Author Topic: tranny won't shift down into 1st  (Read 17378 times)

Offline 4x4orbust

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tranny won't shift down into 1st
« on: August 30, 2010, 04:26:36 pm »
hello everyone.  i recently started driving my 82 again (passed inspection friday,  Yipee!!!)   and am having a little trouble with the tranny.   i have tried searching, but don't know how to search for this issue. 

when i come to a stop (at, say, a stop sign, or red light)  the tranny does not shift down into first gear, it stays in second.   it will shift into 1st if i put the gear selector into first.   it will gear down if i "hammer down", but otherwise i take off in second gear.  when coming to a stop it will gear down from 3rd to 2nd just fine.   i remember someone else having this issue, but do not remember who or where to find it.  any ideas on where to start?   info is in my sig. 

thanks!!
1982 chevy K-10 SWB, 355 th350/np208. 2.5"lift, 33" swampers, headers/duals,  current project

Offline VileZambonie

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Re: tranny won't shift down into 1st
« Reply #1 on: August 30, 2010, 07:24:10 pm »
Adjust detent cable, check modulator adjustment, make sure governor valve isn't sticking.
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline 4x4orbust

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Re: tranny won't shift down into 1st
« Reply #2 on: September 10, 2010, 07:43:39 pm »
what should the modulator be adjusted to?    i would like the screw back to a factory setting, then adjust from there.
1982 chevy K-10 SWB, 355 th350/np208. 2.5"lift, 33" swampers, headers/duals,  current project

Offline fred75

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Re: tranny won't shift down into 1st
« Reply #3 on: September 10, 2010, 11:20:10 pm »
  Modulators can be adjusted to compensate for engine manifold vacuum and/ or adjusted to control shift points. The factory settng would be point at which the shift points in MPH for your particular trans and rear end are met. Adjust, test drive, adjust etc,. How long did the truck sit prior to getting back on the road, and, did it shift correctly prior to putting it up? What if  any work was done prior to the start in 2nd issue? Pull the vacuum hose off the modulator and make sure no fluid is in the hose or nipple. Are you sure the vacuum line is good (test)all the way to the manifold?  On a different note, the troubleshooting chart (starts in 2nd gear, or slips in 2nd gear) points to the intermediate clutch or the intermediate clutch servo piston. Some intermediate clutch servo pistons are plastic and can crack.
'82 C-10 305/TH350-TCC EDL PERF INT W/1406 AFB MSD-6A HDRS

Offline 4x4orbust

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Re: tranny won't shift down into 1st
« Reply #4 on: September 11, 2010, 12:57:35 pm »
i have gotten the truck to shift right from 1st to 2nd to 3rd by adjusting the modulator.   i also reset the kick down cable to see if it helped the no shift down into 1st thing.    it did not help. 

the truck was sitting for ~5 years.  it supposedly shifted fine before it was parked, as well as the tranny was rebuilt and only has about 5000 miles on it.   

there is no fluid on the nipple of the modulator, or in the hose to the modulator.   I have not replaced the vacuum hose yet, but will this weekend to eliminate that as a possibility. 

I am going to bring the truck to a friend of mine who runs a tranny shop this week, hopefully he can diagnose and solve the problem.   untill then,  i am more than happy to try different things if you guys have any more suggestions??!!

thanks!!
1982 chevy K-10 SWB, 355 th350/np208. 2.5"lift, 33" swampers, headers/duals,  current project

Offline VileZambonie

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Re: tranny won't shift down into 1st
« Reply #5 on: September 11, 2010, 02:42:03 pm »
Are you sure the detent cable is adjusted tight enough?
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Offline fred75

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Re: tranny won't shift down into 1st
« Reply #6 on: September 11, 2010, 04:34:05 pm »
   "i have gotten the truck to shift right from 1st to 2nd to 3rd by adjusting the modulator." << Contradicts >> i also reset the kick down cable to see if it helped the no shift down into 1st thing.    it did not help."  ??? ??? Are you saying there is no; full throttle 2-1 or 3-1 shift???  I'm not sure of the symptom your tryin to describe. Originally we were talking about a (in drive) starts in 2nd symptom.

  9/14/2010  Ok I finally get it after looking at this again; "no shift down into 1st thing" = Starts in 2nd. ;)  I see what your saying.
« Last Edit: September 14, 2010, 05:30:44 am by fred75 »
'82 C-10 305/TH350-TCC EDL PERF INT W/1406 AFB MSD-6A HDRS

Offline 4x4orbust

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Re: tranny won't shift down into 1st
« Reply #7 on: September 11, 2010, 05:35:53 pm »
i apologize for the contradiction.    when i come to a full stop, i have to manually shift the truck into 1st (on the column) for it to go into first.  otherwise it will stay in second gear.   after i manualy shift into 1st, it will (now) shift fine from 1st to 2n to 3rd.  it will downshift fine from 3rd to 2nd when coming to a stop, but not into 1st.

also, it does kick down a gear when the pedal is "floored" (from 3rd to 2nd, or 2nd to 1st, but not from 3rd to 1st unless i am going under 20mph or so).  i hope that clears it up a little.

 i re-adjusted the kick down cable to see if it would make the truck shift down into 1st at a complete stop, which it did not.   I adjusted as i thought was the right way.  release the hold tab (not the metal button kind, but the plastic one you pull up to release the kick down cable adjuster thing) then get into the truck and put the gas pedal to the floor.  then get out and push the lock tab back in.  

 i am not sure if it is tight enough, however i will try it again with someone else pushing the gas pedal and me sitting in the engine bay to ensure it did not slip back at all.

also, in reading my last post, i wrote "the tranny was rebuilt and only has about 5000 miles on it"   the rebuild was  done before the truck was parked for the 5 years.  just wanted to clarify that, and the fact that i did not do the rebuild.  


thanks

phil
« Last Edit: September 11, 2010, 05:41:40 pm by 4x4orbust »
1982 chevy K-10 SWB, 355 th350/np208. 2.5"lift, 33" swampers, headers/duals,  current project

Offline VileZambonie

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Re: tranny won't shift down into 1st
« Reply #8 on: September 12, 2010, 08:59:33 am »
make sure governor valve isn't sticking.
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline 4x4orbust

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Re: tranny won't shift down into 1st
« Reply #9 on: September 12, 2010, 10:07:02 am »
where is the governor valve located on the tranny?   

thanks
1982 chevy K-10 SWB, 355 th350/np208. 2.5"lift, 33" swampers, headers/duals,  current project

Offline VileZambonie

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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline 4x4orbust

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Re: tranny won't shift down into 1st
« Reply #11 on: September 12, 2010, 12:30:38 pm »
thanks vile!!   you always come through!! ;D
1982 chevy K-10 SWB, 355 th350/np208. 2.5"lift, 33" swampers, headers/duals,  current project

Offline fred75

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Re: tranny won't shift down into 1st
« Reply #12 on: September 12, 2010, 05:15:32 pm »
        "also, it does kick down a gear when the pedal is "floored" (from 3rd to 2nd, or 2nd to 1st, but not from 3rd to 1st unless i am going under 20mph or so).  i hope that clears it up a little."  

Then the detent cable is doing what it's supposed to do, that's good.

 "i re-adjusted the kick down cable to see if it would make the truck shift down into 1st at a complete stop, which it did not."

And it should not, the detent cable assists in delaying up shifts while at or near full throttle, or, assists/ forces full throttle down shifts.

  Once you get done checking the govenor, we'll go from there... Govenor should be fine because you say it's shifting up through the gears. The govenor assists/ manages shift points.
« Last Edit: September 12, 2010, 05:51:51 pm by fred75 »
'82 C-10 305/TH350-TCC EDL PERF INT W/1406 AFB MSD-6A HDRS

Offline VileZambonie

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Re: tranny won't shift down into 1st
« Reply #13 on: September 12, 2010, 07:41:57 pm »
If the governor valve is sticking/stuck Gov pressure will be high preventing the automatic downshift
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline fred75

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Re: tranny won't shift down into 1st
« Reply #14 on: September 12, 2010, 09:53:12 pm »
  If the govenor is sticking, there won't be any normal consistent up shifting.

 However, if there are multiple issues with that tranny, you may be very well correct!!!  So good to check the Govenor.
« Last Edit: September 14, 2010, 05:45:55 am by fred75 »
'82 C-10 305/TH350-TCC EDL PERF INT W/1406 AFB MSD-6A HDRS