Frame work 1970 C30

[rushingg149]

Replacing the frame from the cab back with a 1986 C30 frame, springs and hangers and rear end.

First things first, I’m refurbishing a 1970 C30 with plans of carrying my motorcycle and trailer on the bed, while pulling a bumper pull travel trailer. It has a 1969 396ci, with a 4 speed manual tranny. I’m replacing the front end with an ’86 front end with disc brakes and power steering. I’m adding a 5 speed manual transmission and an ’86 differential and changing out the ring gear and pinion, in an effort to improve road speed and fuel economy.

The truck has a 12' bed with previous frame extension. They butchered the end of the frame right behind the rear hanger and extended it with 4" channel iron slid into the frame about a foot and bolted with a bolt on each side, to create a hitch. The hitch is hell for stout but I'm not comfortable with the attachment to the frame. The frame has previously been extended 2 foot between the cab and rear end. It is a good weld however it is a butt weld across the frame, with little bracing.

My first plan was to replace the ’70 rear end with a newer ‘86 one, due to the availability the ring gear and pinion. The original ’70 springs are 51” from hanger to hanger and the ’86 springs are 55” from hanger to hanger. Due to the butcher job on the frame at the rear hanger I would have to add to the frame to accommodate the rear hanger and the front hanger would need some adaptation also.

I know the frames are different in shape and size but with some measuring I think I could do the fabrication and it would work better with less frame work then originally required.

The first question of many, I sure is:

What is the length I need beyond the rear axle to prevent overloading the front axle or creating a fulcrum, possibly taking too much pressure off the front axle while pulling a travel trailer? The present length is 13 feet center of axle to center of axle with 4 feet of a 12 foot bed extending beyond the rear axle. This will be a pleasure truck (retirement) not a work truck, I do not anticipate carrying heavy loads on the bed beyond the motorcycle and it’s trailer, approx. 1,200lbs. – 1,500lbs

Any suggestions and or warnings are appreciated. I will include pictures soon, or you can see the truck on a previous post – 1970 C30 delivery

[MARKDTN]

Most big trucks with vans or flatbeds have approximately 2/3 of the bed ahead of the rear axle and 1/3 behind as a general rule. I would think that would be reasonable on a 1 ton as well. Sounds like that is what you had.

[rushingg149]

Originally Posted by rushingg149

Replacing the frame from the cab back with a 1986 C30 frame, springs and hangers and rear end.

First things first, I’m refurbishing a 1970 C30 with plans of carrying my motorcycle and trailer on the bed, while pulling a bumper pull travel trailer. It has a 1969 396ci, with a 4 speed manual tranny. I’m replacing the front end with an ’86 front end with disc brakes and power steering. I’m adding a 5 speed manual transmission and an ’86 differential and changing out the ring gear and pinion, in an effort to improve road speed and fuel economy.

The truck has a 12' bed with previous frame extension. They butchered the end of the frame right behind the rear hanger and extended it with 4" channel iron slid into the frame about a foot and bolted with a bolt on each side, to create a hitch. The hitch is hell for stout but I'm not comfortable with the attachment to the frame. The frame has previously been extended 2 foot between the cab and rear end. It is a good weld however it is a butt weld across the frame, with little bracing.

My first plan was to replace the ’70 rear end with a newer ‘86 one, due to the availability the ring gear and pinion. The original ’70 springs are 51” from hanger to hanger and the ’86 springs are 55” from hanger to hanger. Due to the butcher job on the frame at the rear hanger I would have to add to the frame to accommodate the rear hanger and the front hanger would need some adaptation also.

I know the frames are different in shape and size but with some measuring I think I could do the fabrication and it would work better with less frame work then originally required.

The first question of many, I sure is:

What is the length I need beyond the rear axle to prevent overloading the front axle or creating a fulcrum, possibly taking too much pressure off the front axle while pulling a travel trailer? The present length is 13 feet center of axle to center of axle with 4 feet of a 12 foot bed extending beyond the rear axle. This will be a pleasure truck (retirement) not a work truck, I do not anticipate carrying heavy loads on the bed beyond the motorcycle and it’s trailer, approx. 1,200lbs. – 1,500lbs

Any suggestions and or warnings are appreciated. I will include pictures soon, or you can see the truck on a previous post – 1970 C30 delivery

Added some pictures of my project.

[rushingg149]

Originally Posted by rushingg149

Added some pictures of my project.

Looking for some more input!

[rushingg149]

Originally Posted by rushingg149

Looking for some more input!

Are there any frame guys out there???? If you know of one send him to this thread please

[rushingg149]

Originally Posted by rushingg149

Are there any frame guys out there???? If you know of one send him to this thread please

OK, weekend warriors, surely some of you have some frame experience. Let’s have some input.

[rushingg149]

Originally Posted by rushingg149

OK, weekend warriors, surely some of you have some frame experience. Let’s have some input.

Started frame work by cleaning up the tip of the frame. The end of the frame had been cut off to allow for a hitch made from 4" channel had been slid into the frame. They did a terrible job!
I have added 16" of frame off an '86 to clean up the frame and to add some cross support. Also added support along the frame to support the repair. It looks much better.
Also allows me the choice of utilizing '70 or '86 spring hangers and springs. The'70 springs have 26" on center hangers. The '86 has 26" front hanger center and 31" rear hanger center.

[coops714x4]

here is my 2 cents... IF all your gonna haul on the truck is a motorcycle keep the bed as short as possible. when pulling the camper use a "torsion" load leveler (you can get them at most RV trailer supply's. the reason I say keep it short is 1 it will be easier to back or park. 2 if you leave the bed long it won't be a very practical "driver" 3 with the short bed it will have a certain "cool" factor. now if you plan on "working" the truck you might need all the bed you can get. from the pics you have shown I would take a few feet off, its your truck do what you want. there is a post on here that has pics of all kinds of 1 tons long and short go look it up, I think its call the 1ton dually post. Coop

[rushingg149]

The'70 springs have 26" on center hangers. The '86 has 26" front hanger center and 31" rear hanger center.
I can use the original spring hanger location and utilized the ’70 spring set or I can move the rear hanger back and utilize the rear hanger holes on the original frame and the front hanger holes on the 16” extension allowing me to utilize the ’86 spring set. The ’70 spring set have six leaves and an overload. The ’86 spring set have eight leaves and an overload. I’m leaning on utilizing the ’86 spring set.

[rushingg149]

Sorry, I didn't answer the welding question. I utilized a portion of the frame from the '86 frame to re-enforce the splice within the frame for approximately 3 feet, up to the arch for the differential.

[rushingg149]

Originally Posted by rushingg149

Sorry, I didn't answer the welding question. I utilized a portion of the frame from the '86 frame to re-enforce the splice within the frame for approximately 3 feet, up to the arch for the differential.

Update on frame work.
Added 2”x4”x3/16” tubing for the flat bed and utilized it to stiffen the frame along the 2’ foot splice at the center of the frame as well as the 16” I added to the tip of the frame.