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T56 behind a 461 Pontiac in a 71 Lemans

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  • T56 behind a 461 Pontiac in a 71 Lemans

    so circumstance would have it that a freshly rebuilt t56 has fallen out of the sky into my lap. It was rebuilt for a 454 and it has an LS input shaft. Everything fresh though and I have a build sheet to prove it.

    Anywho, what will I be needing to swap from a t350 to the tremec. I have a bell and adapter for the 454 because this is an srt10 truck trans.

    Shifter
    Hack the trans tunnel
    special speedo cable for electric to mechanical
    driveshaft

    pedals
    Rods
    linkage

    am I on the right track here?

  • #2

    Re: T56 behind a 461 Pontiac in a 71 Lemans

    I don't know about the swap details, guess you gotta work that one out by investigation or with other's help. There's a few common bolt positions between BBC and Pontiac...?

    Having things "fall out of the sky" sometimes...or maybe that's what we call it...is how things happen for someone ready to get things done. The "I can't do it/afford it" story is for the other guys you just left behind.

    Shifter, is stock OK? Hacking the trans tunnel, yep now you're getting into it. Happily, "A" bodies aren't as sensitive to mods there, with their full-frame scheme. Watch out for the floorpan crossmember, if you cut it you have to make up for it.. There's a guy on E-Bay who mods tailshaft housings for a mech. speedo. Clutch, you're going to have to buy pedals and convert to hydraulic, I bet our favorite B.S. sponsor (American Powertrain) could help or you might like to figure it out. Driveshaft, easy when there are shops to help. Leave it for the last thing so you get the dimension right.

    Yeah you're on the right track if this is what you want, Hat's off for having the nerve to get into it, you'll be rewarded, eventually.
    ...

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    • #3

      Re: T56 behind a 461 Pontiac in a 71 Lemans

      I got a deal on the transmission from a guy who had to part with his 70 chevelle. So it didnít fall on my lap and no I shouldnít have bought this trans because I have a lot of other stuff to do before I can install it but I figure the engine is nearing 3 years of build time with a finish in sight so why not take advantage of a deal on a transmission and start another project. I dunno what you meant by leaving others behind but rowing gears is something that I really would like to do with overdrive.

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      • #4

        Re: T56 behind a 461 Pontiac in a 71 Lemans

        By "leaving others behind" I mean all the guys who automatically say T56 to every transmission discussion, but who will never actually invest in one or deal with the advantages/disadvantages.


        And do note there are disadvantages; big, heavy, needing that hydraulic clutch, and the .5 second-overdrive will rarely get used.
        ...

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        • #5

          Re: T56 behind a 461 Pontiac in a 71 Lemans

          Well I figured Iíd give it a run for itís money. Buddy of mine has one in a 2000 (ballpark) Camaro and he beats the crap out of it. I know I only need 5 gears but maybe Iíll take it to a track and push the limit on speed one day after I finish the car. I picked it up to move it the other day and was surprised I could move it so easily. Not a feather but 150 pounds for a trans isnít too bad is it?

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          • #6

            Re: T56 behind a 461 Pontiac in a 71 Lemans

            I've never done the swap into an A-body but I think there is some pretty major tunnel mods to make it happen... that said, it's worth it IMO.

            As for the T56 - I liked it in my 2006 GTO, but it had weak synchros (a long story where the throwout was the problem that GM wouldn't fix but would replace synchros every 10k miles)... outside of that, you'll want a pretty low numeric gear in the rear to take full advantage of that trans (like 3.36ish).
            Doing it all wrong since 1966

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            • #7

              Re: T56 behind a 461 Pontiac in a 71 Lemans

              I do know Iíll have to cut the floor and Iím not happy about it. The end result I feel is worth it though. Less wear and tear on the motor and much better fuel mileage. I control my gears and I have a strong trans. Itís a better trans than the t350 for todayís type of driving

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              • #8

                Re: T56 behind a 461 Pontiac in a 71 Lemans

                for sure. If I never have another T350, it'd be too soon.

                Doing it all wrong since 1966

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                • #9

                  Re: T56 behind a 461 Pontiac in a 71 Lemans

                  I think you'll love it . It makes the car go from just a around town toy , to so.ething you can also road trip to car shows and other destinations that are out of state . I have a ZF6 in my vette and use 6th alot . I'm running a 3.23 year but I'm running short 275.50.17s so if your running more sidewall and therefore more overall height you'll want to drop that accordingly . Like I would like some 3.73s you might want to go 4.11 eventually. May want to switch the input shaft out for a g.m. one that way you can use american powertrain stuff for a chevelle . Pedals , hydraulic ram for the fork or a hydraulic throw out bearing , bellhousing . Keep us posted .
                  Previously HoosierL98GTA

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                  • #10

                    Re: T56 behind a 461 Pontiac in a 71 Lemans

                    Sorry itís been a few days. Iíll definitely take some pics and update the build forum for the car. I got that trans fresh rebuilt for 2200$. Seemed like a steal to me and it was going behind a 454 I think so it was built to be beat on. I just hope that itís worth it, not quite having buyers remorse but that was a lot in savings. Anyhow it wasnít so much that I had mapped out what trans I would use. I just saw the deal and took advantage of it. My next order of business is some body bushings. Iím sure you guys have seen that discussion..... more than likely advised the bushing decision too. When thatís done Iím going to put a 4bbl intake on the engine and start saving up for one of these fancy dancy efi kits. I donít know anyone who rebuilds E85 q jets so fuel injection has to happen. Iíll def keep you guys posted

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                    • #11

                      Re: T56 behind a 461 Pontiac in a 71 Lemans

                      We got a guy that used to do them . Goodness , seems he is a Pontiac lover too . SBG will probably chime back in with the name . He lives in Eastconsin ( upper peninsula of Michigan )
                      oletrux4evr likes this.
                      Previously HoosierL98GTA

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                      • #12

                        Re: T56 behind a 461 Pontiac in a 71 Lemans

                        If itís thumpinn455 (Todd I think)
                        you can blame him for pretty much all of the build. Him talked me into building a stroker and keeping it a Pontiac powerplant.... going E85 with it......walked me through doing disc swap........ 4bbl swap....... header swap....... pretty much everything Iíve done to the car he gave me insight on.

                        If your still out there.
                        thumpin455 thanks

                        when I started 3 years ago I thought Iíd be lucky to put a 4bbl and some headers on the car and now Iím close to a full hotchkis suspension with disc brakes. All new steering hardware, Jeep steering box, rebuilt an hei ignition yanked from a 76 Grand Prix.

                        Now Iím sitting here looking at a 400 stroker next to a t56 and Iím trying to talk myself out of buying a 67 10 bolt posi because I want to finish one of these small projects in the grand scheme.

                        Hard to pass on a $100 posi bop rear though.

                        Crazy how much time you can sink into cold steel

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                        • #13

                          Re: T56 behind a 461 Pontiac in a 71 Lemans

                          I'm not sure I'd pass on that rear if it's use-able to you. Hundred bucks ain't much, it can sit 'til you're ready.
                          ...

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                          • #14

                            Re: T56 behind a 461 Pontiac in a 71 Lemans

                            Do you know any good resources where I can learn a thing or 2 about bop rears? Somebody said that the 64-67 rear end might help my rubbing issue discussed in my other post and Iíll jump on it if it will fix my issue. Every time I search for bop rear end info chevy 10 bolt crap pops up. Bop 12 bolt is the only thing I can get info on. Wonder how many good bop 10 bolts met their end in a scrap yard

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                            • #15

                              Re: T56 behind a 461 Pontiac in a 71 Lemans

                              Do you know any good resources where I can learn a thing or 2 about bop rears? Somebody said that the 64-67 rear end might help my rubbing issue discussed in my other post and Iíll jump on it if it will fix my issue. Every time I search for bop rear end info chevy 10 bolt crap pops up. Bop 12 bolt is the only thing I can get info on. Wonder how many good bop 10 bolts met their end in a scrap yard
                              they met their end because they're not supported in the aftermarket (no axles, one limited slip available) - that said, they're a better rear end then a stock 8.2/8.5 chevy due to the semi-float design. With that said, what used to be extreme-custom is now just a phone call away.

                              https://www.hemmings.com/blog/article/b-o-p-rear-axles/
                              Last edited by SuperBuickGuy; March 24th, 2019, 06:37 AM.
                              Doing it all wrong since 1966

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