IRS 5spd Occmans Razor

[Jacques Lefriant]

I a have reached the conclusion the optimum path would be to employ a 901 based bolt in 5spd box and build bolt on trailing arms that utilize the outer upright from the axle tube. What will be required:
1. donner 901 box
2. 912 flywheel
3. nose cone with speedo drive delete and ears for front mount
4. stub axle that accepts drums or hubs for rotors
5. trailing arm that has an inner brg/seal that replaces the tube in the upright. and attaches to a bracket on the torsion tube.
6. 2 Lobro axles(901)
7. clutch cable as in 911/912
8. 12v starter.
j

[Craig Richter]

Jaques, I'm a big fan of yours, and think you are the perfect guy to tackle this 5-speed project, but this is getting way too complicated. I think that's why there has been no response to your post. Nobody cares about IRS, no matter what theoretical technical benefits there could be. Not legal for racing, too much changing for street guys. I'm not yet sure Berg 5-speed is the best answer, but we need some reality checking here...

[Jacques Lefriant]

Hi Craig
The elitist majority do not look kindly on VW or other non Porsche solutions. The 901 box is perfect since it is a 5spd and robust enough. When you use it in a 356 the normal method is to incorporate many features from the 911/912 which require modification. I propose an non intrusive package which retains the brakes/wheels/shocks and by accident transforms to IRS. WIN WIN.
j

[Craig Richter]

Jacques,
I appreciate the "elitism" bit, because I find myself feeling that way sometimes, in spite of the fact that I've had a lot of positive experience with racing VW parts! And I agree the 901 box could be perfect - strong, reliable and relatively plentiful. I guess I'll just have to wait and see what some of the prototype parts actually look like...
One more question: Will it work with a stock shifter (A/B)?
Thanks J

[Jacques Lefriant]

Stock(B?C) shifter is perfect i even go one better in the 904/906 they put the spring loaded 1st rev action in the box where it belongs and not in the shifter so those parts can be deleted from the shifter.
j

[Craig Richter]

Speedy is a monkey-motion PreA...still work? I suppose doing away with the tunnel reverse light switch would get more swivel room to engage 5th gear...

[gregorycampbell]

Jacques,

I never thought of using the 356 upright. That is a good idea.

Are you thinking of welding ears onto the 901 nose cone or casting an all new one?

Are you thinking the "banana" arm would be fabricated or adapted from something else?

[Jacques Lefriant]

Hi Greg
Eventually having a casting done for the nose cone. The last time i did a conversion i welded in a tube to make use of the space left by deleting the speedo drive. We could also shorten the bell housing and use the 356 flywheel. I reversed the hoop and used the stock mounts. Like the early 911 and the VW irs we would add a needle/roller brg by the stub axle flange with a seal this housing should stradle the the existing spring plate and have threaded holes to cinch up the upright. i hope an existing VW trailing arm could the be cut off and butted to the proposed bearing housing adapter. Althought this aproach does not have the sophistication of the 911 SWB parts it does not require any modification. If one wants to go to IRS i can convert the stock transaxle to IRS.

[gregorycampbell]

Sounds good Jacques. The challenge will be the stub axle bearings/housing. What about at the differential and side cover end. What's the plan there?

[Jacques Lefriant]

Hi Greg
I am going to use a needle brg like the 911. The stub axle pictured is about the right lenght but it was meant for wider drums so the splines would be under the o ring. The Caddrobbi Conversion uses a VW diff from a swing axle VW so IRS won't be a problem since the coresponding pieces are available.
j

[Adrian Rendle]

Jacques, won't you still have the problem of welding a mounting onto the t-bar tube to take the inner trailing arm mounting, unless you could use the gearbox front mount brackets somehow....and you've always got the problem of the inner and outer trailing arm pivots swivelling on slightly different radii

[Jacques Lefriant]

Hi
It would be better to weld the bracket to the tube but you could clamp it over the tube. The pivots don't have to be coaxial or even parallel that is why either they are in rubber or use a spherical bearing. Even if we make the parts they would have to be sold for racing /offroad use only since the liability is enormous. On your other pricepoint issues a stock VW modified box would be an economical replacement for the Porsche 356 unit especially in pre B cars. Conversions have been done with little difuculty and modification but it is generally not an upgrade. If you wan't a 5spd or a robust VW based unit the 901 is competitive and has less Originality issues for the B/C but requires IRS which may be a good thing.
j

[Aki Ruohonen]

Jacques I'm sure you are aware of this product, which I presume is already doing the same than your nose cone except for the mounting ears.

http://www.bugat5speed.de/en/beetle-co/ ... endeckel-2

There is also special front mount for beetle: http://www.bugat5speed.de/en/beetle-co/ ... ront-mount

How about not incorporating the ears to the nosecone but use the same idea and come up with the special traverse front mount instead?

br,
Aki

[Mark Erbesfield]

I have always wondered about newer transmissions for old 356's. Will a 901 fit into a 356 without having to cut metal? Does it bolt up to the 356/912 engine? I guess it does bc the 912's came w a 901. So what else is required to install a 901 into a 356. Sorry about the clueless questions, but don't know a lot about these things. Thx

[Jacques Lefriant]

Hi Mark and others
I am involved in quite a few projects i have to build a house in Nevada close to Reno or my wife will be unhappy.Having once been employed as an engineer i am lobbying for what i think is the best fit. a 901 based gearbox 5spd with IRS that retains the stock brakes, shocks and torsion bars. anything else is a compromise and ads complexity, unoriginality and non Porsche parts. Are there any enthusiasts who would like to participate i could use the help (i Am not talking mental help i am beyond help)
cheers
j