TH350 shifts hard - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Desertryder · 11-26-2009, 11:38 PM

My th350 shifts really hard from park to a gear and going down the road it shifts gears hard. I replaced the vacuum modulator and it still hard shifts.
My truck is a '76 gmc 1/2 ton k15 and used mainly for fishing. I'm afraid I'm
tearing stuff up with it shifting hard. I am also starting to wonder if someone put a shift kit in it. Is there anyway to tell without opening the trans.?

3r!c84 · 11-27-2009, 12:01 AM

sounds like a shift kit. do it shift hard only when your getting on to it?

**old Rusty C10** · 11-27-2009, 12:04 AM

im gonna second the shift kit idea.... as long as the vacuum is good

Manbearpig · 11-27-2009, 12:05 AM

Check your fluid level as well

Desertryder · 11-27-2009, 12:08 AM

I don't have to be gettin on it for it to shift hard. It pretty much does it all the time. Anyway to check it? who puts a shift kit in a gmc beater anyway, thats crazy to me.

3r!c84 · 11-27-2009, 12:08 AM

smell it too.if it smells like burnt toast,dont change your fluid you only going to make it worse

Manbearpig · 11-27-2009, 12:33 AM

Lol I have a shift kit in mine

Desertryder · 11-27-2009, 12:40 AM

lol, i didnt mean to insult. Doesnt it bother you when it throws itself into gear like your waiting to drag race someone?

Twitchin R&C · 11-27-2009, 08:03 PM

make sure you are getting good vacuum from the intake/carb. i know mine was shifting real hard and it wasnt getting good vacuum. we gave it a good tune up(rebuilt/tuned carb, timed, etc) and it fixed the vacuum for the trans as well as the advance on the dist. runs great now.

72freak · 11-27-2009, 09:35 PM

Quote:

Originally Posted by Twitchin R&C

make sure you are getting good vacuum from the intake/carb. i know mine was shifting real hard and it wasnt getting good vacuum. we gave it a good tune up(rebuilt/tuned carb, timed, etc) and it fixed the vacuum for the trans as well as the advance on the dist. runs great now.

Thats my vote!

piecesparts · 11-28-2009, 04:23 PM

Check for a cracked vacuum line. A low vacuum to the modulator will make your tranny shift hard.

11-26-2009, 11:38 PM	#1
Desertryder Registered User Join Date: Nov 2009 Location: Casper, WY. Posts: 15	TH350 shifts hard My th350 shifts really hard from park to a gear and going down the road it shifts gears hard. I replaced the vacuum modulator and it still hard shifts. My truck is a '76 gmc 1/2 ton k15 and used mainly for fishing. I'm afraid I'm tearing stuff up with it shifting hard. I am also starting to wonder if someone put a shift kit in it. Is there anyway to tell without opening the trans.?

11-27-2009, 12:01 AM	#2
3r!c84 Badass Join Date: Jan 2009 Location: lox. fl Posts: 4,586	Re: TH350 shifts hard sounds like a shift kit. do it shift hard only when your getting on to it? __________________ Think outside the box? -84c10 (1stcar)→My Build← -00 Saturn 5spd drop a gear and disappear! 1/4:13:90

11-27-2009, 12:04 AM	#3
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,310	Re: TH350 shifts hard im gonna second the shift kit idea.... as long as the vacuum is good __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

11-27-2009, 12:05 AM	#4
Manbearpig Registered User Join Date: Mar 2009 Location: Midland, Tx Posts: 418	Re: TH350 shifts hard Check your fluid level as well __________________ 1972 GMC C10 Last edited by Manbearpig; 11-27-2009 at 12:06 AM.

11-27-2009, 12:08 AM	#5
Desertryder Registered User Join Date: Nov 2009 Location: Casper, WY. Posts: 15	Re: TH350 shifts hard I don't have to be gettin on it for it to shift hard. It pretty much does it all the time. Anyway to check it? who puts a shift kit in a gmc beater anyway, thats crazy to me. Last edited by Desertryder; 11-27-2009 at 12:13 AM.

11-27-2009, 12:08 AM	#6
3r!c84 Badass Join Date: Jan 2009 Location: lox. fl Posts: 4,586	Re: TH350 shifts hard smell it too.if it smells like burnt toast,dont change your fluid you only going to make it worse __________________ Think outside the box? -84c10 (1stcar)→My Build← -00 Saturn 5spd drop a gear and disappear! 1/4:13:90

11-27-2009, 12:33 AM	#7
Manbearpig Registered User Join Date: Mar 2009 Location: Midland, Tx Posts: 418	Re: TH350 shifts hard Lol I have a shift kit in mine __________________ 1972 GMC C10

11-27-2009, 12:40 AM	#8
Desertryder Registered User Join Date: Nov 2009 Location: Casper, WY. Posts: 15	Re: TH350 shifts hard lol, i didnt mean to insult. Doesnt it bother you when it throws itself into gear like your waiting to drag race someone?

11-27-2009, 08:03 PM	#9
Twitchin R&C Registered User Join Date: Oct 2009 Location: Tulare, California Posts: 38	Re: TH350 shifts hard make sure you are getting good vacuum from the intake/carb. i know mine was shifting real hard and it wasnt getting good vacuum. we gave it a good tune up(rebuilt/tuned carb, timed, etc) and it fixed the vacuum for the trans as well as the advance on the dist. runs great now. Last edited by Twitchin R&C; 11-27-2009 at 08:04 PM.

11-28-2009, 04:23 PM	#11
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: TH350 shifts hard Check for a cracked vacuum line. A low vacuum to the modulator will make your tranny shift hard. __________________ Frank

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