Author Topic: Grinding when shifting gears  (Read 2010 times)

Offline Aaron

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Grinding when shifting gears
« on: April 10, 2018, 07:36:00 AM »
Hello all,

This is only the 2nd time I have posted on this site and I’m realitively new to the square body family and working on trucks. I have a 1979 Chevy K20 with a manual 4 speed granny transmission in it. I know that these older trucks are a beast on their own when it comes driving them but no matter what I do it always grinds when trying to shift into 1st gear or any gear after that. I’m almost 100% sure it has something to do with the clutch not disengaging and needing to be replaced but I would love y’alls feedback on it. Whenever the truck is off it moves into each gear extremely smoothly but like I said earlier, whether I feather the clutch or push it all the way forward, it never goes into gear without having to muscle it in and then having to muscle it out of gear and into another one. And help would be greatly appreciated.

Offline Jason S

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Re: Grinding when shifting gears
« Reply #1 on: April 10, 2018, 08:02:10 AM »
You might check the clutch adjustment itself. Also check for wear in all the clutch release parts, like z-bar (i.e., bell crank, cross shaft, etc) bushings, worn out release linkages and corresponding holes. 

Do you have any idea about how many miles are on the clutch and pressure plate?

Below is a link to the rebuild process on the z-bar - as for the photos, another photobucket phail... 
http://forum.73-87chevytrucks.com/smforum/index.php?topic=28126.msg234354#msg234354
« Last Edit: April 10, 2018, 08:11:44 AM by Jason S »
1973 GMC K2500, Super Custom, Camper Special, 350, TH350, NP203, 4.10's
1974 Chevrolet K10, Custom Deluxe, 350, SM465, NP203, 3.73's

"1) Peace through strength; 2) Trust but verify; 3) Beware of evil in the modern world"

Offline Captain Swampy

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  • Wisconsin
Re: Grinding when shifting gears
« Reply #2 on: April 10, 2018, 05:37:16 PM »
Maybe the pilot bearing is bad. It's in the end of the crank and supports the end of the input shaft when you depress the clutch.
1987  350TBI 700R4  4X4  4.56 gears  33" BFG All Terrain


http://forum.73-87chevytrucks.com/smforum/index.php?topic=32209.0

Offline 1967KaiserM715

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  • 1985 GMC K1500 w/ 6.5 TD
Re: Grinding when shifting gears
« Reply #3 on: April 10, 2018, 06:44:08 PM »
Check the clutch adjustment, but another issue could just be the transmission syncros are shot. If the synchro is worn enough, when it is spinning it can't align right, where as being still, it's easier for the shift collar to push the synchro where it should be.

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Current Vehicles:1985 GMC K10(Daily) 1991 GMC K2500(Daily) 1975 Beetle(not running) 1985 Mercedes 300D(not running) 1952 M35    1967 M715(not running)
 1986 Chevy K30(under repair)