[s-cars] Off topic - New Volvo S60 ? - Drat and double DRAT!

[Ian Duff]

So, is it possible to replace the Haldex center gizmo (for lack of a better term) with some sort of other gizmo, in the same vein as it's possible to replace the rear open diff in n urS4/S6 with a V8 Torsen rear diff? For example, could one remove the Haldex stuff from the housing, and replace it with something more ...ahem... useful? And if so, what might be more useful? A Torsen center diff?

-Ian.

On 06 Jan, 2011, at 11:46, qshipq at aol.com wrote:

> 
> All good things, and my experience as well with regard to resulting driving impressions vs device operation.  To make this easier to conceptualize, it's better to think of the two axles, than the four tires, and use the term f/r axle supported torque, not traction.  Your open vs locked center 5ktq makes sense to me, as spin up on an open diff goes to the axle with the least supported torque (front because of weight transfer off that axle).  The locked c/r in a straight line will 'spin' a single front and both rears equally in *speed*, as you describe, because the f/r axles can not spin faster than the other.  But torque to those axles still follows weight transfer = rears supporting more torque than the fronts by definition, regardless of 'spin'.
> 
> The Haldex is worse than the Torsen with the characters you describe below (a worse bite?).  Simply stated:  A fwd car will handle like a fwd car until it becomes a 4wd car.  As I/Taka/others noted earlier and your experience below, those are two completely different states of dynamic handling.  With the 'performance' Haldex box, all that *can* change is the onset of those two dynamic states.  It's still a fwd car until it becomes a 4wd car, sooner than later can be perceived as a good thing I suppose.  That doesn't change the unlock properties (braking, ebrake turn, steering angle input, etc), which means the performance box only gets you 4wd Dr. Jeckled sooner, but unless you completely lock that Haldex, it will always 'default' to Hyde, a fwd car.
> 
> BTW, the reason VW claims the Haldex can be dyno'd as a front driver, is with the ebrake on, the Haldex will uncouple.  Reminder to Dyno shop, that won't work if you forget to pull up the handbrake - doh!  The reason it can be towed like a fwd car, is that with the engine off there is no coupling of the Haldex possible.
> 
> 
> IMO, a lot of the Haldex goofyness could be eliminated by using it over a center diff awd system.  That adds complexity and costs, which it would appear, Volvo and Audi didn't want to spend the dollars on.  With no other demand, Haldex dropped the development of the Haldex Center diff all together, and dropped it from the 'future' line-up from their website.
> 
> As such, Haldex will always be a compromise to a true AWD system in any performance benchmark.  Having driven both systems, it's not often that 'torsen boy' would actually prefer a torsen center, but I sure would over a Haldex without a center diff.
> 
> Cheers
> 
> S 'T-B/H-B' J
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> -----Original Message-----
> From: Cody Forbes <cody at 5000tq.com>
> To: qshipq at aol.com
> Cc: t44tqtro at gmail.com; mtgadbois at aol.com; pkrasusky at ups.com; s-car-list at audifans.com
> Sent: Wed, Jan 5, 2011 8:42 pm
> Subject: Re: [s-cars] Off topic - New Volvo S60 ? - Drat and double DRAT!
> 
> 
> 
> Well I'm going to go ahead and concede defeat. No doubt you know more about this subject than I. My apologies for the inaccuracies I had previously posted.
> 
> I've always had trouble with the concept of how torque applied to a wheel varies with weight transfer. I can fully see torque that the wheel is able to transmit to the road changing like that, but torque applied to the wheel and torque applied to the ground are different things.
> 
> 
> Ok, heres what I *KNOW*:
> On my 5ktq with the diff locks off if I use the loud pedal in first/second gear lots of smoke comes from the both front fenders if I'm going straight, or the inside one if I'm turning. With the diffs locks on lots of smoke comes from the rear fenders and typically the left front fender if I'm going straight. If I'm turning and use the loud pedal with the diff locks on and in a gear lower then 4th the car yaws rapidly and lots of smoke comes from lots of places.
> 
> On the haldex equipped turbo R32 I just finished building if I use the loud pedal in first/second/third gear lots of smoke comes from the front fenders initially, then after a half of second or so some smoke comes from the rear too. After a HPA haldex controller smoke comes from all corners more often. If I use the loud pedal while turning the car plows initally then snaps into an oversteering monster that might fit in well on twisty mountain roads in Japan (with the stock haldex controller it just plowed forever and ever).
> 
> Note that with roughly the same output but a bunch more weight and less tire my 5ktq with diff locks on is much quicker in a straight line with much less wheel spin.
> 
> -Cody
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> F
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