I'm planning my rear suspension, and I have a few questions. My plan is to use nascar truck arms with a 9" using air bags. I'm wondering if I could use a rear trailing arm crossmember for a 60-72 chevy/gmc 2wd truck, since it uses the same type of trailing bars. Does someone have access to a 60-72 chevy/gmc truck to take some measurements for me ? I need to know the width and heigth of this crossmember, and the distance between the ears that the trailing arms get bolted to.
Another alternative is to build my own crossmember, but if I could use a stock piece from another truck, even though it is a chevy, I'd like to go that route.
Thanks

 

well why dont you make your own cross member? I'm not sure what nascar truck arms look like but if its just a robust square tube 4 link with eyelets at ea end making a crossmener should be a cake walk.

 

Making your own is probably the best way to do this.

 

I don't have a lot of fabrication skills under my belt, which is why I was leaning towards an existing design.Truck arms are essentially two 51" long arms which attach to the rear axle in a similar manner leaf springs attach, then attach to the crossmember located midway up the frame similar to an a-arm on a typical front suspension. There's a set on ebay right now for pictures, search for nascar truck arms.

 

Sounds like an interesting project. If no one chimes in with the GM measurements that you need try the Stovebolt forum;
http://www.stovebolt.com
They are a pretty decent group also. It seems like there was a couple of featured trucks in Custom Classic Trucks or Classic Trucks not too long ago (6 months or so) that had Nascar style trucks in them. The one I remember was a 38 Ford


Good luck
Bobby

 

For everyones information, The frames are exactly the same dimensions at the crossmember mounting point, The crossmember from the chevy fits perfectly inside the frame rails of the 55, heigth and width.
Lynn

 

NASCAR uses those very same Chevy truck trailing arms. Spring mounts on top the arm in front of the axle. Does require a track bar as well. Correct geometry is when the CL of the bars are extended they meet at the front driveshaft U joint.

 

That's what I'm using for trailing arms, The NASCAR ones. I'm probably going to be forced to use a 2 piece driveshaft now, since it appears as though the hole in the crossmember was set up for this. The trailing arms have bushings that are approximately 1/16" too long, but they should fit snugly with a little persuasion.

 

I'd avoid the 2 pc shaft if at all possible. Weld in a NHRA type driveshaft support oval in the center of the crossmember to give needed clearance.

 

The 9 inch is also off center. Which is another reason why I was looking at the 2 piece driveshaft. Is the 2 piece too hard to set up or are there other reasons to avoid it ?

 

You have a carrier bearing that needs to be supported an extra u joint and slip joint. If the U joint angles are not correctly oriented they will wear out very quickly. The offset of the rear end is a non issue, it assures the U joints do not work in a straight line.

 

Thanks, I'll look at the support oval.

Lynn

 

Summit has a number of different flat and tubular ones you might adapt, search driveshaft hoop or loop, or you could make or have made your own out of 1/4" steel strapping or 3/4" tubing.

 

I may have backed myself into a corner. The driveshaft appears to be too far to the passenger side to do this. I dont have my 390 sitting in there yet, but I'm using a volare front suspension with the nascar trailing arms and the 9" which the pinion sits about 2" to the left. The crossmember is set up for a center exit with the trailing arms attaching too close to be cutting a whole lot away.Lynn

 

Where there's a will there's a way, modifications are the norm when building Hot rods. Do you have pictures? Are you offsetting the engine for the Volare? Many with Volare's off set the engine a couple inches to the right for steering shaft/header clearance. That may produce more clearance issues than the pinion offset. 2" at the rear axle does not angle the driveshaft a whole lot at the tranny, but if it is tight, there are ways to get more room. How far behind the front universal is the crossmember? How far apart are the arm mounts?