TH350 downshift from 3 to 2 @ WOT

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Old May 28, 2015 | 02:05 PM
  #1  
davoaz's Avatar
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From: Frozen Tundra, Bismarck ND
TH350 downshift from 3 to 2 @ WOT

At what speed range should transmission downshift from 3 to 2 when pushing accelerator to WOT?72’ 350 with TH350.Transmission is not downshifting. Though it did last cruising season. I’m wondering if the cable connected to accelerator is out of adjustment.Should it be tight with no more room to travel when the accelerator is pressed down to the floor?
Old May 28, 2015 | 02:45 PM
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Disconnect it from the pedal and see if it moves back and forth. It may have broken or seized.
Old May 28, 2015 | 02:53 PM
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Originally Posted by davoaz
At what speed range should transmission downshift from 3 to 2 when pushing accelerator to WOT?
Before WOT, the downshift is controlled by a combination of the governor (which is a function of driveshaft speed) and the vacuum modulator (which is a function of how far you've got the pedal pushed). So there is no one speed at which it should downshift. It's a curve.

At WOT the downshift is commanded by the detent cable and should happen at any speed -- up to a certain limit (to prevent over-revving the engine).
Old May 28, 2015 | 03:45 PM
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Disconnect it from the pedal and see if it moves back and forth. It may have broken or seized.


I can move it back and forth w/o disconnecting it. There is about an inch of cable between the sleeve and the wire crimp. When pushing throttle down in WOT I can still pull the cable crimp ~ 1/4" out of the sleeve. The how to adjustment picture in the chassis manual doesn't explain how much play there should be.
Old May 28, 2015 | 03:50 PM
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There should be no play in the cable at wot. The inner cable can break inside the outer sleeve and you can't tell until you disconnect it and tug on it to see if it slides out. Pull gently and see if it stops. The adjustment sleeve on the end of the cable is self aligning at wot.
Old May 28, 2015 | 05:30 PM
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Not sure what you mean by inner cable. I only see one cable and it goes through the retainer, bracket and sleeve. I was able to turn the cable retainer where the sleeve slides into and take the slack out of the cable at WOT. Took it for a test spin and now it downshifts. However, the retainer is really loose and I can see how over time it lets the slack out. BTW, thanks for the help.
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