LT1 T56 I have NEVER been this confused!

Discussion in 'High Tech Retrofits' started by earlysecond, Mar 5, 2009.

  1. earlysecond

    earlysecond Veteran Member

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    Drop, I have a 4.10 posi rear. I agree that 1800 may be a little low. I have a truly weird motor though. It is basically a de-tuned stroker which is happier at lower revs, in fact, since it shifts to 2nd in 10 feet and is out of gears by 45mph it is sort of a pain. My machinist friend, the guy who built the motor seems to think that it will best cruise at a straight 2K if he had to guess.

    When I say weird, I mean that it is a 383 built with basically a stock 400 crank, 6" rods, pretty standard for a stroker. The heads are basically stock replacement "torker"series heads from ProTopline. They have 176 cc runners and the chambers are 72 or 76 cc's. The carb may be on the small side too a 670 street avenger holley. The cam grind is about as close to an old gen LT1 grind as you can get, it is pretty tame all around. This engine seems to run best off idle to about 3 grand. It IS set up all wrong for what it is doing! I accept that and it is my fault. I would like to see what it is capable of with a decent tune and still ahve some gears left at higher revs.

    I will look at some of the links you posted and find a good calculator to figure this all out. Hopefully, I can accomplish all of my goals and make this thing a pro touring style cruiser! If you see me going wrong, keep correcting me. I do not know enough about these issues and would rather learn from other peoples' experience rather than trail and error.
    Brent

    M
     
  2. 79ZED

    79ZED Veteran Member

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    Proper drivetrain angle for GM cars is normally 3 to 3 1/2 degress. Other than notching the underfloor brace a bit ( which is about 0.7" less with the LT1 compared to the LSx) and cutting for the shifter, you'll be fine. If your engine is internally balanced, any two piece seal SBC/BBC 153 tooth neutral balanced conversion flywheel for an LT1 will work. Lts to chose from....aluminum or steel.

    John
     
  3. earlysecond

    earlysecond Veteran Member

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    ZED,

    My engine is EXTERNALLY balanced so I either go with the proper, externally balanced SBC flywheel OR get a neutral balanced one and have it balanced OR bolt on the weight that goes between the crank and flyweeel. The only flywheel complication was that I was attempting to save about $150 by buying a used one that came off of of a BBC set up.

    Thanks for the driveline angle info. I was under the impression that if you went completley stock LT1 that your cut in the tranny mount did NOT interfere with the tranny hump reinforcemnt at all, at least I think that is what you were referring to?

    We shall see and it is probably not that far off until I find out all of this fun stuff for myslef!

    Thanks,
    Brent
     
  4. sbca96

    sbca96 Veteran Member

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    I was refering to the hassle, but yah the "kit" will be MORE then what you
    currently have into your T56 setup (barring any more surprises). Getting a
    used TKO will save a lot of cash, thats what I did, I sold my T56 for 1000,
    and then bought a used TKO for 600, and the adapter to use my existing
    bellhousing, clutch, etc in the Avanti.

    What I posted on page 2 :

    You can get a brand new TKO 500 for roughly $2000, craigslist a used one.

    TKO500 / 600 info :
    http://www.5speedtransmissions.com/tr-3550.html

    Save some coin and get a TKO/TKOII like I did (used $600) :

    http://www.5speedtransmissions.com/3550_tko.html

    Buy a whole kit for under $4000 :

    http://www.standardtransmission.com/tko_kits.html

    The TKO/3550 is rated at around 500 ft lb max, which should be fine for a
    383. I got one for the Stude which has a 330 ft lb factory rating. Driving
    a 350 hp LS1 powered GTO T56 shifted each day, I can say that you dont
    use 6th gear that often. A higher 5th would eliminate 6th. You ARE NOT
    going to break a TKO any easier than a T56. It took me a little bit of time
    to get my brain OVER the novelty of having a T56 Avanti. Thing is, why
    go through the hassle when there is an easier solution available?

    Tom
     
  5. earlysecond

    earlysecond Veteran Member

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    Tom,

    On your point, I agree that I could have saved some hassle. Maybe more that I know as I have not begun to put this together yet! But, if I did not make it known, my original goal was a working 6 speed tranny for as little money as possible.

    At one point, with all new parts, the swap was approaching 4K. Since then, I have sourced some used parts and gotten some better pricing. I am back down to 1750 without the driveshaft mod and balance.

    I have started cleaning up what I have and so this post may quit down a bit.

    I repeat my caution. If you have a T56 that is out of a '93-'97 Camaro. . .GET the WHOLE thing or nothing and be Prepared to use what has been called an inferior clutch set up. Now that McLeod started selling the LT1 modular bell, life will be more simple, but also more expensive. Convienence has a cost in life and in musclecar upgrades! There is still a bit of hot rodder and fabricator blood in me though! PLUS I am very impatient so that is largely what is demonstrated in this long and whiney post.

    Brent
     
  6. 1981z28owner

    1981z28owner Veteran Member

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    i would just like to add that getting a LT1 t56 is not the end of the world at all. just have to change input shaft and front plate to convert to LS1 style. It was extremely easy, just a few bolts, and they now even have an input that is longer than LS1 style so u do not have to use special input bearing if using old style mechanical clutch.
     
  7. 79ZED

    79ZED Veteran Member

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    earlysecond,

    Whether it's internal or externally balanced, there are flywheels in aluminum and steel that will work with your engine. If you can't find an externally balanced flywheel and have to use a balance weight ( not a big deal) you can probably get a more accurate balance if your machine shop has the balance info for your rotating assembly. If the engine hasn't been balanced, I'm sure the add on weight will be close enough ( they usually go for over rather than under balance).

    There is nothing " inferior " about a pull style clutch. There is no inherent advantage to a "push" style clutch other than making it easier to use a concentric slave cylinder. Push style clutches are more common, and cheaper because of that. Nothing more.

    John
     
  8. earlysecond

    earlysecond Veteran Member

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    ZOwner,

    I see where there are kits to change the input shaft, cover PLUS they include an adapter plate. Now comes the drawbacks, the kit with the shaft and LS style case with bell adapter is $600.

    The next concern. You say a couple of bolts and to big deal. Help me understand how that is possible. When one builds a T56 it is all dependant and BUILT on that face plate.

    HOLY CRAP Owner, you are right, I never looked closely at the exploded parts diagram until just now! What a major epiphany! The input shaft and face plate are not nearly as conencted as I once assumed. I thought that the input shaft was the end of the main shaft, I should have just thought it through. Additionally, in the parts diagram part 1D is labeled "adapter plate" it looks as if it would replace the front cover and bolt right to the front of the housing. This solves a couple of problems. 1. you either loose a lot of the spacing on the front cover that eats up the shaft 2. AND OR while you are in there, you can change to the longer LS shaft.
    Thanks for pointing that out and educating me, did you try to tell me that before? IF so I apologize!

    Now we are back to price, I have seen the longer input shafts, most on back order BTW, for $299. I have not researched individual "faceplates" so I have no idea. Follow my thinking here, if you buy an LT1 T56, change the necessary items, shaft and faceplate to the shown adapter plate, then you are good to go with either an aftermarket bell and clutch set up (with an LS1 face plate) or a traditional style mechanical clutch?

    Thanks again for pointing this out, I have sourced, if not purchased, all of the parts that I need for the pull clutch. It is good to hear that it is not inferior or weaker. This is the route that I decided to go.

    I think I will go further reasearch what has been pointed out to me.

    Brent
     
  9. earlysecond

    earlysecond Veteran Member

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    Has anybody on this board, personally or with help, ever rebuilt one of these transmissions? It is about all that I can do not to go out an rip it apart to see how it works. I understand though, that it may not be a good idea! LOL

    I am still fence sitting on whether or not to have this thing rebuilt BEFORE I put it in the car. The rebuild kit is not killer expensive. If the transmission could be rebuilt before a major problem, catastrophic failure could potentially be avoided.

    OK, I am not going to be the one to try this, of course. Just an hour ago I thought that the input shaft was the end of the main shaft DUH! All the parts on the diagrahm just facinate me! There is a bunch of stuff in there.

    While I was able to source and price an LS1 input shaft at $178, available from thegearbox.org, I still do not see any kind of mid plate or face plate. Are there adapter plates that completley REAPLACE the mid plate? It would be ideal to remove the mid plate (the plate through the input shaft exits) remove about 1.5" from the front cover. THEN be able to bolt an LT1 sourced T56 to an older mechanical clutch and bell WITHOUT an extended bushing and witout having to cut into the tranny hump reinforcment as the overall length would be shorter!

    I must still be missing something. Either the part exists or there is a reason why it cannot be done this way. The adapter plates for an LT1T56 bolt on TOP or to the front of the "midplate", extend the overall length of the assembly, eat up an inch of input shaft that is critical and make the mount look sort of stange (of little concern). Am I misunderstanding this too?
    Brent
     
  10. 1981z28owner

    1981z28owner Veteran Member

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    it is easy to do. i have never dealt with a T56 before in my life and just bought gaskets/seal, front bearing races (while i was there), and repair manual (had all specs). It took me about an hr or two to change it all out and was done. I bought the front plate on ebay and was lucky enough to find a guy who wanted to trade his LS1 input for LT1 input. I also was able to sell LT1 bellhousing and it was almost a wash for the swap.
     

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