Re: GM 4L60E Transmission Adapted for 1955 Packard 400

Posted by Tim Cole On 2011/12/19 19:43:12

Hi Folks:

I read through all of this and figured I'd throw my two cents in.

I particularly agree with the reciprocating weight comment as regards Ultramatic. The torque converter is way too heavy and, I think, subject to internal fluid slippage.

I was unaware that ad hoc changes were being made on the production line, but that is really scary considering that the trans is only a two speed.

Years ago, the old timers I knew talked about Ultramatic in terms of "good ones" and "bad ones". I saw good ones go to the junkyard because the cars had 100,000 miles on them. Then I saw low mileage cars that never got used because they had "bad ones" and lived in the shop. I drove good ones and they were not bad. Once I even towed a Caddy 12 up and down hills with no problem.

If you are lucky enough to have a "good one" the Ultramatic will perform adequately without much trouble. For those who are having problems because they're stuck with a "bad one" the only other option besides rebuilding a whole nother Ultramatic (possibly another bad one) is to ditch the darn thing.

So don't let UltraDogma trouble your decisions.