Sgt. 56

Ok I have searched through countless threads and all the posts were helpful but I still didnt find the answer I needed. What is the difference between the LT1 and LS1 T56 trans? I have read that the LT1 works with my Gen IV 454 but nobody states why it is better than the LS1. I thank you all from the previous posts in the past because I was able to obtain information on the flywheel application. I guess the only other question I have is about the throwout bearings and pilot bearings and what part #'s work best for my application depending on what T56 people recommend. I already removed the T5 setup and plan on retaining my stock pedals but using the hydraulics from the T56.

So what transmission does everyone recommend along with throwout bearing and pilot bearing? Any help and tips is greatly appreciated.

85MikeTPI

iTrader: (2)

The crank flange of the LS motor is closer to the engine block than on the LT1/SBC/BBC motors, thus the input shaft of the transmission is longer on the LS-T56. The LS-T56 is also setup for a Hyd-TOB mounted to the front (mid-plate) of the T56, while the LT1-T56 has a clutch fork that actuates the TOB riding on a sleeve around the input shaft.

In terms of exchange, the LT1 and LS T56s only differ in the Bellhousing/Mid-plate/input-shaft and swapping these three components between them can clone that type of T56. (Make an LT1-T56 work with a LS engine, or make a LS-T56 work with a LT1/SBC/BBC)

There are adaptions you can do to the LS-T56 to make it work on a SBC/BBC:
- Buy a conversion bellhousing that spaces the transmission back further in the tunnel and mates the input shaft to the SBC/BBC pilot location. Everything back of the clutch gets pushed back, shifter, torque-arm, Xmem, driveshaft.
- Buy an adapter plate that mounts the LS-T56 to the 4-bolt T5/Muncie/T10/etc. style bellhousing. This retains the old bell/clutch/actuation but still moves everything behind the clutch back over 2in.

The LT1-T5 retains the stock location/length of the torque-arm and driveshaft and places the shifter in a resonable location relative to the T5, but since it has the shorter pull-style pressure-plate, any 2pc RMC SBC/BBC needs a (expensive) conversion flywheel to make it work.

Sgt. 56

Well I guess that's why people run the LT1 due to the ease of retaining parts and installation. Good to know! I've been pricing the flywheels and wow! They are pricey items for sure. So no problems with the input shaft and the BBC?

85MikeTPI

iTrader: (2)

The SBC and BBC mount transmissions in the same manner, so no issues with the input shaft. (if that's what you're asking?)

Sgt. 56

I knew the trans mounted fine but I thought I read in a few older posts of someone having trouble mounting the pressure plate to the flywheel due to it being a BBC. I couldn't see where a problem like that would happen if the parts were all correct.

built91Z28

My personal opinion (and this is what I'm doing) is to run the LS trans with the adapter plate. This way you can run the bellhousing you have now and since you would then use all 3rd gen hydraulics the 3rd gen pedals wont be a problem either. You could also upgrade to a SFI aproved bellhousing later on, or now, and you can step up to the bigger clutches if you need to. If you need to ditch the clutch fork for header clearance, Ram, McLeod, and a few other I think make hydraulic throwout bearings for the T5 which would work for you. This is also what I am doing. I will say that I can not personally say what these bearings act like as my car is not driving yet, but my bearing is on order and should be here tomorrow. Ram said as long as your using a stock style pressure plate then their bearing will work fine.

Sgt. 56

Just a question.... If you run the adapter plate and SFI bell housing doesn't that change the distance the trans sits back in the tunnel?

built91Z28

Yea it will move the trans back a little. Basically you woul have to shorten the driveshaft a little. I would say that you would have to work something out with the torque arm as well, but with a 454 under the hood I hope you werent going to use a trans mounted torque arm anyways. You may also have to get a little creative with the shifter as far as putting a bend in it.

The SFI bellhousing itself though wont change anything. Its the same thickness as your T5 bellhousing. Its just that the T5+adapter plate or the SFI+adapter plate is longer than a LT1 T56 setup. But most people also seem to prefer the push style clutch rather than the pull style like the LT1 T56 uses.

Sgt. 56

I was hoping to find a torque arm that would mount to the new cross member. Still researching on those. So far Spohn seems to be on everyone's top list.

Sgt. 56

So for those that have done this with the BBC which of these model trans are you running?

JSACRA

iTrader: (2)

ive also heard the lt tran is a little stronger than the ls tran maybe not by much

85MikeTPI

iTrader: (2)

This is incorrect, and in fact the opposite in some ways.. Consider deleting it so search engines won't perpetuate the falsehood.

Also, was it worth opening up a 6month old thread for this tidbit ?

JSACRA

iTrader: (2)

as a matter of fact it was very worth it 6 months or 6 year useful information, is useful information

92 BBC Z

I use an LS1 T-56 behind my BBC. The easiest way is to use Quicktime's bellhousing, it corrects all of the differences the LS1 tranny has over the LT1 like overall length, and shaft length, and bolt patterns. I also use the concentric slave,(internal hyd. throw-out bearing) for which the bellhousing is configured for. I found that the flywheel & pressure plate for a 1974 BBC Corvette(there is two kinds: stock and H.D. which has 30% more holding force) can be had in a 1-1/8 26 spline,which is what is needed. Plus its steel(not sfi though) and balanced for a 454. There are some pic in my album if interested. I also use Spohn's LS1 T-56 cross member. I can also tell you which driveshaft is the correct length. That info alone can save alot of time and money, if interested.

92 BBC Z

jmd

iTrader: (4)

Incorrect information is not useful.

92 BBC Z

92 BBC Z

92 BBC Z

92 BBC Z

Oh, I also used a Timkin needle bearing pilot bearing.

JSACRA

iTrader: (2)

i said ive heard the the lt1 stlye was stronger, never stated if it was a fact. so for a member to know better that was his/her time to chime in. the time about being 6 months later is irrelevant. if theres useful information a member ought to know about it.

iluvmy91camaro

Ok, so I'm a little bit fuzzy after 4 hours of time searching for the proper part for my BBC and LS1 T-56 swap and now its after 1 am. So with the quicktime bell. It doesn't push anything back at all? but it is 509 dollars. F*** ! But the spacer just moves the tranny back a little and can be used with what bellhousings? I have a T-56 bell and a muncie bell. And with the spacer you can just get the std. Ls1 clutch and pp etc. no weird conversions? Can someone post a Part Number for the spacer please? Preferably a summit part # since i live 5 mins away. Thanks for the help cause im totally lost at this point and am just staring at high numbers and blown budgets.


I found something (?) a guy called the gearbox makes some sort of spacer, will that get the job done? and what clutch setup and linkage etc. would i need? THANKS SO MUCH!

92 BBC Z

I'm not sure what you are asking , but if you have a ls1 t-56 and the Quicktime bell housing, then you dont need anything else. It comes with a scatter shield not a spacer.

85MikeTPI

iTrader: (2)

It DOES push the trans back, as listed just above in this thread. You'll need to deal with the shifter, xmem, driveshaft, torque-arm with the quicktime bell. Did I try to already help you in another thread and you said you knew what you were doing???

thegearbox.org is a company run by Judy and Kevin, very nice folks.. They sell the spacer that allows any 4-bolt (T5, muncie, saginaw, lakewood, etc.) bellhousing/clutch/linkage to adapt to the LS1 T56. http://www.thegearbox.org/catalog/it...17/4803441.htm But this spacer will still have the same setback as the quicktime bell..

There's no way around the longer input shaft mating to a SBC/BBC/LT1 without a setback. The LT1 T56 is a much easier fit, but you just have to deal with the expensive conversion flywheel in alot of cases, and the weaker pull-style clutch of the LT1.

You have to decide what clutch/FW/Bell you want, then start buying/adapting from there..

iluvmy91camaro

Yeah I think you did help me, twice actually. HA! but I got it. I was just unsure on if the quicktime bell pushed everything back or not. I'm going to go with the spacer anyways for cost. I must have misread the thread after reading threads for 3 hours.. Thanks so much for the help, finally once I scrape some money up I can move on with my project!! (goal is to make thirdgen fest next spring!)
I owe you big 85MikeTPI

Rock-Bert

Hi all, hope Iīm allowed to ask this here, but it seems to be the best thread I found to answer my question.

So I have a 93īLT1 Trans Am with the LT1 6-Speed Tranny and want to put in a LS6 out off of a Corvette thatīs lying in my garage.

So my quetion is, can I use the LS engine with the LT Tranny and what do I have to change?

Thanks a lot for your help,
Rob

85MikeTPI

iTrader: (2)

It's usually better to start your own thread, especially as you start drifting away from the original thread topic.

The '93 won't be able to get a LS1 front plate/input shaft swap because of the different (M28/M29) gear ratios. Which leaves you with esoteric aftermarket bellhousing/clutch/flywheel arrangements.. Since the '93 is a weaker T56 to begin with, your easiest path would be to sell it and just get a LS1 ('98-'02) Fbody T56...

Rock-Bert

Hello Mike, sorry didnīt want to hijack...
But thanks for your advise, thatīs bad news. :-(

Rob

nick251984

how much longer does the quicktime housing make the ls1 t56 ? does it still just bolt in using spohns crossmember or did you have to modify it? and how is shifter location? thanks