por1984

951 track car was considering using a 944s ring and pinion but then i ran across this--------------

"Using a 944S ring & pinion in a 944 Turbo transmission.
The answer is: DON’T.

There have been many reports of 944 Turbo transmissions self-destructing because of this modification. Basically, the 944S ring & pinion just can’t handle the power of a turbo. So just say no to this modification. It might be ok for street use, but a transmission rebuild is mighty expensive"

can someone lead me in the right direction?????

special tool

S - no
S2 - yes

f1rocks

Are you trying to stay class legal (E or F?)

If so, you will not stay in class. If you're not worried about staying in stock class and you're not going nuts on power I've heard they will take it.

Special Tool recommended it to me. That makes it gospel right Lutj?

f1rocks

Lutj beat me to the post....

SD Porsche Fan

sh944 has put the ring and pinion from an S2 in his 951. He is also running Vitesse Stage II. If you want to challange him in 3rd or lower gear you'd better be in a VERY fast car!

por1984

what i read of pca rules it would be legal but would bump me from "f" to "e" class.
do i just use a s2 trans or will s2 ring and pinion work in my 951 trans???
thanks for the quick response.
bill

SD Porsche Fan

s2 r&p will work in your 951 trans.

Here is a link to his post on the subject:

https://rennlist.com/forums/944-turbo-and-turbo-s-forum/232729-best-mod-yet-s2-ring-and-pinion.html

por1984

thanks for the link and info.
bill

JET951

i would recommend the 944s crownwheel and pinion. many of these conversions were carried out in australia and none had any problems. the 944s2 ratio is too similar to the standard turbo ratio. the 944s crownwheel and pinion is treated in the same was as the turbo so it is just as strong as the turbo one. and they are cheap new. i got one recently for my 86 turbo for about $2000 australian. made a hell of a difference

special tool

Jet - you don't know what you are talking about with respect to the S2 R&P.

The S is NOT a good mod for a turbo. The S2 is MUCH lower than the turbo and MUCH stronger than the S.

The people posting on this thread speak from experience, not hearsay.

Porsche-O-Phile

What he said. I've heard of an S transmission being used in conjunction with a 968 3.0L engine (in an early car!) and it's extremely quick off the line - almost as quick as some of the Mustangs and other solid-rear-end cars I've driven. Yes, I've driven it - it was very impressive for quickness. I really highly doubt it would stand up to the extra power of a turbo (particularly a modded one) though and I can't vouch for how durable the setup is, even with "only" the 968 3.0L engine.

jean_noir

turbo gear ratios
1st 10:35 (3.500)
2nd 17:35 (2.059)
3 25:35 (1.400)
4 29:30 (1.034)
5 35:29 (0.829)
R 12:42 (3.500)
fdr 8:27 ***(3.375)***

944 s2 gear ratios
1st 10:35 (3.500)
2nd 17:35 (2.059)
3 25:35 (1.400)
4 29:30 (1.034)
5 36:28 (0.778)
R 12:42 (3.500)
FDR 8:31 ***(3.875)***

check clarks garage for more details

Oddjob

This one just keeps coming up, but needs to end! The 3.889 944S R/P is NOT as strong as either the Turbo 3.375 or S2 3.875 R/P. The 3.889 S Pinion is smaller in diameter and the ring gear teeth are smaller than the Turbo or S2 R/P dimensions.

If you ***** foot around in a 220 bhp stock turbo, you might get some mileage out of an S R/P, but if you actually drive the car, the R/P's days are numbered.

This has been common knowledge in porsche/performance/technical circles for years. There are articles/letters from Bruce Anderson and others in Panorama tech sections dating back to OCT 89 on the subject, stating that there had been known failures of the 944S 3.889 R/P when used in a 944 Turbo (in under 10k miles), and that Porsche openly stated that the S R/P was not a strong as the Turbo and should not be used in that application.

When I got involved in this hobby in '92, there were already at least two local 944 Turbos that had swapped out to the S2 ring and pinion. And I have seen several other 944Ts upgraded with the S2 R/P since then. The S2 R/P is as strong as the Turbos and will last, no problem. Its also a good performance upgrade for acceleration. The S2 3.875 R/P is noticeably shorter than the 3.375 Turbo, and is so close in ratio to the S 3.889, that no one would be able to tell the difference.

I highly recommend being very careful about passing on incorrect/unfounded information. Because someone with even less knowledge may listen to that advice and potentially cause significant and expensive damage to their car/mechanicals.

JET951

all im saying is that we have used it in our workshop in thee cars now and we havnt had a problem. i am not speaking from hearsay, ive actually done it. it makes the car extremely tractable in lower gears. and i do track my car( although it is only putting out 310 hp) quite a bit in australia. if you look in the new car featues of the 944s in 1987 it states that the crown wheel and pinion was treated the same way as the turbo with heardened teeth. where as the 944s2 isnt treated that way. im not saying the s2 one isnt strong. i know america is a different market to australia so just to clarify im going down to work today to look through our manuals. By the way i work for an indipendant porsche specialist in sydney, my dad. he worked for porsche for 15 years and then started his own garage about 11 years ago. i have worked for him for 5 years now. well that was my first post here so it looks like ive made some new friends already.

JET951

well your right. the 944s2 ratio is very similar to the s ratio. but the s doesnt have smaller teeth, it does have more teeth but they are not smaller. when porsche designed the pinion they changed the RO value so the teeth of the pinion are the same size as the turbo and s2. have you really seen these break, im interested. what sort of power was the car putting out