'71 Super Beetle Autocross Build

[Jadewombat]

I agree with Marc. I thought of transplanting a 002 in my '66 bus, but wound up not doing it after finding out how much work is involved to remove the gearstack and use an adapter plate, etc.

That being said, the single-side cover (SSC) bug transmissions ('73-up) are pretty strong, the '75-up being the strongest. The mainshaft is from a 002. They can handle about 100hp in stock form, up to 150hp with some upgrades.

http://vwparts.aircooled.net/Quaife-Lim ... -t1-33.htm
http://www.ranchotransaxles.com/store/p ... f9ukv6tb90

or El cheapo kit:

http://www.phantomgrip.com/

I'd just run a T1 until something breaks or you get wheel slippage. If you plan on being North of 150hp, yeah 002 is probably worth the trouble. North of 200hp, well...

http://www.shoptalkforums.com/viewtopic ... 1&t=101402

[madmike]

Drag racer here, a 73-on SSC will work great for what your doing
heck ,I got 6 pass out of a bone stock 73 with a 1915 & a 2276 with a frickin turbo on them, banging gears I pulled it apart acpl. weeks ago and installed new syncros just for shits&giggles and to install a 10t/15t superDiff and everything still looked good

[ChadH]

OK here's what I have to work with, other than the 002.

Right is an AH trans someone gave me. I have no idea if anything has been done to it, or if it needs a rebuild.

Middle is a A_ case from my '72 Thing. Looks like it would have a 3.88 R&P. The letter code is too pitted to read. It's probably an AK. Reading up on 181 transmissions, the AL had an LSD. I'm not going to get my hopes up, but it might be worth taking the side cover off to have a look.

Right is an empty AH case from a transmission I broke and took apart for fun.


Also, there's the transmission in the car. I'm too lazy to crawl under it right now, but I'm 99% sure it's a stock '71 AM with a 4.38.



More thinking out loud, I could potentially use that empty case as a jig for a DIY rebuild. Not sure If I have the skills to go that deep though.

FWIW, the engine will be a 2110, with dual 40 IDF's. I'm thinking around 120 hp. Autocross doesn't require hard launches like drag racing. In fact, our courses are set up with a hard turn, immediately off the start line to discourage wild burnout starts.

[Jadewombat]

The ZF lsd is a 40% locker, worth checking for it though. But yeah, pretty rare and AW is the code of things with LSD.

[Marc]

I've had a few adult beverages so this may not be 100% accurate but I'll throw it out there, I'm sure I'll be corrected if it's wrong

See the 11mm-head bolt on the bottom of the gearcarrier housing on the AH boxes (next to the nosecone)? That's a clue that it has the early mainshaft. Late `72 AHs were double-sideplate & 4.125 but had the stronger-First mainshaft without that bolt...also got the late, larger-diameter clutch cross-shaft.

Single sidecover transmissions generally debuted for 1973 and had the 3.875 R&P...the most-common US-market code was AT. I thought that the AK Thing boxes were still DSC in `72. SSC with a 2-bolt nosecone has to be a pretty rare stock configuration...

I can't vouch for the veracity of the information here, but it's interesting, in that apparently Thing boxes were made in 4.375, 4.125, and 3.875 with different Fourths and in some cases an odd-ball Third. I suppose the only way to know for sure (without surgery) would be to start counting turns**: http://www.oocities.org/vwtyp181/181_3-2.htm

The AM was never offered in the US, its 4.375 R&P was matched to 1200/1300 engines in Europe/Canada. They're a pretty hot item for Bajas with big tires, it'd behoove you to crawl under and verify that.

**

If it's a swingaxle it's most likely got a 4.125 or 4.375 ring & pinion...if it's 4.125, 3rd should be 1.26 and if it's 4.375 3rd could be 1.26 or 1.32.
Most IRS Type I transmissions you'll come across in the US will be AH (4.125 R&P) or AT (3.875). 2nd gear will be 2.06 and 3rd will be 1.26 99.5% of the time, so for example if you put it in second with one wheel off the ground and it takes 4¼ turns of the crank to get one turn of the wheel, you have a 4.125 R&P. (2.06x4.125)/2=4.25
If it takes 4 turns it's a 3.875 (2.06x3.875)/2=3.99
If it takes 4½ turns it's a 4.375 (2.06x4.375)/2=4.51
This assumes that 1st and 2nd gear are still stock - considering the expense involved in replacing the mainshaft to get different 1st/2nd gears, that's a pretty safe assumption unless you're dealing with a trans built by/for a hardcore drag-racer.
If in doubt you can repeat in 3rd gear, if it takes just over 2½ turns it's a 4.125, if just under it's a 3.875. A 4.375 will take either 2-3/4 or almost 3 turns depending upon which 3rd it has. Since it's not uncommon to replace 3rd with an aftermarket shorter gear, keep an open mind when using 3rd to determine R&P. The most common is 1.48 but there are many others.

Once you've confirmed what the R&P ratio is you can check to see which 4th you have, you may need to rotate the crank enough to get 2 or more turns out of the wheel to be able to discern the difference between, say, a .89 and a .93 here. Late AH transmissions had a .88 4th, earlier were all .89 unless the trans started life in a bus in which case it could be .82.

[Marc]

I guess what I'm thinking is, I've been through the sweat and tears in fitting the 002 into my Thing, which is now one of two donor/parts cars I'm going to use for this build. I was just looking at an old thread I did for that, re-living the experience...FWIW, It has nearly new type 2 CV's, shorter axles, 100mm stub axles and flanges etc. that are just sitting in my yard rotting away. It would be a lot of work to get it installed, but I do know what's involved. I found the shifting on the bus trans to be no better or worse than a beetle trans. The problem is, once I install it, it's going to be a big PITA to go back to a Type 1 trans if I want...

Oh. That helps a lot, if you already have the necessary bits and the know-how to put the 002 in. If the internal shift linkage hasn't already been upgraded, I suppose you could cross your fingers and run it...but of course when it fails you'll have to yank it for repair. The most common failure in my experience (assuming the little "donut" is OK) is for the bracket to crack/break at the 90° bends...you may want to preemptively weld some little gussets to that for insurance.
http://www.ratwell.com/technical/091Tra ... l#nosecone

[ChadH]

Boy - this would sure be a lot easier if I just had one trans, because I would just run it, and deal with it.

From what I gather, the single side plate trans from the Thing may be the best candidate - and maybe isn't even a stock 181 trans? I'll need to spend some more time with it, clean it up, see if I can read the code more clearly, and spin it to see if I can determine the ratios.

I'm feeling less enthused about the 002 swap. It's a lot of work, and I'll be stuck with it if It doesn't work out. At least with the type 1 transmissions, I'll have opportunities for a quick swap - maybe even be able to do a rebuild on one (at my leisure) while another is in the car.

If I can, I'll still use the 100mm CVs, since they are a little bit more stout.

I appreciate the advice and discussion - I never really paid all that much attention to the subtleties of the different transmissions until now.

[Marc]

...From what I gather, the single side plate trans from the Thing may be the best candidate - and maybe isn't even a stock 181 trans? I'll need to spend some more time with it, clean it up, see if I can read the code more clearly, and spin it to see if I can determine the ratios...

Most likely it's an AV code. SSC and 2-bolt nosecone are stock on those, as is a 4.125 R&P. Beetle 4.125s used a Gleason gearset; for the 181 a stronger Oerlikon was chosen (although they could still get a Gleason if the supply of Oerlikons was exhausted). Engraved markings on the perimeter of the ring gear will identify it...you may be able to make them out through the drainplug hole. If it's a 4.125 you'll see either G833 or O833. When counting turns on the bench, to avoid error caused by differential internal movement you'll want to hold the opposite CV flange - a long bolt through one of the CV bolt holes is one way - and remember that the diff will then double the output turns on the flange you're watching.

Oh, on the newer transaxles the number denotes the date of manufacture (I guess there must be duplicates, cuz they probably built more than one per day) in DD-MM-Y format, e.g. 23082 would be Aug 23 1972.

[ChadH]

Things are starting to make sense. The case looked like it might have AV, but the lists I was referencing all ended at AU, so I thought the 'V" might be a scratch or rock ding. I'll look again tonight.

[Jadewombat]

Check the CV size, too. The thing output flanges should be bigger than the beetle ones, which is a plus. It takes a lot to break a CV (not offroading of course), but T1 ones are good to about 100hp with a hi-po motor and T2/thing bigger CVs can handle quite a bit more, then Porsche 930s...

You'd have to change over the stub axles out at the wheels, but again the 924/944/thing ones are the same size and swapping them out isn't too big a deal.

[Marc]

...You'd have to change over the stub axles out at the wheels, but again the 924/944/thing ones are the same size and swapping them out isn't too big a deal.

The spline length on the Thing axles is greater to allow for the thicker CV inner race; you can have the race milled down to fit over Bug axle shafts, they're virtually the same overall length. Some have turned the axle down instead, but that's dodgy (adds stress risers). Bus CVs are usually cheaper than Thing/924; less angularity potential but if you aren't off-roading that's not a concern.

[madmike]

Hey Chad, You can probably get away with just stock type 1 CV's ,if u can't find the 100mm ones
them 6 passes I made was on stock ones

[ChadH]

I already have 100mm flanges, stub axles, and low mileage CVs, so I might as well run 'em. I can't remember If I have type 2 or type 4 CV's offhand. Arg..I'm pretty sure though I tossed the 181 axles though..this is what reinforces my pack-rat tendencies.

Also double checked the single sided trans. It's AV 130773 (July 13,73)

It'll still be 6-months or more before I get too deep with this stuff, I still have a ton of bodywork to do, but it's always good to think ahead.

[Marc]

Thing axle on top, Bug on bottom... the Thing looks longer here because they're lined up at the inner end of the splines; actually the overall length of the Thing axle is ~5mm less.

We used a late transaxle for my son's drag toy and had issues. 1879cc, dyno'd at ~130 lb-ft, and it managed to rip the teeth right off of the fine-tooth Third. It's possible that the carnage may have started with a stray bit of metal in the oil - no way to tell after the fact. But regardless, the early-style coarse-tooth 3rd/4th gears can handle a lot more abuse without failing...all aftermarket close-ratio gearsets are coarse.

[ChadH]

Thought I'd post up some progress. Still need to check through my boxes 'o crap to see if I still have my 181 axles, and (embarrassingly) I still haven't crawled under the car to see what trans I have in the car.

I removed the gas filler door and patched in some sheet metal. Heat from welding warped the surrounding sheet metal, and I created a lot of wavy crap that need a lot more hammering and filler than I expected. Lesson learned, I'll go slower with the welding of future work. This was pretty un-necessary, but "racecar"





Then onto the hood. It's a replacement hood, German, but not perfect. Spent some time getting out some bungles. This isn't going to be a show car, with a show car finish, but I'm a bit anal, so I had to fill trim holes and do the best I can do smoothing out ripples.

]



Sprayed some 2k, and found that there's still some ripples that need work. Here's where I need to decide how "perfect" I want the bodywork. Being anal, and in no hurry, I'll probably smooth it out some more. Block sanding is kind of a zen relaxing thing for me, so I'll probably work on it some more.



I have a front apron to install. I'll probably use some cool Dzus fasteners to attach it, since I might want access to the sway bar mount bolts, and will eventually tie the cage to this area.