The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > Heavy Haulers

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 09-27-2021, 08:39 PM   #1
cornerstone
Senior Member
 
cornerstone's Avatar
 
Join Date: Apr 2014
Location: Azle,Texas
Posts: 2,034
C50 5 speed?

I've recently transformed a 1968 C50 grain truck into a dump truck and plan on driving the behemoth on the highways fairly regularly. It still has all of its original equipment, a 327 with a 4 speed manual and a split rear differential. 58 mph is all she's got. (downhill with a tailwind) Every time I run through the gears I wish there was one more gear to grab. My thoughts are to swap out the 4 speed gearbox with a 5.

Has anyone done this? Am I asking for something I'll regret? Any help or advice appreciated!
__________________
Brian


1972 C10, "Loyd", LWB to SWB, 5.3, L83/6L80e, 4:11 Tru Trac, Air Ride, VA, DD, 20" Coys, 4 wheel disc, A quick LS swap turned into a 4 year frame off.
cornerstone is offline   Reply With Quote
Old 09-28-2021, 07:16 AM   #2
lexadmn
New Member
 
Join Date: Feb 2020
Location: West Plains
Posts: 18
Re: C50 5 speed?

If I am wrong, hopefully someone will correct me.
I don't think a 5 speed will do you any good for achieving a higher "mph" as the final drive is 1 to 1, just as it is on 4 speeds unless you find something like a Clark V0 overdrive 5 speed - which the final drive is 1 to .8, or another form of overdrive.
Attached Images
 
lexadmn is offline   Reply With Quote
Old 09-28-2021, 08:39 AM   #3
C10 - C90 Bill
Registered User
 
C10 - C90 Bill's Avatar
 
Join Date: Nov 2001
Location: Moneta, VA USA
Posts: 2,757
Re: C50 5 speed?

Right, the regular 5-Speed will still be 1 to 1. It will just give you 2 extra gears in-between and most likely a much lower Granny Gear.

Brian, when you say "one more gear to grab" which gear would you be referring to?

If you are desiring another last gear, you would need an Overdrive as lexadmn has mentioned.
__________________
'60-'72 Chev/GMC Fan
GMC 9500 Fan
Detroit Diesel Fan
C10 - C90 Bill is offline   Reply With Quote
Old 09-28-2021, 09:44 AM   #4
cornerstone
Senior Member
 
cornerstone's Avatar
 
Join Date: Apr 2014
Location: Azle,Texas
Posts: 2,034
Re: C50 5 speed?

Yes, thanks guys, an overdrive of sorts. I remember I had a 6 speed manual once that had a .67 final ratio, if my memory serves me correct.
__________________
Brian


1972 C10, "Loyd", LWB to SWB, 5.3, L83/6L80e, 4:11 Tru Trac, Air Ride, VA, DD, 20" Coys, 4 wheel disc, A quick LS swap turned into a 4 year frame off.
cornerstone is offline   Reply With Quote
Old 09-28-2021, 09:59 AM   #5
ky-donzi
Registered User
 
Join Date: Jun 2012
Location: madisonville ky
Posts: 210
Re: C50 5 speed?

Almost all of the older 5 speeds were 1:1 final. There were a few with OD and if I remember correctly they had weird shift patterns. Some achieved OD by swapping the gears on shaft cluster. So a 1,2,3,4,5 became a 1,2,OD,3,4 3rd was revered to become OD.

The reason I tell you this is the old OD transmissions weren’t very impressive, look for a modern 5 sp out of a more modern med duty truck, or used a nv4500. In a 2wd format they are easy to find, and if you get one from a 3500hd it will have a parking brake on the tail shaft.
__________________
61 GMC 4x4 1-ton flatbed 4bt cummins, ranger od, sm465, np 205, d60F, d70R 4.11 10,000 ramsey PTO winch.... SOLD

73 k5 350/sm465/np205

Last edited by ky-donzi; 09-28-2021 at 08:48 PM.
ky-donzi is offline   Reply With Quote
Old 09-28-2021, 10:19 AM   #6
C10 - C90 Bill
Registered User
 
C10 - C90 Bill's Avatar
 
Join Date: Nov 2001
Location: Moneta, VA USA
Posts: 2,757
Re: C50 5 speed?

Either that or go with a Brownie with an OD. An Auxiliary Trans that you mount in back of your present trans. You will then have 2 Shifters, but all the gears you will need with OD to boot. Although they are not that easy to find and a little work to install.
__________________
'60-'72 Chev/GMC Fan
GMC 9500 Fan
Detroit Diesel Fan
C10 - C90 Bill is offline   Reply With Quote
Old 09-28-2021, 11:00 AM   #7
ky-donzi
Registered User
 
Join Date: Jun 2012
Location: madisonville ky
Posts: 210
Re: C50 5 speed?

If an aux trans is an option, I use to have a truck with a ranger od unit, advanced adapter makes them. It performed well. It would be alit complicated tho with a ranger and a 2sp rear end. Thief proof
__________________
61 GMC 4x4 1-ton flatbed 4bt cummins, ranger od, sm465, np 205, d60F, d70R 4.11 10,000 ramsey PTO winch.... SOLD

73 k5 350/sm465/np205
ky-donzi is offline   Reply With Quote
Old 09-28-2021, 11:42 AM   #8
ky-donzi
Registered User
 
Join Date: Jun 2012
Location: madisonville ky
Posts: 210
Re: C50 5 speed?

If an aux trans is an option, I use to have a truck with a ranger od unit, advanced adapter makes them. It performed well. It would be alit complicated tho with a ranger and a 2sp rear end. Thief proof
__________________
61 GMC 4x4 1-ton flatbed 4bt cummins, ranger od, sm465, np 205, d60F, d70R 4.11 10,000 ramsey PTO winch.... SOLD

73 k5 350/sm465/np205
ky-donzi is offline   Reply With Quote
Old 09-28-2021, 08:14 PM   #9
sweetk30
Registered User
 
sweetk30's Avatar
 
Join Date: May 2012
Location: horseheads,ny rust belt
Posts: 2,754
Re: C50 5 speed?

read up on the military 2.5ton 5speed . there o.d. on 5th but funky shift pattern . also they basicly bolt up to a gm bell housing that had a 5 speed factory . ( i have a whole extra bell setup from a med duty gas 5 speed )

otherwise browny box / aux box and another lever on the floor to shift .

keep in mind the brakes and tires and steering on these old girls was NOT ment for 70+ mph use so watch what mods you do and be prepared for the next round of upgrades .
__________________
77-k30lb BIG truck build .
87-k30lb budget beater build .
85-k30lb the plow machine build .
85-c10sb summer fun toy .
-----------------------------
HOLLEY SNIPER efi = worst case of p.i.t.a i ever had .

EDELBROCK pro flo 4 = best deal going so far . love my setup works great.
sweetk30 is offline   Reply With Quote
Old 10-02-2021, 11:19 AM   #10
factorystock
Registered User
 
factorystock's Avatar
 
Join Date: Feb 2007
Location: west coast
Posts: 2,831
Re: C50 5 speed?

Quote:
Originally Posted by lexadmn View Post
you find something like a Clark V0 overdrive 5 speed - which the final drive is 1 to .8, or another form of overdrive.
I agree, the Clark 280 VO was the optional overdrive back in the day with the .8 overdrive, which IMO, would be perfect. Modern overdrives, like the NV, are more common, but are around .7 overdrive ( larger step down in rpm ). Like ky-donzi mentioned, the 1 ton 3500HD version has the much needed parking brake drum. Make sure the NV4500 is a good unit first, many have noisy bearings that need a professional rebuild.
factorystock is offline   Reply With Quote
Old 10-02-2021, 12:02 PM   #11
C10 - C90 Bill
Registered User
 
C10 - C90 Bill's Avatar
 
Join Date: Nov 2001
Location: Moneta, VA USA
Posts: 2,757
Re: C50 5 speed?

Curious if the NV4500 will bolt right in. If not, what mods would be needed to make a complete swap?
__________________
'60-'72 Chev/GMC Fan
GMC 9500 Fan
Detroit Diesel Fan
C10 - C90 Bill is offline   Reply With Quote
Old 10-02-2021, 09:56 PM   #12
factorystock
Registered User
 
factorystock's Avatar
 
Join Date: Feb 2007
Location: west coast
Posts: 2,831
Re: C50 5 speed?

Here is a good write up on the installation in a 1 ton http://67-72chevytrucks.com/vboard/s...t=nv4500+1+ton
factorystock is offline   Reply With Quote
Old 10-02-2021, 10:51 PM   #13
va72longhorn
Senior Member
 
va72longhorn's Avatar
 
Join Date: Dec 2009
Location: Culpeper, VA
Posts: 331
Re: C50 5 speed?

Is there an option to incorporate a two speed rear into a C30?
va72longhorn is offline   Reply With Quote
Old 10-03-2021, 12:50 PM   #14
C10 - C90 Bill
Registered User
 
C10 - C90 Bill's Avatar
 
Join Date: Nov 2001
Location: Moneta, VA USA
Posts: 2,757
Re: C50 5 speed?

Quote:
Originally Posted by va72longhorn View Post
Is there an option to incorporate a two speed rear into a C30?
Not without installing a 2-Ton Rear and even then it would still be 1 to 1.

But if you are talking aftermarket, that would be a great idea. An Electric 2-Speed Rear with the high gear being high enough to be like an Overdrive.
__________________
'60-'72 Chev/GMC Fan
GMC 9500 Fan
Detroit Diesel Fan
C10 - C90 Bill is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 09:31 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Copyright 1997-2020 67-72chevytrucks.com