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Author Topic: '83 TH350 tranny not shifting  (Read 19575 times)

Offline Red 83

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'83 TH350 tranny not shifting
« on: January 27, 2012, 05:43:57 pm »
I just had a crate 305 installed in my '83 C10. It has a TH350 transmission. Before the new engine was put in, the truck drove just fine (except for the fact that I couldn't feel it shift to 3rd). Now that I have a new engine, the transmission won't shift when it's in Drive (D). It will shift by moving the gearshift manually. Has anyone else had this problem?
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1983 C10 Scottsdale - 305, TH350  Ol' Red

Online bd

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Re: '83 TH350 tranny not shifting
« Reply #1 on: January 27, 2012, 06:10:25 pm »
Check the trans fluid level.  Then make sure the detent cable is connected to the throttle linkage and adjusted properly, and that the modulator valve is correctly plumbed to manifold vacuum and receiving vacuum.  You can also verify adjustment of the shift linkage.  Just make sure the shop put everything back together correctly and hooked up the peripherals.
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Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Red 83

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Re: '83 TH350 tranny not shifting
« Reply #2 on: January 27, 2012, 06:16:08 pm »
I already checked the tranny fluid, it's fine. Is the detent cable the same thing as the kickdown cable?
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1983 C10 Scottsdale - 305, TH350  Ol' Red

Offline 87454westernhauler

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Re: '83 TH350 tranny not shifting
« Reply #3 on: January 27, 2012, 06:24:11 pm »
i would check to make sure the vacumn line to the module is all hooked up and not leaking first.
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86 c10 350 sbc 700R4 Daily Driver
79 gmc c20 350 th350
78 k1500 4x4 350 th350

Online bd

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Re: '83 TH350 tranny not shifting
« Reply #4 on: January 27, 2012, 08:00:01 pm »
Quote from: Red 83 on January 27, 2012, 06:16:08 pm
I already checked the tranny fluid, it's fine. Is the detent cable the same thing as the kickdown cable?

Yes.
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Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Dr_Snooz

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Re: '83 TH350 tranny not shifting
« Reply #5 on: January 27, 2012, 11:18:48 pm »
I would double check the installation of the shifter linkage.
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Offline Red 83

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Re: '83 TH350 tranny not shifting
« Reply #6 on: January 29, 2012, 10:00:24 am »
Well, I found the problem. It was a metal vacuum that wasn't hooked up to the modulator. Now it shifts just fine.
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1983 C10 Scottsdale - 305, TH350  Ol' Red

Offline 87454westernhauler

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Re: '83 TH350 tranny not shifting
« Reply #7 on: January 29, 2012, 10:32:27 am »
i had the same problem with my 80 c10, i had the carb off to do something and had knocked the vacumn line off of the module and had same issue as u. glad it was any easy fix!
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86 c10 350 sbc 700R4 Daily Driver
79 gmc c20 350 th350
78 k1500 4x4 350 th350

Offline nlauffer

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Re: '83 TH350 tranny not shifting
« Reply #8 on: February 02, 2012, 11:52:29 pm »
Interesting post.  I am also working on an 83 with a TH350 that won't shift.  I replaced the modulator with an adjustable one and ran a new vacuum line to the manifold tee.  The shift linkage is fine.  The fluid level is fine.  It just started this a few days ago.  The kickdown cable has never been hooked up since I have owned the truck.  It seems to be about 2-3 inches too long.  I removed the governor and found that the gear is worn quite alot.  I am going to replace the gear.  What are some other things I might need to check?  If the kickdown cable is the correct one, how do I adjust it that much? And what is the proper way to adjust it?  I know you can modify the governor, but how much pressure are the springs supposed to produce.  It seems they don't do anything.  I moved the weights up and down and could see the shaft moving.  Also, after replacing the modulator and vacuum hose, it will now shift, but if I give it very much throttle, it kicks back down. What do you guys think?
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Offline VileZambonie

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Re: '83 TH350 tranny not shifting
« Reply #9 on: February 04, 2012, 11:02:16 am »
Replace the governor gear and get a new detent cable.
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Offline nlauffer

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Re: '83 TH350 tranny not shifting
« Reply #10 on: February 05, 2012, 08:48:12 pm »
I was not able to get just a gear in short time, but a buddy had a governor in his garage.  It was in great shape and I think it had been modified.  The springs were 1 green and 1 red.  My old ones were yellow.  It now shifts amazing.  I am going to buy a new detent cable.  Also I think a HOlley 600 is next.  I found a remaned one on Ebay for 169 it is vacuum secondaries and electric choke.  I was pretty shocked when I called the trans shop and they told me it was only 325 for a tranny rebuild.
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