| Transmission vacuum modulator [message #209793] |
Tue, 04 June 2013 08:16  |
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SeanKidd
Messages: 747
Registered: June 2012
Location: Northern Neck Virginia
Karma: 4
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Senior Member |
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Will any TH425 vacuum modulator work with our GMCs or is it "special"
Sean and Stephanie
73 Ex-CanyonLands 26' #317 "Oliver"
Hubler 1-Ton, Quad-Bags, Rear Disc, Reaction Arms, P.Huber TBs, 3.70:1 LSD Honda 6500 inverter gen.
Colonial Travelers
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| Re: Transmission vacuum modulator [message #209803 is a reply to message #209793] |
Tue, 04 June 2013 08:40  |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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| SeanKidd wrote on Tue, 04 June 2013 08:16 |
Will any TH425 vacuum modulator work with our GMCs or is it "special"
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From old posts...
I purchased it at Advance Auto Parts, Part # MD48.
Ray
The post from Dec 09 Manny Travao
The only thing that I would add is that your modulator should look
different. Its bigger and black, and the vacuum connection is on the
side of the modulator. the original modulators have been obsolete for
a long time. The new modulator that we use for the motorhome is the
single red stripe with the adjustment screw.
Turning the screw in (clockwise) increases the pressure for shifting
at higher pressure.
Turning the screw counter-clockwise decreases the pressure for shifting sooner.
Turning the screw either in or out is not really linear. It takes
several turns. You're pushing/releasing a spring and it binds then
snaps. So as you crank the screw in, the spring twists, then springs
back..
I set the pressure at 16#s. It seems to work for most folks. nice
smooth shifting (3.07, 3.21, 3.42, 3.55)
18#s seems better for folks with 3.70 and 4.10 final drives.
When Nick lets me know they're replacing the final drive, I usually
set it to 18#s.
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: Transmission vacuum modulator [message #209822 is a reply to message #209793] |
Tue, 04 June 2013 10:40 |
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SeanKidd
Messages: 747
Registered: June 2012
Location: Northern Neck Virginia
Karma: 4
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Senior Member |
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Thank you for that information,
Sean and Stephanie
73 Ex-CanyonLands 26' #317 "Oliver"
Hubler 1-Ton, Quad-Bags, Rear Disc, Reaction Arms, P.Huber TBs, 3.70:1 LSD Honda 6500 inverter gen.
Colonial Travelers
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