m1009 Shifting Speeds

[warblazer4x4]

If you have m1009 with the Gm TH400 what is your average shifting speed for each gear under normal driving conditions, im trying to compare to see if perhaps there is something wrong.

 

[Westech]

1st to 2ed 15mph...... 2ed to 3rd......25 to 30mph

 

[Bobert]

Mine goes from 2nd to 3rd at 35-40.

 

[Westech]

thats a little high..... unless you got your foot in it. that can be adjusted by adjusting the TPS on the right side of the injection pump

 

[CARNAC]

Had the same issue with an old one at the unit. It was the vaccum modulator. I think the cost is about $15 at the autoparts store. Took about 20 minutes to change for a rookie. Seem to recall it takes some fine tuning to adjust it.

Check out the -20 (change 2 is the one I have) manual under trouble shooting procedure #51 on page 2-55. That will help you narrow it down.

The MAX again MAX speed changes should be 25, 35, and 55 while in 2 wheel drive.

Hope that helps

 

[warblazer4x4]

thank you

 

[acetomatoco]

I force my upshifts by lifting right foot just before automatic shift is about to happen... have set the IP control for easy shifts.. The modulators will vary, and the cucv are famous for delayed shifts because of the IP control...of VACUUM

 

[warblazer4x4]

is there anyway to adjust the transmission on these to shift earlier?

 

[IRWFO]

Check Jegs or Summit racing. B&M makes a few things to fine tune shift points.

 

[CUCVFAN]

is there anyway to adjust the transmission on these to shift earlier?

Rotate the top of the vaccum adjustment on the IP toward the rear of the truck. I would caution that it's not good to allow the tranny to always shift at low rpm. You not only tend to lug the engine, but the line pressure stays low so it's harder on the clutches...

The GM service manual has the recommended shift points for a TH400, but I don't have it in front of me right now.