What are the differences in the ls1 and lt1 t56 trannies. Has anyone cunverted an ls1 model to work with a small block? I have already done the conversion but mine pops out of reverse. It seems there are more 98 & ups available than 97 & down. Is it as simple as switching the bell housing & clutch or is the input shaft different? Can the input shafs interchangeable?

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'92 Z28
5.7 TPI
T-56 six speed
Pro 5.0 shifter
3.73's
SLP 1-3/4" Headers
SLP Cat-Back
52mm TB
Extrude Honed Intake/Ported plenum
Hypertech Prom

 

Sorry about the last sentence above, I meant to say are the different model input shafts interchangeable?

 

I know the bellhousings are different, but I also think the clutch hydrolics are different. I was looking at an LS1 six speed setup for my 3rd gen (already have a t-56 installed) and was told I would have to change the slave cylinders again.

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1992 Pontiac Firebird 350/Six Speed
1987 Toyota Pickup 383/500+ HP

 

I would say it is possible to change the INPUTSHAFT out, since it is LONGER than the 97-Below. I don't think that TREMEC TOTALLY REDESIGNED the tranny just for the LS-1 change, they just installed the new inputshaft, front cover, bellhousing, and hydraulics. You would need to get a 93-97 front and inputshaft for it to work in the conventional fashion, since the 98-up front cover DOESN'T have provisions for the CLUTCH FORK POST.

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88 Monte SS 355 TPI/LT-4 HOT CAM/AFR Hydra-rev/ T-56 6-Speed

 

THats good to know the Lsl tranny has a longer input shaft. Does anybody know just how long it is. The aftermarket T56 also has a longer inputshaft because of the 1/2 inch plate that adapts it to the stock bellhousing. This means maybe we could build our own adaptor plate and use an ls1 tranny or at least the ls1 inputshaft.

 

I too have been wondering this. My suspicion is that the LS1 is very similar to the aftermarket t56. The input shaft on my aftermarket is a lot longer than the production one. Does anyone have the tag number from a LS1 six speed? I wouldnt mind calling Tremec and trying to find out the differences, but I need the tag number from an Ls1. I think that if you get an ls1 six and use the t-5 bell with a custom adapter plate it would all work. But I am not sure about the tailshaft. Too bad it is such a pain calling Tremec and talking to the idiot tech guy. Last time I called he couldnt even answer my questions!

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If the women don't find you handsome they should at least find you handy
88 GTA Notchback with 91 gfx and ROH Snypers
Aftermarket T-56 (pain in the A$S but worth it)
Lots of things to do still

[This message has been edited by scooter (edited January 19, 2001).]

 

Oh also what spline count is th LS1 tranny? That makes a difference in how much of a pain it is. If it is the same (26 I think?) it would make the whole job easier.

 

OK here is all the data on the different T56 transmissions:
Input shaft length: ['93-'97: 9.188 in] ['98-up: 10.75 in] [aftermarket T56: 6.66 in]
Input shaft spline count: all have 26 splines
Bellhousing depth: ['93-'97: 4.882 in] ['98-up: 5.531 in] [aftermarket T56: 6.290 in]

These numbers are straight from the june 2000 issue of Car Craft

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1991 Z28 - 350 TPI, T56, McLeod street clutch, ported plenum & runners, AFPR, Holley Annihilator ignition box and wires, Hooker shorty headers w/o AIR, no cats, Flowmaster muffler, homeade ram-air, SSM subframe connectors, Steve Spohn adjustable torque arm and T56 crossmember

 

I just emailed I guy who has a ls1 t56 I the said from butting the ruler up against the tranny to the end of the inputshaft was 7.25 inches. Any body with a aftermarket T56 Know the measurment on your input shaft?

 

A guy on ebay is selling a ls1 tranny right now here are the numbers from it

12552099 K1982
13 86 017 28328