3/4 to 1/2 ton conversion

[CJ Loeffelholz]

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]

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]

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]

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]

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]

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]

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]

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]

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

[62gmc910]

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]

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]

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

[Chevy Fleetside]

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

[sighlurr]

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

[63burban]

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]

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

[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.

Originally Posted by DSIGH

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

CaptainFab - thoughts?
Posted via Mobile Device

Originally Posted by DSIGH

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

[sighlurr]

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]

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