I am considering switching to a an automatic transmission to replace the turbo 400 in my 1964 electra to something with an overdrive. What is the best way to make this happen?? Is there a transmission similar to the T400? Thanks,
You can get an adapter, and run something like a 700R4 or 200R4. Or get a Gear Vendors overdrive unit and essentially turn your ST400 into a 6spd with overdrive. Nothing else will directly bolt up to the Nailhead.
Ok, so if I do this I am going to use this kit http://www.transmissionadapters.com/Nailhead_install.htm What else do I need t know? Driveshaft? Kick down? Mounts? Linkage? Has anyone done this before? Thanks, Larry
Hi Larry, I have a 700R4 hooked to my 425. All 700R4 transmissions use a Chevy bolt pattern. The Brendtsen's adapter is beautiful and works perfectly. The only problem is that it spaces the engine about 2 1/2" forward - or you will have to move the transmission the same distance rearward. I would move the tranny rearward so that I could still use the stock engine mounts and not have to redesign exhaust, hoses, etc. You will probably have to modify (or at least move) the transmission crossmember and shorten the driveshaft. My only issue with the Brendtsen's adapter setup is the crankshaft extension. It is beautifully machined out of steel and weighs about 10 lbs. I hate unnecessary weight and had Rob Giroux make me a new extension out of aircraft-grade aluminum. It weighs about three lbs. If you want a bottom torque converter cover, you will need to get creative. Do bear in mind that the 700R4 shifting is cable-controlled and the THM400 uses vacuum. You will have to design and build linkage and brackets for the cable. Or you could just install a higher gear ratio in your differential...
At the bottom of this page is a thread for a adaptor kit for sale. I think Wes was giveing a good deal. I am useing one also and so far so good. It is VERY tight in my a-body. Not sure about the other bigger body cars. John is right you will have to shorten the drive shaft and move the cross member a little.
Thanks for the bump 66gsconv. The adapter I have for sale is much thinner than the bendstens adapter at 3/4" to 1" thick and has an aluminum crank spacer. 66gnconv has much more experience with actually using the adapter than I, so he can let you all in on any secrets. I was (am if the kit does not sell) going to use a built 200r4 as it's slightly shorter than the 700r4, has a better overdrive ratio, and it's light. I considered just going with a gear vendors overdrive unit but on the x-frame cars like the Electra, LeSabre, Riviera, Wildcat there is little to no room available to put that unit in without doing major surgery to the "X" portion of the frame.
