Re: Twin Ultramatic Range?

Posted by Joe Hall On 2013/12/7 13:26:17

Tim,
As far as converting, I agree, and have been there- done that. In 2002, I bought another 56J with Ultra transmission, which came with a trunk full of misc Ultra parts. I got the motor started pretty easly, backed it up and pulled forward a few times, and decided no more Ultramatic for me. So I used a TH400 conversion available at the time from Jack Nordstrom in Texas. After restoration and 41,000 miles of driving pleasure, I sold the car, and the TH400 was still working beautifully. AFAIK, it still is. The kit even came with a shift quadrant to match the Th400 shift pattern.

If I were to do another Ultra conversion today, no question I'd follow in a couple of others' footsteps here and go with a 700R tranny. To drop the RPMs with the above TH400, I replaced the original 3.07 rear end with an AMC 2.53. But that would not be necessary with a 700R, due to its .7 overdrive.

When right, the Ultra is OK, but even my old friend John Brian said they generally need rebuild about every 50,000 miles. I also do not particularly care for the personality of the Ultra, in that it seems to have a mind of its own when it comes to upshift and downshift; the driver is simply along for the ride :)