Converting Auto Equipped Truck Cab to 4 Speed Manual - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Dave K. · 12-14-2017, 07:29 AM

Cab 1: 1968 2wd Auto
Chassis to be installed on: 1968 4wd K20 Long bed

Just curious what needs to be done to modify 68 2WD cab originally equipped with an auto to accept a 4 speed floor shift. I have a nice 68 Cab I wanted to use for a project and the project has a 4 speed (a K20 long bed). Understand I have to change up the pedals (are they a direct bolt in)? Also I'm guessing the hump and cover for the 4 speed has to be added in but not sure how much work that is... as well as the transfer case shifter hole and such. Interested if anyone has insights here--better yet pics!

Thanks, Dave.

Dave K. · 12-15-2017, 06:44 PM

Nada on the input front here? Someone must have done this before.

**'68OrangeSunshine** · 12-15-2017, 06:54 PM

There's a Z-Bar pivot bracket on the drivers side frame, you'll have to cannibalize off a manual frame, or build your own from a short piece of angle iron.
Don't forget to 'neutralize' the Neutral Safety switch in your wiring harness. Not necessary with a manual transmission, but an unmodified Automatic harness will be always open without bridging this gap.
You will need a high hump panel.
The clutch pedal should slip on the same axis as the brake pedal. Not sure how. There is a clutch pedal return spring inside the cab, not present in TH production cabs.
I haven't done this myself, but I have an OEM-automatic K/5 I want to ressurrect with an SM465/T221 tranny/transfer case.

Dave K. · 12-16-2017, 09:40 AM

Thanks for the input. I have the manual cab and such so transferring the parts from the to the auto cab shouldn't be a problem. I have the high hump as well . Point taken about the harness, good catch. I hope the peddle assembly and such is just a direct bolt-in.... can't imagine why it wouldn't be.

**Classic Heartbeat** · 12-16-2017, 01:32 PM

Pedal assembly is direct bolt in. WES

Ugly 61 · 12-16-2017, 08:04 PM

Actually the clutch pedal shaft will slip into the hollow center of the brake pedal shaft and if I remember correctly the clutch pedal shaft is held in place by a e-clip. I did this conversion in reverse several years ago. You can take your auto shift lever out of the steering column or replace the column with one from a manual trans. truck

Don Quixote · 12-18-2017, 06:46 PM

FYSA, I happen to have a V8 Z-bar and the engine side mount bracket. I swapped a 292 back into mine recently and I have some V8 stuff kicking around. I think I have a crossmember as well.

demian5 · 12-19-2017, 05:35 PM

Ive been thinking about it and if I did, I would use a hydraulic pedal and slave cylinder to operate the factory fork to eliminate the crappy pedal height and z-bar issues. The novac i like because you have to pull nothing.

http://www.superchevy.com/how-to/tra...raulic-clutch/

http://www.moderndriveline.com/catal...ic_masters.htm

http://transmission.moderndriveline....aulics-c25.htm

https://www.novak-adapt.com/catalog/...-hcr3/kit-hcrc

12-14-2017, 07:29 AM	#1
Dave K. Registered User Join Date: Jul 2009 Location: Milwaukee, WI Posts: 575	Converting Auto Equipped Truck Cab to 4 Speed Manual Cab 1: 1968 2wd Auto Chassis to be installed on: 1968 4wd K20 Long bed Just curious what needs to be done to modify 68 2WD cab originally equipped with an auto to accept a 4 speed floor shift. I have a nice 68 Cab I wanted to use for a project and the project has a 4 speed (a K20 long bed). Understand I have to change up the pedals (are they a direct bolt in)? Also I'm guessing the hump and cover for the 4 speed has to be added in but not sure how much work that is... as well as the transfer case shifter hole and such. Interested if anyone has insights here--better yet pics! Thanks, Dave.

12-15-2017, 06:44 PM	#2
Dave K. Registered User Join Date: Jul 2009 Location: Milwaukee, WI Posts: 575	Re: Converting Auto Equipped Truck Cab to 4 Speed Manual Nada on the input front here? Someone must have done this before.

12-15-2017, 06:54 PM	#3
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,047	Re: Converting Auto Equipped Truck Cab to 4 Speed Manual There's a Z-Bar pivot bracket on the drivers side frame, you'll have to cannibalize off a manual frame, or build your own from a short piece of angle iron. Don't forget to 'neutralize' the Neutral Safety switch in your wiring harness. Not necessary with a manual transmission, but an unmodified Automatic harness will be always open without bridging this gap. You will need a high hump panel. The clutch pedal should slip on the same axis as the brake pedal. Not sure how. There is a clutch pedal return spring inside the cab, not present in TH production cabs. I haven't done this myself, but I have an OEM-automatic K/5 I want to ressurrect with an SM465/T221 tranny/transfer case. __________________ Every 25 years I like to rebuild that 292, whether it needs it or not. Last edited by '68OrangeSunshine; 12-15-2017 at 07:00 PM.

12-16-2017, 09:40 AM	#4
Dave K. Registered User Join Date: Jul 2009 Location: Milwaukee, WI Posts: 575	Re: Converting Auto Equipped Truck Cab to 4 Speed Manual Thanks for the input. I have the manual cab and such so transferring the parts from the to the auto cab shouldn't be a problem. I have the high hump as well . Point taken about the harness, good catch. I hope the peddle assembly and such is just a direct bolt-in.... can't imagine why it wouldn't be.

12-16-2017, 01:32 PM	#5
Classic Heartbeat Project Junkie! Fishing Poor!! Join Date: Dec 1999 Location: Olympia,Wa. 98512 Posts: 10,770	Re: Converting Auto Equipped Truck Cab to 4 Speed Manual Pedal assembly is direct bolt in. WES __________________ On-line catolog Classic Heartbeat Pickup Parts WEHEPP@comcast.net Call us Toll Free (888) 338-2502 Like Us on Facebook No appointment necessary. 72 BB Chevy Custom Deluxe / Custom Camper 67 I-6 (Soon to be 5.7 LS1) Panel 68 BB Chevy Short Bed 72 6.0 LQ9 Short Bed Chevy 4X4 Olympia's fastest growing truck parts supplier. Olympia's home for Wayward Chevys

12-16-2017, 08:04 PM	#6
Ugly 61 Registered User Join Date: Jan 2015 Location: Clyde KS Posts: 91	Re: Converting Auto Equipped Truck Cab to 4 Speed Manual Actually the clutch pedal shaft will slip into the hollow center of the brake pedal shaft and if I remember correctly the clutch pedal shaft is held in place by a e-clip. I did this conversion in reverse several years ago. You can take your auto shift lever out of the steering column or replace the column with one from a manual trans. truck

12-18-2017, 06:46 PM	#7
Don Quixote Registered User Join Date: May 2008 Location: Woodlawn, TN Posts: 275	Re: Converting Auto Equipped Truck Cab to 4 Speed Manual FYSA, I happen to have a V8 Z-bar and the engine side mount bracket. I swapped a 292 back into mine recently and I have some V8 stuff kicking around. I think I have a crossmember as well. __________________ Rocinante: 1972 GMC C25, 292, SM465, 14 bolt, power nothing, 440k and still handles my PCS moves Jorge: Kia Roller-skate with lots of buttons for the wife Wovoka: 2017 Indian Chief Vintage, better on gas but not much So far, this is the oldest I've ever been.

12-19-2017, 05:35 PM	#8
demian5 Registered User Join Date: Aug 2016 Location: Lake Forest, CA Posts: 2,177	Re: Converting Auto Equipped Truck Cab to 4 Speed Manual Ive been thinking about it and if I did, I would use a hydraulic pedal and slave cylinder to operate the factory fork to eliminate the crappy pedal height and z-bar issues. The novac i like because you have to pull nothing. http://www.superchevy.com/how-to/tra...raulic-clutch/ http://www.moderndriveline.com/catal...ic_masters.htm http://transmission.moderndriveline....aulics-c25.htm https://www.novak-adapt.com/catalog/...-hcr3/kit-hcrc __________________ "Work hard, use your vacation days." 1970 C15 GMC Long Bed 1986 C20 Scottsdale 1983 K2500 Sierra Classic Suburban 6.2 Instagram: C10sofOC



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