TH350 transmission
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Joined: Apr 2004
Posts: 78
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TH350 transmission
I have a TH350 that won't upshift to 3rd when it gets hot. What kind of problem does that sound like? It shifts fine when cool or even tonight I had no issues as the outside temp had dropped to low 80's and I just cruised at 65 mph. What would cause this issue?
Thanks for any advice.
John
Thanks for any advice.
John
Drifting
Joined: May 2006
Posts: 1,480
Likes: 2
From: Circleville Ohio
Vader Vette
Does it have A modulation valve? sounds like it .Sticks out the side or the tranny and makes the proper vaccume or something to make the tranny shift. Im Not a tranny man (but just change out those bumbers i could get down to some help)You can have my old 400 when I swap it for my 200r with OVerdrive.looking now I think my low gaer band is going bad ( it sat for 15 years and only 3000 driven miles in that period of time.46 k miles total.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
A malfunctioning vacuum modulator unit will change the shift points...but won't prevent an upshift. Upshifts are made when the range shift valve sees enough governor pressure to cause it to "fire". The most likely suspects are the governor unit; a clogged governor filter screen; a stuck shift valve; bad seal(s) on the high range clutch piston; or weak charging pump that can't make enough pressure to get the high range to engage. Take your car to a "reputable" tranny repair shop and ask them to troubleshoot it; they should be able to determine the cause.
