Trans case question

[DanielPip]

Trans gurus:

Other than the pinion bearing/nut, are there any functional differences in Beetle dual side cover cases?

I have two: one AH(IRS Bug) and one DC(IRS type 3) case, and I'd like to build up a spare box converted to swing with axles and everything as a spare.

Obviously, I'll need a diff and swing covers, plus all the usual rebuild bearings and parts. Plus a shorter 3rd and 4th from Weddle, I'm making a close(r) ratio box.

The trans in my car is a converted IRS to swing, but early 4 bolt pinion.

Thanks

[vwracerdave]

The type III case should be the same but may not always have the mounting holes for the Type I rear trans mounts but you can drill those yourself no big deal.

The Type III transaxle may have the stronger 4.12K R&P gear.
_________________
2017 Street Comp Champion - Thunder Valley Raceway Park - Noble, OK
2010 Sportsman ET Champion - Mid-America Dragway - Arkansas City, KS
1997 Sportsman ET Champion - Thunder Valley Raceway Park - Noble ,OK

[DanielPip]

Thanks Dave. I run a 3.44 in a 550 Spyder replica. I may end up with a 3.88 and a Quaife.

I won't be using either 4.12 IRS diff.

I also noticed the reverse fork(steel) and gear is different from my early brass reverse fork.

[[email protected]]

The later cases have the 20mm throwout bearing cross shaft that will have a longer arm for the cable for more leverage. Also later cases will have the tube the bearing rides on which is a little nicer set up imo. The latest 3.88 “AT” cases have a little larger mainshaft needle bearing in the case on the 1st gear side, but both of your AH/DC cases probably both have the same smaller bearing.

[gears]

Daniel, I'm curious why you're going close ratio with a light Spyder replica .. is this car for autocross or highway?
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com

[DanielPip]

The car is multi use. Mostly twisty street driving. Occasional autocross and track use.

Road tires are 205/60/15 and are about 24.7" diameter.

I'm getting track rubber in 205/50/15, they are 23" diameter. Shortens the effective ratio about 9 percent. Great for autocross, OK for track as the front end gets light above 110-120 anyway, so new gearing would limit top speed to 120 something.

The real reason I want to change 3-4 is street driving. Driving through town you're either high in second or almost lugging third.

The car has plenty of power, that's not an issue. But with 3.80/2.06/1.26/0.89 the rpm drops between gears are a bit much. The close ratio would fix this and add 400-500 rpm. This would get the engine more into it's best range for torque and cooling. It would also make it a little more fun to drive I think. The car is a LOT of fun the way it is, but I think it could be a bit better.

It's got 147 ft.lbs. @ 3800, 172hp @ 6000. Car weighs 1500 pounds wet.

If I could find a swing ZF, it would be as close to perfect as is possible.

It has been suggested to me many times to change to IRS and a 5speed, either Berg5 or a 901. It's a LOT of cutting, design, and fitting to do so. I'm not willing, car is too new. It's a Vintage Motorcars Spyder, and I'm running the PBS shifter with custom nosecone and solid mount. There is a custom trans strap combined with German HD bellhousing mounts, Engine/trans stays planted very well. I'd like to make it as good as I can.

[DanielPip]

I came up with a couple very close setups, one with 3.44 and one with 3.88. I've been playing with this calculator for a while:

http://www.teammfactory.com/calculator/205/60/15/2...3500/1/0/2

It's a bit more expensive to change 1-2(using 3.88:1) rather than 3-4(keeping 3.44).

I'd appreciate your feedback. I've only built one transmission several times.

First time was to replace Chinese crap main and diff bearings installed by now defunct Tran West in 2002. It was REALLY noisy after 35,000 miles and my abuse. I got the best parts available from Weddle, German and Brazilian bearings. New Sway Away axles. Good used fulcrums.

Second time I zinged the 3rd synchro and slider bad doing 4-3 without clutch in far enough. I had to had file a few synchro hub teeth. Works fine. My fault, absolutely.

This time, 2nd gear synchro cracked in the narrow area where it rests on the slider catch keys. Aggressive autocross 1-2 shift. Easy fix. My bad.

I have to put the diff and axles in and get it back in the car. Shafts are installed, adjusted, and smooth shifting has been restored. I'm around 43,000 miles now.

[[email protected]]

Weddle’s calculator has a little more info.

https://weddleindustries.com/gear-calculator

I’m having trouble viewing the entire number in your linked calculator. The first looks like a 1.48/1.125 3rd/4th? Weddle has a 1.44 that would make this spacing a little closer. The “percentage of pull” helps a lot to show how even the spacing is.

You could get a new true LSD GT Swing diff from Gears for probably not much more than what you would find a factory ZF Swing diff for.

[gears]

550 Spider replica -- mid-engine configuration? LSD really shows its worth in rear engine configuration, while TBD is more than sufficient for mid-engine. Obviously I'm "biased", but I'd spend a few dollars more for the higher quality GT TBD over a Quaife TBD.
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com

[DanielPip]

Yes, I've been using Weddle calculator too. And I've used the Percentage pull. That was fun to play with to get percentage as even as possible.

First trans is 3.44 final 3.80/2.06 stock 1-2
3-4 is 1.39/1.04.

I believe this to be the best compromise between fun and livable: for 4 speeds, for my use, and in this car.

[DanielPip]

Pablo, yes mid-engine. Ends up at 45-55 Front to Rear weight bias.

And thank you, I didn't know about GT. They look REALLY nice. And I just figured out why you are biased LOL! GT is you, correct?

Does it work with a 3.44? Or is it limited to a 3.88 like Quaife?

I've heard a ZF will work with 3.44 swing. Will it?

Personally, I'd rather buy something new rather than mess with old and questionable.

Thanks for your responses.

[gears]

I honestly don't know the 3.44 fitment answer for our LSD and TBD (or ZF's). Given the quality/strength of GT housing(s), I imagine one or the other could be modified. (Edit: It appears the GT LSD would easily clear.)

A Spyder replica is such a nice vehicle, why not spend a bit more and use a steel-sleeved aluminum Rhino case or even an Autocraft?
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com

[[email protected]]

A lot of the issues with a 3.44 is the size of the pinion gear. The last one I put together just “kissed” the cross shafts protruding a Swing super diff. The easy solution was to turn the diff down a bit. If you can’t modify the diff, you may be able to surface grind the end of the pinion. It looks as if the GT LSD necks down quite a bit, but the TBD looks like the main housing is not much smaller in diameter than the ring gear seat.