Hard shift high to low range

[Hammerhead]

(05-07-2017 )Mrkentee Wrote:  Oil was changed less than a year ago. When I get service at Speedco, they put a little on that plate to show you when they check it. Always looks good. I will check it.

A visual look at a couple of drops on a plastic card will not tell you if you have small coolant intrusion.
The fiber material in synchros absorbs small amounts of coolant masking the intrusion, but the chemicals in the coolant destroy the fiber material.
The synchro material is somewhat sacrificial. It's purpose is to either speed up or slow down the gears in the back end of the transmission making smooth shifts. When they don't function as intended, the gears don't match speed quick enough which is why it hammers in hard. The air shifter is bringing the gears together whether the speed is matched, or in this case not which is why it's shifting hard. Once your stopped, or at very low speeds, the gears are no longer spinning, or doing so slowly enough, which is why it doesn't do it then.