Carpokes Porsche Forum

The 968 to 951 transmission upgrade is turning out to be quite an expensive project. Here are the numbers:
1) Purchase used "60K miles" 968 6-speed from RL member - $3500
2) Also purchase 968 axles, shifter, and shift rod with trans - $500
3) Decide to have the trans checked out - shipping from Virginia to Catellus Engineering in Stow, MA - $409
4) OS Giken G50 LSD from Racer's Edge - $1950 + $45 shipping
5) RL seller buys back factory Torsen - ($1000) credit
6) Teardown and complete overhaul by Catellus Enginering. Trans needed 2nd, 3rd & 4th gears, shift sleeves, all bearings, all Syncros, etc., etc. - $6309
7) Catellus Engineering buys back original used 3rd gear - ($150) credit
8) Shipping to Seattle area - TBD

So, anyone contemplating having your trans overhauled... just be prepared for a potentially large expense. And the sooner you can get any trans work done, the better, as parts are becoming harder, and more expensive to find.

It does look nice though, and Kevin is great to work with.

@Catellus Engineering is indeed great to work with. When he did mine, he was very good about not replacing parts unless they really needed it. Do you think the RL seller knew the tranny was so worn out inside? I had the opposite experience. Bought a noisy transmission that we assumed needed a full rebuild, and Kevin didn't have to change that much at all inside. Luck of the draw I guess.

p.s., that transmission looks like a work of modern art!

Tom wrote: Sat Sep 02, 2023 4:19 pm @Catellus Engineering is indeed great to work with. When he did mine, he was very good about not replacing parts unless they really needed it. Do you think the RL seller knew the tranny was so worn out inside?

The trans came out of a damaged 968 cab from Florida and supposedly only had 60K miles, so I don't think the seller really knew its condition. Whoever owned it must have been really poor at shifting gears to chew up so many expensive parts. I certainly didn't want to spend this amount, but it would have been much worse if I found out later after it was installed, so in that regard I'm glad I had it rebuilt.

Did you change gear ratios at all?
I've always been intrigued by a 6MT swap on my 91 S2, but I don't like that it's not much taller. I want a lazy 6th for cruising around. 3k at 70mph is really tiring.

stitch2k1 wrote: Mon Sep 04, 2023 7:11 pm Did you change gear ratios at all?
I've always been intrigued by a 6MT swap on my 91 S2, but I don't like that it's not much taller. I want a lazy 6th for cruising around. 3k at 70mph is really tiring.

I did not change any gear ratios. The 968 has 3.182, 2.000, 1.435, 1.111, 0.912 and 0.778 with a 3.778 R&P.

The 944 Turbo has 3.500, 2.059, 1.400, 1.034 and 0.829 with a 3.375 R&P.
The 944 S2 has 3.500, 2.059, 1.400, 1.034 and 0.778 with a 3.875 R&P.

Based on the gear charts I have an S2 at 3000 rpm in 5th should be 75 mph, not 70. 3000 rpm in a Turbo is about 81 mph, and 3000 in a 968 is about 77 mph.

There might be a Euro TDI 6th gear that fits the 968 trans since it's similar to the Audi 01E, but I can imagine it being very expensive.

Latitude48 wrote: Tue Sep 05, 2023 12:47 pm The 944 Turbo has 3.500, 2.059, 1.400, 1.034 and 0.829 with a 3.375 R&P.
The 944 S2 has 3.500, 2.059, 1.400, 1.034 and 0.778 with a 3.875 R&P.

Based on the gear charts I have an S2 at 3000 rpm in 5th should be 75 mph, not 70. 3000 rpm in a Turbo is about 81 mph, and 3000 in a 968 is about 77 mph.

Unless I have a tach reading incorrectly, by a lot, then that is not the case in practice. I am on a stock rear wheel size and tire size still, and my speedometer reads dead accurate.

stitch2k1 wrote: Mon Oct 23, 2023 1:21 pm

Latitude48 wrote: Tue Sep 05, 2023 12:47 pm The 944 Turbo has 3.500, 2.059, 1.400, 1.034 and 0.829 with a 3.375 R&P.
The 944 S2 has 3.500, 2.059, 1.400, 1.034 and 0.778 with a 3.875 R&P.

Based on the gear charts I have an S2 at 3000 rpm in 5th should be 75 mph, not 70. 3000 rpm in a Turbo is about 81 mph, and 3000 in a 968 is about 77 mph.

Unless I have a tach reading incorrectly, by a lot, then that is not the case in practice. I am on a stock rear wheel size and tire size still, and my speedometer reads dead accurate.

You are welcome to download these Excel gear charts I put together for the 968, 944 S2, and 944 Turbo.
https://1drv.ms/x/s!AtHS0jWEezJSzg6Vo7Z ... 8?e=ityLaM

Be interested in your opinion once you've installed and driven the car. I did the same swap and have never liked the gearbox as much as my old 5 speed. Imprecise gear selection at times has thwarted and annoyed me. Trying to shift from 5th into 3rd a particular bugbear. Hopefully it's just an idiosyncrasy (sorry, bad pun) of my particular transmission. It was provided to be via California Motorsports who went through it and made a couple of oiling mods and installed their billet side case too.

This scenario recently played out in my shop as well.

Purchased an AOS with LSD added by a PO (1,700).

Shipped back and forth from ATL to MA (500).

Extensive inspection and rebuild by Mr. Transmission back to factory specs. Checkbook balance lightened accordingly (5,200).

Granted, I'm not in quite as deep as you are at this point, but still...I can relate...it is the price of playing the game.

This will be mated up with a Blacksea refurbished TT.

Transmission work doesnt have to expensive. It is cause it requires big boy tools. I only went in to clean, inspect and replace all synchro's. All the bearings seemed fine and was in spec to the degree I could measure them. I didnt have a specific tool to measure the front Pinion and end bearing distance to the Thou so no perfect.

For Reference, My Day job and experience was being a machinist for about 3 ish years. ALSO I didnt say I was a good one .