A solid axle conversion is the process of removing the independent suspension of a vehicle and replacing it with a solid or single-piece axle and replacing the related suspension components that are used with the axle. This can be completed on the rear or front suspension of a vehicle. The solid axle conversion is popular on some brands of four-wheel drive trucks, as well as on some independently-, rear-suspended sports cars. The primary reason for a solid axle conversion is to apply more power to the suspension without fear of damaging the weaker, yet more expensive, independent axle system in the vehicle.
Typically done only in racing or competition-type vehicles, the solid axle conversion is an intricate and detailed process that involves extensive fabrication and chassis alteration. The process is started with the removal of the tires and wheels of the suspension system that is being removed. Once accomplished, the axles and all related hardware for the independent axles are removed from the vehicle. This commonly requires the removal of all brackets, supports and related suspension pieces with a cutting torch or cutting wheel. Once removed, the chassis is smoothed by grinding, and then repainted to prevent rust from forming on the bare metal.
With the new solid axle in place under the vehicle, the solid axle conversion is commenced with the attachment of the new spring supports being welded to the frame. The shock mounts are also attached to the chassis by welding. Once the new axle is positioned on the new springs, any control arms, brackets and related components are welded into place on the chassis. In a front solid axle conversion, the steering gear must also be attached to the new axle and the axle supports and panhard bar must be welded to both the axle and the chassis. This will ensure that the new axle remains centered in the vehicle even under severe cornering.
Brake lines are typically part of the final installation process and are plumbed from the wheel cylinders to the proportioning valve or the master cylinder, depending on the vehicle. Most solid axle conversion swaps will also include the replacement of the driveshaft. Most conversions utilize an outside agency to produce a replacement driveshaft due to the intricate balancing required in the creation of a new driveshaft. Careful measurements are required to get a driveshaft that is long enough, but is not too long. This is a critical step in any solid axle conversion to ensure proper driveability once complete.