SM420 Problems Wont go into gear - The 1947 - Present Chevrolet & GMC Truck Message Board Network

F-85 · 03-06-2012, 12:01 AM

I just bought myu buddys 65 GMCwith 305E and SM420. It was working fine. But the last 2 days has been getting worse going into gear and now it almost wont go into gear. I cant go into second at all. But all the other gears work fine when not running. But running it wont go into any gear.

F-85 · 03-06-2012, 12:35 AM

Its something to do with the pressure plate. Its bending the rod that gos from the pedal to the Zbar. Any ideas?

krazy_texan · 03-06-2012, 01:26 AM

you can check that but if that where the case you would think that you would have that issue with all the gears. i seem to recall having a similar problem years ago on my sm465 but cant remember what i did to fix it.

*blackedoutharley* · 03-06-2012, 06:20 AM

Process of elimination... disconnect the rod that comes through the floorboard and see if the pedal frees up. if so then reconnect it and remove the one that goes from the zbar to the clutch fork... this should diagnose a binding zbar.

F-85 · 03-06-2012, 08:42 AM

I figured it out last night. I think it was just Time and a stiff pressure plate. I took the rod out bent it back straight and welded a pc of rod along side of it to stiffen it up. I know its not the best solution. But i was stuck at the shop last night and i had to do something. Im gonna end up swapping this trans (maybe motor and trans) This spring anyway. If i stick with manual ill get a regular pressure plate, and a new rod. Thanks for the tips guys.

03-06-2012, 12:01 AM	#1
F-85 Registered User Join Date: Jul 2010 Location: Paw Paw,il Posts: 389	SM420 Problems Wont go into gear I just bought myu buddys 65 GMCwith 305E and SM420. It was working fine. But the last 2 days has been getting worse going into gear and now it almost wont go into gear. I cant go into second at all. But all the other gears work fine when not running. But running it wont go into any gear.

03-06-2012, 12:35 AM	#2
F-85 Registered User Join Date: Jul 2010 Location: Paw Paw,il Posts: 389	Re: SM420 Problems Wont go into gear Its something to do with the pressure plate. Its bending the rod that gos from the pedal to the Zbar. Any ideas?

03-06-2012, 01:26 AM	#3
krazy_texan Registered User Join Date: Oct 2002 Location: West Des Moines, Ia Posts: 3,233	Re: SM420 Problems Wont go into gear you can check that but if that where the case you would think that you would have that issue with all the gears. i seem to recall having a similar problem years ago on my sm465 but cant remember what i did to fix it. __________________ Krazy Texan My Trucks are made with Wrenches not Chop Sticks 1967 GMC 3/4 ton "Johnny Cash" 1990 v1500 suburban 1967 Ford f100 Swb 4x4 "green bean" GOD BLESS JESUS, JOHN WAYNE, AND THE ALAMO

03-06-2012, 06:20 AM	#4
blackedoutharley Account Suspended Join Date: Jul 2007 Location: Plumas Lake, Ca. Posts: 1,009	Re: SM420 Problems Wont go into gear Process of elimination... disconnect the rod that comes through the floorboard and see if the pedal frees up. if so then reconnect it and remove the one that goes from the zbar to the clutch fork... this should diagnose a binding zbar.

03-06-2012, 08:42 AM	#5
F-85 Registered User Join Date: Jul 2010 Location: Paw Paw,il Posts: 389	Re: SM420 Problems Wont go into gear I figured it out last night. I think it was just Time and a stiff pressure plate. I took the rod out bent it back straight and welded a pc of rod along side of it to stiffen it up. I know its not the best solution. But i was stuck at the shop last night and i had to do something. Im gonna end up swapping this trans (maybe motor and trans) This spring anyway. If i stick with manual ill get a regular pressure plate, and a new rod. Thanks for the tips guys.



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