Re: Ultramatic gearbox problem slipping direct drive clutch

Posted by humanpotatohybrid On 2024/7/7 16:48:12

Hello George,

Glad to hear my diagnosis was spot-on. It isn't always! And good that you are up and running again before the big event.

I suspect that the direct drive circuit was shorting to the converter relief circuit because of the missing pin, while at the same time blocking the relief circuit vent port.

The consensus is generally that as long as the transmission is in good condition and adjusted properly, you should be able to shift from low to high and back. Especially on the low to high shift you should get off the throttle so that the engine does not flare up. The high to low shift you can let the engine flare up a little, so it will rev-match on Low engagement. You may wish to experiment and find what patterns result in smooth shifts with neither flaring nor the revs dropping too low.

Shifting while driving is not necessary except in limited circumstances like driving up or down large, long hills that can't be done in direct drive (up) or there is insufficient engine braking in high gear (down).

You may wish to review #16–20 on the troubleshooting section which details how and what can go wrong on manual shifting.