REAR SUSPENSION & TRACK DAY
By Mark Ansted and Stan Hammond
Last month we began an article series showing what can be done to upgrade and improve a 1965 Chevy C-10 pickup. We followed along as the crew from Early Classic Enterprises showed how to rebuild the front end with all new suspension components and upgrade the front brakes from drum to disc. They also added a quick ratio power steering box and front sway bar to bring this Classic up to modern standards. With the front end completed, we can now move to the rear suspension and follow this makeover step by step as the transformation continues.
Here we proceed to the rear of the truck and install the Early Classic Enterprises 6-inch drop rear coils along with their shock mount relocator kit and Super Track Bar kit, which Early Classic Enterprises recommends with any of the larger rear drops on these trucks. When we finished, we headed back out to our proving grounds to see just what kind of difference we could make with our previous lackluster numbers. We think you’ll be surprised.
1) Here’s what we have to work with, a tired, worn out 40-year-old rear suspension. The 1960-’72 Chevy models came stock with a rear coil spring/trailing arm setup, and the GMC models had rear leafs. However, Chevy’s could have been special ordered with leafs and vice versa. Our makeover candidate has the coil spring setup. It’s an excellent design overall, but one that can definitely be improved upon.
2) These are the rear suspension components from Early Classic Enterprises that we chose for the project. The front-end received a total of 4 inches of drop with the combined spindles and springs. Since these trucks came from the factory with close to 3 inches of rake, a 6-inch rear drop kit was selected to match the front. Shown are the coils, U-bolts, shocks, shock relocator kit, and track bar kit.
3) With the truck back on the hoist, the rear springs are removed by first removing the shocks and them removing the retaining bolts on the top and bottom of the spring.
4) Early Classic Enterprises 6-inch drop coils will lower the rear of the truck to match the front, without needing to C-notch the frame. They bolt in place just like the stockers.
5) Several geometric changes occur when you lower a vehicle, and early GM trucks are no exception. Probably the two biggest are the shock angle and the panhard bar geometry. Fortunately, Early Classic has solved both issues with their shock mount relocator kit and adjustable panhard bars. Their rear shock mount relocator kit corrects the shock angle by 22 degrees, standing the shock back up to the factory angle and allowing it to function properly. The shock mount kit consists of both upper and lower brackets that mount in the same location as the original parts.
6) The upper rear factory shock mounts are riveted in place on the shock crossmember, and the rivets need to be drilled out or chiseled off.
7) Once removed, the new brackets bolt in place using the supplied hardware into the original holes.
8) The coil spring/trailing arm rear suspension used a panhard bar to locate the rear axle side to side, or laterally. By lowering the rear end, the radial arc of the bar shifts the rear axle to one side causing the truck to track crooked down the road.
9) On rear drops of 5 inches or more, Early Classic designed their Super Track Bar kit to solve this problem, and like the shock mounts, it’s a bolt on affair. The left side of the bar mounts in the original frame bracket, and the right side uses this supplied piece that captures between the rear axle saddle and the trailing arm.
10) The lower shock mount is simply held in place on the bottom of the trailing arm by the rear axle U-bolts. The new lower shock bracket is also a direct replacement of the original mount, and its reversed design extends the shock travel.
11) The new dropped shock will now stand at the stock angle, making it significantly more effective.
12) The last adjustment to be made is centering the rear end under the truck by turning the threaded end in or out and tightening the jam nut.
13) With all of the components in place and torqued to specification, it’s time to see the return on our investment.
14) We took a short trip back to California Speedway in Fontana to conduct our follow-up testing. In our preliminary trials, we started in bone stock fashion with the exception of radial tires. As you can see, this setup left a lot to be desired.
15) We then upgraded to a shiny new set of 17x8 Cragar Street Pros wrapped in Hankook Ventus St Tires. 255/50R17’s were chosen for the fronts and 275/55R17’s filled out the rear fender wells.
16) This wheel and tire package took the 60-0 braking distance down from 266ft. to 237ft. and the slalom speed from 32.4mph up to 36.2mph.
17) With the new Early Classic Enterprises front disc brake conversion installed, the braking distance dropped an additional 65ft., netting an impressive 172ft. The remainder of the suspension upgrade yielded another significant gain through our 420ft. slalom course. This speed was increased another 5mph to 41.2mph. A notable improvement in the handling characteristics of this truck is evident in these before and after (headlights on) photos.
18) The 200ft. skid pad was our next test. Its purpose is to evaluate the truck’s ability to stay planted to the pavement while traveling in a circle at a high rate of speed. Measurements are recorded both clockwise and counterclockwise then averaged. Due to time constraints in our initial test, we only tested this truck with the 17-inch wheel and tire combo. Although the large tires were beneficial, the factory suspension was seriously lacking. After several hairy laps in each direction, the best result was .72g. One could only speculate how low this number would have been on stock tires.
19) Again, Early Classic Enterprise’s suspension products paid off. The 1-1/4-inch front sway bar and lowered center of gravity provided dramatic improvement, not to mention a more confident “seat of the pants” feeling when driving on the edge. The result of this go-around was a .80g average.
20) Not bad for a forty year old truck! This Mid-‘60s makeover is well under way proving the do-it-yourselfer truck owner can buy off-the-shelf components and upgrade their truck to modern standards on a realistic budget.