Re: 1956 400 Ultramatic Transmission Questions

Posted by Andrew M on 2021/2/24 19:18:32

HH56 wrote:
With all the transmission changes in and out I would also wonder about the throttle linkage being adjusted properly or maybe not hooked up.

If the Direct drive clutch was slipping the car would still get over 20mph but you would hear the engine revs be a bit high and louder since it is still driving thru the converter. If the high range clutch was slipping then the torque might not be able to get to the rear wheels and the high range clutch is needed with either drive range. It is not used in low though and if it still won't get over 20 when low is selected then it might be a stuck reactor inside the converter. I believe Ross has mentioned the reactor issue being a common malady and also one that quickly causes the trans to overheat. What is the condition of the fluid -- bright red or dark and brownish and does it smell burned?

The clamping force of the high range clutch plates is very dependent on having the correct throttle pressure as determined by the linkage and adjustment. At low engine speed and torque not much clamping force is required but more engine power needs more throttle pressure which in turn controls and increases the modulated pressure being applied to the high range clutch to force the plates more tightly together so the higher torque can reach the wheels.

Here is a picture of the linkage on the carburetor. It is adjusted pretty much to the front. The measurement of where the gas pedal meets the linkage to the firewall is 3 1/2". I think I read somewhere that the linkage to the transmission was supposed to be closer to the middle, instead of at the front.

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