Installed new vacuum modulation unit in TH400

chromebumpers

chromebumpers

solid fixture here in the forum
Staff member
When I removed the old modulator it seemed to be full of Trans fluid, is that normal?

The new modulator is the adjustable type. I took the car out for a run and leaned hard on the pedal. Under full throttle the wheels broke lose and again going into 3rd. I think the Trans shifts too high. Any suggestions how to find a good street able adjustment without multiple trips back to the lift? It's too low to crawl under and a pita with physical limitations.
 
Turn the screw that is an adjustable air bleed a 1/4 turn in or out at each attempt to adjust.
Fine tune 1/8 turn increaments.
 
Thank you Brian, I'll do that.
Funny that the car is performing like that without the kick-down switch not connected. In theory this couldn't happen because without the kick-down a down shift actuated by WOT is impossible - or am I wrong? Weird!
 
I only changed out this modulator because I was already doing a trans service and since these things are cheap I went for it and as it turns out I'll be able to avoid bending the new exhaust to make it around the modulator.

But I'm wondering if the old modulator wasn't working properly as I don't know if it should be full of Trans fluid.
 
Fluid running out of The Vacuum Modulator Trans side OK.
Out the Vacuum port not Ok Richard .
 
Original GM NOS Vaccuum Modulators were application specific.
All discontinued.
Only Find them on Ebay sometimes.
 
You must log in or register to reply here.
Back
Top