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Discussion Starter #1
hi everyone I have a 62 nova 400 with a 194 and a powerglide trans.
when diving from a stop, once i get to about 3000 rpms it shifts into high gear but after a few seconds it shifts back down to 1st gear and wont shift back up until I stop and then gradually speed up and then it does the same thing all over again. I have checked the fluid and its fine. I'm thinking about taking it to a shop but i don't want to put much money into it because i'm planning on replacing it in about a year, so a temporary fix would be fine.
thanks for the help.
 

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Check your vacuum line from carb to modulator vale on transmission. It may be run with steel line, but converts to rubber hose at both ends. It's dirt cheap, maybe replace it at both ends.
If that doesn't help I would replace the modulator valve too. It's cheap as well. That's where I would start. Probably $20 for these parts. Try searching this site for answers too. Hundreds of trouble shooting ideas are already on here.
 

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Check your vacuum line from carb to modulator vale on transmission. It may be run with steel line, but converts to rubber hose at both ends. It's dirt cheap, maybe replace it at both ends.
If that doesn't help I would replace the modulator valve too. It's cheap as well. That's where I would start. Probably $20 for these parts. Try searching this site for answers too. Hundreds of trouble shooting ideas are already on here.
What he said
 

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Agreed check vacuum 18 inches is about right 1st check at the carb. Then check it at the modulator so you are sure your line is good. 1 thing to look at quick see if the kick down linkage fell off...bushings go bad and it can fall out of it's hole. Let us know what you find. Good luck!
 

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So - - with my 69 …… it came with a 250ci & 2sp Powerglide. Then, I had another (alumn case p/g) ; so, I take that "spare trans" to Prescott / Tranny Shop (not their real name = = changed to protect the "dumb-ass" guy that screwed up my tranny) . Mind you - this was a spare trans … and, it DID have a "different out-put shaft" ..…. I point that item out - "he says - no problem" (take note) . After a month , I call said shop - just checking - they haven't even started on it yet ………….. Why Not ? "Well you said you weren't in a hurry" ---------- that should have been my 1st hint ----------- then, another three weeks, they call , and my trans IS Ready.
………. plus - - - this was just a "rebuild - - No remove or install .

I go and install my "new rebuilt spare transmission" (my stock tranny in the car was good ---- I was working , at that time & had money too spend , just thinking ahead …… that why-not have a 'fresh rebuilt trans' .
So, I do the swap …………. get-in & drive out 4 miles ; trans IS-NOT - Upshifting ………………………………………….. and, 4 more miles back home ……………………………………. "still not shifting ---- just staying in low gear. Then, I keep adjusting my linkage ( like 100 to 850 times) …………. then, I get my 11 yr old daughter to hold the inside shift-handel - - while I adjust the lower - linkage (for the 793 time) ……….…………. everything LOOKS LIKE IT IS Working .

"WRONG"

This car went and sat for a year because THAT NEW Transmission Would - NOT Shift correct.

Later, I think that I'm going too "get that trans too work. I get my "new wife = Diana" out there to help me ------ and, she IS a "CAR Guy Type" ===== well you know What I mean ===== .
All the adjusting on the linkage LOOKS GOOD ………….. but ………… same - o - same - o ;
HERE's the KEY : the linkage Does look to-be working correctly - - BUT - - not happening . I go to my
"back-up transmission" = = = which is the 'original p/g that I was replacing' …….
FROM THIS CAR …………... check out that shifter - shaft ……. YES ……. it also seems to work correctly. Then, I hit-on-the-thought ……………………………….……………………………………………………………………………………………………………………………………………… , remember that "take - note" - - - too change my
"shifter - output - shaft" … that I commented on above ? ?

They DID Change that item , with the correct out-put shaft . "wala" --- let me check that ; so I removed the (original p/g trans oil pan) ; had too remove the "valve - body , and removed the COMPLETE Shifter Shaft.
That "shaft' ; my friends = = = = = IS a Two-piece shaft . The outer shaft that sticks out-side the trans ; and, an inner shaft that makes the "Gear Selection" inside the trans .

Lo - and - behold ; the outer shaft WAS working - looked like it was shifting into each gear (and, it was). But, the inner shaft Was Not Moving …….. the two shafts go together / and, are "splined together" . ……………. Those "Donkey Turds" that changed the shifter - shaft ; did-not even check too make sure the trans even worked. (Granted, this was just a "bench rebuild job" - - - I did the 'remove & install) ……….. and, still took them 7 weeks too get done . …….

next post ….……….. I'm cooling down ……………...
 

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Are you still sitting down …………………….. good .

Here is my answer to the op . . . on my trans . . . it was working , just staying in low gear - - - not shifting into high. Even tho the shifter linkage & indicator was showing correct . . . . the "inside shaft" was not 'shifting or even moving ; for that matter. After I 'Changed my shifter out put shaft complete (again) - - - that P/G trans ran for 19 years ; it's still in the shop . still good - - - I just changed over to a T 5 5speed , because I want too "shift gears" . When , I removed my tranny 'oil pan' you could look up inside and see that the trans
Was Not Moving The inside part of the shaft . - - - - - - This may-not be your trouble …………. but, the regular guy does not know that they (p/g transmissions) have / use two "shifter shafts" = splined together .
I could have 'saved me about 845 different linkage adjustments' ……..

True _ Story . . . . . this is how I learn a lot about my Nova .

Thanks , for listening …………. I'm just saying , jim
 

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Shane T
If your P/G tries to up-shift (or does go into high) , then it may not be the shifter , causing u'r trouble .
But, do check all u'r linkage & shifter rods …. (if they are good , then u'r golden) . Column shifter - or - floor shifter ? ?
I'd sure check that 'modulator valve' - - - - - -they are 'cheap' , install a new one, & then make sure of u'r
vac - line is good .



Hey ---------------------- and , WELCOME to SNS .






............… jim
 

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Well ….…. I sure hope you have checked all this - - - -


" like - - - - the hand-bone , connected to the arm-bone , connected to the shoulder-bone . . . . . . they all work together " .

install a new 'modulator valve' & make sure there IS Vac coming out at the Bottom connection .
I make my lower connection - - - full time 'manifold vac'

later , jim
 

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Hi,
Is the vacuum line hooked up to the port under the carb plate. Its the lower of the two ports on the front of the carb. My P/G would thunk when downshifting and not shift properly until I plugged it until the lower port on the carb. Good luck.
 

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Discussion Starter #12
Hi everyone
Good news I checked the vacuum line and it was fine so today I swapped the modulator for a new one and changed the fluid. it worked. it shifts better than my 2001 pickup. thank you guys. You saved me a lot of money not having to take it to a mechanic
 

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Thanks for posting what you found to fix it. That makes better mechanics out of all of us!
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ . . . what Bob said ; thanks for the up-date .
(feed-back is good) .

and, it's called = NPHNP . later , jim
 

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Hi everyone
Good news I checked the vacuum line and it was fine so today I swapped the modulator for a new one and changed the fluid. it worked. it shifts better than my 2001 pickup. thank you guys. You saved me a lot of money not having to take it to a mechanic
It's really f*ing hard to kill a powerglide. Glad you got it.
 
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