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Old 10-03-2005, 10:47 PM
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TH350 shifting hard

I have an '82 Chevy Van with a th 350 tranny. When I start it it shifts hard into gear when the engine rpms are up, and when stopped at a stop sign it doesn't shift back into gear until my rpms are up again. I have checked the fluid level and it seems ok but I have seen alot of other threads were folks are having to overfill their fluid to get it moving. I have a slight leak at the rear seal at the drive shaft. To check this fluid does the transmission have to be in gear or neutral?
Any help would be appreciated.

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Old 10-04-2005, 03:32 PM
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350

It sounds like you have a vacuum modulator problem. This is at the right rear of your trans with a vacuum line (rubber or steel tube) going to it. With the engine running, you should have good strong vacuum at the modulator, 18"Hg if you have a gauge. If you don't have vacuum there, look for the leak between the engine intake manifold vacuum fitting and the trans. If you have strong vacuum at the modulator, I would replace it (less that $30). If your modulator has trans fluid present at the vacuum hose fitting, it is shot.

Your fluid level should be checked in Park. The directions are printed right on the trans dipstick.

Good Luck,
Rick
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Old 10-04-2005, 07:56 PM
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Quote:
Originally Posted by ArmyofOne
I have an '82 Chevy Van with a th 350 tranny. When I start it it shifts hard into gear when the engine rpms are up, and when stopped at a stop sign it doesn't shift back into gear until my rpms are up again. I have checked the fluid level and it seems ok but I have seen alot of other threads were folks are having to overfill their fluid to get it moving. I have a slight leak at the rear seal at the drive shaft. To check this fluid does the transmission have to be in gear or neutral?
Any help would be appreciated.

I am curious if your word choice here is confusing.

You say it " shifts hard into gear when the engine rpms are up".... Do you mean you move the shifter from park to R or D and nothing happens till you rev the engine?

You say : " when stopped at a stop sign it doesn't shift back into gear until my rpms are up "....... By this comment do you mean the tranny drops in a neutral / no gear state with the shifter still in "D" ? You must rev the motor for the tranny to "jump" into gear?

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Old 10-06-2005, 02:39 PM
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Yes to the:
" the tranny drops in a neutral / no gear state with the shifter still in "D" ? You must rev the motor for the tranny to "jump" into gear?"
I am going to try the modulator and check the lines for leaks.
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Old 10-06-2005, 05:55 PM
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350

Sorry, I think I misunderstood your original post. You probably have a fluid level problem or possibly plugged filter, pump, or basic hydraulic problem. Does the problem also happen in Reverse, or only Drive?

Thanks for the clarification,
Rick
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Old 10-06-2005, 08:46 PM
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a modulator will not cause a tranny to drop out of gear, unless the fluid is being sucked from the tranny through a bad diaphram inside the modulator.

Pull the rubber vacuum hose to check for oil in the hose at the modulator... should be dry
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Old 10-14-2005, 09:37 PM
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IMHO if it "slams" into gear when you rev it and not just slipping i would guess it to be a bad TQ converter.
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Old 10-15-2005, 12:14 AM
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My bet is dirty filter.
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Old 10-17-2005, 03:38 AM
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Could be a bad low/reverse clutch pack, does it hunt between top and second on the highway?
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