Transmission Thoughts

I have three quick questions.

Is the 968 6 speed stought enough for the LS conversion?  

Also is the 6 speed gearing ok for the conversion?  

Should I purchase a 951 "S" transmition to replace the 6 speed?

Thank you for your time!  

What do you plan to do with the car, daily driver, autoX, race, etc? Does the 968 gearbox have LSD?

The car will be a street car and "no" on the LSD.  I am a old man (53 this year) so I will not be deep in the throttle like a teenager, lol.  I don't want to be sitting on the side of the road when I do hammer it!

As of this moment I am trying to make a deal on a 1991 S2 coupe that has been converted (LS1) from front to back and I mean everything!  Very nice car that was built with cost no object.  So if the deal falls through I am going to convert my 93 968.

I had a S2 Cab that was going to Eric for a conversion and some lady pulled out of a strip mall about a week before the car was on it's way to Texas and plowed into it.  If you look on page 10 in the "Body Mods" section under the 'GTS headlight topic you will see my old S2 Cab. The car was totaled out by her insurance company.  I made out ok in the settlement.  So I replaced the car with a black on black 6 speed 968 with 68k miles.  It's a pretty nice car.

Being old does not mean you will not be hard on a car, I'm living proof.

The 968 trans should work fine. You will not be able to use the 968 torque tube without designing a different adapter.

If I don't make a deal on the 944 Eric will be doing my swap. I'm sure he will know what to do. A pre requisite is to rebuild the torque with "Black Sea" Super bearings. I was mainly interested before I go see him to talk about the swap if it comes down to it, is will the 968 trans work. I didn't know if the 6 speed gearing was totally wrong for the LSx and if it was strong enough for what I want to do with the car. Thank you for the response!

I went with a 968 because it seemed the best fit for the LSX motor. As the build went on I found the 6 spd really wasn't right and the Turbo 5 speeds offered better ratios to fit the LSX torque. I sold the six speed to a 944 racer and bought an AOR 5 speed. That also needed a 944 torque tube and two axles and the transaxle carrier along with the mount. The 968 engine compartment is also slightly narrower than the 944/951 and that has it's own issues. I love the 968 lines but if I was to do it over I'd look for a 951 track car with a blown engine. With a bit of luck the 968 Chimera will be alive in a month or so and thats after five years of work.

Take a look here;

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Thank you pormgb,  that was a very informative post!  A few people has told me that the S2 trans is the best for the swap because of the gears are a little higher then the turbo's.  I really don't know that is just was told to me.

I have also told to not do a conversion on my car because it's a really nice car and the 968 were built in such small numbers and just a few year that they might grow in value over the years.  I believe they will grow in value but not really very much.

I want to thank Jim7.  It's nice to know about what is needed to swap the trans.

jws wrote:Thank you pormgb,  that was a very informative post!  A few people has told me that the S2 trans is the best for the swap because of the gears are a little higher then the turbo's.  I really don't know that is just was told to me.

I have also told to not do a conversion on my car because it's a really nice car and the 968 were built in such small numbers and just a few year that they might grow in value over the years.  I believe they will grow in value but not really very much.

With LS1s, you don't want too high gearing unless you have a massive cam with a high rpm power band; these motors have tons of torque so they can pull hard with low gearing and final drive. Take a look at a C5s gear ratio and final drive compare it to a 944/968 and you will see what I mean.


Corvette C5;
1st Gear 2.66:1
2nd Gear 1.78:1
3rd Gear 1.30:1
4th Gear 1.00:1
5th Gear 0.74:1
6th Gear 0.50:1
Reverse 2.90:1
Final Drive 3.42:1

944 Turbo;
1st Gear   3.500
2nd Gear  2.059
3rd Gear   1.400
4th Gear   1.034
5th Gear   0.829
Reverse    3.500
Final Drive 3.375)

My car has a 968 transmission coupled to an LS6, I don't mind the 968 transmission apart from higher highway rpms. My car also has cam just under 600 lift and likes to be above 3000rpm, the 968 transmission make it a blast to drive.

That final drive for the C5 trans is for the Z06, if i am not mistaken. My trans is the Zo6 with the 3:42 but with little effort can change to the 2:91. I think the base vette is the 2:91. But dont quote me. I will start my car with the 3:42 ratio and will decide after if i want to change. Final drive depends on what you want the car to do. Just my 2 cents it would appear the base vette can come with a selection of ratios. But the Zo6 is the 3:42 checked on GM site.