A couple of questions on differentials

[TouringBubble]

Alright guys ... some basic questions on differentials.

First, how horrible is it going to be trying to rally the Beetle with an open diff? From what I've heard they are very capable off road with a stock transaxle, but the thought of an open diff with the tight maneuvers needed for Rallycross makes me worried.

Secondly, anyone know if you can weld the diff in a VW transaxle? From looking at how the diff works, it's a standard open diff, so it should be possible ... but I just don't know if the transaxle part would be an issue. If it's possibly, I'd likely get a spare trans to weld just for comparison to see how a locked diff improved/hindered the handling in the dirt.

[nicktcr]

The open diff will work for the most part in the dirt. If you end up having a good bit of grip though, you will probably get frustrated and be able to tell where you're losing time, especially in tight corners.

I don't think you'd want to just outright weld it. Normally I'm actually for welding a diff (because it's freaking awesome, right?), but in the dirt, at low speeds, I think it would probably be a bit too much. You'll understeer like crazy into a corner, and then snap to oversteer once you get on the power.

If you want to "try" a welded diff without actually welding your diff, assuming (like you say) your differential is just like a standard diff, you could get a spool and it'll make it feel exactly like a welded diff, but is easily removed in the case that it's horrible.

[Ryan-L]

In rallycross limited slip is the best option. You get the added traction but yet you can still do tight maneuvering. Next best option is the plain old open diff, not as much forward bite but you still have good handling in the tight stuff. The worst options by far is the welded or spool diff. It has the most forward traction but it will make your vehicle unable to turn fast and under-steer like a cruise ship. I've had all three types in my car and would take the open diff and 500lbs of ballast over a welded diff for rallycross.
Look forward to seeing that bug next season!!

[TouringBubble]

Thanks Ryan. I know the best option is a limited slip. The issue is that the only Lsd I've found is way out of my budget ... $1100 or so just for the part. It's that, or I happen across a factory Lsd from a Thing, but those are rare.

Guess i'll keep the open diff.

[kilgojr]

http://www.ebay.com/itm/Super-Beetle-Transaxle-1972-up-Original-Manufacturer-/160592467830?pt=Motors_Car_Truck_Parts_Accessories&fits=Make%3AVolkswagen&vxp=mtr&hash=item25640e9776

[TouringBubble]

Stronger option, but still no LSD. In the US, the LSD was almost exclusively in the Thing.

[Cholewa]

Open diff is all about weight transfer, where LSD/Welded/Lockers are foot controlled.

With my little experience with this, I'll say that driving ed's 2002 with the welded/locked whatever it was diff was a struggle, but it was super fun and after some time behind the wheel I think it wouldn't be an issue. Driving the volvo with the open diff is much easier to handle and is much more forgiving, but not nearly as sideways.

I don't know what you're going for with rallyx, fun or competitive, but that should probably weigh in on your decision more.

[TouringBubble]

I think any good driver would be faster with a LSD as you can power out better. An open diff limits traction on exit in the dirt, which is my concern ... power to the ground drops constantly until the loose wheel gets grip. With an LSD power is transferred to the wheel with more grip so it's not all lost. you are still limited to the friction of the loose surface, but not also by the wheel with the least grip.

I don't think there is a gap between fun and competitive ... they can be the same. I mean, Edwin won a national championship in the car you are referencing. Sure, go out and drive sideways constantly you won't be fast, but an LSD is about putting power to the ground, not just getting sideways.

[chuck schultz]

Sure, go out and drive sideways constantly you won't be fast

http://youtu.be/4UjKmPGFSkk ;^)

[TouringBubble]

http://youtu.be/4UjKmPGFSkk ;^)

That's "good" sideways ... I'm talking constant 75º slip angles. And you know that ...

[nicktcr]

It's like I said. Depending on how much grip you have...

If you have your car set up super awesome and it has lots of grip and is real stable, you'll def want the LSD because you'll have enough traction to actually use it, but if the car doesn't grip real well, the open diff is super forgiving, and since you don't have a ton of traction anyway, you'll be fine. Grip being a relative term here since we are talking about dirt/mud.

If there's some sort of VLSD option for the thing, that could be good. It would provide that corner exit power delivery you're looking for, but won't be so aggressive that you understeer everywhere and then spin out on corner exit.

Also, since you'll be kinda getting used to RWD, I'd say stay open, until you can feel it holding you back. Also, if you're sharing with Katie, she'll have a much easier time getting the feel of things with an open diff.

I would leave it alone for now, and run a season or two with it open and get a good solid feel for RWD technique in the dirt before stepping up. If you learn the fundamentals early, you'll be able to appreciate it later with upgrades.

[TouringBubble]

Good call on the Katie point ... I hadn't thought about her rection to it yet.

[Cholewa]

It might be a good idea to head over to RallyAnarchy and ask those guys over there.

They mostly do stage stuff, but I think some of them have experience doing RX or shorter slower stuff and they are all very knowledgeable on the technical side of things.

[kilgojr]

http://bham.craigslist.org/pts/2750151665.html

saw this on cg

[TouringBubble]

Thanks for the link, but it's a swing axle setup. Mine is IRS ... like '71+.