VW Racing's Quaife Diff....

[Teutonic_Tamer]

Interesting write up RR.

I've often wondered what that diff would be like and if it is as good as quattro in most 'ordinary ' conditions ( wet roundabouts, pulling out at junctions etc )

RRs Quaife is merely a cross-axle diff, which is basically improving traction to just the front driven two wheels. With "quattro", though dependent on variant, all four wheels receive traction, so a correctly set up 4wd system, ie Torsen, will always provide better traction than even the most sorted of front wheel drive cars.

[Mook]

so a correctly set up 4wd system, ie Torsen, will normally provide better traction than even the most sorted of front wheel drive cars.

Corrected for accuracy - don't forget that a properly sorted FWD car with the same or fewer bhp can often get round a track quicker than a 4WD car (Torsen or otherwise) because it's generally lighter

Yes Shark, I'll prove it next time I see you on track

[Teutonic_Tamer]

Haldex is in the TT and A3 applications. Torsen is in anything up from that. Both are labelled "quattro" and Audi's marketing insists that a TT has "permanent" 4wd, however it is more accurately described as "permanently available."

Yup, Audi merely use the word "quattro" for marketing purposes, irrespective of the actual 4wd technologies used.

Haldex is also used in VW models that share the same platforms and models of a similar size. R32, Golf TDi 4mo, Tiguan (sp?) use Haldex, Passat and Phaeton use Torsen.

The latest Passat has gone to Haldex, because it is based on the Golf 5 platform, rather than the Audi A4 platforms of old.

And just like Audi, Volkswagen use "4MOTION" purely as a marketing term for all their 4wd cars.

And following in the same vein, VAG stablemates Seat use "4", and Škoda use "4x4" - to nomenclate their 4wd offerings.

I'll happily admit (after driving a new S3) that Haldex is getting better, but proper 4wd it isn't.

Agreed. Recently had a full days very hard play in the latest R32 - what a crock of brown stuff. Horrendous understeer at slow speeds, and the more throttle I applied to dial out the understeer, the worse it actually became. As for very hard cornering at speed, the transition in grip to the rear is scary!

My old B6 S4 with its massive V8 ahead of the front axle was hugely better than any Haldex.

My current RS with its 40:60 diff really is a pleasure, and gives superb traction dynamics, which could never be achieved by Haldex (unless they had two, a la Veyron ).

Edited October 6, 2008 by Teutonic_Tamer
speeling mistooks

[Teutonic_Tamer]

....Thanks for that explanation, Ben - Much appreciated .

It leaves me thinking that Audi are totally wrong to use the title "quattro" for what is Haldex "permanently available". If I bought an Audi which was stated by them to have "quattro" and it was anything less than the real thing, I would be consulting solicitors!

But their sales brochures generally state if their quattro-equiped cars (A3q/S3/TTq/TTS) actually use the Haldex system. I also think that the Audi website also confirms that "quattro" is merely a marketing term, though I could be wrong on both issues!

[Teutonic_Tamer]

....

I've learnt that the new Mk6 GTI electronic diff called XDS....

"...is actually still part of the gearbox, but is "controlled" by the ESP/ABS system, in the same way that the Mk5 EDL (Electronic Differential Lock) is. It basically works using "pulse width modulation" in exactly the same way as the Haldex controller - in that the "diff" itself can not "sense" the levels of torque (applied torque, wasted torque, and useable torque), like an ATB diff such as Torsen/Quaife/Peloquin can."

"...the Quaife is identical to Torsen - and a Torsen diff is used in the rear axles of the Audi R8 and Audi Q7, along with all centre diff applications in longitudinal mount VAG four wheel drive cars (except the Veyron, R8, and Q7)."

[Thanks to Sean aka Teutonic_Tamer]

<cough>

How do!

So, which would I prefer? - A Haldex-style diff or a Torsen-style diff? - No brainer, the Torsen-style Quaife.....

Agreed, but you don't get any choice. R32, S3 and TTS all = Haldex.

[Teutonic_Tamer]

Corrected for accuracy - don't forget that a properly sorted FWD car with the same or fewer bhp can often get round a track quicker than a 4WD car (Torsen or otherwise) because it's generally lighter

Nope. I was right. I merely stated traction. I certainly made no mention of "lap times".

[sternocleidomastoid]

....

(I don't know whether to address you as "Sterno" or "Mastoid" - the rest is too much of a mouthful!)

Yes, the Mk5 GTI has TC as part of ESP. The ESP can be switched off via a button in front of the gear stick. The ESP always defaults to being On whenever the ignition is switched on. On the road I always drive with ESP On - Imo it's not a matter of proving you're a man by switching it Off! But different cars behave differently.

Don't ask me about the exact structure regarding TC and ESP on the Mk5 - It gets complicated! But the TC icon in the speedo lights up every time the wheels are losing traction and signifies the ESP coming to the rescue.

One result of having a mechanical diff like the Quaife is that the TC sensor system is less frequently called upon to instruct the ESP (or however it works). In other words, the ESP follows the Quaife's physical responses rather than rely on electronic sensors which can either go wrong or get dirty like my Wheel Speed Sensors did and which probably then fooled my ESP into action which caused wheel snatching in compensation - Not confidence inspiring!!

Someone who knows more than I do may post that I'm talking bollox but I offer this as being to the best of my knowledge.

Having spent as much as £1,500 on any mod, the placebo effect naturally comes into play - You say to yourself (or your SWMBO) "Of course it works well - I spent all that money on it and of course I make the best decisions". However, the Quaife is something which has such a physical result that it's not simply your butt-dyno. Whether spending the money is worth it to you or not can only be your decision but I have no regrets and everybody who has either done the same or owned a FWD car with LSD already installed, has nothing but good to say about it - It's an often overlooked mod.

Cheers Robin+++. I think i'll wait and see what the january tax bill is before making any final decision. After owning the car for nearly a year an a half i didn't know it had TC as part of the esp. i must be being too careful with my right foot! (ps "sterno" is fine)

[shark_90]

The latest Passat has gone to Haldex, because it is based on the Golf 5 platform, rather than the Audi A4 platforms of old.

Good knowledge! I didn't know that it was based on the Golf platform, and that really puts me off now!

[Teutonic_Tamer]

Good knowledge! I didn't know that it was based on the Golf platform, and that really puts me off now!

The Golf 5 platform is actually very good. It is also used by the A3 and S3, and the TT. But it does miss the Torsen.

[shark_90]

And it's the Torsen I'd be missing I'm a bit of a quattro whore

[Teutonic_Tamer]

And it's the Torsen I'd be missing I'm a bit of a quattro whore

So based on that premis, you would have to turn down a Veyron then?

[Mook]

He would, but only because there wouldn't be any room for a sprog in the back

[shark_90]

I'd be interested to know how the Veyron's system works. 2 x Haldex couplings?

[Teutonic_Tamer]

I'd be interested to know how the Veyron's system works. 2 x Haldex couplings?

Yup.

One at the front and one at the rear. And it doesn't actually have any "centre" diff at all - both front and rear props are permanently driven at equal speeds. And I gather the actual Haldex units needed some serious uprating to cope with the extra torque, because the standard units (like on the TTq/S3/R32) do have a torque handling limit.

Edited October 16, 2008 by Teutonic_Tamer
speeling mistooks