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Thread: Lt1 t56

  1. #1
    Senior Member..now yer posting! bikedad's Avatar
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    T56 for my RX7

    I blowed up the T5 yesterday.
    What's an LT1 T56 going for and does anyone have one for sale?

    Looks like I'll probably be needing a special fly wheel for my 2 piece rear main block as well.
    Last edited by bikedad; 05-07-2013 at 09:19 AM.

  2. #2
    Ol' School BAD LS1's Avatar
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    Lt1 t56

    Expect to pay around 1500 for one in working order. Try LTXtech.com
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  3. #3
    Senior Member..now yer posting! bikedad's Avatar
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    I'll check it out. Thanks.

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    Post whore Lawn Pac Champion Irish's Avatar
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    Lt1 t56

    Why can't you use the fly wheel you have?

  5. #5
    Senior Member..now yer posting! bikedad's Avatar
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    Quote Originally Posted by Irish View Post
    Why can't you use the fly wheel you have?
    I'm not absolutely positive yet. From what I've read so far it seems there's a special conversion flywheel for the Gen1 SBC 2 piece rear main seal to run an LT1 T56.
    I'm still looking at what it all will take to accomplish the conversion.
    I was told I need this fly wheel>>>Centerforce#183-700107

  6. #6
    Post whore Lawn Pac Champion Irish's Avatar
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    Lt1 t56

    Quote Originally Posted by bikedad View Post
    I'm not absolutely positive yet. From what I've read so far it seems there's a special conversion flywheel for the Gen1 SBC 2 piece rear main seal to run an LT1 T56.
    I'm still looking at what it all will take to accomplish the conversion.
    I was told I need this fly wheel>>>Centerforce#183-700107
    Before you spend a dime, find out why you need a "special" flywheel. I could see having to run a t-56 clutch and pressure plate.

    I don't understand what your rear main seal has to do with the trans bolting up.

  7. #7
    Ol' School BAD LS1's Avatar
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    i have just heard its factors that have to do with with the requirement of the LT1 unique clutch and pressure plate, and the balancing is the biggie, the SBC is externally balanced, the LT1 FW is meant for internal and has to be neutralized to work with the sbc configuration, also a small 11" clutch has to be used too. I guess mcleod makes the flywheel. This was all on a 400 crank though as a buddy of mine just swapped one into a 383 powered monte ss. More or less ditto on what Irish said about the research, you might be able to get away with a stock lt1 flywheel on a 355, the LT1 used the same rear main as the 86 + SBC's
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  8. #8
    Senior Member..now yer posting! bikedad's Avatar
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    I'm doing a lot of research before I pull the trigger on this. I was originally under the impression that an LT1 T56 would just bolt right up to my current block but now I'm not sure.
    It might all boil down to just sticking with a beefier T5.
    I do like the idea of having the extra gear though. At 70mph I'm at 3000rpm. I'm kind of stuck with the 4:10 gears in the diff unless I want to swap out the diff to an 8.8 Cobra/Explorer diff conversion that's available but not cheap.

    A couple of guys from my Norotors forum said this might be a viable option. http://www.thegearbox.org/catalog/it...17/4803441.htm
    Then I just run an LSx T56 and stick with my current clutch config. I'm currently running a Centerforce DF clutch assembly and it's been great.
    Plus LS T56's are more available.

    This is looking like it's going to turn into an interesting project but this car has been nothing but an interesting project from day one.

  9. #9
    Jack of all Asses Wagonbacker9's Avatar
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    the adapter plate looks like a very viable option IMO. And you could probably recoup some of its cost selling the bellhousing (or picking up a trans without one)
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  10. #10
    Senior Member..now yer posting! bikedad's Avatar
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    Admins, this thread could probably get moved out of Classifieds to Auto and Tech > Old School Muscle Forum.
    I'm going to keep adding to this as things progress for anyone else looking to do a swap like this.

    I think I sourced an LS1 T56 with 70K on it. I'm going to use the adapter plate and extended pilot bearing from here...http://www.thegearbox.org/catalog/it...17/4803441.htm
    I'll need to change my clutch disc to 28 spline. I'll see if my drive shaft needs re-sizing but so far it doesn't look like it will.

    I'm probably going to put my Pro-5.0 shifter for T5 up for sale very soon.

  11. #11
    A regular know-it-all Tetris Champion Snake Champion Lasagna From Heaven Champion Mac Man Champion Mahjong. Champion Mini Putt 3 Champion Plastic Saucer Champion Ratman Ralph Champion Prince Valiant's Avatar
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    Do you know what the ratio's of your current t5 are?

    It does look like regardless, you should generally come out ahead going with the t56.

    Though some t56 use a 6th gear ratio of 0.62:1 which isn't much better than the highest ratio t5's 0.63:1, it appears the t56's you're looking at generally use a 0.50:1 ratio.

    Some T5's O/D's though are as high as 0.81:1

    Another nice side benefit is that your 4.10's probably won't seem as steep in the lower gears either anymore...you should have a longer 1st with the t56's. The ones you're looking at feature 2.66:1 first gears, 1.78:1 2nds...

    while t5's range b/w 4.03:1-2.95:1 with a lot of 1st gear ratio's solidly in the 3.3 range and second gears in the 2.33-1.94:1 range.

    Your ubber light/very torquey car will appreciate the longer legs...and easier to control wheelspin
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  12. #12
    Senior Member..now yer posting! bikedad's Avatar
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    Quote Originally Posted by Prince Valiant View Post
    Do you know what the ratio's of your current t5 are?

    It does look like regardless, you should generally come out ahead going with the t56.

    Though some t56 use a 6th gear ratio of 0.62:1 which isn't much better than the highest ratio t5's 0.63:1, it appears the t56's you're looking at generally use a 0.50:1 ratio.

    Some T5's O/D's though are as high as 0.81:1

    Another nice side benefit is that your 4.10's probably won't seem as steep in the lower gears either anymore...you should have a longer 1st with the t56's. The ones you're looking at feature 2.66:1 first gears, 1.78:1 2nds...

    while t5's range b/w 4.03:1-2.95:1 with a lot of 1st gear ratio's solidly in the 3.3 range and second gears in the 2.33-1.94:1 range.

    Your ubber light/very torquey car will appreciate the longer legs...and easier to control wheelspin
    I never did determine what my gear ratios were with my current T5. A friend of mine has a T5 in his swapped RX7 but he definitley has a taller ratio T5 than mine.
    My first gear was useless. I actually would launch in 2nd gear at GLD.
    I just lived with it for a long time knowing I would eventually have to replace the trans. I never expected it to last as long as it has. 5 years and over 60 fairly hard runs at GLD plus the goofing around on the street. Mostly street tires but last year were drag radials.
    I'm looking forward to the extra gear. I'll be able to cruise it better and longer trips.
    Controlled wheelspin/drift will be nice.

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