Re: Ultramatic Hard Shifting into Reverse

Posted by HH56 On 2017/5/14 17:46:17

How is the idle speed? Packard recommended 450 rpm in neutral or 375 in high range and while there is a little leeway, if the engine is idling appreciably faster than those numbers the transmission takes quite a jolt as it takes the load and slows the torque converter and engine down.

I don't think pump pressure will appreciably change the reverse action. The reverse piston gets full front pump pressure of 160-180 psi. Unlike the low band, there is no modulation of the reverse pressure.

There is very little cushioning action in the Ultra and piston application of the bands is abrupt in reverse. The lower pressure on the low piston may allow a bit of spin so the load isn't transmitted as abruptly. High range application is not quite as noticeable as either band because there is a layer of oil between the clutch plates. They can spin a small amount as they take the load of the torque converter before they lock together.

IIRC, Ross was able to devise a restriction on the exhaust side of the 55-6 TU reverse piston to slow down the application speed and cut the jolt a bit but I don't know if a similar mod is a possibility for the regular Ultras.