T56 with LS7 clutch?

[LAMBSKIN71]

Hey guys,

I have a 07 6.2 L92 motor, stock, with the G8 intake (L76 i think, dont remember the nomenclature) and a T56 out of a 99 T/A, with stock throw out bering and slave. I am using a LS7 flywheel clutch and pressure plate bought new from a local GM dealership. I am using a stock GM truck starter from a salvage yard which is working fine, the issue is when the peddal is depressed the clutch isnt engaging, you can hear the bearing touch the fingers of the pressure plate but you cant shift through the gears. Now there is a 1/4" spacer between the bell housing and trans case from Mcleod, i followed their instruction and took the measurements from the rear of the bell housing to the pressure plate and then from the front of the trans to the front of throw out berring and theres a 3/8" difference. Now, I talked with Mcleod and they said this set up will not work with a stock clutch slave and throwout berring because of the recessed flywheel and the way the self adjusting LS7 pressure plate work. I also talked with The guys at centerforce and they said that it should work that from the sound of it I just need to put a spacer behind the hydraulic slave. I have a local machine shop that is making one and should be done this week.

Before I waste time and money putting this back in the car can someone tell me if this will or will not work? Im getting two different answers from two reputable sources. This is all going in a 71 Chevelle too.

Can someone shed some light on this for me, in laymans terms?

[Musclerodz]

should work with a correct sized spacer. we are running a ZR1 clutch behind a magnum t56 and I have the info that was given to me to make it work somewhere saved.

[LAMBSKIN71]

Thanks,
The space idea seems the logical solution to me too, do you forsee any issue from moving the slave out on the input shaft 3/8"? And what is the deal with the three fingers on the pressure plate that stick up further than the rest, I get that its self adjusting but I didnt understand how that would affect the way the rest of the parts worked or shouldnt work together, according to Mcleod.

[Nine Ball]

Now there is a 1/4" spacer between the bell housing and trans case from Mcleod

What is this spacer for? Can you remove it?

What is happening is that your slave cylinder doesn't have enough travel to fully disengage the clutch. That spacer is likely the cause of it. Since you moved the trans 1/4" backwards, that means the slave now has 1/4" less travel into the clutch. Put another 1/4" spacer behind the slave, where it mounts to the trans, and you should be good to go.

Also, be sure you have an adjustable clutch master cylinder, with a threaded rod. That will also help you fine tune the engagement point of the clutch.

[dhutton]

Just about all you would ever want to know and then some:

http://ls1tech.com/forums/manual-transmission/1030815-does-your-clutch-setup-need-shim.html

This has got me wondering now since I used an LS7 clutch and no shim. Should be starting it in a few weeks so I will see how it goes. I might order that shim kit just in case.

Don

[MaxHarvard]

Camaro Performers did a really good write up on how to measure for correct slave cylinder depth. It's the Feb 2012 book... really good article.

[LAMBSKIN71]

Initialy the .25" spacer is because aparantly the input shaft of the T56 is longer than the automatic that was originaly behind the motor, keep in mind my motor is a truck motor so the crank shaft is different, it uses the small pilot bering, when I stabbed the tranny the first time the in put shaft was bottoming out before the bellhousing was mating up with the back of the block.

If anyone else needs a slave spacer let PM me and let me know and Ill talk to the machine shop and see if it'd be something they would be interrested in making and selling on here.Their pricing seems to be reasonable.

[GeoffP]

So does your engine have the thick crank flange like some of the truck engines or is it the thin LS style crank flange? I also wondered if the truck crank used a smaller pilot bearing - is it the same as small block chevy or something else? Thanks! You saved me some grief on my build... I should mention that I also bought a complete LS3/LS7 clutch setup complete with the flywheel so any info you can share would be really helpful!!

[LAMBSKIN71]

The L92 Truck / Suv crank flange isnt any thicker if I recall correctly, but it does use the pilot berring that sits in outer most slot, but it is drilled for both berring sizes. I had to pull the larger diameter berring out and press in the smaller diameter berring that the LS3 and 7 corvette crankshaft uses. I imagine you will have to do the same thing I did and put a spacer in your transmission too, and another behind the slave cylindar. Try bolting it together first and see what happens before buying a bunch of spacers, then if it doesnt go together youll know where to start looking, the pilot berring is cheap enough and you can get it at a local GM house.

Did you use the "recessed" flywheel? The guy at Mcleod said there is some issue with using that flywheel with stock T56 transmission parts, I dont see how that is possible.

[67ragtp]

should work with a correct sized spacer. we are running a ZR1 clutch behind a magnum t56 and I have the info that was given to me to make it work somewhere saved.

Mike, Any chance you could share this info, Im curious what kind of TOB gap is necessary for this dual disk setup and if a standard fbody slave will work with it. Does the complete clutch assy move the fingers to close to the trans face requiring a spacer, I think katech uses some kind of bell housing spacer for ls9 setups.

Rich

[GeoffP]

I'll just plan to pre-assemble my engine to the trans so I can check everything prior to putting it in the car. Sounds like it'll be time well spent!

[LAMBSKIN71]

Still waiting on Machine shop to cut the spacer, went back and re measured, looks like .450 is going to be the magic number, for my set up at least. I am still concerned about the three raised fingers on the LS7 pressure plate, not sure how that is going to affect things, I was told to meassure to the rest of the fingers that are about 1/16" lower than the three,

[samckitt]

I'm somewhat curious about this too. I have an LS2 from a Trailblazer SS, and am putting a T56 magnum behind it with LS7 clutch. I bought the bigger/outer bearing for the crank thinking it was more durable because it's bigger. Am I going to have to change it & go with the smaller/inner one? What throw out bearing do I need?

Thakns,
Scot

[LAMBSKIN71]

Being that you are using a "truck" motor too, I would assume you would have the same issue as I did, I just went to the local GM dealer and went to the parts dept and told them what i had, they gave me the smaller bering that sits further in the back of the crank, using the larger bering would have caused there to be about a one inch gap between the back of the block and the face of the bell housing. You may need to use a spacer and longer dowell pins like i did, and then ANOTHER spacer for the throw out berring. Then again the issues Ive had may be unique to me because Im using a newer 2007 6.2ltr Escalade bottom end and an older T56, the newer cranks may just be different than the earlier LS based motors.

[LAMBSKIN71]

Oh and Im using the stock T56 throw out berring and hydraulic slave.

[GeoffP]

I really looked my setup over really close this past weekend. I think I'm going to be fine with the smaller roller bearing without needing any spacers. The larger bearing is definitely not going to work without spacers. Everything appears that it will work. I hope to test fit the engine and transmission together in a couple weeks and will share my experience here if I don't forget.

[andrewb70]

There is no need for any spacer, anywhere. The L92 crank is no different than the older LS1 crank in terms of the way that the pilot bearings are positioned. Keep in mind that there isn't a manual transmission option that was ever offered in a SUV.

There are two styles of pilot bearing, the f-body style, which sits deep inside the crank and has a relatively small OD, and the LS7 (maybe Corvette in general) style pilot, which sits further back on the crank (where the torque converter used to be) and has a much larger OD.

If you are using a F-body T56 with a stock bellhousing, then all you need is the f-body style pilot bearing and a stock slave assembly, which will work with the LS7 style clutch.

Also keep in mind that using spacers between the transmission and the bellhousing is not recommended, unless it is machined perfectly and has alignment dowels incorporated in the design. Not having the dowels can potentially throw off the input shaft to crank alignment which will cause poor shifting, increased wear, and clutch release problems.

Andrew

[LAMBSKIN71]

Andrew, thanks for your help. Couple of questions though. I did use the F body pilot berring but, when I went to mate the transmission to the block the trans shaft bottomed out before the bellhousing even touched the engine block. What would cause this? Also the spacer I used was machined for this trans and bellhousing with the holes for the dowell pins and even came with longer dowell pins.
Second question, does the stock F body slave and berring engage the LS7 pressure plate and clutch in the same way as it does the stock F body pressure plate and clutch? I mean i know it engages the same way, I guess what my concern is the three fingers that are higher than the rest of the fingers of the pressure plate, is this something I should be concerned with?