Manual Transmission T56 | T5 | MN12 | Clutches | Hydraulics | Shifters

T56 Conversion help.

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Old Jan 31, 2016 | 01:05 PM
  #1  
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Default T56 Conversion help.

If anyone could help me work this out, I would greatly appreciate it. I am so lost.

I have a T56 from a CTS-V. Before I realized this would not work in my swap, I bought a Monster Iron 11" Clutch (MCI11CTSVP) w/ 18lb flywheel and billet release bearing support. The transmission is being mated to its original LS6 with its original bellhousing.

When I went to test fit it, I realized the shifter position was way off and wouldn't work, cue F Body shifter conversion. I took it to a local shop to have the tailhousing converted for the F body shifter and slip yoke.

Upon getting the transmission back, we tried to install the CTS-V slave cylinder, and it doesn't fit. One of the hoses out of it is way off from where the relief in the front plate? (midplate?) is for it. Call the transmission shop and find out he also converted the front plate thinking it was actually going in to an F body. He said we can just unbolt that front plate and swap it over in a couple minutes no big deal.

One of the issues is, I have no idea what was actually done internally. I have no part numbers on the invoice, simply "Conversion Rebuild" and "mainshaft, tailhousing, front plate, shift rod, bearings and seals".

Are the "main shaft" and the "input shaft" the same part? I don't think they are. Is there any way to tell what input shaft is in this thing at this point? I read somewhere that the F body input shaft is a different length then the CTS.

Now, my biggest worry, if he did install the F body input shaft and it is different then the CTS shaft, is my clutch going to work? and can I simply put the CTS front plate back on?

any help sorting through this appreciated.
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Old Jan 31, 2016 | 05:21 PM
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Okay I can't speak on the differences if any in the ls front plate but your trans coming from a cts-v is a mn12. They have triple cone synchronizers, the f-body doesn't. I done this recently and used a gto main shaft and gto/f-body tail shaft housing. The tail shaft housings are the same. I don't know why they would change the front plate. I am still using the cts-v slave cylinder with a Katech spacer and a ls7 clutch. I did have to machine off about. 200 from the spacer t o get my clutch to slave dimensions right. Had I of had a f-body bell housing it would've been spot on with the spacer. The cts-v bell housing is a bit longer. I had to have a f-body shift rail machined for the trans so I'd have a reverse lock out that worked. Now I can use either the front or rear shifter location.
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Old Feb 3, 2016 | 10:05 PM
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You should be good with:
T56 from a CTS-V,
Iron 11" Clutch (MCI11CTSVP),
LS6 with its original bellhousing,
And the bigger style pilot bearing.
Because these are matched for length, pilot bearing engagement, and clutch spline engagement.

notch the F-body front plate for hose clearance and keep the CTS-V slave cylinder. There was no reason to use the F-body front plate.

Swapping the front plate on a new-bearings build "in a couple minutes" without re-setting bearing endplay/preload is a bad idea for bearing and trans. life. Your builder should be able to answer to what endplay/preload was set to in your unit.

Mainshaft is the splined output shaft. The GTO piece is used in this conversion.
Maindrive is the input shaft. The shorter CTS-V piece is retained (along with pilot bearing, clutch and bellhousing so things match) There's no way to use an F-body input in this unit due synchronizer design differences.
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