Quaife ATB Helical LSD

[sonny]

Quaife ATB Helical Limited Slip Differentials are a direct replacement for the standard, factory-fitted ‘open’ differential and can transform the performance of any vehicle.
As engine power outputs increase, the ability to use this extra performance becomes more important. Wheelspin may look spectacular, but such loss of traction from either a standing start or exiting a bend wastes time, whether driving on the road, circuit, rally stage or drag strip. Fortunately, Quaife's patented Automatic Torque Biasing (ATB) Helical Limited Slip Differential (LSD) is an effective, well-proven, low-cost solution.

The ATB units are designed using the latest CAD techniques and CNC machined to ultra-tight tolerances from high quality Corus steel billets. The completed units are then subjected to rigorous in-house inspection with 3D coordinate measuring machines. Such quality means that, unlike a conventional plate-type LSD, the Quaife ATB unit requires no special maintenance or rebuilds, is long-lasting, and retains the standard method of lubrication, making for an easy, pain-free upgrade.

Unique, Quaife patented design prevents complete loss of drive that occurs with some conventional differentials when one wheel slips
Never locks, inherently safe
Controlled power transmitted to all driving wheels
Automatic in operation
Eliminates harsh torque steer and under steering characteristics of other types of LSD
Gear operated (no plates to wear or break)
Direct replacement for standard unit
Used in all forms of motorsport and suitable for road use

http://www.demon-tweeks.co.uk/Performan ... 4392/23203




So thought Gents, what you reckon?

[Timster]

Well out of my league ... but isn't that how they used to design diff's ?... back in the day.

What design is in the B7 RS4?

[stu]

Would it make much of a difference in the B7 RS4's quattro setup? I thought the combination of the Torsen LSD in the middle and open diffs at the front and the back was the perfect combination. Or have I been lapping up Audi's (and the car critic's) spin too easily? Are you thinking in terms of a replacement for the Torsen (increasing the torque bias to the rear), or sticking one between the rear wheels?

I looked into getting a Quaife LSD for my old Z4 Coupe a few years ago as I found the open diff frustrating when playing on the corners. I spoke to a man at Birds (BMW tuners) who were selling them as upgrades to the open diffs non-M cars. The Quaifes were supposed to be the bee knees for any powerful beemer without forking out for an M-differential. Narrowed the dynamic gap between the 335i/d and the M3. I think purchase and fitting was around £1,200. Quick and easy to do.

[sonny]

My thoughts exactly, the Quattro drive train s perfect, I don,t have any experience in this department, so wondering what others thoughts are.

I seem to recall last year someone talking about having an LSD up front installed, said it perfected his initial turn on on track.

[PetrolDave]

My thoughts exactly, the Quattro drive train s perfect, I don,t have any experience in this department, so wondering what others thoughts are.

I seem to recall last year someone talking about having an LSD up front installed, said it perfected his initial turn on on track.

Without ESP if you had one front wheel and one rear wheel on smooth ice then because the front and rear diffs are open then you would be going nowhere even with quattro (as all the torque would be sent to the spinning wheels) - so the ESP gets round some of the issues of having two open diffs.

But up the speed to above the level where ESP works (because it cuts off to avoid overheating the brakes) and having an LSD front and rear as well as the Torsen centre diff could further improve the handling in extremis at speed.

[P_G]

Do you know what speed it cuts out at Dave?

[sonny]

So yay or nay Dave for the Q LSD diff?

[bam_bam]

[PetrolDave]

So yay or nay Dave for the Q LSD diff?

I would say yay if you're looking for the ultimate handling and/or Winter performance.

[adsgreen]

Front LSD is of IMO of a limited benefit.
Whilst they can have a benefit under braking but with modern 4 channel abs and control systems not as apparent.
So it's mainly power application scenarios - not many corners have power on turn in so can't see how it's going to give benefit there.

With the centre diff I don't think having open doffs front and rear is such a big problem.
As soon a you unload the inside wheel all drive to that axle is gone but the centre diff should shunt it forward so not going to lose all drive like front or rear wheel drive. What you may get is a bit of power on understeer which isn't great but you'd hope with the default 60/40 split that should be balanced initially.

What would be useful is to get a log of individual wheel speeds to find out what's going on - your driving style and setup will give different results. You may be able to get this from Vag Com but on other cars I've tapped the abs nsor wires (not the ones from the wheels but from abs controller to engine ecu)

There's a lot of debate on other forums and my experience with lsd's is mainly rwd but I think there's no such thing as a free lunch. With lsd's you introduce a little high speed understeer that is noticeable in fast sweeping corners. Also you trade rear traction by running nearer the traction circle of the axle but if you cross over and exceed the available traction then it'll snap quickly. Without an LSD things happen much slower and easier to catch.

What problem you trying to fix?

[duud40]

QDF4Q does not fit the RS4 rear diff.

[sonny]

What problem you trying to fix?

Not any problem, you know how it is, if there is something out there that can make the driving sensation a little better then i'm all ears. I'm guessing it will help with understeer?

[PetrolDave]

QDF4Q does not fit the RS4 rear diff.

Who are QDF4Q? Or is that some kind of bizarre "text speak"?

[adsgreen]

It's a quaife product code.

[PetrolDave]

It's a quaife product code.

That everybody knows - not!