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#1 |
*************
![]() Join Date: Apr 2005
Location: Pensacola, FL
Posts: 17,846
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Transmission shifting to soon....
My TH350 will shift first through third prior to getting up to 15 mph. Even if you get on it with mild throttle, it shifts really quick and then seems like it's lugging the motor (if you manually shift it, everything works great). I've checked and double checked the vacuum and I have no fluid coming out of the modulator. It has been working fine and just recently started doing this. Could the modulator be stuck or bad? It's a Sid Neal built transmission with less than 2K miles. Thoughts? TIA.
__________________
Rob - https://www.instagram.com/hart_rod_c10 As Iron Sharpens Iron, So One Man Sharpens Another. Proverbs 27:17 FOR SALE: DBW pedal bracket - http://67-72chevytrucks.com/vboard/s...d.php?t=651123 FOR SALE: Hood Brackets http://67-72chevytrucks.com/vboard/s...d.php?t=679945 1987 Silverado SWB - 34.5K original miles http://67-72chevytrucks.com/vboard/s...d.php?t=801834 1969 SuperBurb - http://67-72chevytrucks.com/vboard/s...d.php?t=200387 1968 Farm truck - http://67-72chevytrucks.com/vboard/s...d.php?t=358692 1968 SWB - http://67-72chevytrucks.com/vboard/s...d.php?t=551258 1948 Chevy - http://67-72chevytrucks.com/vboard/s...=122164&page=3 |
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#2 |
Burnouts are therapeutic
Join Date: Jun 2007
Location: lancaster, south carolina
Posts: 852
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Re: Transmission shifting to soon....
some modulator valves are adjustable so you can adjust shifts if memory serves me correctly, I think it adjusts with an allen wrench. but if it just started doing it the valve may be bad. hopefully someone with more knowledge will chime in .
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1969 CHEVELLE SS 1972 C10 ALMOST DAILY DRIVER 1968 C10 RUSTBUCKET (MISSION IMPOSSIBLE) 1972 PONTIAC LEMANS CONVERTIBLE (WIFE'S CAR) "My wife and I were happy for twenty years. Then we met." - Rodney Dangerfield "The difference between genius and stupidity is that genius has its limits." - Einstein |
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#3 |
Registered User
Join Date: Jan 2009
Location: Aurora,Il ..born,raised and still live in the same house
Posts: 286
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Re: Transmission shifting to soon....
I replace my bad t350 with another (junkyard) turbo 350 and it wouldn't shift at all.
I replaced the vacuum modulator (new at napa for $10 bucks) and then it shifted way too soon just like yours. so i took off the original vacuum modulator from the bad t350 and it shifted fine. If not i would have tried another vacuum modulator or gone to the junkyard and pulled a couple to try the different shift points. seems like the different vacuum modulators all give different shift points |
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#4 |
sharp as a marble
![]() Join Date: Jan 2007
Location: atlantic beach,florida
Posts: 1,082
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Re: Transmission shifting to soon....
pull the vacuum hose off of the modulator. See if it is adjustable. Remove the governor cover from the drivers side of the trans. I cannot remember ( old fart ) it the cover has a bell wire ( hoop ) or if it has four 1/4 bolts to hold it on. Anyway, after removing the cover, remove the governor. There will be an assembly that is about 3-4 inches long. At the end nearest the cover will be two ' wings' and at the other end will be a nylon gear. The gear can become ' apple cored " thin in the middle. If the gear is that way replace it. it is held on with a roll pin. Should be able to get one from a trans shop, don't know if NAPA carries them. After replacing the gear wash the governor assy, very well with brake clean and work the wings back and forth as you do it.
As for the modulator, IF I REMEMBER, if there is a straight slot screw inside of the vacuum nipple turning it in will make the shifts later. Do you have the kickdown cable connected to the throttle linkage? needs to be. IIR this will also delay shifts with 1/2 + throttle. WELL GET TO WORK!!!!! |
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#5 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: Transmission shifting to soon....
check to see if the kickdown cable came disconnected from the carb. If it has not, then try adjusting it. Make sure it hasn't snapped.
Odds are the modulator is fine. If anything would have changed, it would have gone from shifting fine to not shifting at all. After inspecting the cable I'd pull the govener and see if it is working properly. |
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#6 |
Cops, ha, catch me if you can!
Join Date: Jun 2009
Location: Santa Barbara, CA.
Posts: 271
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Re: Transmission shifting to soon....
Kick down Cables x2. I adjusted my cables a few weeks ago because it shifted to early and hardly kick down when I stood on it. Know it does not shift till about 2000 RPM and it kicks down with less than half throttle, it will also hold a gear longer if I am going up hill.
__________________
72 C-10 Stepper 350/TH350 3.73 in the back Edelbrock intake and Carb Hooker Comp Headers 275/60R15 on Rallies ![]() ![]() |
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#7 | |
*************
![]() Join Date: Apr 2005
Location: Pensacola, FL
Posts: 17,846
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Re: Transmission shifting to soon....
Quote:
__________________
Rob - https://www.instagram.com/hart_rod_c10 As Iron Sharpens Iron, So One Man Sharpens Another. Proverbs 27:17 FOR SALE: DBW pedal bracket - http://67-72chevytrucks.com/vboard/s...d.php?t=651123 FOR SALE: Hood Brackets http://67-72chevytrucks.com/vboard/s...d.php?t=679945 1987 Silverado SWB - 34.5K original miles http://67-72chevytrucks.com/vboard/s...d.php?t=801834 1969 SuperBurb - http://67-72chevytrucks.com/vboard/s...d.php?t=200387 1968 Farm truck - http://67-72chevytrucks.com/vboard/s...d.php?t=358692 1968 SWB - http://67-72chevytrucks.com/vboard/s...d.php?t=551258 1948 Chevy - http://67-72chevytrucks.com/vboard/s...=122164&page=3 |
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#8 |
Senior Member
Join Date: May 2009
Location: Fort Worth, TX
Posts: 6,370
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Re: Transmission shifting to soon....
Pull the governor cover and inspect the governor for broken springs.
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#9 |
Registered User
Join Date: May 2009
Location: Morongo Valley
Posts: 130
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Re: Transmission shifting to soon....
wow I guess im not the only one with this problem i dont have the kick down hooked up either.... mines shifting really early...
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#10 |
Registered User
Join Date: Apr 2009
Location: Weatherford, OK
Posts: 220
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Re: Transmission shifting to soon....
mine shifts early too with kickdown hooked up. I don't care though as I'm looking for a 700r4
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#11 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: Transmission shifting to soon....
with no kickdown, it will shift early.
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#12 |
Senior Member
Join Date: Jul 2006
Location: Blountville, Tn.
Posts: 3,904
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Re: Transmission shifting to soon....
I'll also say check the governor, easy as pie to replace. I had one go bad on me but that was along time ago, can't remember the symptoms though.
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*We could learn a lot from crayons... Some are sharp; some are pretty;and some are dull. Some have weird names; and all are different colours;but they all have to live in the same box. * You may be only one person in the world, But you may also be the world to one person. * Some mistakes are too much fun to only make once. Two rules in life. 1. Never sweat the small stuff! 2. Everything is small stuff! |
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#13 |
*************
![]() Join Date: Apr 2005
Location: Pensacola, FL
Posts: 17,846
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Re: Transmission shifting to soon....
OK, I figured out the problem and yes, it turned out to be me....
![]() ![]() EDIT: I spoke to a very knowledgable tranny guy and he said the kickdown has NO effect on the normal operation of the transmission. He said the only purpose was to drop the transmission down into 2nd. I will however get this connected as soon as I gain a little room underneath the carb enclosure. More to come on that later, ![]()
__________________
Rob - https://www.instagram.com/hart_rod_c10 As Iron Sharpens Iron, So One Man Sharpens Another. Proverbs 27:17 FOR SALE: DBW pedal bracket - http://67-72chevytrucks.com/vboard/s...d.php?t=651123 FOR SALE: Hood Brackets http://67-72chevytrucks.com/vboard/s...d.php?t=679945 1987 Silverado SWB - 34.5K original miles http://67-72chevytrucks.com/vboard/s...d.php?t=801834 1969 SuperBurb - http://67-72chevytrucks.com/vboard/s...d.php?t=200387 1968 Farm truck - http://67-72chevytrucks.com/vboard/s...d.php?t=358692 1968 SWB - http://67-72chevytrucks.com/vboard/s...d.php?t=551258 1948 Chevy - http://67-72chevytrucks.com/vboard/s...=122164&page=3 Last edited by Hart_Rod; 04-19-2010 at 05:14 PM. |
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#14 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: Transmission shifting to soon....
the kickdown does in fact hold the tranny in first and second when you are at wide open throttle, and even at medium throttle to a much lesser extent.
Drive a vehicle around the block with a properly adjusted one, then disconnect it and go for a drive. It will be obviouse. |
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#15 | |
*************
![]() Join Date: Apr 2005
Location: Pensacola, FL
Posts: 17,846
|
Re: Transmission shifting to soon....
Quote:
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__________________
Rob - https://www.instagram.com/hart_rod_c10 As Iron Sharpens Iron, So One Man Sharpens Another. Proverbs 27:17 FOR SALE: DBW pedal bracket - http://67-72chevytrucks.com/vboard/s...d.php?t=651123 FOR SALE: Hood Brackets http://67-72chevytrucks.com/vboard/s...d.php?t=679945 1987 Silverado SWB - 34.5K original miles http://67-72chevytrucks.com/vboard/s...d.php?t=801834 1969 SuperBurb - http://67-72chevytrucks.com/vboard/s...d.php?t=200387 1968 Farm truck - http://67-72chevytrucks.com/vboard/s...d.php?t=358692 1968 SWB - http://67-72chevytrucks.com/vboard/s...d.php?t=551258 1948 Chevy - http://67-72chevytrucks.com/vboard/s...=122164&page=3 Last edited by Hart_Rod; 04-19-2010 at 07:41 PM. |
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#16 |
Cops, ha, catch me if you can!
Join Date: Jun 2009
Location: Santa Barbara, CA.
Posts: 271
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Re: Transmission shifting to soon....
I have a TH350 and I can Tell you, when I adjusted, it held the grear longer then it did when it was out of adjustment. I can really notice it in second gear. Oh yeah, it will hold third till the engine blows
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__________________
72 C-10 Stepper 350/TH350 3.73 in the back Edelbrock intake and Carb Hooker Comp Headers 275/60R15 on Rallies ![]() ![]() |
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#17 |
*************
![]() Join Date: Apr 2005
Location: Pensacola, FL
Posts: 17,846
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Re: Transmission shifting to soon....
What did you adjust? The kickdown or the modulator?
__________________
Rob - https://www.instagram.com/hart_rod_c10 As Iron Sharpens Iron, So One Man Sharpens Another. Proverbs 27:17 FOR SALE: DBW pedal bracket - http://67-72chevytrucks.com/vboard/s...d.php?t=651123 FOR SALE: Hood Brackets http://67-72chevytrucks.com/vboard/s...d.php?t=679945 1987 Silverado SWB - 34.5K original miles http://67-72chevytrucks.com/vboard/s...d.php?t=801834 1969 SuperBurb - http://67-72chevytrucks.com/vboard/s...d.php?t=200387 1968 Farm truck - http://67-72chevytrucks.com/vboard/s...d.php?t=358692 1968 SWB - http://67-72chevytrucks.com/vboard/s...d.php?t=551258 1948 Chevy - http://67-72chevytrucks.com/vboard/s...=122164&page=3 |
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#18 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: Transmission shifting to soon....
the 400 doesn't have a kickdown cable on it.
I've had a tranny rebuild guy tell me the same thing. Had another one tell me that the modulator wouldn't keep a trans from shifting. (while it won't technicly keep it from shifting, if disconnected it'll make it 'hold' the gear till 4500 - 5500 RPM) We no longer use that guy for obviouse reasons... he was a parts swapper and didn't know how the trans actually worked. The guy you are talking to may be like him too, or he may be too familiar with late model stuff and has forgotten old school 3 speed GM trannys. They have been out dated for a long time, so it is a possibility. With the kickdown disconnected, you'll only get 4000 or so RPMs out of first, and then second will only hold on for a moment before going into third. Some call this 'stacked shifting' The kickdown will hold each of the lower 2 gears untill the govonor tells it to shift. |
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#19 | |
*************
![]() Join Date: Apr 2005
Location: Pensacola, FL
Posts: 17,846
|
Re: Transmission shifting to soon....
Quote:
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__________________
Rob - https://www.instagram.com/hart_rod_c10 As Iron Sharpens Iron, So One Man Sharpens Another. Proverbs 27:17 FOR SALE: DBW pedal bracket - http://67-72chevytrucks.com/vboard/s...d.php?t=651123 FOR SALE: Hood Brackets http://67-72chevytrucks.com/vboard/s...d.php?t=679945 1987 Silverado SWB - 34.5K original miles http://67-72chevytrucks.com/vboard/s...d.php?t=801834 1969 SuperBurb - http://67-72chevytrucks.com/vboard/s...d.php?t=200387 1968 Farm truck - http://67-72chevytrucks.com/vboard/s...d.php?t=358692 1968 SWB - http://67-72chevytrucks.com/vboard/s...d.php?t=551258 1948 Chevy - http://67-72chevytrucks.com/vboard/s...=122164&page=3 |
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