400 trans shift points?

[JG62]

yesterday I took my rebuilt trans up some steep hills for the first time.I was annoyed at how the trans upshifted at low rpm.I'm familiar with the adjuster on the side of the inj pump.I would like the trans to downshift when it gets to a more steep part on the road but it has to be wot for that.Can I adjust the downshift point? Also,can I adjust the upshift points to a higher rpm without risking damage to this tranny?thanks

[britannic]

Providing you're pulling enough vacuum with the vacuum pump, you can either use the seat of the pants method to adjust the Thottle Position Vacuum Valve on the IP, or the correct way:

The seat of the pants method, is simply to adjust the TPVV on the IP by rotating it toward the cab (for earlier shifts) or towards the radiator (for later shifts) a bit at a time, until your shifts are where you like them.

The proper way, which of course should be used :D to prevent damage etc.:

1. Install transmission vacuum valve on fuel injector pump with 2 screws. DO NOT fully
tighten screws. Transmission vacuum valve must be free to rotate on fuel injector pump.

2. Attach vacuum source to lower vacuum nipple. Attach vacuum gauge to upper vacuum nipple. Bring vacuum down to 20 in. Hg.

3. Insert valve gage block (fabricate from .646" bar stock) between gauge boss and wide-open stop
screw on throttle lever. Rotate and hold throttle lever against valve gauge block.

4. Loosen the 2 transmission vacuum valve screws, if not already loose. Slowly rotate transmission
vacuum valve clockwise (toward front of truck) until vacuum gauge reads 8 in. Hg. Hold transmission vacuum valve in this position, and
tighten 2 screws.

5. Check adjustment by releasing throttle lever then rotating throttle lever against valve gage block. If vacuum gauge does not read 8 in. Hg,
loosen 2 transmission vacuum valve screws and repeat steps 2-5.

[JG62]

Thank you Britannic.I will try and do this correctly today.

[JG62]

I have adjusted the shift points as per Britannics instructions and now the transmission stays in the gear longer and the shift is more positive.Tell me if I'm wrong but basically that .646 gauge bar just holds the injector pump fully closed? I think it is a big improvement over how it was.It still only downshifts under full throttle which is the way it is designed I guess.I wish it would downshift at a little less than full throttle.If I'm going up a hill and it becomes real steep I would like it to downshift without moving the steering column shifter.Anyway it is a great improvement.Next job is to install transmission cooler and new lines.Thanks!

[Peter J. Bierman]

In order to get earlier down shifts you have to adjust the kickdown switch at accelerator pedal.
There is not much adjustment but the sooner it engages the sooner the downshift.
With a drillbit or a file you modify the position of the switch.

Good luck, Peter

[britannic]

You can tweak the shift points using the seat of the pants method. Also, check that your WOT throttle switch is working, it's up near the top of the accelerator pedal and controls the downshifting at certain engine and road speed ranges, when you stamp on it.

[JG62]

I love the way the transmission upshifts now.It feels like the truck is more powerful.Thurs, I'll look into that wot switch I look forward to straightening that out.thanks guys