‘74 C-30 Dually Front Suspension Questions

[bigtexasrob]

Hi all, first post to the site, came to the forums because I can’t find answers to the questions I have. Guess that’s what I get for “needing” a dually. Anyways, let’s jump into it. Truck in question is a ‘74 C-30 dually longbed that originally had the 350 and a “four” speed.

1) What differences are there between the C-30 and C-10 front suspension member? How different are the control arms?

2) Do I need to shorten/modify the front suspension member to lay the truck flat on rails, or will control arms and drop spindles handle it? It seems that the front member sticks down too far to set the truck flat.

3) Any resources for or members here that fabricate custom control arms? I’m looking for something a little different.

[SCOTI]

Originally Posted by bigtexasrob

Hi all, first post to the site, came to the forums because I can’t find answers to the questions I have. Guess that’s what I get for “needing” a dually. Anyways, let’s jump into it. Truck in question is a ‘74 C-30 dually longbed that originally had the 350 and a “four” speed.

1) What differences are there between the C-30 and C-10 front suspension member? How different are the control arms?

2) Do I need to shorten/modify the front suspension member to lay the truck flat on rails, or will control arms and drop spindles handle it? It seems that the front member sticks down too far to set the truck flat.

3) Any resources for or members here that fabricate custom control arms? I’m looking for something a little different.

The frame rails are taller on a C30 vs a C10. Spindles & springs will get it close but not on the rails. You'll need about another 1.5". Do a pancaked x-member or z'd front frame, spindles, + bags & it will plant the x-member/rails.

The upper control arms on a 74 C30 are like pre-73 C10's utilizing the rubber lined steel bushing. Ball joints are interchangeable. The lower arms are also like pre-73 C10's as far as the bushings but utilize a larger OD lower BJ so they're not interchangeable.

What specifically are you wanting as far as modified a-arms?

[bigtexasrob]

Re: Pancaked x-member
This is the process of cutting and raising the bottom of the stock front member, correct?

Re: Modified a-arms and springs/spindles
I’m looking for a 3” wider/3” lower arm with a bag bracket, and will then install a 3” drop spindle. By my college drop-out math, it should ride comfortably at the correct height, maintain usable wheel angle (fenders will be modified as well) and lay on the ground or very close to it.

[SCOTI]

Originally Posted by bigtexasrob

Re: Pancaked x-member
This is the process of cutting and raising the bottom of the stock front member, correct?

Re: Modified a-arms and springs/spindles
I’m looking for a 3” wider/3” lower arm with a bag bracket, and will then install a 3” drop spindle. By my college drop-out math, it should ride comfortably at the correct height, maintain usable wheel angle (fenders will be modified as well) and lay on the ground or very close to it.

Yes on the Pancaked x-member (also known as sectioning).

I'm guessing your plan is to run 3/4 ton hubs & longer arms to allow dialing in dimensions for some shaved 10-lugs (thus the need for longer/custom arms)?

My dually has a 1.5 pancaked/sectioned x-member, 3" spindles, & bags. It plants the front x-member & frame rails firmly on the ground when air'd out. It rides like a stock height truck. I do have aftermarket front inner wheel tubs & step notch w/raised floor/tubs in the rear. Nothing hits @ all.

At ride height.....
Front is 26" @ the center of the wheel well lip w/a ~30"OD front tire.
Rear is 27" @ the same spot w/a 31.5"OD tire.
Frame rails are about 4.5-ish inches off the ground under the center of the cab.

[bigtexasrob]

Exactly the plan, exactly the answers I needed. I appreciate it!

[SCOTI]

Originally Posted by bigtexasrob

Exactly the plan, exactly the answers I needed. I appreciate it!

I'd suggest Lowboy Motorsports but it appears you already have according to IG