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Thu Oct 23, 2008 10:00 am

There is a Thing for sale that quite a distance from me but has captured my attention.

I understand the Thing has essentially the same engine for its year as a Beetle or Karmann Ghia of the same year but the transaxle is geared differently (assuming all are in their stock form). I also understand the tranny could be swapped such that the Thing would be happier on the highway. (And, yes, I know the Thing isn't the most aerodynamic vehicle conceived.)

The Thing that has my attention has a fairly stock engine as far as I can tell from the ad. At least it is listed as having the stock displacement.

The Thing has larger than stock tires on it (size unknown at this point). The ad also says it has a tranny with a super diff and a 4.62 ring and pinion to accomodate the larger tires.

(1) Does such a r&p also accomodate highway driving as well as the taller tires (maintaining all of the assumptions made above)?

(2) Would this transaxle accomodate an engine with greater torque such as a Type IV engine?

My Super Beetle had a tranny with a super diff when I had a 2056cc Type IV engine put in. The r&p was considerably different as was the application. My Super's 3rd and 4th gear were also welded.

(3) Would this be a good idea for this Thing eventually (if not already welded)?

Thu Oct 23, 2008 12:00 pm

As the tire diameter increases, it takes more torque to get them moving. The higher R&P basically multiplies the torque output. As an example of this, 3.88 was the standard final drive for a Bug. It was upped to 4.12 for the heavier and less aerodynamic Thing, and further raisied to something like 5.38 for some Buses (heaviest and least aerodynamic). As you can see, a higher R&P ratio puts down more torque, which is needed for getting the car going. The higher R&P has a downside though. A late model Bug tops out around 73mph, a Thing around 68mph, and most Buses chug along at 55-60mph.

The tires relate to this in that a larger diameter can cover more ground with fewer rotations (and increase speed to a certain extent). However, as the diameter increases, it becomes harder to get them turning. This is why the car needs more torque, and the reason for the higher final drive. It depends on how large the tires are as to how well the Thing will do on the highway.

As for larger engines, no the R&P and Super Diff do not have a huge affect on the ability of the transmission to handle the power. A system is only as strong as its weakest link, and in this case, that would be the stock gears and axles. It will have the same HP/torque limits as a standard Bug tranny, which can handle a stock T4 engine without too much fuss.

Fri Oct 24, 2008 1:10 pm

Thanks for your concise explanation. I at least understand the effects that happen and can happen.

I will try to find out the tire sizes. I have a feeling from what I just read this particular Thing is happiest as a daily driver but with limited highway exposure. If true, that's too bad. I really thought I finally found my fun car.

Fri Oct 24, 2008 1:37 pm

It does depend a lot on how large the tires are. There is always the chance that they help its highway ability. Plenty of Baja guys run 31in tires with 4.12-4.38 R&P's, and say they can get their Bugs to 60 with no problem. Neither car is especially suited for routine highway use, unless you add a big engine (T4 or similar size) or a tall 4th gear (which you won't want to use much below 45mph).

Btw, I am no expert on this, so I might be wrong.

Fri Oct 24, 2008 5:16 pm

yellow73kubel wrote: Neither car is especially suited for routine highway use, unless you add a big engine (T4 or similar size) or a tall 4th gear (which you won't want to use much below 45mph).

If you are considering a bigger engine with a bunch more torque, then you should also consider higher gearing to be able to keep it usable. The stock bug gearing was designed for the narrow torque curve of the T1 engine. When you open up that curve, you'll want the gears to match.

I've got a 2270 T4 (Jake Raby's 1st "torquer") and have ripped through first gear on a reinforced tranny twice - but that was with some spirited driving. While I'm having the good tranny fixed, I've got the old stock tranny in there, and the gearing is way too close. Although I can start in 2nd and skip 3rd, I don't want to put that stress on the old tranny (don't want to blow it up until the replacement is done) but I usually shift out of first within 100 feet of a start - PLENTY of torque, but no gearing to use it.

Also, just because 3rd and 4th are welded, doesn't mean the tranny can no longer be changed. Additionally, I doubt someone would have welded them with a stock or mildly modified T1.

From your description, it sounds as if someone properly compensated for larger tires with a change in the gearing. That's great! It's what should be done, and very often overlooked. I'd guess that it probably drives pretty well. If you were to change out the power plant, you should consider transmission mods based on your intent. If you're looking to build a stump puller and don't care about freeway performance, then you could probably leave the tranny alone. If you want a higher top speed, you should consider changing the R&P and/or several of the gears. Either way, the super-diff is helpful.

I love driving the Thing with that T4!

Thu Oct 30, 2008 12:29 pm

Ian Epperson wrote: From your description, it sounds as if someone properly compensated for larger tires with a change in the gearing. That's great! It's what should be done, and very often overlooked. I'd guess that it probably drives pretty well. If you were to change out the power plant, you should consider transmission mods based on your intent. If you're looking to build a stump puller and don't care about freeway performance, then you could probably leave the tranny alone. If you want a higher top speed, you should consider changing the R&P and/or several of the gears. Either way, the super-diff is helpful.

I love driving the Thing with that T4!
That was my take, also. Unfortunately, I don't have the specifics on the tire sizes as I have not received any answers. I don't know if it is sold or if I'm not being taken seriously since I'm on the other side of the continent and asked about driving it home. (I know shipping is an option, too.)

It would be a perfect candidate for a T4 but it seems perfect as is so I wouldn't be forced into a timetable to enjoy it -- that proved to be a winning formula with my Super.

Thanks for the insight. If there's anything new to report, I'll be back on this thread.