Re: ultramatic direct drive kick-down, fine throttle adjustment?

Posted by HH56 On 2021/8/4 14:49:23
This sounds more like a Ross special question so if he doesn't see your post maybe a PM would get a good suggestion or two as to what to do next.

Have you checked the governor and throttle pressures? In reading this bit from the training manual on how the direct drive valve and kickdown works, it sounds as if one of the pressures might be out of spec. Maybe due to adjustment or maybe due to a worn bushing allowing a pressure to be lost so it cannot do what is needed.

I think at the least I would verify the thottle pressure because if that pressure is low several things can be seriously affected. The caveat is the test point is an internal port directly on the valve body and I don't know if a hose fitting can be attached without the extended depth test fixture and pan. Another question for Ross.

Aside from the DD application, among the other very important functions of throttle pressure is to act on a valve which determines how much clamping pressure is applied to the high range clutch discs. More speed and torque from the engine means more pressure is needed to clamp the discs together. Too little pressure and they will slide against one another and burn.

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jpg  DD valve.jpg (150.30 KB)
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