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79 Automatic won't shift

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Old Aug 30, 2001 | 08:28 PM
  #1  
JME's Avatar
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From: Dover NH
Default 79 Automatic won't shift

My 79 TH350 3sp won't shift unless I shift it "manually" from 1 to 2 to 3. Fluid is up to level and is not burnt. I changed the filter last summer.

Any ideas?

Jamie
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Old Aug 30, 2001 | 08:56 PM
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Stingy74
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From: Regina Saskatchewan, Canada.
Default Re: 79 Automatic won't shift (JME)

Check to make sure the vacuum line at the tranny hasn't come off. I think it's called a vacuum modulator, right tranny guys?
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Old Aug 30, 2001 | 09:16 PM
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Default Re: 79 Automatic won't shift (Stingy74)

Did this happen all of a sudden or did you buy the Vette this way? Stingy is right about checking the vac modulator connections first.
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Old Aug 30, 2001 | 10:14 PM
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Default Re: 79 Automatic won't shift (JME)

You may want to check out the "Will Not Shift" section of this page (http://users.erols.com/jerryp58/corvette/BNM7.jpg) of the B&M Shift Kit instructions.

A broken/cracked vacuum line is one possibility, as are loose valve bolts (not really likely unless someone's been in there recently), and kick-down cable misadjustment.

You didn't run over any trash in the road or anything like that recently did you?

BTW, I see this is your first post, WELCOME :seeya


[Modified by jerryp58, 9:15 PM 8/30/2001]
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Old Aug 30, 2001 | 11:26 PM
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From: Dover NH
Default Re: 79 Automatic won't shift (JME)

Thanks for the information and the welcome. I've owned the car since 1990. New Hampshire weather only allows for partial driving time, so I've only accumulated 30k miles over the 40k I bought it at. Its been sitting all summer until this weekend, when the shifting problem occured. I'll check out the vacuum lines tomorrow.
Thanks again,
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Old Aug 31, 2001 | 12:59 AM
  #6  
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From: Toronto
Default Re: 79 Automatic won't shift (JME)

JME, EXACT same thing happened to me last summer. All I did was reconnect disconnected vacuum. No biggy. :yesnod:
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Old Sep 2, 2001 | 05:40 PM
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From: Dover NH
Default Re: 79 Automatic won't shift (JME)

PERFECT!!!

A simple split in the vacuum line was the culprit. A little left over vacuum hose and now... the car shifts like a dream!

Thanks to the guys that helped me out.

Jamie
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