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  • Chevy AT swap.

    If one were to do the Chevy automatic trans swap is there a way to retain the mounts at the bellhousing? I had thought about modifying mounts to install a late model Chevy AT into a Tri-5 Chevy to work with the adapter or fabricating something similar and then adding a rear crossmember to support the tailhousing. I was going to do the T-5 swap but my knee has started giving me trouble again plus my wife refuses to drive a stick and I want her to be able to drive the car. I have a tweaked 200-4R that would be perfect behind my 289 so I might as well use it.

    Also, I would like to add P/S to make it easier for her and I read somewhere that a '58 & later system could be added to my '55 C-body. Mine has the Ross box now. I wouldn't mind swapping the column as well so I could have a floor shift column as I plan to use a Gennie Shifter.

    Any advice, hints or leads on parts would be GREATLY appreciated!

    Who needs Detroit Muscle when you've got a "South Bend Bullet"?

  • #2
    Why can't you weld something to the adapter plate that would hook it to the original stude bell to frame mounts?

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    • #3
      That's one option I have considered, I was kind of hoping someone here had already "been there and done that" and could give me some insight.

      Who needs Detroit Muscle when you've got a "South Bend Bullet"?

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      • #4
        Hipp -

        I wouldn't weld anything to the adapter plate..! You end up warping it..!

        If the plate you have hangs out far enough..a coupla holes and a bolt on bracket would be much better. Or the same on the bellhousing. If there is places near the bottom you could drill and tap a hole or two..use that.
        Actually..if below the center-line of the bellhousing is clear, a well designed bracket and carefull welding there might work. But stay away from anything critical...so no warping takes place directly on any mating surface.

        Why don't you want to add a crossmember?

        Mike

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        • #5
          quote:Originally posted by Mike Van Veghten

          Hipp -

          I wouldn't weld anything to the adapter plate..! You end up warping it..!

          Why don't you want to add a crossmember?

          Mike
          I was thinking "bolt on" to add the mid-mounts not welding, there are kits to do this in a Tri-5 and my intent was to modify one of those or make my own based on them. Although with properly applied heat sinks and the right settings heat shouldn't be an issue. I'm adding a crossmember to support the rear so I will have support in 3 places. I recall other people's experiences putting a late model aluminum case AT in a Tri-5 Chevy using the stock front mounts and a rear crossmember with no support in the middle. Not good and I have personally snapped a bellhousing off a TH400 at about 85 MPH, not for the above reasons but the end outcome would be the same. Not something I care to repeat. [:0]

          Who needs Detroit Muscle when you've got a "South Bend Bullet"?

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          • #6
            Ran a 63 Hawk with an Oldsmobile 425 and a TH400 with front mounts and a tailshaft mount more than 80,000 miles without any problem. Mid 60's Cadillacs used front mounts with a TH400 without any problems. It is true that the front mounts vs mid block mounts that some of the GM cars used will increase the moment at the transmission / engine interface and will therefore increase the load on the lower screws of the trans bellhousing. However I wouldn't worry about it too much.

            David L
            David L

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            • #7
              quote:Originally posted by 64Avanti

              I wouldn't worry about it too much.
              Unfortunately I do, it's just the way I am.

              Who needs Detroit Muscle when you've got a "South Bend Bullet"?

              Comment


              • #8
                GM designed the TH400 to work with both front and mid mount engines with the tail shaft rear mount. I don't know of any TH400 applications where the transmission just hangs. You may want to do the math and determine the actual loads on the engine / transmission interface for the two cases.

                David L
                David L

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                • #9
                  quote:Originally posted by 64Avanti

                  GM designed the TH400 to work with both front and mid mount engines with the tail shaft rear mount. I don't know of any TH400 applications where the transmission just hangs. You may want to do the math and determine the actual loads on the engine / transmission interface for the two cases.

                  David L
                  I'm not using a TH400, I'm using a 200-4R.

                  Who needs Detroit Muscle when you've got a "South Bend Bullet"?

                  Comment


                  • #10
                    You did say that in the first post, I didn't pay enough attention. I would still look at the two cases of loads.



                    David L
                    David L

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                    • #11
                      quote:Originally posted by 64Avanti

                      You did say that in the first post, I didn't pay enough attention. I would still look at the two cases of loads.



                      David L
                      That's OK.

                      If the 200-4R were a 60's casting I might consider it but by the time it came into existence in the early 80's the bean counters had all of GM's castings down to the bare minimum. While it's not a heavy trans as automatics go it's not a very thick casting either. I've seen TH350 casess of the same vintage break right in front of the pump in late model cars with side mount engines. I just rather not take the chance.

                      Who needs Detroit Muscle when you've got a "South Bend Bullet"?

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                      • #12
                        Doesn't a 4wd 700r4 have a reinforced bellhousing?

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                        • #13
                          I used just the tailshaft mount during the first season out with our '53 (289/200R4). No failures, but I kept noticing an odd rumbling/resonence noise under certain conditions. Then someone pointed out the the large unsupported span between the front and rear mounts. I just added a straight piece of 1x2 tubing that supports the front part of the bellhousing. No noise and no problems in over 20,000 miles.


                          Steve Hudson
                          The Dalles, Oregon
                          1937 Dictator Flatback sedan (for sale)
                          1949 "GMOBaker" 1-T Dually (workhorse)
                          1953 Commander Convertible (show & go)
                          1953 Champion Starliner (custom/rod project)
                          1954 Champion Coupe (daily driver)
                          1960 Hawk (future project?)

                          Steve Hudson
                          The Dalles, Oregon
                          1949 \"GMOBaker\" 1-T Dually (workhorse)
                          1953 Commander Convertible (show & go)
                          1953 "Studacudallac" (project)

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                          • #14
                            Evidently I don't understand the problem. None of the late Chev motor/trans setups have any support at bellhousing. Front motor mounts are on front sides of block, and trans mount is at rear of trans. When I changed trans from a 400 to a 700 R4, I had to move trans mount forward.
                            Bob

                            Own '53 Commander Starliner. Red w/beige top. 350 Chev/700R4. Tilt,cruise,A/C.http://i76.photobucket.com/albums/j3...ontheBeach.jpg
                            Own \'53 Commander Starliner. Red w/beige top. 350 Chev/700R4. Tilt,cruise,A/C.http://i76.photobucket.com/albums/j30/Bobphyl/StudeontheBeach.jpg

                            Comment


                            • #15
                              The Stude motor is heavier and the motor mounts are about 4" further forward than the smallblock.


                              Steve Hudson
                              The Dalles, Oregon
                              1937 Dictator Flatback sedan (for sale)
                              1949 "GMOBaker" 1-T Dually (workhorse)
                              1953 Commander Convertible (show & go)
                              1953 Champion Starliner (custom/rod project)
                              1954 Champion Coupe (daily driver)
                              1960 Hawk (future project?)

                              Steve Hudson
                              The Dalles, Oregon
                              1949 \"GMOBaker\" 1-T Dually (workhorse)
                              1953 Commander Convertible (show & go)
                              1953 "Studacudallac" (project)

                              Comment

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