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Swap a TH350 for a 4L60E?

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  • #16

    Re: Swap a TH350 for a 4L60E?

    First thing. 4L60E and 700R4/4L60 are virtually the same, except one has an electronic controlled valvebody. Lots of parts interchange, like the upgrades, 4L65 planetarys, beast sunshells, servos, etc. You can do the non electronic transmissions and use a constant pressure valve body to make the TV cable non critical, I did that in my 70 GTO. It works great and is behind a very healthy 455. The VB is $300, how much is the control box to run the E? You can put a gear driven speedo in the 700/60 easily, if it has the VSS you change the output shaft and put in a gear. The E needs the VSS so you can't swap it out and need to have an electric speedo. more $$$.

    Second thing, the 700R4/4L60/E are close enough to the pick up Th350 that you don't need to shorten the driveshaft. The pick up trans has a tail shaft between the long and the short.

    How much power can they handle? It depends on lots of things, stall speed, vehicle weight, rear gears, etc. How long it can handle it depends on how you drive, how much heat the trans sees, and keeping up with the maintenance. A quality converter is highly recommended, a cheap one will put too much heat into the fluid, and you definitely want to keep the lock up.

    2004R works too and has a constant pressure VB available for it as well.

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    • #17

      Re: Swap a TH350 for a 4L60E?

      personally i would never swap out a working TH350 for a 700R4/4L60E,
      even with the added O/D. if you must have O/D, the 2004R is a far better
      trans--or keep the TH350 and do a gear vendor over/under as mentioned earlier.

      highest factory rating on 700R4 was 260ftlb, and although many MANY people
      run em behind 500+hp motors, believe me-- for every one "success" story like that,
      theres a thousand "catasrophical mechanical failure" stories concerning either the
      700R4 or the 4L60E.

      i have been A.S.E. certified in 5 areas since 1992, and one of them is automatic
      transmission overhaul. i have rebuilt more transmissions than i can count, all
      the common TH350/400, 2004R, C4/6, 904/727, and yes the 700R4/4L60E.

      just my opinion, take it as you will. in the end--your car, your decision, your money.

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      • #18

        Re: Swap a TH350 for a 4L60E?

        For those wondering, as this thread was started five years ago - the TH350 ended up giving up on the "working" part and ended up being replaced with a 4L60E. I didn't need to change the shift linkage, but did need a different transmission mount and ended up moving the crossmember. Didn't need any clearancing mods though.
        TheSilverBuick likes this.

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        • #19

          Re: Swap a TH350 for a 4L60E?

          My 71 6.0 LS with stock 4l80e trans mission is putting 285HP to the ground. Everything is stock. The tunner said the 4l80e takes about 60hp off the rear wheel HP rating. I didn't have to touch the tunnel on it and it's the low hump one. I also went to a 1 piece drive shaft on a stock LWB truck. Motor trans have been in the truck now almost 4 years. It's been on 2 power tours with this setup and not one problem.

          Click image for larger version

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          Nothing better than waking up everyday!
          LS 6.0 installed 2013 L/H, 2014 HRPT 20 anniversary L/H

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          • #20

            Re: Swap a TH350 for a 4L60E?

            Handsome truck!

            Dan
            Andy4639 likes this.

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            • #21

              Re: Swap a TH350 for a 4L60E?

              For those wondering, as this thread was started five years ago - the TH350 ended up giving up on the "working" part and ended up being replaced with a 4L60E. I didn't need to change the shift linkage, but did need a different transmission mount and ended up moving the crossmember. Didn't need any clearancing mods though.

              I'm very close to pulling the trigger on a Microsquirt purchase to control a 4L60e in my Firebird. The damn transmission pan of the 200-4r simply leaks and leaks more. Plus I plan on putting 4.56 gears back in it, possibly this weekend, and the 200-4r governor doesn't like changes like that. The 4L60e is just sitting in storage waiting to be installed.
              74NovaMan likes this.
              Escaped on a technicality.

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              • #22

                Re: Swap a TH350 for a 4L60E?

                Thanks. I think so to!
                Nothing better than waking up everyday!
                LS 6.0 installed 2013 L/H, 2014 HRPT 20 anniversary L/H

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                • #23

                  Re: Swap a TH350 for a 4L60E?

                  I'm glad you went with the 4l60e and it is working great! I agree the 2004r is a good tranny, but the parts arent around anymore. We have around 12 direct drums for a 2004r at the moment but someone will snatch them up all at once really soon.

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