Hey guys I have a turbo 350 trans in my 56 and I was doing a car cruise down main last weekend and all of a sudden it decided to stop shifting. I could get it into drive but it will not shift into second gear unless the RPMs get high enough then it will shift but thats not healthy. I am wondering if any of you have encountered this before and could shed some light on things. It also jumps really hard when I put it into gear. Thanks for any help.
Turbo 350 not shifting
56rod
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Hey guys I have a turbo 350 trans in my 56 and I was doing a car cruise down main last weekend and all of a sudden it decided to stop shifting. I could get it into drive but it will not shift into second gear unless the RPMs get high enough then it will shift but thats not healthy. I am wondering if any of you have encountered this before and could shed some light on things. It also jumps really hard when I put it into gear. Thanks for any help.
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It sounds like a possible modulator valve problem... Check to see if the vacuum line came unplugged either at your intake manifold or your modulator valve at your trans..
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2,418 Posts
A lot of times if the modulator goes bad you will find transmission fluid in the vacuum line when you pull it loose from the modulator.
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959 Posts
I think Belairrudy is on to something. The modulator is what controls shifting in the TH350 and it uses vacum from the manifold to do so. Like BR says it may be the modulator or hose connection. Be sure to check the entire length of the vacuum hose to insure there is no damage between the manifold and modulator. Do you know if you have an adjustable modulator, some newer modulators can be adjusted for shift RPM range. Have you tried manual shifting to see if it will go into the gears manually, 1st to second, second to 3rd?? Another thing to check is the adjustment on the kickdown cable..if the adjustment is off now for whatever reason it may still think you are in passing gear and won't shift until like you say the rpms are high enough.
Let us know what you find....
Jim
Let us know what you find....
Jim
Yeah I will take a look. When I manually shift it goes into 1st hear but I have not had any luck with it shifting to 2nd and so on. I don't know transmissions very well but I will take a look and let you guys know. Thanks for the help.
You wont if the modulator is disconnected.
Really? interesting. What does that tell me?
The other end has came off the modulator and is a vacume leak.
Yep! Most common cause is a vacuum line that has become disconnected (or the rubber hose has cracked) either at the vacuum modulator or at the intake manifold/carb.
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Modulator went out on a 69 Elky I had. I could manually shift it but that was it. :wavey:
bowtie-trifive
bowtie-trifive
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NO SHIFT
I had a TH350 that stopped shifting and it ended up being the governer thats behind that thin steel housing with the holddown on it.The transmission shop replaced it and it shifted like new.
GREG
I had a TH350 that stopped shifting and it ended up being the governer thats behind that thin steel housing with the holddown on it.The transmission shop replaced it and it shifted like new.
GREG
Hey guys. Just wanted to let you know that i got under the car and found the vacuum hose disconnected so I reconnected it and securured it better. I took it out for a test drive and it ran like a champ. Thanks so much for all the help.
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Good to hear ity was a simple fix.. :congrats:
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Hey I having the same problem and I check the the vacuum hose everything seam to connected right now my question to you guy if over fill my tranmission can that cause it to not shift and over heat
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1 Posts
It was my vacuum line next to the transmission that wasnt allowing a good vaccum
What would make turbo 350 trans not shift if it’s to a LS 5.3
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