swap 944S2 pinion and ring 083F in 951 gearbox 016R help

[ajrlredondo]

Hello:

I want to swap the Porshce 944 S2 pinion and ring (083F gearbox) in my 951 gerabox (016R with LSD). It is a race car used in tracks and I want to get less maximun speed, and my question is if it is possible and enough strong to hold the torque and if it is possible to fit the LSD with the 083F pinion and ring. The ratios are 8:27 in 951 Turbo and 8:31 in 944 S2.
The problem is that I don´t know if the pinion is the same and if I can fit the 951 gears that are strenghthen with the 038F pinion and ring


Can anybody help me with this?

Thank you very much in advance

[Pete T]

Yes, you can swap. The S2 transaxle is basically a 951 without a coolet and with a different R & P. The 8:31 differs from the 9:35 in that it has been strengthened. It has the larger ring gear diameter with wider teeth, the larger pinion bearing and the wider 3rd gear.

It is not shot peened like the Turbo S is however. So if you have a Turbo S box (code AOR) to have the same reliability you would nee to get the R & P shot peened.

[Jim c]

If this is the job I think it is.
There is a thread by Jim Shearen explaining how to do this job so do a search.
Jim S worked it all out but never got around to doing the job.

I have done this job and Jim S instuctions are pretty good.
You will need to machine the front case to fit the larger CW and front bearing.
I have a cad dwg of the 4mm spacer plate between bell housing and main case.
I also put the strengthing plate in at the rear housing.

It is not a small job, it is a marathon and I spent about 30hrs including working out PCD for the cad dwgs(spacer plates).
If you want the drawing let me now.

Good luck

Jim c

[ajrlredondo]

Thank you very much Jim C and Pete T!!!!!

I have questions about that. It will be reliable the R P 8:31 in my car?? Because
I think that I can´t shot peneed the S2 R and P.

And Jim, of course I want your draw if you don´t mind but I don´t understand which strenghthened plate you refer because I had tought fit my Turbo S streghtened gears in the S2 R and P but "I also put the strengthing plate in at the rear housing"???

My email is ajrlredondo@telefonica.net

Thank you very much again and please send me your draw to make the spacer plate

[Pete T]

You don't need to do any machining the case. The S2 gears will go in as a replacement. The case is the same as the 951 (turbo) including the wider gear so a spacer is not required either way. You can swap the ring and pinions between each transaxle without any modifications.

[ajrlredondo]

Thank you Pete for your answers. I have bought one S2 gearbox to try to swap the pinion and ring. But what about the reliability that you told in your reply?? Because I´m not sure if this 8:31 944S2 Pinion and Ring will hold the torque (now 410Nm). What do you think?? I wouldn´t like broke the gearbox.

[Pete T]

I wouldn't expect this to be a problem. The 8:31 is much stronger than the 9:35 (3.888) used in the earler transaxles. It should be comparable to the 951 non "S" set. The turbo S is the only on that was shot peened.

The 9:35 is the same gear set as the one used in the AUDI 016. The 8:31 is much stronger. As I said earlier, it is larger in diameter and has wider and thicker teeth with a larger tooth contact area. The difference between the 9:35 and 8:31 is probably something like the difference between the 915 early gears vs the 8:31 late set except on the AUDI based one the ring gear is also larger in diameter.

I would expect the same durability with the 8:31 gear set as the standard 8:27 951 gear set. The Porsche factory training manual states that the reliability of the S2 transaxle is equal to the 951 transaxle.

You could always get the set cryo treated before installation. The biggest killer of these transaxles is overheating and drag race starts. There is a guy on the 944 v8 board that has a 944 with a Chevy LS1 with a Magnuson supercharger. He hasn't been to a dyno but suspects 600+ HP at the flywheel. He is running a stock non S 951 transaxle with cryo treated gears. He runs on the street and also quite a bit on the track. He hasn't had a problem yet although it has only been one season.