Type 1 performance gearbox advice: will this work?

[VWCOOL]

I have two gearboxes:

A dual-side plate (1302/1303 circa 1971/2?) 4.125 IRS
A single side plate (off-set rib - circa 1976) 3.875 IRS

I wish to install the 4.125 R&P into the '76 SSP case with a lowered third gear (1.5:1 aftermarket) and the 0.93 fourth gear from the original 3.875/SSP box to create a street/track performance box for one of my toys.

I wish to install the remaining bits - the 3.875 R&P, plus its original gear-set but with the 0.89 fourth gear - into the dual-side plate case to create a wide-ratio 'freeway flier' type box (and maybe convert it to swinger) for use with a 14-inch wheeled Beetle.

Will I run into any parts compatibility/interchangeability problems with the gear-sets and diffs in these two donor boxes?

Building the 'performance' box is the priority. Any and all actual experience/knowledge/advice appreciated!

[bugguy076]

I don't see any problems with what you want to do. If you know how to work on trannys, you should not have any trouble shuffling parts around.
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Grubby Fingers Racing
1976 Drag Bug
1967 Street Bug

[Casting Timmy]

Hopefully your single side plate has the nine tooth main shaft, I am doing a similar performance trans for my beetle in the IRS transaxle rebuild thread. I am going to use an earlier third from a swingaxle 1.32 for my third. This will require some cutting on the gear and clutch hub to get them to work together though.

10 15 diffs are stronger than 11 17 tooth diffs, hopefully you got two of the stronger ones. Unfortunately most of these have ben opened up before so you don't know what you have until its opened.

[VWCOOL]

Thanks lads; I'm vaguely aware if a few differences with 'early' and 'late' late-type (ie: post 1968, not 40-horse) trans such as brass vs steel selectors, hence my questions.

I'll be working with a mate who has a chopped trans case to use as a jig and who is clever/trained with Subie trans.

The 'donor' boxes I have - I am lucky enough to have collected several of each type - are highly unlikely to have been fiddled with

[Bruce]

For your performance 'box you will have to use the SSC's original main shaft and gears. This main shaft has 9 teeth on first gear and is much stronger than the earlier 10 tooth first. You will be keeping the original gear carrier and main shaft ball bearing with this main shaft as the earlier parts don't fit.

The 4.12 will fit with no mods other than setting the pinion depth and ring gear backlash.

The third gear you need must be a 002 type gear set. If you already have it and it's a 113 type, you will have to modify it to work on the splined main shaft.

If your racing requires a lot of hard and fast shifting, the stock .93 gear is not for you. When you slam gears, small bits of steel get broken off, then they float around in the oil. When these bits get between the gear teeth of 4th gear, they cause the fine teeth to chip off. Creating another bit of steel floating around. Eventually, the teeth get so badly broken up the gears strip completely. The coarse tooth gears are strong enough that small bits of steel in the oil don't hurt them. If you buy a coarse tooth gear, get a 002 type.

For the DSC gearbox with the tall gears, you will keep the main shaft and all the gears original to the DSC case together. The 3.88 R&P will fit without any problems except for the shim changes (same as with the 4.12 above).
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[VWCOOL]

Thanks, Bruce, that is the guidance/advice I need to attempt these builds.

yes I will be buying the 002 type cog for third gear.

The Z-case SSP box - with the 4.12 diff with close third - will be used for hill climbs, where I use lots of 1st, 2nd and 3rd.
Top/4th gear won't get much (ab)use - it will be used for cruising/street driving.
I have another box with a low 3rd and 4th gear that I use for drag racing and will install for tracks where speeds are high enough for 4th gear to be relevant/important. That's the box I use now, however, I feel its 1st and 2nd gears over a 3.875 diff are a little too tall for the quite steep tracks I race and around 8% percent lower gearing will help.

There is a Quaife going in, too

Once again, thanks

[Casting Timmy]

I was looking over weddles site today, they have a 1.32 coarse tooth third for $35. I think that is an early swing ratio, might need a special washer under the synchro cone and modify the 3.4 hub on third side.

Not the lowest third, but a good bang for the buck.

[VWCOOL]

Hi Timmy, I will be fitting a third gear ratio of (around) 1.5:1. I have this in my present box and it ROMPS so I wish to keep around this ratio but with the slightly shorter diff to also help with first and second

[Casting Timmy]

Very nice...I bet it does pull good with that!

[VWCOOL]

yeah it's damn fine fun! Took it to the drags again last night

[Jordan16]

Hoping I’m in the right area as my search got me this far 😂 I’m looking at getting a new performance gearbox(I’ll probably end up building it) but I’m not sure what ones best for me. So I’m getting a 13b conversion and I’m looking for a gearbox that can handle anywhere between 200-300 on the road. Most likely towards the 200 end. I’ve been looking at this website https://www.vwheritage.com/beetle/beetle-transmission/performance-gearboxes-uprated-parts and some of the box’s they have, could anyone say which one is best for me so I know the spec for the future. Cheers, jordan
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1971 1300 beetle

[Casting Timmy]

Based on your location I'd contact John Walklett of Classic VW Transmissions, he's over there with you.

The 3.80 first is the weaker of the two factory firsts, you want Weddle or at least a 3.78 first preferably with at least the 091 ilder in the box. I know John gets 091 mainshafts cut to the Weddle hybrid, which would give you the lock nut on the end of the mainshaft with the splined holding power.

You don't want keys or a 3.80 first

[Jordan16]

[gears]

Here's a hint for your 13b conversion: If you use a later trans with large pinion bearing, you should machine the case for the earlier mainshaft needle bearing. The later style needle bearing doesn't hold up to sustained high rpm.
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aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com