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View Full Version : FWD limited slip?



48855
11-23-2006, 07:31 PM
Did the b5 FWD come with limited slip diff. or are they open differentials?
If they're open, does anyone know of a company that might carry a locking diff?
Thanks.

a4rings
11-23-2006, 07:45 PM
Definitely doesnt have a limited slip. qualife prollly makes one, or mabe stasis?

sean1.8t
11-23-2006, 07:48 PM
STaSIS one is only for us quattro boys

mike-2ptzero
11-23-2006, 07:54 PM
Best thing is to ask the Passat guys which use the same fwd trans as the A4.

scirocco78
11-24-2006, 09:02 AM
Quaife from Autotech. I've had one for a few months now.

onemoremile
11-24-2006, 10:07 AM
Stasis won't work on a FWD Tiptronic. Driving a FWD with an LSD is interesting.

The more the differential tries to get the tires going the same speed the more the car understeers. The front tires have to rotate at different speeds to make it around a corner. The LSD's need to prevent this means you can't get on the gas until later than with an open diff.

Torque steer doesn't go away because the tires are still sending torque back and forth depending on slip. The difference is that torque is sent to the grippy wheel as opposed to the slippy one. The net effect is that the steering wheel tends to pull the other way.

I've autocrossed my 94 Jetta GLX VR6 (172hp, open front diff, well set up suspension) extensively and had the opportunity to drive a nearly identical car with a Quaife. The feeling was much different but the times were pretty much the same. I had been consistently beating him by about 1-2 seconds. He rode shotgun with me and I with him. We drove each other's cars for some timed fun runs in an attempt to see what the real difference was. We both came to the same conclusions. His car put the power down slightly better in a straight line but had heavier steering and was harder to keep on line. Mine felt lighter and went into and out of corners better.

If you're looking for better performance at the drag strip then read this article.
http://www.hotrod.com/techarticles/turbo_tech_q_and_a_supercharger_comparison/
He gives real empirical data for drag launch testing of open and posi (fully locked) rear differentials. Since a FWD has much less weight on it's drive wheels when launching it should see even less of a gain.

The real key to performance is in the rubber. My street tires are 225/50-16 Sumitomo HTR Z with a UTQG (tread wear rating) of 160. They are much stickier than the wider Pilot Sports they replaced. Tires like these and a suspension that takes advantage of them will give you better performance than an LSD. They are only 61 bucks each at the Tire Rack too.


Here is the opening of that article. Really, everyone should read it. It is very informative and the car is incredible.
Online Editor’s note: The November ’01 issue of Hot Rod featured an extraordinary twin-turbo ’66 Mustang owned by Bill Watson, a jet engineer with Garrett/Honeywell. He generously supplied us with way more detail on his project car that we could fit in that issue, so we decided to include this question-and-answer interview that explains why he considers turbocharging superior to either supercharging or stroking an engine for more power. You may not agree with all of his points, but he knows his stuff. (After all, his Fastback runs in the 11s on—get this—SlimFast 215-section tires!) Blower buffs are invited to email us their alternative views on the best way to obtain boost.

Wizard-of-OD
11-24-2006, 03:18 PM
Originally posted by scirocco78
Quaife from Autotech. I've had one for a few months now.
Bet you paid through your ass for it....[eek]

Easy & cheap - Audi V8 rear differential = LSD
You need to modify the differential housing on the gearbox to fit the V8 diff.
Why use a V8 diff? Costs $150US @ your local breaker...

onemoremile
11-24-2006, 04:40 PM
Did the V8 have the electronic locking feature or was that only the for the centers in the old skool quattros?

What style diff is in the V8 rear?

onemoremile
11-24-2006, 04:48 PM
I've found that it is a Torsen but haven't found the ratio. It obviously has to match the trans to avoid burning up a diff.

scirocco78
11-25-2006, 03:04 PM
Originally posted by Wizard-of-OD
Bet you paid through your ass for it....[eek]

Easy & cheap - Audi V8 rear differential = LSD
You need to modify the differential housing on the gearbox to fit the V8 diff.
Why use a V8 diff? Costs $150US @ your local breaker...


This will fit a FWD tranny?

48855
11-26-2006, 04:39 PM
Yeah, first FWD car and I was thinking like it was RWD.
I guess a 100% lock wound'nt be a good idea. Is there any 50% locking diff's? Im sure its not going to be worth the money but just a thought.