1. dukeboy_318

    dukeboy_318 FABO Gold Member FABO Gold Member

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    LT1-LS1 T56 Transmission Conversion:


    So, I am getting ready to swap a T56 into my 440 dart. I, like so many others, looked for the cheapest route to do this. Let me preference this by saying that IF you are swapping a 6 speed manual into your older Mopar to go behind a Hemi or even an LA series, odds are, you will be money and time ahead going with a TR6060 transmission from a newer Challenger. By the time you buy a Brand X T56 and convert it, the cost savings will be very minimal, if any. Of course, if you are like me, running a big block or have the need/desire to run an SFI approved bellhousing, then yes, a Brand X or a Viper T56 are about the best options.

    First, let’s understand the T56 and where you may find them.

    The T56 has several variants over the years. Member, @Riddler, has a very good writeup on some of these differences, found here. T-56 Transmission Install Thread

    Early models can be had in a variety of cars, ranging from the Viper, to Ford Mustangs, Camaros, even in the SRT10 pickups. Going prices range from 500 to 5000. By far, the most popular and easiest to find, equating to the cheapest option for the transmission itself is the LT1 Version offered in the GM F-Body cars, (Firebirds, Camaros from 1993-1997). That said, there are a few drawbacks to this, which is why I write this up. I purchased an LT1 T56 for 600 bucks.

    There are actually TWO, versions of the LT1 T56. While you can search the TAG numbers, I’ve found that often times the paper tags are missing, or unreadable and who knows what someone may have done to it throughout the years. The best way and only surefire way to know for sure which version you have, is to pull the midplate and input shaft and simply count the number of teeth on the input shaft gear. DO NOT, DO NOT rely on the casting numbers on the case components. They used the same numbers on the cases for a variety of engine/year/model combos, and there is no way short of the paper tag of knowing if you have a 29 or 31 tooth input. Again, count the teeth.

    There are only 2 options for the number of gear teeth. 29 or 31. If you have a 29 tooth gear on your input shaft, walk away from it, sell it, scrap it etc. It can NOT be used in a swap and there is no converting it to a 31 tooth set without replacing literally, all the internals. It is also the weakest T56 as a ft lb rating of 350. The 29 tooth was a one year only transmission, 1993 and only in some lower performance model GM Cars. They are a bit rarer because of that but do come up from time to time. So before buying, verify the tooth count.

    The 31 tooth count is the one you want. This will allow you to do the conversion I am about to walk you through. Because of the short length of the LT1 input shaft, combined with the fact no one makes an LT1 to Mopar anything bellhousing, the swap to an LS1 style mid-plate and input shaft is required. Again, only can be done on a 31 tooth input gear set.


    upload_2019-5-15_8-2-20.png
    LS1 input on the left, LT1 input on the right.


    After much research, the best deal is to get the complete kit from RS Gear in New York. This kit will set you back roughly 490 bucks but includes EVERYTHING needed to do this swap, including bearings, shims, bolts, instructions etc. You can piece-meal this kit on your own via the world wide web, however, this kit came out cheaper in price.

    Kit from RS Gear is part number LT1/LS1.



    upload_2019-5-15_8-2-41.png
    LS1 Midplate above


    LT1 Midplate below, notice the provisions for a clutch lever/throw out bearing arm.
    upload_2019-5-15_8-3-0.png
    LT1 Midplate Above.



    Components of the RSG Kit. Notice the varying shims it includes as well as the bearings.
    upload_2019-5-15_8-3-56.png


    More to follow as I go through this.
     
    Last edited: May 15, 2019
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    • dusterizer

      dusterizer Member

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      Was researching this also, on the T56 wiki ( Borg-Warner T-56 transmission - Wikipedia) it looks like vettes and f-bodies were 27 spline, and newer heavier T56s were the 31 spline, also "read" just online somewhere though, that the torque ratings of the transmissions were subject to certain components and could be rebuilt with with stronger parts, making the 27 splines more reliable up to the 450lb ft range?
       
    • dukeboy_318

      dukeboy_318 FABO Gold Member FABO Gold Member

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      Vipers were 30 spline.

      but yes, to answer your question, you can significantly upgrade it. The most common upgrade is the shift fork and pads. followed by upgrading to the Viper Mainshaft and input. But the biggest weakness in the F body T56 was the shift fork on the 3/4 gear. It was thin aluminum, had plastic shift pads and would wear out or break under hard shifting. Common upgrade is to replace that fork with a Titaninum one with bronze pads, roughly 150-200 bucks for the upgrade. Which mine will be doing. Later model T56s and Viper T56s had steel shifter forks which helped and that upgrade is only 60 bucks.
       
    • dusterizer

      dusterizer Member

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      I had misread the info, I was thinking spline count not gear teeth like you said, any way known to hunt out which vehicles had 31 tooth setup, maybe 94-97 vetts, trans ams, and SS camaros?
       
    • dukeboy_318

      dukeboy_318 FABO Gold Member FABO Gold Member

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      All GM T56s had the 31 tooth except for one year, 1993, EARLY 1993. They are rarer.

      Best bet if you’re sourcing one from GM car is a 98+ with the LS engine. Otherwise, no one makes a bell to fit the LT1 versions of the 94-97
       
    • dukeboy_318

      dukeboy_318 FABO Gold Member FABO Gold Member

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      And forget about vette versions. It’s simply not possible. The vette version has a unique midplate as well as an included transaxle. It’s too short for a Mopar to as is and converting costs more than buying one that will bolt in
       
    • Cazbah362

      Cazbah362 Well-Known Member

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      Dukeboy- Any updates? did you install into an A body?
       
    • dukeboy_318

      dukeboy_318 FABO Gold Member FABO Gold Member

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      Crap, yes. I need to get some pics uploaded. I’ll update this later today
       
    • dukeboy_318

      dukeboy_318 FABO Gold Member FABO Gold Member

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      Forgive me, I forgot to update this thread entirely.

      So the very first step you are going to do BEFORE, i REPEAT BEFORE anything else, is make sure the trans is perfectly VERTICAL, not partially, not horizontal.

      Do this BEFORE verifying the 31 tooth gear by removing the midplate. If you remove the midplate with the trans other than vertical, with the output shaft down, you will end up fighting this thing and cussing, ALOT!

      For mine, I took the tall, homemade engine stand I have, and simply strapped it to it. There are companies that sell a special adapter plate that allows you to turn your engine stand into a transmission stand that will hold the trans vertical, but for me, it wasn't worth the 200 bucks. So I strapped it down and then for added safety, added some plastic shipping wrap and some 2x4s to keep everything nice and solidly secured.

      43C8997A-3B61-42A5-A250-C8B1F7000574.jpeg

      Next step is to press on the input shaft bearing. This comes not installed and you have to do it. I found that a piece of 10-12 inch long, 1.75 inch exhaust tubing works perfectly. its fits over the shaft and matches up on the bearing. If you have a better kit, by all means use it, but I'm cheap and it worked. I used a Harbor Freight press and had it on in seconds.

      BF191206-CB17-44DF-A9B8-F8ADB2BAD77A.jpeg

      Next step is to remove the midplate and the old LT1 shaft. The retaining bolts are 9/16s. You will have to wiggle the shafts a bit to get the input shafts out and then back in. Do not pry on the main or counter shafts, it doesn't take much and it'll go on. Then on the mid plate, make sure the bearing races are installed, I used the shims from the old LT1 midplate for the time being. Later, during the rebuild I will properly set the run out and shaft play, at which time I will update this to show how to do it.

      To re-install the midplate, simply bolt it back together.

      Couple other quick notes, keep the plugs from the LT1 midplate as the kit does not come with those and you will need to re-use them.

      There is no gasket between the midplate and the case. Tremec FSM recommends a high temperature, black silicone, i used the "Right Stuff" from permatex that is formulated for gear oils as it met the same specs as the Tremec Brand called for.

      D3285C4E-4E78-4FB3-9E20-E6EA36F79953.jpeg

      F2464F6B-9FD2-4759-92C7-6426C0544E8B.jpeg

      Now, remember how I said to make sure the trans was perfectly vertical before removing the midplate? This is why. If you don't have the trans at vertical when you remove the midplate, the shifter rails will drop down and out of alignment. In order to get them re-installed, you'll need to remove the two bolts that align the rails. They are a true PITA to remove. They come factory with a heat activated thread sealant and have to be re-heated to be removed. If you find yourself needing to remove them, a plumber's torch, a good quality impact gun and a superior quality Torx bit in the T40 size is needed. I broke two Harbor Freight Torx Bits, a 20 year old craftsman bit and a couple Husky brand T40 bits trying to get them out. Finally, I paid the 40 bucks for the Snap-on diamond coated, high torque T40 bit, a single bit. That removed the bolts without a problem. The others wanted to bend, twist, snap and did not fit near as tight as the Snap-on, save the headache, buy the Snap on bit if you find yourself in this situation.

      3058AAC4-B65A-4A4D-8576-FFAD601D39FA.jpeg

      Lastly, one thing I found that was cool about the T56 shift, it has the same bolt pattern as the Mopar 833 shift handles. I was able to bolt up my Hurst Mini- Indy shifter right to it. I've got to get some longer M10 threaded bolts but it'll work just fine.

      94E9C909-D622-4518-BF2C-A2698842D8C1.jpeg

      8C621B20-E039-4D03-BB96-74B8DC0BC876.jpeg
       
      Last edited: Dec 20, 2019
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      • Dartsun

        Dartsun Mopar Dude

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        Do you have to run a SFI flywheel? I have a T56 magnum for my 408 and have a MP flywheel from a previous project.
         
      • dukeboy_318

        dukeboy_318 FABO Gold Member FABO Gold Member

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        Not unless you're running a class that calls for it. That said, I am planning on it because the cost is nearly the same. Just has to be a 130 tooth flywheel and you'll have to use a mopar 2 bolt starter. As for the clutch, a 10.5 in clutch disc is going to be needed. You'll need a kit from the corresponding T56 model you have, so like a Chevy if its a GM T56.
         
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        • Tony brunelle

          Tony brunelle Member

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          I found this adapter for 425.00 not sure if it will work there are several others out there for the same price
          Screenshot_20200107-233227_Google.jpg
           
        • dukeboy_318

          dukeboy_318 FABO Gold Member FABO Gold Member

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          Itwon’t work. That bellhousing is designed to adapt to a T56 Magnum to a Mopar small block. The T56 magnum has a different mid plate than the LT1 version T56s that we are discussing here. That would work on 98 and newer T56 Magnums and the Viper T56. But not for this model T56.
           
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