TH350 Help
Thread Starter
Instructor
Joined: Aug 2010
Posts: 233
Likes: 18
From: Monrovia Md
TH350 Help
I took my 1981 automatic (mostly stock) ride out this weekend and it would not shift out of first gear -- If I got it with practically no-load up to 5k RPM it would shift to second HARD, then seem to go from second to third normally, and downshift normally.
I am not a transmission guy at all. Reading the service manual leads me to believe the pressure modulator or the governor may cause this -- any thoughts/help would be appreciated!
I am not a transmission guy at all. Reading the service manual leads me to believe the pressure modulator or the governor may cause this -- any thoughts/help would be appreciated!
Racer
Joined: May 2007
Posts: 370
Likes: 0
From: Cherry Hill N.J.
check vacuum to transmission modulator .
it is a rubber hose from carb port to a metal line running from passenger side of engine along side and under distributor down rear of engine ending with a rubber vacuum hose to modulator.
I hope this is not confusing and is helpful
Good Luck
it is a rubber hose from carb port to a metal line running from passenger side of engine along side and under distributor down rear of engine ending with a rubber vacuum hose to modulator.
I hope this is not confusing and is helpful
Good Luck
Racer
Joined: Jan 2008
Posts: 288
Likes: 0
From: Schaumburg Illinois
The first guy is right I think. Check the vac line to the modulator. If it is plugged or falls off the trans end this will happen. Modulator is located on the passenger side of the trans. You can get to it without jacking up the car. Peek under there and see if the rubber line is connected to the nipple on the back of the modulator. If not, slip it back on, its not secured by a clamp on anything and sometimes they fall off.
Drifting
Joined: Jun 2010
Posts: 1,781
Likes: 15
From: Oxford Ohio
Sounds like you have low pressure and your clutch packs are slipping. First check the fluid level and the modulator hose though. Check the color of your fluid. If it's dark, darker than normal to almost black there has been to much heat. Usually slipping clutches. Could be material gone and you have steels on steels or a lip seal let go and bleeding off the pressure.
Either way TH350s are an easy build and the good kits aren't that expensive. You can make a few changes and get it shifting harder. Replace the wave rings with clutch steels. A couple other mods will help with the oil pressure.
Either way TH350s are an easy build and the good kits aren't that expensive. You can make a few changes and get it shifting harder. Replace the wave rings with clutch steels. A couple other mods will help with the oil pressure.
Thread Starter
Instructor
Joined: Aug 2010
Posts: 233
Likes: 18
From: Monrovia Md
Well you where all CORRECT -- Thank you -- the vacuum line was disconnected from the modulator. A couple of weeks earlier I had put a distributer shielding on the car for the first time in 25 years, I must have jostled it loose.
Replaced the modulator with a new one -- car runs great -- I love when a scary problem is fixed with a $10 part!
THANKS AGAIN
Replaced the modulator with a new one -- car runs great -- I love when a scary problem is fixed with a $10 part!
THANKS AGAIN
Racer
Joined: Jan 2011
Posts: 266
Likes: 0
From: York Pa.
That's great..an easy fix there..just wanted to ask if you got it in ok..some of these are adjustable with an allen wrench in the vacuum port..if it shifts funny then chances are it is adjustable..turn it in for higher shifts and out for lower..it probably wont say its adjustable on the box..just got to stick the allen wrenck in there and see if it grabs!
