LT1 T56 swap confusion

Discussion in 'Transmission & Driveline Topics' started by HBomb, Oct 29, 2017.

  1. HBomb

    HBomb New Member

    Jan 21, 2017
    I have been all over google and done so much research I feel more confused now than when I started. I've got an early 4th gen LT1 T56 that is going in my 77'. It will go in at the same time as a 383 stroker with 1 piece rear main in the spring. My car is currently a Muncie 4 speed. The web is chock full of info on the swap but the specifics of it get hazy. Unfortunately an LT1 version was all that was to be had around here after looking for months and from what I gather an LS1 T56 would be a much easier swap. For $600 though I figured it was still a good buy. My question is what do I need to make this work? Sadly the search on the forum here doesn't work too well for this since "T56" is too small of a tag word and I'm sure this question has been answered. Can I keep it mechanical clutch with the LT1 T56 or is that not an option? If that isn't an option what is my option for swap kits? ATS, Weir and Mcleod are not coming up with anything anymore that I can find since those came up in most of my searches on forums. The transmission came with the bellhouse, the hydraulics, the clutch and the flywheel. I know I need to shorten the driveshaft, get a yoke, and probably just go with a whole new gauge cluster anyways.
  2. BonzoHansen

    BonzoHansen Administrator Lifetime Gold Member

    No. You need all the parts from/for that car. Bell, all the clutch parts and I think even the starter. Did you get all those parts too?

    I don't know those transmissions well enough, other than they are different from the rest. A number of guys here have done it. I am sure some will chime in

    I will give you a search hint that helps here and really anywhere. Open google. type this in: LT1 T56.
    The underlined part is what you are searching for, change to meet your needs.
  3. HBomb

    HBomb New Member

    Jan 21, 2017
    Ah good to know on the search part thanks!! I was getting frustrated.

    As for parts no starter but that's easy enough to buy. I got the bell, clutch, flywheel, and hydraulic line. But even then how do I make it work with my clutch pedal?
  4. HBomb

    HBomb New Member

    Jan 21, 2017
    Woe that was a lot. Thanks for the link! Only thing unanswered is where do I get a bracket to mount the hydraulic setup to my clutch pedal? Everyone mentions an ATS bracket and when I search it nothing comes up by that name or even brings up a conversion bracket. I don't mind sticking with the pull style clutch if I can get a bracket to make it all work.
  5. 71RS/SS396

    71RS/SS396 Veteran Member

    Aug 26, 2008
    Wake Forest NC
    Detroit Speed, Speed Tech, amongst a few. The bracket should be the same as any used for a LS swap.
  6. black_aerocoupe

    black_aerocoupe Veteran Member

    That's good you're going with a 1pc. rear main seal. Triple verify it has the third starter hole and you're good there.

    Mechanical is do-able, but hydraulic is the way to go.

    I can't suggest a kit, other than getting one of the firewall master cylinder plates. If you modify the crossmember to put the output at the same height as stock (measure twice, weld once!) that part is done.

    And if you're not going to ECM engine control, going to an electric speedo is a good move.
  7. HBomb

    HBomb New Member

    Jan 21, 2017
    Perfect. This totally clears things up. Finally found the plate I need through Detroit speed. I like the feel if a mechanical clutch myself but I'm sure I'll enjoy the hydraulic haha. Thanks so much for the help guys. There's just been way to much confusion between the LT and LS trannys and it seems like MOST info and writeups are geared towards the LS. Can I ask what the greatest downfall to the pull style clutch is though? Is it just the limited space?
  8. black_aerocoupe

    black_aerocoupe Veteran Member

    Most of the bitching about the Valeo pull clutch was when it was new in the 89 Vette, and then the 93 Camaro, there weren't replacements for $100 like there was for '92. And the "carburetor crowd" wasn't able to get Hays to put a way overrated pressure plate on one. Then, the much lower PP bolt rating means when they got over torqued, the PP didn't work properly, causing part-blaming. It is actually an effective, solid design, when installed properly. I mean, how often is an 11" clutch the wrong choice for a street car?
  9. Todd80Z28

    Todd80Z28 Moderator Staff Member Lifetime Gold Member

    Jun 11, 2002
    Northern VA
    One-piece rear means you use all the LT1 parts- bell housing, flywheel is a straight bolt-on for one piece rear main, clutch and PP match the flywheel, of course.
    Driveshaft output is TH-350 27-spline yoke... I think your '77 is 31-spline if it's a Super T-10. Driveshaft should be 45.5" center-to-center (yokes, that is).

    Regarding the clutch hydraulics... You could be lazy like I was and just bolt it to the firewall. I used a couple of big washers to load-spread, and put the clutch master cylinder through the firewall. I always meant to do the proper bracket (I have original drawings for it from CHP in the mid-90s), but I've just never got around to it. I guess it's not the best idea, but 22 years and 70,000+ miles later (most of that city... lots of clutch), it hasn't failed me.

    The bracket- ats clutch master cylinder bracket
    HBomb likes this.

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