Tech Letter Of The Month
Wants 3/4-Ton GM Axles For CJ
Q I have a 1986 CJ-7 that I would like to convert to 3/4-ton Chevy Corporate 10-bolt/14- bolt axles. I would also like to do a springover conversion with the suspension. There are several goals that I need to accomplish. I need 33-inch tires and I want to keep the center of gravity as low as possible while lifting the Jeep.
What issues should I expect with the steering? Should I inboard the springs? Are reverse-wrap springs necessary for a springover? I am not sure if I will have over-width issues, but narrow tires and wheels should help. I hope to cover the rest with big flares. I know that I will need custom springs, steering components, etc., but which aftermarket suppliers offer Chevy axle-to-Jeep frame conversion products? Any advice you could offer on this conversion would be greatly appreciated.
A No doubt about it: Full-width axles will cause the wheels to stick out way past the fenders. In fact, just about the entire tire will be out from under the fender with a standard offset wheel. I have seen a lot of people use wheels with lots of backspacing to narrow the track, but then you have the problem of the tires hitting the front springs when you turn if you go too far with the backspacing.
As to the springs, on a CJ the front springs have to be outboarded about two inches in order to clear the front differential housing. Blue Torch Fabrications (http://bluetorchfab.com) has a really easy way to do this. Their kit includes a new front bumper that incorporates the spring mounts, which they claim makes a much stronger mounting point rather than trying to add them off the side of the frame. Mountain Off Road Enterprises (www.mountainoffroad.com) also offers a kit that takes a slightly different approach to the mounting problem and seems to work just as well. Both of these kits are designed for a springover/reverse-shackle suspension system.
Keep in mind that you're going to have to do a few more things. For proper tie rod and drag link clearance, you probably are going to have to go to some different steering knuckles or add some high steer-type steering arms to the existing knuckles. You're also going to need a front driveshaft with a very long slip yoke to handle the extra rearward movement of the axle as the springs compress.
Keep in mind when deciding on what springs to use that you will gain about five to six inches of lift just with the springover conversion. It's pretty common to use the wider YJ-style springs in stock form or a mild lift. Naturally, you're also going to have to build new shock brackets both on the axle and on the frame. You might want to read the Jan. '10 edition of "Willie's Workbench," which dealt with springovers in depth.
Axle hop most likely will be a problem, and a military-wrap spring eye does seem to help along with a reverse wrap. I would advise some sort of a pivoting-link traction bar for the rear axle, such as the one Sam's Off Road sells (www.sams4x4store.com).