Re: Twin Ultramatic Lifespan.

Posted by Ross On 2022/10/12 7:34:00

Good question William. Engine runaway on the low-high shift--even a little bit-- is a no-no and a sign that the throttle pressure is set a bit too low, or that the low band is adjusted a tad too loose. If that "flare" can not be adjusted out the high range clutches or the bushings and seals that operate them are suspect.

A soft or groaning direct engagement is often a sign that the direct clutch has gotten hard and glazed or that the pressure supply is failing, usually due to worn bushings.

Peter, a small increase in residual pressure in the convertor will oppose the direct clutch. I suppose as long as you are not getting slipping your filter is OK.

On the trans I build I always modify the valve bodies for higher shift points so the trans in not in the middle of the brisk acceleration period when it makes its l-h shift (Usually in the middle of the intersection). I find the factory setting quite annoying in that regard. Then direct comes in at the period of lightest accel and I usually lift my foot slightly to bring it in when I wish.

As much as we may grumble about Ultramatics please keep in mind that the competition had their troubles too. Hydramatics were reliable and efficient but the shift characteristics of the early ones were so annoying I can't bring myself to buy a car afflicted with one.