Re: Ultramatic Shifting Question

Posted by HH56 On 2012/7/22 14:01:36

Misread the question in my first response. My bad, but not the first or last time.

Believe originally it was recommended to use high range for all driving. Low was only for emergency pulls. Tim gives good advice but the fact the writer let off the gas before shifting to high goes a long way to prevent issues.

I believe some of the trans guys have said it was the shift under load where low was released almost immediately effectively going into neutral letting engine speed up while high was still trying to engage made the clutches slip severely. The clutch plates had to slow the engine back down again and transmit power at the same time. Burning the clutch plates was the primary cause of problems.

In late 53 because so many owners were doing the low to high manual shift, they introduced a revised shift timing kit to help the situation. The details are in Sept 53 Service Counselor Vol 27 #9 but essentially it slowed low band release and sped up high engagement. A few months later there was another revision to the timing pin included in the kit to refine the shift a bit more. The pin in the original kit was found to have a bit of an overlap issue under some conditions with two gears at once on occasion.

The gear start and later TU's just followed along automating, revising and refining that treatment with controls and piston units more suitable to that operation. There was a learning curve again with the new arrangement but by the end of production, most of the bugs had been worked out.