on the other hand, will tend to minimise slippage at the inside wheel by simply locking the two output shafts hard and fast to each other. The disadvantage of this is the harshness of the mechanism and the resultant effect upon the stability of the vehicle, particularly when powering out of corners. Locking the two output shafts together (via the clutch mechanism) may be the best way to stop the inside wheel from spinning, but it isn't the best way to power through a corner (simply because two wheels that are locked together can't follow a path around a circle). In other words, locking two wheels together (to prevent slipage) doesn't maximise the amount of power the car can put down on the ground.

[billgatese30]

Locking the two output shafts together (via the clutch mechanism) may be the best way to stop the inside wheel from spinning, but it isn't the best way to power through a corner (simply because two wheels that are locked together can't follow a path around a circle). In other words, locking two wheels together (to prevent slipage) doesn't maximise the amount of power the car can put down on the ground.

To be fair though Geoff, they are only locked by a certain amount, (i.e. 25% on a std e30 diff), its not like it is acting like a spool when it engages (unless you have it set ridiculously high on purpose).

I know what you are trying to say though.

[GeoffBob]

Locking the two output shafts together (via the clutch mechanism) may be the best way to stop the inside wheel from spinning, but it isn't the best way to power through a corner (simply because two wheels that are locked together can't follow a path around a circle). In other words, locking two wheels together (to prevent slipage) doesn't maximise the amount of power the car can put down on the ground.

To be fair though Geoff, they are only locked by a certain amount, (i.e. 25% on a std e30 diff), its not like it is acting like a spool when it engages (unless you have it set ridiculously high on purpose).

I know what you are trying to say though.

Sorry Bill, you are quite right.

Where I have used the term "hard and fast" above I mean that the transition from open to locked is sudden. It's an on/off type of thing, with very little in between. I don't mean to imply that they are solidly locked together. Looking back I can see how this might read - my mistake.

The Quaife is stated as being capable of up to 80% lock, but varies progressively from 20% (factory pre-load) up to the full 80% as a function of the difference in torque between the two output shafts. Its begining to make sense to me why the Quaife has a reputation for eating tyres (80% lock is not far off from a spool). A very tight corner (at speed) could eat a lot of rubber.

[billgatese30]

Locking the two output shafts together (via the clutch mechanism) may be the best way to stop the inside wheel from spinning, but it isn't the best way to power through a corner (simply because two wheels that are locked together can't follow a path around a circle). In other words, locking two wheels together (to prevent slipage) doesn't maximise the amount of power the car can put down on the ground.

To be fair though Geoff, they are only locked by a certain amount, (i.e. 25% on a std e30 diff), its not like it is acting like a spool when it engages (unless you have it set ridiculously high on purpose).

I know what you are trying to say though.

Sorry Bill, you are quite right. I didn't mean that they were totally locked together.

Where I have used the term "hard and fast" in my earlier posts I mean that the transition from open to locked is relatively sudden. It's an on/off type of thing, with very little in between. I don't mean to imply that they are solidly locked together. Looking back I can see how this might read - my mistake.

The Quaife is stated as being capable of up to 80% lock, but varies progressively from 20% (factory pre-load) up to the full 80% as a function of the difference in rotational speed between the two output shafts. Its begining to make sense to me why the Quaife has a reputation for eating tyres (80% lock is not far off from a spool). A very tight corner (at speed) could eat a lot of rubber.

I know what you were getting at, I just thought I would point it out for anyone else who may have grasped the wrong idea.

[Jon_Bmw]

I wonder if the problem with quaifes spinning the inside wheel up is the fact the engine easily overcomes that preload torque-thus spinning the wheel.

What the Quaife ATB diff will do, however, is to redistribute a percentage of the torque from the slipping wheel back to the outside wheel. it doesn't elimate slip, but it does optimise the amount of power the engine can put to the ground. Unfortunately, you pay for this (if you use it) in the form of tyre wear.

But what percentage? My friends experience is that it was costing him time as he was wasting a fair bit of exit speed spinning one wheel. The reason I didn't go with one is that they are not that highly regarded for FWD cars from what I have read. Most people who use a quaife 205 for more than just on the road get frustrated with them. But as I eluded to earlier, I think it is due the inherrent problems with FWD rather than the diff per se.

I am not sure that I will ever completely understand all of the theory behind these diffs(without that book you reccomended!) so I went on what works for my car from other peoples experiences.

With regards the metro and the engine It is a crazy little thing, only hindered by its afformentioned problem and the class that it ends up in due to its capacity

[GeoffBob]

What the Quaife ATB diff will do, however, is to redistribute a percentage of the torque from the slipping wheel back to the outside wheel. it doesn't elimate slip, but it does optimise the amount of power the engine can put to the ground. Unfortunately, you pay for this (if you use it) in the form of tyre wear.

But what percentage?

A percentage that varies from 20% (factory pre-load) to 80% according to the difference in torque between the two output shafts. Meaning that the greater the torque difference between the two output shafts the greater the percentage coupling between the two sun gears (and thus output shafts). This is the Quaife's party trick - its ability to vary the amount of lock (and thus optimise power delivery to the ground)

Sorry, I wrote "according to the difference in rotational speed between the two output shafts" in my previous post, and then edited it. The Quaife is, of course, torque dependant, not velocity.

Jon, I value and repsect the fact that you prefer a plate LSD. I am not trying to convince you that a Quaife is better - I think it's more a case that I enjoy discussing the pro's and con's of either type, and appreciate learning from peoples experience with both.

[GeoffBob]

I know what you were getting at, I just thought I would point it out for anyone else who may have grasped the wrong idea.

Thanks Bill, I appreciate you pointing it out. I can see now that I should have worded that statement better

[Jon_Bmw]

What the Quaife ATB diff will do, however, is to redistribute a percentage of the torque from the slipping wheel back to the outside wheel. it doesn't elimate slip, but it does optimise the amount of power the engine can put to the ground. Unfortunately, you pay for this (if you use it) in the form of tyre wear.

But what percentage?

A percentage that varies from 20% (factory pre-load) to 80% according to the difference in torque between the two output shafts. Meaning that the greater the torque difference between the two output shafts the greater the percentage coupling between the two sun gears (and thus output shafts). This is the Quaife's party trick - its ability to vary the amount of lock (and thus optimise power delivery to the ground)

Sorry, I wrote "according to the difference in rotational speed between the two output shafts" in my previous post, and then edited it. The Quaife is, of course, torque dependant, not velocity.

Jon, I value and repsect the fact that you prefer a plate LSD. I am not trying to convince you that a Quaife is better - I think it's more a case that I enjoy discussing the pro's and con's of either type, and appreciate learning from peoples experience with both.

I'm starting to understand it more now

Also, I think prefer is the wrong word. For my application(FWD) I was advised the plate was the right way forwards - going on other peoples experiences. If I had the money I would buy both and choose the one that was actually the best...but sadly...

I just hope that everyone wasn't wrong and a quaife would have been better!

[stratos]

GeoffBob,
As we are now approaching the depths of winter here I wont be doing anything with my car untill March / April so I have plenty of time to make a decision on the diff.
Also plenty of time for all of the other jobs on the car.
I look forward to your test of the ATB.

[bss325i]

Back in 2005 a friend of mine had a 2001 ford focus 2.0 ESP. We fitted a quaife ATB diff and koni adustables and it transformed the way it handles and cornering speeds were exceptionaly higher.

The original ford focus RS also uses a quaife ATB and as far as i know its the only production car that does.

From when the ATB first came out and up untill he purchased his (under my reccomendation) everything i had read about it was that it was more suited to FWD application than RWD. Why, i cant remember.

[bss325i]

I have also considered an ATB for my E30 as i'm not keen on the locking action of the 25% locking plate type LSD it has.

My old S50 powered E30 (now billgatese30's) has the diff from a Z3M coupe/roadster which i believe is a torsen type LSD which, i felt had a much more progessive feel to the locking action.

Whats you oppinion on this Chris as you can make the comparison as well due to having a sport with stock LSD?

I would even consider on of these for my 325i but the ratio (3.15) is all wrong for the getrag 260 box. I would need a getrag 265 "dogleg" box to make that work, which i have also considered but that also has its own issues.

[billgatese30]

Well, its hard to tell as with the quicker rack it is alot easier to catch any slide as it develops and I haven't used the clutch plate diff on the track although it does seem a little more progressive.

What I can safely say is though that the torsen diff in the S50 works great on the track, anyone with an S50 with a clutch plate diff that I can drive to compare

[bss325i]

Well, its hard to tell as with the quicker rack it is alot easier to catch any slide as it develops and I haven't used the clutch plate diff on the track although it does seem a little more progressive.

Which seems more progressive? The torsen or clutch type?

In your oppinion?