1/2 vs. 3/4 ton? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

shelby987 · 05-24-2005, 03:24 PM

I seem to remember reading a while back that the 3/4 ton trucks have boxed frames, where as the 1/2 ton trucks have the c channel frames, is this correct? and I know that the two variants run different axles and springs, but can anyone give me more specifics than that?

thecatseye66 · 05-24-2005, 04:19 PM

Larger brakes-- pads, wheel cylinders, and brake springs (not sure about the master cylinder--the front spindles are different as well...larger hubs (8-lugs)...
Along with larger spindles and axles (Dana 60,70 and Eaton rear ends) The wheel bearings are larger on those components as well to handle more load.

I know my 3/4 ton has a heavy-duty stabilizer bar and a rear end stabilizing link that isn't on my 1/2 ton.

I'm not sure about the frame differences though...

laplander · 05-24-2005, 04:35 PM

I've seen several trucks that have been switched from one to the other, so if there are differences they must still be compatable with the other's running gear.

Nik

BobS · 05-24-2005, 05:10 PM

The frames are basically the same, 3/4 tons aren't boxed.

Bob

**pjmoreland** · 05-24-2005, 05:23 PM

I believe the 3/4 Ton Chassis have a couple angled braces between the side rails and the crossmember that the driveshaft passes through. There was a picture in a thread several months ago.

thecatseye66 · 05-24-2005, 05:26 PM

Quote:

Originally Posted by BobS

The frames are basically the same, 3/4 tons aren't boxed.

Bob

I think Bob is right...
I keep hearing different things about the frames...my 1/2 ton frame doesn't look any different than my 3/4 (both '68s). One guy on this board once wrote that they used thicker steel in the 3/4 but I can't tell a difference.

Anyone ever read anything "official" on this in any GM publication?

Maximum Overdrive · 05-24-2005, 05:35 PM

My 3/4 ton frame isnt any different than by 1/2 ton frame. Front end parts and the rear end are heavy duty compared to 1/2 ton and thats about it.

Longhorn Man · 05-24-2005, 07:02 PM

The 3/4 ton has some bracing that the 1/2 ton doesn't. That is it as far as frames.
The trailing arms on a 3/4 ton are stronger.

72 CustomCamper · 05-24-2005, 07:38 PM

I know the front brakes on the front of my 72 C/20 uses the same D52 brake pads as my 86 K/10...

Chuck

67chevemall · 05-24-2005, 08:13 PM

same frame stronger "gusets" on the 3/4 ton.
rear end is bigger and so is the brakes

**Yukon Jack** · 05-25-2005, 10:51 AM

The GM restoration packet indicates the C10, C20, K10 and K20 frames all use 39,000-lb-test steel. The C10 frame section modulus is 2.98 while a K10 frame section modulus is 2.70.

The C20 frame section modulus is 3.71. The K20 frame section modulus is 3.48.

I found this definition of section modulus:

Section Modulus - A measurement that is calculated based on the shape of the cross section of the rail (what the frame rail looks like when it’s viewed from the end).

A tall rail made of thick material will have a higher section modulus than a short rail made of thinner material.

Additionally, adding an insert will increase the section modulus of the rail. Section modulus has a direct effect on the stiffness of a rail.

BobS · 05-25-2005, 10:57 AM

Any mention of the section modulus for a C30?

**Yukon Jack** · 05-26-2005, 02:16 PM

My restoration pack unfortunately only address the 1/2 ton and 3/4 tons.

BobS · 05-27-2005, 12:08 PM

Will they do a restoration pack for a C30?

Robert1970C20rstbukt · 05-27-2005, 09:49 PM

There's hardly anything about C20's in the resto pack I got. It covers mostly C10s, but I have a lot of the dealer manuals and parts books for the 10 thru 60 series trucks, this is the most recent book I have, got it for free too!

vtblazer · 05-28-2005, 07:22 AM

Here's a link for alot of frame info/specs for ya.
http://www.chuckschevytruckpages.com/framespecs.html

05-24-2005, 03:24 PM	#1
shelby987 Registered User Join Date: Mar 2005 Location: Just outside Durham, NC Posts: 894	1/2 vs. 3/4 ton? I seem to remember reading a while back that the 3/4 ton trucks have boxed frames, where as the 1/2 ton trucks have the c channel frames, is this correct? and I know that the two variants run different axles and springs, but can anyone give me more specifics than that?

05-24-2005, 04:19 PM	#2
thecatseye66 '68 C-20 396 CST CC Join Date: Mar 2005 Location: Spokane, WA Posts: 454	Larger brakes-- pads, wheel cylinders, and brake springs (not sure about the master cylinder--the front spindles are different as well...larger hubs (8-lugs)... Along with larger spindles and axles (Dana 60,70 and Eaton rear ends) The wheel bearings are larger on those components as well to handle more load. I know my 3/4 ton has a heavy-duty stabilizer bar and a rear end stabilizing link that isn't on my 1/2 ton. I'm not sure about the frame differences though... __________________ 68 C-20 396/TH400 CST Custom Camper NOW W/DISC BRAKES 01 Jetta Turbo Daily Driver 84 Yamaha Virago 700 - Alaska to Florida Via Maine & Mexico

05-24-2005, 05:10 PM	#4
BobS Senior Member Join Date: May 2001 Location: West Central Minnesota Posts: 568	The frames are basically the same, 3/4 tons aren't boxed. Bob __________________ V-6....only GMC Trucks have it! 62 GMC W5000 NAPCO-V6 65 GMC 2500 NAPCO Panel-V6 66 GMC 1000-V6 66 GMC 1500-V6 67 GMC K1500-SBC (originally a KM-V6) 68 GMC C1500-V6 68 GMC C1500-V6 68 GMC Suburban C2500 70 Chevy K20-SBC 71 Chevy C30 Longhorn-SBC 72 GMC Suburban C1500-BBC 72 Chevy C10-SBC 72 GMC C5500-ToroFlow Diesel

05-24-2005, 05:35 PM	#7
Maximum Overdrive December 21, 2012 Join Date: Apr 2000 Location: Black Eagle, Montana Posts: 1,634	My 3/4 ton frame isnt any different than by 1/2 ton frame. Front end parts and the rear end are heavy duty compared to 1/2 ton and thats about it. __________________ *"!Ama Sua, Ama Kjella, Ama Lllulla!"*

05-24-2005, 07:38 PM	#9
72 CustomCamper huh ??? Join Date: Nov 2002 Location: Fredericksburg,Va. Posts: 3,369	I know the front brakes on the front of my 72 C/20 uses the same D52 brake pads as my 86 K/10... Chuck __________________ 90 Blazer Silverado 350w/ 700R4 and 32" Kelly's "I am a bomb technician. If you see me running try to keep up!"

05-24-2005, 04:35 PM	#3
laplander Registered User Join Date: Nov 2002 Location: NM Posts: 705	I've seen several trucks that have been switched from one to the other, so if there are differences they must still be compatable with the other's running gear. Nik

05-24-2005, 05:23 PM	#5
pjmoreland Senior Member Join Date: Jan 2005 Location: CA Posts: 5,406	I believe the 3/4 Ton Chassis have a couple angled braces between the side rails and the crossmember that the driveshaft passes through. There was a picture in a thread several months ago.

05-24-2005, 07:02 PM	#8
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	The 3/4 ton has some bracing that the 1/2 ton doesn't. That is it as far as frames. The trailing arms on a 3/4 ton are stronger.

05-24-2005, 08:13 PM	#10
67chevemall Registered User Join Date: Apr 2003 Location: NB Posts: 3,367	same frame stronger "gusets" on the 3/4 ton. rear end is bigger and so is the brakes __________________ 1968 Chevy C10 307 3ott fleetside 1967 Chevy C/10 V8, 3spd, fleetside lwb.Sold 1967 Chev C/10 step, 383, M21. SOLD

05-25-2005, 10:51 AM	#11
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,683	The GM restoration packet indicates the C10, C20, K10 and K20 frames all use 39,000-lb-test steel. The C10 frame section modulus is 2.98 while a K10 frame section modulus is 2.70. The C20 frame section modulus is 3.71. The K20 frame section modulus is 3.48. I found this definition of section modulus: Section Modulus - A measurement that is calculated based on the shape of the cross section of the rail (what the frame rail looks like when it’s viewed from the end). A tall rail made of thick material will have a higher section modulus than a short rail made of thinner material. Additionally, adding an insert will increase the section modulus of the rail. Section modulus has a direct effect on the stiffness of a rail. __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

05-25-2005, 10:57 AM	#12
BobS Senior Member Join Date: May 2001 Location: West Central Minnesota Posts: 568	Any mention of the section modulus for a C30? __________________ V-6....only GMC Trucks have it! 62 GMC W5000 NAPCO-V6 65 GMC 2500 NAPCO Panel-V6 66 GMC 1000-V6 66 GMC 1500-V6 67 GMC K1500-SBC (originally a KM-V6) 68 GMC C1500-V6 68 GMC C1500-V6 68 GMC Suburban C2500 70 Chevy K20-SBC 71 Chevy C30 Longhorn-SBC 72 GMC Suburban C1500-BBC 72 Chevy C10-SBC 72 GMC C5500-ToroFlow Diesel

05-26-2005, 02:16 PM	#13
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,683	My restoration pack unfortunately only address the 1/2 ton and 3/4 tons. __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

05-27-2005, 12:08 PM	#14
BobS Senior Member Join Date: May 2001 Location: West Central Minnesota Posts: 568	Will they do a restoration pack for a C30? __________________ V-6....only GMC Trucks have it! 62 GMC W5000 NAPCO-V6 65 GMC 2500 NAPCO Panel-V6 66 GMC 1000-V6 66 GMC 1500-V6 67 GMC K1500-SBC (originally a KM-V6) 68 GMC C1500-V6 68 GMC C1500-V6 68 GMC Suburban C2500 70 Chevy K20-SBC 71 Chevy C30 Longhorn-SBC 72 GMC Suburban C1500-BBC 72 Chevy C10-SBC 72 GMC C5500-ToroFlow Diesel

05-27-2005, 09:49 PM	#15
Robert1970C20rstbukt Registered User Join Date: Jun 2004 Location: Beeville, Texas Posts: 1,943	There's hardly anything about C20's in the resto pack I got. It covers mostly C10s, but I have a lot of the dealer manuals and parts books for the 10 thru 60 series trucks, this is the most recent book I have, got it for free too! Attached Images __________________ RJD 1984 Chevrolet C30 welding truck 454/SM465 1977 GMC C15 pickup 350/TH350 1970 Chevrolet C20 pickup 350/TH400 1970 Chevrolet K20 Suburban 454/TH350 1969 GMC 8500 478M V6/5 spd winch truck

05-28-2005, 07:22 AM	#16
vtblazer Registered User Join Date: Oct 2003 Location: Central Vermont Posts: 8,538	Here's a link for alot of frame info/specs for ya. http://www.chuckschevytruckpages.com/framespecs.html



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