TH350 Trans question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

garyed08 · 07-29-2010, 06:49 PM

Hey everyone, i have me a little problem. i have a 1968 C10 with 1972 Suburban running gear. 350 engine, TH350 Trans, 3.07 Rear. Edelbrock 1406 carb and 2101 intake. my question about the trans is when im goin down the road and i kick it down to passing gear it goes right from 3rd to 1st gear and then shifts right back into 3rd again. could it be the vacuum modulator, or is my trans about to retire. any help would be very much appreciated

garyed08 · 07-29-2010, 09:50 PM

changed the vacuum modulator just for the hell of it and it does the same thing.

gdogg14 · 07-29-2010, 11:12 PM

I cant answer your tranny question however I wanted to know how your truck runs down the hiway with the 3.07 rear end, what is your RPM @ 70mph?

garyed08 · 07-30-2010, 06:24 AM

at 70mph i am turning 2500 rpm

gdogg14 · 07-30-2010, 10:14 PM

Cool! thats is what Im shooting for. Thanks

garyed08 · 07-30-2010, 11:48 PM

no problem.

garyed08 · 08-02-2010, 10:44 PM

tttt

raycow · 08-03-2010, 07:02 AM

When you take off from a stop in drive does it upshift normally? That is, does it have 2nd gear then? What happens when you manually shift to 2nd?

Ray

garyed08 · 08-03-2010, 08:49 PM

it upshifts perfectly fine. but when im on the highway and im goin about 55 and wanna kick it down to passing gear it completely bypasses 2nd gear and goes straight to 1st then 2nd and finally 3rd. but it doesnt stay in 2nd either jumps right back to 3rd. when i downshift from 2nd manually its fine. the motor revs up to about 3000rpm and goes right back to 2500 rpm when i put it back in 3rd.

garyed08 · 08-03-2010, 08:52 PM

when this thing kicks down to 1st gear it just about hits 6000 RPM

raycow · 08-03-2010, 09:53 PM

It sounds like a governor or valve body problem. Start by checking the governor first, as it is a lot simpler than the VB.

Ray

raycow · 08-04-2010, 03:16 AM

On second thought, start with the cable adjustment.

Ray

garyed08 · 08-05-2010, 05:14 PM

adjusted the cable and still does the same thing. where in the trans in the governor. are they easy to change?

mario1128 · 08-05-2010, 07:48 PM

located towards the rear of tranny believe its on drivers side near tail housing under a domed cover aprox 3 inches in diameter

garyed08 · 08-05-2010, 10:20 PM

ok thanks ill check it out

garyed08 · 08-06-2010, 02:49 AM

decided to take it to the local trans shop and he got it fixed in less then an hour. he said it was something with the valve body. dont remember what he said all i know is it cost me $30 to fix and it shifts like its brand new again. thanks for all your help. he said the governor and the kickdown cable were perfect.

garyed08 · 08-06-2010, 02:50 AM

also decided to sell the truck. i need money to finish my other projects.

07-29-2010, 06:49 PM	#1
garyed08 Registered User Join Date: Mar 2008 Location: Carbondale. pa Posts: 22	TH350 Trans question Hey everyone, i have me a little problem. i have a 1968 C10 with 1972 Suburban running gear. 350 engine, TH350 Trans, 3.07 Rear. Edelbrock 1406 carb and 2101 intake. my question about the trans is when im goin down the road and i kick it down to passing gear it goes right from 3rd to 1st gear and then shifts right back into 3rd again. could it be the vacuum modulator, or is my trans about to retire. any help would be very much appreciated

07-29-2010, 09:50 PM	#2
garyed08 Registered User Join Date: Mar 2008 Location: Carbondale. pa Posts: 22	Re: TH350 Trans question changed the vacuum modulator just for the hell of it and it does the same thing.

07-29-2010, 11:12 PM	#3
gdogg14 Registered User Join Date: Jun 2010 Location: Wyandotte, OK Posts: 15	Re: TH350 Trans question I cant answer your tranny question however I wanted to know how your truck runs down the hiway with the 3.07 rear end, what is your RPM @ 70mph? __________________ Greg A. Thurman I took this photo at a rest area near Washington DC I wish I had my 67 gas guzzler to park there. Gulf War Vet (USN) Retired Firefighter 67 C-10 72 C-10

07-30-2010, 06:24 AM	#4
garyed08 Registered User Join Date: Mar 2008 Location: Carbondale. pa Posts: 22	Re: TH350 Trans question at 70mph i am turning 2500 rpm

07-30-2010, 10:14 PM	#5
gdogg14 Registered User Join Date: Jun 2010 Location: Wyandotte, OK Posts: 15	Re: TH350 Trans question Cool! thats is what Im shooting for. Thanks __________________ Greg A. Thurman I took this photo at a rest area near Washington DC I wish I had my 67 gas guzzler to park there. Gulf War Vet (USN) Retired Firefighter 67 C-10 72 C-10

07-30-2010, 11:48 PM	#6
garyed08 Registered User Join Date: Mar 2008 Location: Carbondale. pa Posts: 22	Re: TH350 Trans question no problem.

08-02-2010, 10:44 PM	#7
garyed08 Registered User Join Date: Mar 2008 Location: Carbondale. pa Posts: 22	Re: TH350 Trans question tttt

08-03-2010, 07:02 AM	#8
raycow Registered User Join Date: Mar 2003 Location: San Francisco, CA USA Posts: 2,454	Re: TH350 Trans question When you take off from a stop in drive does it upshift normally? That is, does it have 2nd gear then? What happens when you manually shift to 2nd? Ray

08-03-2010, 08:49 PM	#9
garyed08 Registered User Join Date: Mar 2008 Location: Carbondale. pa Posts: 22	Re: TH350 Trans question it upshifts perfectly fine. but when im on the highway and im goin about 55 and wanna kick it down to passing gear it completely bypasses 2nd gear and goes straight to 1st then 2nd and finally 3rd. but it doesnt stay in 2nd either jumps right back to 3rd. when i downshift from 2nd manually its fine. the motor revs up to about 3000rpm and goes right back to 2500 rpm when i put it back in 3rd. Last edited by garyed08; 08-03-2010 at 08:50 PM.

08-03-2010, 08:52 PM	#10
garyed08 Registered User Join Date: Mar 2008 Location: Carbondale. pa Posts: 22	Re: TH350 Trans question when this thing kicks down to 1st gear it just about hits 6000 RPM

08-03-2010, 09:53 PM	#11
raycow Registered User Join Date: Mar 2003 Location: San Francisco, CA USA Posts: 2,454	Re: TH350 Trans question It sounds like a governor or valve body problem. Start by checking the governor first, as it is a lot simpler than the VB. Ray

08-04-2010, 03:16 AM	#12
raycow Registered User Join Date: Mar 2003 Location: San Francisco, CA USA Posts: 2,454	Re: TH350 Trans question On second thought, start with the cable adjustment. Ray

08-05-2010, 05:14 PM	#13
garyed08 Registered User Join Date: Mar 2008 Location: Carbondale. pa Posts: 22	Re: TH350 Trans question adjusted the cable and still does the same thing. where in the trans in the governor. are they easy to change?

08-05-2010, 07:48 PM	#14
mario1128 Registered User Join Date: Jan 2009 Location: cheshire ct Posts: 55	Re: TH350 Trans question located towards the rear of tranny believe its on drivers side near tail housing under a domed cover aprox 3 inches in diameter __________________ 72 chevy former 1ton converted to 1/2 ton roller 350 engine , turbo 350 and a 12 bolt on leafsprings with a flip and drop springs

08-05-2010, 10:20 PM	#15
garyed08 Registered User Join Date: Mar 2008 Location: Carbondale. pa Posts: 22	Re: TH350 Trans question ok thanks ill check it out



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08-06-2010, 02:49 AM	#16
garyed08 Registered User Join Date: Mar 2008 Location: Carbondale. pa Posts: 22	Re: TH350 Trans question decided to take it to the local trans shop and he got it fixed in less then an hour. he said it was something with the valve body. dont remember what he said all i know is it cost me $30 to fix and it shifts like its brand new again. thanks for all your help. he said the governor and the kickdown cable were perfect.

08-06-2010, 02:50 AM	#17
garyed08 Registered User Join Date: Mar 2008 Location: Carbondale. pa Posts: 22	Re: TH350 Trans question also decided to sell the truck. i need money to finish my other projects.

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