Any open diff. cars?

[fornetti14]

Anyone running a MK1 (Rabbit GTI) with an open diff?

Comments on this idea are welcome.

[shwah]

I ran open for a while with my A2.

My comment - it is slower. By over a second a lap. Lock it up IMO.

[Eric Parham]

You're likely to gain 1-2 seconds when switching from an open diff to a LSD (e.g., VW Motorsport or KAZ), TBD (e.g., Quaife or Torsen) or locked (e.g., welded or spool). The locked diff has a learning curve (and different suspension setup), while the TBD (e.g., Quaife) is just like driving an open diff but faster. The LSD (e.g., VW Motorsport) is comparable to the TBD/Quaife but slightly better in the dry and slightly worse in the wet. A TBD seems to be the easiest on tires, and might actually pay for itself in tire savings over a couple of seasons.

[Dave Zaslow]

An open diff will be slower. When you've maxed out your learning curve on your present equipment you should consider upgrading.

I used a Quaiffe in my Rabbit and liked it a lot.

Tried Joel High's Rabbit with a welded diff and hated it.

Have a VW Motorsport (clutch type) in the A3 Golf and love it. The best of all worlds.

Bildon has a spool (locked) and a clutch type for the 020 trans. The clutch type is about the same $ as a torsen.

[rabbidmk1]

I ran a welded diff. in my MK1 and loved it. I had a Quaife in my street rabbit (300hp 1.8t) and didnt like the cornering in it as much. In my opinion, a welded diff. is faster on a short, tighter track, the Quaife or clutch type will have less drag and be faster on a track with longer straights.



Aaron

[shwah]

When I ran an open diff, I ran with no front anti roll bar to minimize inside wheelspin.

When I locked it I ended up installing a front bar because I don't need the inside tire to be on the ground anymore.

[Eric Parham]

When I ran an open diff, I ran with no front anti roll bar to minimize inside wheelspin.

When I locked it I ended up installing a front bar because I don't need the inside tire to be on the ground anymore.
[/b]

That, in a nutshell, IS the issue with a welded diff (or spool). You think you "don't need" to keep the driven inside wheel on the ground because the car won't turn when you do. On the other hand, with more than 60% of the weight on the front in a FWD application, you necessarily overload the outer front with inner front lifted by a swaybar, and theoretically can't corner as quickly on just one wheel

[shwah]

Surely a topic that could provide loads of debate. There is a lot more involved in a quick lap than theoretical cornering force. For me a locker is best. For some a limited slip diff is best. Either is better than an open diff for our application.

[Joe Craven]

I used to race in a Northern California series called GTI Cup which was a spec series. We opened up the specs a bit and allowed sway bar changes and/or limited slips. I went with an open dif, stiffened my rear sway bar and removed the front bar. Car handled great and I got a bit of wheel spin in maybe 1 or 2 of the slow corners (2 and 11) at Sears Point (Infinion) or Thunderhill (2&13). We had some great close racing and I was able to run side by side with Quaife LS equipped GTIs and found that the advantage was there but minimal, not really enough to keep me from being competitive and winning a fair amount of the races. If I had to estimate a time improvement, I would estimate .1 to .2 seconds per lap.

BTW, those Quaifes are heavy and add additional rotating mass that the GTI has to accelerate out of the corner.

-Joe Craven

[BlueStreak]

I'm running the original gear and open diff in my A1 GTI right now, and in the two races I have run in this car, that was the difference between my car (which ran second), and the class winner

I'm not sure I'm going to change it, because if I do, what will I use as an excuse for finishing second? My wore out V700s?

[JimLill]

just remember that a TBD requires that BOTH wheels have some kind of traction... even token traction... airborne=0

[mattbatson]

I went with a welded because it was the cheapest alternative from running an open (which in my car, is really slow)

Totally changes everything you know about driving a FWD.

Likes to be loose. Loose is fast with a welded. After braking, you kinda pitch it in to get the rear loose and then full throttle. The rear steps out, and the front tires pull you through the corner. It can be quite fast.

Matt Batson
ITB Suzuki Swift

[msogren]

I have driven open, quaife , and welded. The welded is faster into the turns, under brakes. It wont lock up the inside front wheel, the midturn -out is much faster(10-20 ft most turns)> it is the hardest to drive. My car goes straight, in the turn, off power. It needs full power and puts it down the best. the fastest in the rain, by far. Same engine, (a year older) @ sebring , the car went from a 2:48 to a 2:45. That is from a top ten car to a winner. The setup required a lot less rear bar and less rear air#. It was scary loose withthe open diff setup. I thought that I had made a big mistake the first lap, but luckily I had a easil;y removed rear bar, .
The other side benny is that the car keeps going when driven hard over the curbs, often needed to make the pass or open the exit line, like tower turn or T 14-15-16.
I wil take the locker, regardless of price, it is the fastest for me and is vastly more entertaining than any semi locker.
I have a quaife in the rental car, but when it is for me to go fast, it will get the welded.)that trans is for sale)
Mike Ogren

[racer_tim]

Yea, a welded diff requires a different driving style. Brake in a straight line, turn in, mash the loud pedal, and aim for the exit.

Yes, you do give up a little bit due to the scrubbing off of speed, but the advantage of both wheels "pulling" through a turn, is a great advantage. It feels like it's "pulling" from the inside, and that's because it is, since the inside wheel is traveling the least distance.

It is a PITA to drive around in the paddock, and to make 90 degree turns, or put it on the trailer, but when it's at speed, it's a charm, compared to driving an open diff, and listening to the inside wheel "chirping" trying to gain traction.

Just my $0.02 worth

[mattbatson]

plus it's cheap!

the only possible problem with welded is, that it may work the front tires harder then a LSD or torsen type. Not sure if this results in more abuse of the fronts, or if this hurts lap times over the course of the race.

I have no scientific proof behind this, just a hunch.

[msogren]

My tire wear improved and the optimal camber decreased from 3.5 to around 2.5 front. I often run the fronts at different settings. Sebring likes the T 17 with the right front at 1* and the left at 2.5.
The rear tire heat came up and the 4 tires showed a lot closer tread life. The axle life shortened... But it is worth the hassle . MM

[spiro13]

I ran a MK 1 Rabbit with an open diff for years. If you choose to do the same hear is a tip. Run a softer suspension set up. Somewhere in the area of 400lbs. front and 350lbs rear spring rates. No front bar and two rear bars. Make one bar a good one like Shine sells. If you can find a GTI bar or one from a convertible that will do for the other.

Soft -yes, Lots of body roll-yes. But more traction than with the high spring rates.

Tony