Coil Over Rear Suspension

 

When I first lowered my S-10 I used the standard method, lowering blocks. I also removed the "helper" leaf and one other leaf spring. This method gave me about 5 inches of total drop. Additional time was spent adding the necessary shims to adjust the pinion angle and playing around with different shock combinations. In the end I was not happy with the way the truck handled. My truck didn't have a very good feel when cornering, the rear suspension had a loose feeling. I considered adding a rear sway bar to tighten up the feel , but I rejected that idea. 

I began thinking about what my end goal is with the truck's suspension. I sat down with a sheet of paper and began thinking, if I had to start with a bare frame, what would I do? I decided to go with what I'm most familiar with. I work on the weekends as a Nascar Technical Inspector at a local speedway. I've spent hours underneath racecars and the most common rear setup is commonly known as a "Truck Arm" suspension. The term "Truck Arm" comes from the use of long trailing arms found under late 60's early 70's Chevrolet trucks. A truck arm rear offers many variations on set up depending on the type of race track. The truck arm setup can vary between coil over shocks, or coil springs and conventional shocks. This is the same rear suspension you will find under today's Nascar Winston Cup race cars. The Winston Cup cars use conventional coil spring and shocks. Coil Over suspension isn't allowed. 

The suspension I designed uses ideas from a wide variety of cars.  I designed arms that would connect to the brackets that currently mount the front of the leaf springs. After careful measuring I found that rear arms from an '85 Mustang would mount perfectly in the S-10 leaf spring mount. I gave thought to using rod ends instead of rubber bushings, but the rod ends would be a little to ridged for everyday street use. The Mustang arms were cut off just behind the bushing area. A 30 inch section of 2"X2" (3/16th inch wall) tubing will become the new trailing arm. After a few minutes grinding on the cut off section of Mustang arm, the two pieces were Mig welded together. The shocks are Carrera Model 3363, Stroke 6.10, Closed length 11.25, Extended length 17.35 . The springs are rated at 200 lbs. 

Before I dismantled the rear suspension I measured the rear axle location using several reference points. Once the leaf springs are removed you had better know exactly where the rear axle needs to be.

 

Mustang trailing arm ends welded to the new trailing arms

 

Complete arms

 

Self centering coil over shock mounts. These are available from Stock Car Products in Richmond, Va  www.stockcarproducts.com 

 

Coil over shock without the spring installed.

 

The truck arm mounts in the same bracket as the leaf springs

 

The rear of the arm mounts to the factory rear axle pads. I also used the factory u bolts and u bolt plate. A 4 inch section of square tubing was welded to the rear of the arm. The additional tubing gave me a location to weld the lower shock mount. The brake line bracket was cut and moved. I'll reattach the bracket when final ride height is set. 

 

A long section of 1" X 1" thick wall tubing was welded across the frame to act as an upper shock mount. Yes, that is a small weld bead where the axle pad meets the control arm. I did that to make sure things were lined up prior to setting the locating pin. The rust on the shock bar matches my frame! LOL!

 

The C cutout is reinforced with 1/4 inch plate

 

The Panhard bar is connected to a frame bracket on the left side. The bracket was fabricated from 3 by 3 inch square tubing then welded to the frame. 

 

 

The right side of the bar is connected to the trailing arm. The "Red" spring will be replaced with a chrome spring at some point. 

 

This was a very inexpensive conversion. Steel tubing is very cheap, the shock mounts were less that 30.00. My neighbor allows the use of his Lincoln Mig Welder for Beer. One of my Ford friends gave me the old Mustang arms. The shocks were picked up used from a friend that sold all of his racing gear. The Panhard bar was ordered from www.stockcarproducts.com I spent less than 125.00 on the complete setup.