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700R Transmission Swap Into GT Hawk, Completed & Running Great

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  • 700R Transmission Swap Into GT Hawk, Completed & Running Great

    I know there are plenty of reports on this conversion in various Studes, but thought I'd add mine to the pile.

    I got the transmission out of a 1992, 3/4 ton Chevy Van, wrecked with 84,000 miles on it, for $220. It looked and smelled good inside, so I simply freshened it up with new seals, gaskets, filter, rear bushing, and proper speedo gears. While the pan was off, installed a TCI lockup kit for the torque converter. I installed a rebuilt torque converter from AutoZone for $89; OEM style low-stall, per spec for the Chevy van. Reused the original TVC that came with the tranny, and it connected to the General Motors TBI linkage on the car, like it was made for it (it was). The TVC was easy to dial in, after reading the instructions about a dozen times.

    After install, the required drive-shaft length measured at 55.5", so I bought a new one off ebay, shipped to my door for $210. (The OEM drive-shaft, with FOM, was 51.75".)

    I slipped the motor as far forward as the original, slightly oblong mount holes allowed. Still, to clear the rear of the tranny oil pan, about 1" of the forward edge of the bat-wing was removed, across the entire breadth of the pan. This will also allow removal of the pan without dropping the bat-wing, if ever needed.
    An OEM style rear mount fit nicely along the forward edge, of the top of the bat-wing.

    The right side exhaust had to be rerouted, away from the pan. I ran it outboard, and up and over the bat-wing, similar to the left side.

    I did not have to bend or cut any part of the car floor for clearance. There were a couple of tight spots, i.e. at top of the bell housing on the passenger side, but still enough clearance. I did the swap with the motor in the car.

    I reused the original column shift, and shift rod. For linkage I bought a LoKar kit for $55, but only needed the ear on the transmission. It is very adjustable, and allowed for a smooth shift pattern, and spacing is near identical to stock.
    I used a shift quadrant from a mid-60s Chevy with PowerGlide. It simply needed to be trimmed to fit. It only shows Park-R-N-D-L, but I like it that way. It is very stock looking, except the 'R' is in a different location.

    The conversion kit called for a 6 cylinder car starter, and I was a little skeptical. But it whirls the motor over faster than the OEM starter, and it fires immediately, as it always has with the HFI.

    I left the 3.07 rear end in the car, at least for starters and am glad I did, as it seems like a real good match for the 700R. The transmission is smooth as silk. It up-shifts to 2nd under light throttle at around 20 MPH, to 3rd around 30, 4th around 50, and TC lockup shortly after. It kicks down as it should, and I like the smooth, stock-like gear shifts. A manifold vacuum operated switch disconnects the TC clutch when engine vacuum drops low enough, I'd guess around 8 pounds.

    Total cost has been a little over $1600, and I think it was well worth it. It is a fairly big job though. Actually more of a project than a job, since it entails quite a bit of re-engineering.
    Last edited by JoeHall; 03-13-2014, 10:37 AM.

  • #2
    Well done Joe, thanks for the report. Looking forward to a few more reports about the driving experience.
    Pat Dilling
    Olivehurst, CA
    Custom '53 Starlight aka STU COOL

    LS1 Engine Swap Journal:


    • #3
      Thanks for the update. Which adapter did you use the one from Howards or Myers? Trying to decide which one to purchase.




      • #4
        I used Howards for my T-200-4R assembly into my 54 wagon. Very nice kit.



        • #5
          I did not buy Howard's, and am unsure how many versions of this kit exist. I used one that is basically a well designed kit, with well thought out clearances and bolt attachment provisions. But it had a few issues: The pilot hole in the flange adapter for the TC snout was about .075" too large (1.780" v. 1.705"). When I complained, the seller said it would be OK that way. But I persisted, so he sent another flange, with a machined sleeve installed so it fit with .003'-.005" clearance.
          Looking on the internet, it appears every TC on every 700R from the 1980s to 1990s used the same size snout as I bought (OD:1.703"). So I think the seller either needs to provide a 1.705-1.708" ID flange, or part numbers for a series of TCs with larger snout. He did not say there was a larger snout, only that mine would be OK, as was. To me, a TC with up to .0375" of radial run-out was unacceptable. At any rate, the car is now smooth as silk, and vibration free.

          Another issue: The kit had no provisions for dowel alignment pins. Again, the seller said they were not needed. I disagreed, so installed my own, but it took extra materials and work. When I talked to Phil at "Fairborn" his kit includes pre-drilled holes, aligned with a spare motor, which at least serve as a pilot for reaming oversize if needed. His kit also includes a pair of oversize pins.

          Still another issue: The gizmo that slips over the motor flange, in order to center the adapter plate, was about .0005" too small. It would only go over the flange with light hammer taps, then it was to tight to extract. I removed the adapter plate and hack-sawed a slit down the middle of the gizmo, and it then slipped right off. I reused it again to recenter the plate, and that time it came off easily. Even slit, it still did its job of centering the plate. So I think next time I'd just slit the gizmo in the first place.

          This is a conversion that calls for above average mechanical savvy many of us do not have. The above issues could make a major difference in a person's experience with installing, and later driving a GM tranny in a Stude. Even if a kit cost another $100 in order to address the above, it would sure beat the heck out of having to remove the tranny again to make things right.

          Overall, after addressing the above, I am satisfied with the kit, and EXTREMELY happy with the 700R. I just wanted to mention the above issues, to make others' path a little easier, if deciding to install a 700R in a Stude.
          Last edited by JoeHall; 03-13-2014, 12:04 PM.


          • #6
            Pictures of an install and the "re-engineering" would be a great help..


            • #7
              Originally posted by SScopelli View Post
              Pictures of an install and the "re-engineering" would be a great help..
              I agree. With just a written description it is kinda like describing an elephant to a blind person. Unfortunately, I am one of the worst at taking pix. Once I get out in the garage and get my hands dirty, I just focus on the business at hand. I had been getting my son to come out and take pix on occasion, but regretfully did not do so with this project.

              OTOH, before I began the job, I looked at lots of pix in the archives here, and elsewhere on the internet with brand-X cars. Also read a lot. So what I am saying is there are lots of pix already out there, and a lot has been written as well. Its a good idea for most of us to do our homework first on a job like this.

              Sorry bout that,


              • #8
                What engine do you have?