LT1BC

My LT1 (from a 94 F-Body) currently has a A4 attached to it.

Am looking to swap in a C5 T56 Z06, with M12 gears. I've figured most of the other issues (new main shaft, etc. etc.) I've to contend with, but am little short on understanding what is needed as far as the bell housing and converting over to hydraulic clutch set up.

As this is a full on conversion, I'll need all the "up front" parts so any help in identifying what combination of parts needed would be greatly appreciated (in getting the right parts the 1st time).

My initial question is re the right input shaft for this. I have found listings for LT1 input shafts that specify 31 teeth, 2.66 1 st gear. As the C5 Z06 is a M12 with a 2.97 1st gear, will I need a different input shaft specific for an M12 gear set, or what I am to look for?

Also, if changing to to hydraulic clutch linkage, will the OEM bell housing work, or am I looking for a aftermarket, such as Quick Time?

I'll likely have more questions, but these are the 2 main ones for now.

Jeremy@RPMTransmissions

iTrader: (12)

My best recommendation would be sell or trade the C5 T56 for an LT1 T56. To put a C5 T56 behind an LT1 will require a $600+ Quicktime Bellhousing, switching the clutch and flywheel to a push style clutch so you can use an LS1 slave cylinder. You will have over $1,000 in parts just to convert the transmission from C5 to an F-body style T56. It just doesn't make sense. There are M29 ratio LT1 T56 that have very similar ratios to an MN12 C5 T56. I'd recommend getting yourself one of those and saving a LOT of hassle.

LT1BC

Thanks for the candid feedback Jeremy.

I expect to be able to get a used bell housing for $200 so that will help offset a big chunk of the costs, and as with any other new, rebuilt, or used trans I may be able to get my hands on, it likely won’t come with the clutch linkage etc. so these are things I’ll have to get anyways.

At the end of the day, I may end up going a different direction, but for now, I’d like (at least) to see how I might be able to go ahead with the C5 M12. The major missing thing I wasn’t clear about is which input shaft for an LT1 if using an M12 gear set would be compatible (given what I’ve found so far all LT1 input shafts seem to point at the 31 teeth 2.66 1st gear compatibility)?

Anyone know/help with this info? Thanks.

Jeremy@RPMTransmissions

iTrader: (12)

I guess I should have been more descriptive with my reply. You can't run a single cone synchro style LT1 input shaft in a triple cone synchro style C5 T56. This will require using the original C5 input shaft. Which means you can't use the LT1 bellhousing or midplate. And that leaves you using an LS1 F-body midplate and hydraulic throwout bearing instead of the fork. This will require using a different clutch and flywheel.

LT1BC

Want to make sure I've got this correct.

Retain the C5 input, go with an LS1 F-body mid plate and bell housing, a LS1 F-Body hydraulic throw out bearing, and LS1 F-Body clutch and flywheel?

dgcustomz

iTrader: (127)

This is what I would do..
Get your Z06 input splines machined down to an Lt1 size. This will only work with a single disk clutch as you are running out of splines.
Lt1 front midplate with new seal
F-body shift rail-#13-86-100-007
f- body rear offset socket #1386-598-016
F-body extension housing with new seal-#13-86-566-024
GTO mainshaft-#TUFP2065
2 speedo snap rings-sp56-50
1 speedo gear-#13-52-110-013
1 speedo sensor#13-86-140-006
grind off the lever from the front offset socket that engages the reverse lockout solenoid. That way you won't have to purchase this for an f-body.
This will allow you to use all LT1 related items such as clutch, clutch fork, slave basket, etc...
Hope this helps...

LT1BC

Thanks dgcustomz.

As this is a A4 to T56 swap, I don't have any of the LT1 T56 parts, so I'll be sourcing whatever I need.

Instead of the GTO main shaft, and since I'm going in this far, I'm considering upgrading to the SSR 32 spline, so I'll have some machining to on the tail housing.

The plan is to run a twin disc, so if there's a straight forward option to the LT1 input (or machining the C5 input), I'm all for that.

Will a input shaft from a LS1 F-Body work for a twin disc, and if I go that direction, can use all LS1 F-body stuff (bell housing, mid plate, and flywheel, hydraulics etc.)? That's the main question/answer I'm still not clear on.

dgcustomz

iTrader: (127)

If you go to an LS style bell, front plate, slave, you can use the input as it is. You will need to go to a push style clutch and not a pull. I don't know the exact measurement from the Lt1 to Ls1 bell outer face to see if the input will be too long. I do have a roller cam sbc laying around and can see if the length will work. Give me a little bit.

LT1BC

Hey DGcustomz, thanks for the effort.

Re the "input as it is", is that the LT1 F-body, LS-1 F-Body, or C5 input?

jmd

iTrader: (4)

None of the above, depending on what parts you actually have, and what you're actually using, and what you have planned for the transfer case end of things.

Is the plan still to go with a 32 spline SSR mainshaft, can you actually buy one right now, or is it on backorder?
And still going with Gen I SBC with 1pc rear main seal?

LT1BC

I have the core C5 M12 and that's it. I can gather the other pieces based on what is needed and compatible. The 94 LT1 has been in the vehicle for a few years.

I checked online, and there are a few places that have the SSR shaft but don't want to order it until going this route was figured out (or NOT).

I've been doing what research I can, and from what I can gather, the GTO and Vette share the same input shaft, part # TUEF1218 (they share the same 2.97 1st gear). That makes sense re DGCustomz's suggestion for the GTO main shaft, but if I'm in this far, as long as the SSR shaft is compatible, I'd like to go with that. I've got the tail housing figured out, so the focus now is the front part.

So if retaining the C5/GT0 input shaft, its limited to a single disc, or what are the options to being able to use a twin disc? And then for the mid plate, what do I use, the LS1 F-Body, or ??? And same question with the bell housing???

Hoping this gives the required info to make this clear on what I'm trying to do, and for someone to help figure this out. Thanks

LT1BC

Hey JMD, I had tried to answer your questions in the above thread.

Does that provide enough info for more input as what I can (or should) use for a input shaft (and I'd like to go with a twin disc clutch). I plan on upgrading and running hydraulic clutch set up.

What can you suggest or advise I do or use? Thanks

I was also hoping DGCustomZ might be able to provide some help, but he seems to have got busy and not been back online for a bit now.

Zach Mccarthy

will it be a lot cheaper if you had the m12 t56 transmission? I mean I have a m12 t56 transmission from a 04 GTO and I have an lt1 z28 with borg and warner t56 transmission. What I'm wondering is all you have too do is use ls1 bellhousing, input shaft, face cover and clutch setup?

Jeremy@RPMTransmissions

iTrader: (12)

Unfortunately the LT1 M29 input shaft will not work in the GTO triple cone T56. You're better off finding yourself an LT1 transmission to start with.

Zach Mccarthy

so there's no way to change input shaft? I've heard people doig these swaps

Jeremy@RPMTransmissions

iTrader: (12)

You can take an 94-97 LT1 F-body T56 and put a 98-02 LS1 F-body T56 input shaft and mid plate on them. Or you could take a 98-02 LS1 F-body and put a 94-97 F-body input shaft in it. But the 97-04 Corvette and 04-06 GTO T56 is a different design and parts can't be mixed with the earlier design.

Brandenhs

iTrader: (2)

What about this ?
http://www.eecis.udel.edu/~davis/z28..._Fbody_T56.pdf

As far as I understand it can be done using the SSR main shaft the fbody case and the c5 guts/gears
I was going follow this to build the junk fbody t56 I just got taken on.

AMP-D

FWIW, if you need a Corvette shaft that is the LT1 length, we can machine our shaft to the proper length and still have enough splines to run a twin disc if you so choose to. This would allow you to convert a Corvette unit to a LT1 style easily.