Gearbox query

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Sorry didn t quite know which section to ask this question? I ve potentially now found myself with a spare 911 gearbox from a 74 car (905 /915? sorry bit 911 ignorant) I had thought it might be ideal if I married it up to the Type 4 I have, 5 gears is always better then 4 and better ratios than a type 1.

My question, has anyone done this? How feasible is it and what modifications in terms of flywheels/clutches/starter motors, bellhousings etc do I need to make to get the two up and together and in communication.

Does the gearbox need any modification to line up to the beetle axles etc..

Thanks James

[MdR]

That box should be a 915 (I believe) so it'll have a fully round bellhousing with nowhere for the stock T1 mounts to sit. This is overcomeable (kool, a new word) with a bit of cutting & welding.
I've fitted a '72 911/01 'box to a VW T1 chassis & have a "T4" engine mated to the 'box. (Under a '51 Crotch coolered Split window shell )
The engine is actually a 914/4 motor, the practical difference is the flywheel, it has a deeper ring gear & is designed to mate to the Porsche box as in the 914/4 from the factory. You would need a 912E flywheel as these were T4 to 915 from the factory. There are also aftermarket suppliers of flywheels.
I have modified the clutch release mechanism to work as a pull type a la stock VW rather than the push type in the 911 using a 914/4 release arm & pivot point. I think this route is different for your 'box. Hydraulic push slave cylinder instead?
I have made the driveshafts line up by fitting the 'box as far forward in the chassis as I easily can (with out moving the torsion bars outward )
I initally used 914/4 output shafts & CVs as these fit the T1 CV splines on the drive shaft & the diff. I have since upgraded to coarse spline (I think) 915 output flanges with T2 CVs these fit the diff & the drive shaft splines but the CVs a tad thick so I put them on the surface grinder at work & slimmed the down. I guess my later mod would do for yours but be aware that these CVs are huge & mean alot of clearancing on the frame horns.
All this lot is still stuck in my garage & has never turned a wheel so I can't comment on the driveability of the 5 speed over the stock 4 speed with it's huge 2nd to 3rd ratio gap...
If you want to give me a call I'll happily chat about it.
Martin

[904GTS]

The 915 box is designed to operate the pull type clutch pressure plate used from the 2.2 911 onwards, these clutches will not mate up to a 914 or T4 flywheel. The best/easiest box to use is the 911 which Martin refers to, this was only used on the 2.2 911 series which used a pull type clutch but with a conventional release arm, this arm can be swapped for a 914 release arm and bearing and will then operate the stock 914/T4 clutch, I have a vague recollection that you may have to relocate the pivot ball for the release arm, I can check this out for definite. Also depending on whether you have a 914 or T4 flywheel you may have to space the pivot ball out from the gearbox casing to get enough travel on the arm, this is because the friction ssurface of the T4 flywheel is recessed deeper intom the flywheel. The 911 box also has two flats which with a small amount of grinding will allow you to use the T1 mounts, you would also need to modify the floorpan for the shift rod to enter under the torsion bar housing and fabricate a nose mounting.

Keith Seume's excellent book " VW Beetle Performance Handbook" has some good pictures of this conversion ( you know where to send the commission cheque Keith)

[MdR]

You can still use the 915 'box it's just more of an arse to fit. A friend had just had one fitted to a T1 chassis by Jon Rathbone http://www.jonrathboneracing.co.uk/
If you choose to go for the slightly earlier 'box as I have you will need to move the clutch arm pivot point if you use a 914/4 release arm.
I am not sure if a T4 flywheel will work in place of a 914/4 one as it is my understanding that not only is the friction surface in a different place but the ring gear is too so that starter motor will not engage properly.