3/4 to 1/2 ton conversion - The 1947 - Present Chevrolet & GMC Truck Message Board Network

CJ Loeffelholz · 08-01-2010, 10:17 AM

Have any of you guys ever changed a 3/4 ton to a 1/2?
I've got a '65 3/4 ton LWB. I'm seriously considering making it in to a 1/2 ton truck.

What are the differences between a 1/2 ton and 3/4 ton chassis?

If it's just the A-arms, rear end, springs and track bar, I'd be better off keeping the frame and just locating a donor truck.

Fursphere · 08-01-2010, 10:21 AM

Why do you want to convert it? What is your end goal for this project?

I would think it would be easier to just trade the entire truck for what you want.

CJ Loeffelholz · 08-01-2010, 10:24 AM

The body is already off the truck, and most of it is in epoxy. It will be a really nice driver when complete. I need to start the chassis restoration soon, but I much rather have a 1/2 ton.

6863m · 08-01-2010, 12:16 PM

I am not following why. Gas milage, doesn't a 3/4 ton look just like a 1/2 ton as long as you have the same wheels and tires. And you can soften the ride I would think with some changes.

CJ Loeffelholz · 08-01-2010, 02:35 PM

Most importantly, I don't want 8 lug wheels, I want 6 lug wheels. Also, in my experience, it's a lot easier to find highway gears for 1/2 ton trucks than 3/4 ton trucks. Finally, 1/2 ton parts seem to be available longer than 3/4 ton parts. I struggled to find a number of parts on my earlier 3/4 ton and vowed to never build a 3/4 again.

Anyway, my question relates to the differences between the 1/2 ton and 3/4 ton chassis.

Fursphere · 08-01-2010, 02:53 PM

Funny, after buying my 2001 K1500 Silverado - I vowed to never buy a 1/2 ton again! Something about owning a truck with limited use just drives me insane.

As far as your rig -

I believe they are the same - just heavier springs and a bigger powertrain. The 4x4s are quite a big different though.

EDIT:
Ok, per LMC trucking catalog... Its just slight differences in the suspension parts. Like the front and rear coil springs have different part numbers 1/2 vs 3/4...

6863m · 08-01-2010, 03:08 PM

Fursphere, I am with you on the 1/2 ton. I have 2004 Sierra 1/2 ton and I am considering buying a early 70's 3/4 ton and cleaning it up and doing some cosmetics. When i finish the current project. I can just park it until I need it or my wife makes me sell something.

CJ Loeffelholz · 08-01-2010, 03:19 PM

Modern trucks that you're planning on using for hauling are a different story. The most this truck will ever haul is a cooler. The really steep gears make the truck pretty highway unfriendly, and I have a lot of cool 6-lug wheels that I'd like mount on there.

The only difference in the power train that I know of is the rear end. Obviously, the 3/4 ton has bigger brakes, and obviously the wheels are different. The A arms are most likely different, and the tracking arm too. I think even the cab mounts are different. The cab mounts on this 3/4 aren't like the 1/2 ton cab mounts.

Sillyoldman · 08-01-2010, 04:42 PM

I just swapped out F&R 3/4 to 1/2 ton lowering springs. Much softer ride and stance imo.

62gmc910 · 08-01-2010, 10:05 PM

I believe the rails are a little thicker steel but other than that it is pretty much the same . Look thru the FAC sticky at the top , 70suburban had a 6 bolt disc parts list I think . as to the rear axle 73-79 4x4s have 6 bolt most are gm 12 bolt lots of gears available

**Captainfab** · 08-02-2010, 01:02 AM

On these years of C20's you can't just change the lower control arms as the shafts mount differently. It would be easiest to just change the crossmember and all for a '73-'87 C10 unit. As for the rear differential, a '71-'72 will be a bolt in, The '73-'87 rear differentials are the same width as the '71-'72 (which by the way are 1.5" wider than the '63-'70 rear differentials) but you will need to remove the leaf spring pads and weld on the trailing arm mounts. Also you will need to add some sort of mount for the panhard bar. You should be able to transfer the one from your HO52 rear differential to your new one.

raycow · 08-02-2010, 11:34 AM

Quote:

Originally Posted by CJ Loeffelholz

I've got a '65 3/4 ton LWB. I'm seriously considering making it in to a 1/2 ton truck.

You can't make truck into a "real" 1/2 ton, because the 3/4 ton frame is heavier. However, you can make it close enough so that most people won't notice.

Swap the springs of course. The 1/2 ton rear will bolt up to your stock trailing arms. On the front, swap everything from the control arm shafts out, and also the steering linkage if the tie rod ends are different where they attach to the spindles.

Ray

sighlurr · 02-13-2013, 04:55 PM

Quote:

Originally Posted by raycow

You can't make truck into a "real" 1/2 ton, because the 3/4 ton frame is heavier. However, you can make it close enough so that most people won't notice.

Swap the springs of course. The 1/2 ton rear will bolt up to your stock trailing arms. On the front, swap everything from the control arm shafts out, and also the steering linkage if the tie rod ends are different where they attach to the spindles.

Ray

Is this true? The 3/4 frame rails are actually heavier? That seems odd.

CaptainFab - thoughts?
Posted via Mobile Device

**Chevy Fleetside** · 08-02-2010, 01:05 PM

I will be putting 1/2 ton suspension in mine also. Mostly for drivablity. Lots of Freeway.. I have also thought about selling it.

63burban · 02-13-2013, 06:14 PM

CJ, Didn't we go through this already. After you move you can buy a Morrison chassis. B>} Maybe this summer I'll change your chassis over for you.

sighlurr · 02-13-2013, 08:41 PM

I've heard the rear cab mounts are different...

**Captainfab** · 02-14-2013, 01:31 AM

Yes, I believe the C20 frames are slighter heavier. The C20 and up trucks do have a different style rear cab mount, but the location is the same as the C10 cab mounts. The C20 trailing arms also have added reinforcement on them.

Quote:

Originally Posted by DSIGH

Is this true? The 3/4 frame rails are actually heavier? That seems odd.

CaptainFab - thoughts?
Posted via Mobile Device

Quote:

Originally Posted by DSIGH

I've heard the rear cab mounts are different...

sighlurr · 02-14-2013, 01:58 PM

Quote:

Originally Posted by Captainfab

Yes, I believe the C20 frames are slighter heavier. The C20 and up trucks do have a different style rear cab mount, but the location is the same as the C10 cab mounts. The C20 trailing arms also have added reinforcement on them.

Right on. Thank you. Crisis avoided!

ACK · 02-14-2013, 02:47 PM

Quote:

Originally Posted by DSIGH

I've heard the rear cab mounts are different...

I came across this article a couple of days ago regarding the 1/2 and 3/4 ton mounts http://www.persh.org/pickup/c20_cab_mounts.htm

08-01-2010, 10:17 AM	#1
CJ Loeffelholz Registered User Join Date: Jul 2010 Location: Wisconsin Posts: 63	3/4 to 1/2 ton conversion Have any of you guys ever changed a 3/4 ton to a 1/2? I've got a '65 3/4 ton LWB. I'm seriously considering making it in to a 1/2 ton truck. What are the differences between a 1/2 ton and 3/4 ton chassis? If it's just the A-arms, rear end, springs and track bar, I'd be better off keeping the frame and just locating a donor truck.

08-01-2010, 10:21 AM	#2
Fursphere Registered User Join Date: Nov 2009 Location: Rancho Cordova, CA Posts: 54	Re: 3/4 to 1/2 ton conversion Why do you want to convert it? What is your end goal for this project? I would think it would be easier to just trade the entire truck for what you want. __________________ 1966 C10 Panel (3/4 Ton 4x4 Conversion) 2001 K1500 Silverado

08-01-2010, 10:24 AM	#3
CJ Loeffelholz Registered User Join Date: Jul 2010 Location: Wisconsin Posts: 63	Re: 3/4 to 1/2 ton conversion The body is already off the truck, and most of it is in epoxy. It will be a really nice driver when complete. I need to start the chassis restoration soon, but I much rather have a 1/2 ton.

08-01-2010, 12:16 PM	#4
6863m Registered User Join Date: Feb 2009 Location: Alpine Ca, Posts: 123	Re: 3/4 to 1/2 ton conversion I am not following why. Gas milage, doesn't a 3/4 ton look just like a 1/2 ton as long as you have the same wheels and tires. And you can soften the ride I would think with some changes.

08-01-2010, 02:35 PM	#5
CJ Loeffelholz Registered User Join Date: Jul 2010 Location: Wisconsin Posts: 63	Re: 3/4 to 1/2 ton conversion Most importantly, I don't want 8 lug wheels, I want 6 lug wheels. Also, in my experience, it's a lot easier to find highway gears for 1/2 ton trucks than 3/4 ton trucks. Finally, 1/2 ton parts seem to be available longer than 3/4 ton parts. I struggled to find a number of parts on my earlier 3/4 ton and vowed to never build a 3/4 again. Anyway, my question relates to the differences between the 1/2 ton and 3/4 ton chassis.

08-01-2010, 02:53 PM	#6
Fursphere Registered User Join Date: Nov 2009 Location: Rancho Cordova, CA Posts: 54	Re: 3/4 to 1/2 ton conversion Funny, after buying my 2001 K1500 Silverado - I vowed to never buy a 1/2 ton again! Something about owning a truck with limited use just drives me insane. As far as your rig - I believe they are the same - just heavier springs and a bigger powertrain. The 4x4s are quite a big different though. EDIT: Ok, per LMC trucking catalog... Its just slight differences in the suspension parts. Like the front and rear coil springs have different part numbers 1/2 vs 3/4... __________________ 1966 C10 Panel (3/4 Ton 4x4 Conversion) 2001 K1500 Silverado Last edited by Fursphere; 08-01-2010 at 03:02 PM.

08-01-2010, 03:08 PM	#7
6863m Registered User Join Date: Feb 2009 Location: Alpine Ca, Posts: 123	Re: 3/4 to 1/2 ton conversion Fursphere, I am with you on the 1/2 ton. I have 2004 Sierra 1/2 ton and I am considering buying a early 70's 3/4 ton and cleaning it up and doing some cosmetics. When i finish the current project. I can just park it until I need it or my wife makes me sell something.

08-01-2010, 03:19 PM	#8
CJ Loeffelholz Registered User Join Date: Jul 2010 Location: Wisconsin Posts: 63	Re: 3/4 to 1/2 ton conversion Modern trucks that you're planning on using for hauling are a different story. The most this truck will ever haul is a cooler. The really steep gears make the truck pretty highway unfriendly, and I have a lot of cool 6-lug wheels that I'd like mount on there. The only difference in the power train that I know of is the rear end. Obviously, the 3/4 ton has bigger brakes, and obviously the wheels are different. The A arms are most likely different, and the tracking arm too. I think even the cab mounts are different. The cab mounts on this 3/4 aren't like the 1/2 ton cab mounts. Last edited by CJ Loeffelholz; 08-01-2010 at 03:22 PM.

08-01-2010, 04:42 PM	#9
Sillyoldman #16876 Join Date: Apr 2005 Location: Auburn WA Posts: 12,266	Re: 3/4 to 1/2 ton conversion I just swapped out F&R 3/4 to 1/2 ton lowering springs. Much softer ride and stance imo. __________________ Posted via Stationary Device '71 Custom Deluxe C-20 402. '67 Buick Special 455. '49 Plymouth Special Deluxe. *"I love that old car smell"* *Some people are like Slinkies... not really good for anything, but they still bring a smile to your face when you push them down a flight of stairs.*

08-01-2010, 10:05 PM	#10
62gmc910 Registered User Join Date: Nov 2009 Location: Cremona AB Canada Posts: 370	Re: 3/4 to 1/2 ton conversion I believe the rails are a little thicker steel but other than that it is pretty much the same . Look thru the FAC sticky at the top , 70suburban had a 6 bolt disc parts list I think . as to the rear axle 73-79 4x4s have 6 bolt most are gm 12 bolt lots of gears available __________________ 62 GMC 910 short fleetside 454 super t10 14 bolt w/gov lock 70s c20 front discs (built in the 80s) 65 GMC 930 dualwheel 292 4spd all origonal 39k mi(my sons truck) 63 GMC 950 camperized school bus, (Gus the bus) 350 4speed 2 speed rear 64 GMC 950 "spare" bus 283? 4speed detroit locker 53 GMC 1ton dual wheel bus 78 GMC c25 short course off road race truck(son's truck) 355 th400 14 bolt (www.wheel2wheel.ca) 88 Peterbilt 379 longhood (hauls race truck)

08-02-2010, 01:02 AM	#11
Captainfab 60-66 Nut Join Date: Mar 2007 Location: Coeur d'Alene, Idaho Posts: 23,252	Re: 3/4 to 1/2 ton conversion On these years of C20's you can't just change the lower control arms as the shafts mount differently. It would be easiest to just change the crossmember and all for a '73-'87 C10 unit. As for the rear differential, a '71-'72 will be a bolt in, The '73-'87 rear differentials are the same width as the '71-'72 (which by the way are 1.5" wider than the '63-'70 rear differentials) but you will need to remove the leaf spring pads and weld on the trailing arm mounts. Also you will need to add some sort of mount for the panhard bar. You should be able to transfer the one from your HO52 rear differential to your new one. __________________ Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE

08-02-2010, 01:05 PM	#14
Chevy Fleetside Registered User Join Date: Sep 2006 Location: San Francisco Posts: 4,782	Re: 3/4 to 1/2 ton conversion I will be putting 1/2 ton suspension in mine also. Mostly for drivablity. Lots of Freeway.. I have also thought about selling it. __________________ "A man and his truck, what a beautiful thing" 65 Short Fleetside BBC 65 Long Fleetside 283 3 on the tree for now. my build thread http://www.67-72chevytrucks.com/vboa...d.php?t=259536 Last edited by Chevy Fleetside; 08-02-2010 at 01:06 PM.

02-13-2013, 06:14 PM	#15
63burban Chevy addict Join Date: May 2012 Location: Iron Ridge, WI Posts: 1,085	Re: 3/4 to 1/2 ton conversion CJ, Didn't we go through this already. After you move you can buy a Morrison chassis. B>} Maybe this summer I'll change your chassis over for you.

02-13-2013, 08:41 PM	#16
sighlurr ______________ Join Date: Sep 2006 Location: Danville, CA Posts: 1,285	Re: 3/4 to 1/2 ton conversion I've heard the rear cab mounts are different...



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