PLEASE, do not beat me up if this has been answered before...I only have dial-up and trying to search is terrible!!!!!

Will the LS1 T56 flywheel bolt up to a 1992 305? Is there dimensional difference between the LS1 and TPI crank where the flywheel bolts? They are both one-piece RMS motors, but I just do not know much about SBC's. Is there anything I need to be aware of??? Please, don't just say it will not work...tell me what is different and what has to be modified. How far off will the shifter be from the factory 3rd gen location?


It will be awhile before I can build/install my Poncho motor and I miss shifting gears...so this will help some!

Thanks for your help!!!

 

Ls1 t56s mate differently that lt1 t56s and will not work with a gen 1 sbc. Perhaps somebody else can explain in more detail

 

Thanks, Wes...but I am fairly sure the Ls1 bellhousing bolts to gen 1...so not sure what you are referring to when you say "they mate differently". I know there are issues with the LT1 flywheels and the pull set-up is a real hassle...used it behind my 4th gen Pontiac motor swap...but the LS1 looks like an easy conversion. Was hoping someone has done this before. I read somewhere that the crank may need to drill deeper for T56 snout.

 

Well I could've been wrong, but I've been helping a buddy with a 350/t56 swap into a s10 and we were both under the impression that you couldn't get one from a LS1 to work right. Idr why tho so If I'm wrong I'm sorry for spreading misinfo lol

 

LS1 T56 input shaft is too long. You need an LT1 T56 to work with your 305.

The transmissions are indeed the same except for the input shaft and mid-plate. An LS T56 can be converted to work with an old-school small block, but quite frankly thats cost prohibitive and you're better off finding an LT1 version.

 

Agreed. However, LT1 T56 cores are selling for under $1k these days. Just saw a 50k mile unit sell for under $800 on LS1.tech. You are better off selling the T5 (has a surprising amount of value, $400 to $900) and buying an LT1 T56.

 

I have every intention of mating an LS1 T56 to my 383. I have a Lakewood bell housing (scatter shield) and a McLeod adapter plate for the transmission. They were acquired from a friend who had done the same behind a built 355. He tells me I'll need a special pilot bearing to receive the input shaft, and because of the adapter plate, will need the drive line shortened.

Adapter plate available at Summit

http://www.summitracing.com/parts/MCL-8-207/All/

 

Im looking to get rid of my LT1 T56 for an LS1 T56 right now. Maybe we can work out a deal.
The difference is the input shaft is longer in the LS1 T56 and the clutch set up is different.

 

Thanks Boreen, but I do not care to use another LT/T56. I have one in my 4th gen and I much prefer the LS clutch set-up.

Looks like no one has completed a LS/T56 swap, so when I can get a few days free, I will pull the 700r4 and see for myself. There can't be that much difference...

 

https://www.thirdgen.org/forums/tran...ld-2piece.html

 

Thanks Al...I read that link again but honestly, if I am reading correctly, that has to do with two-piece RMS motors and not one-piece RMS like the 86-92 305/350 motors. The two-piece cranks do not stick out as far as a one-piece, so there would have to be something to correct for this. But I am interested in one-piece RMS motors and a cheap way to stick a 6 speed behind it until I can build my Pontiac motor.

 

Apparently, I'll be running into that same issue when I get ready to do the swap, mine is a one piece rear main seal also. I have the scatter shield and adapter plate from the thread I linked above, just waiting for the funds to get the tranny. I'll have to give my friend a shout and see what bushing to use if the 8617 from McLeod is too long or won't fit the crank. I'm putting the bell housing on this weekend, so I'll take the opportunity to take some meaurements for bushing.

 

1986-2003 one-piece RMS SBC have the same crank face depth from the rear of the block. LS engines are .4" deeper. I have no idea on Pontiacs but I bet you do.

The pilot (both deep / small and shallow / large) is the same on all Chevy cranks dimensionally.

That link above is 100% relevant to your question. Only the flywheel needs changed due to balance and bolt-pattern only.

 

Other options:

http://www.weirhotrodproducts.com/ which effectively spaces the LS trans. away from the Gen I / II SBC or Rat so the input works with the crank.

An adapter (with countersunken bolts so it bolts to the bellhousing and the trans. bolts to it) is made by McLeod. I had one back in 2005. Pic below.

Quicktime RM-6023.


Of course those methods has the potential to:
- move the shifter back.
- need careful attention to the LS throwout bearing distance from the pressure plate and shimmed accordingly.
- need an extended pilot bearing or bushing to match where the end of the input is.
- Driveshaft shortening.