For years we've been telling you to stay away from front lift blocks. Not only are they a danger to you, but to everyone around you as well. What makes them so bad? It all boils down to simple physics. Whether driving off-road at high speeds or cruising down the freeway at a normal pace, your vehicle creates a certain amount of rolling momentum. Whenever the brakes are applied, roughly 70 percent of the vehicle's weight is transferred to the front axle. This pitching action causes the front axle to roll forward, thus applying extreme pressure on the front U-bolts and springs. When you add a block into the equation it elevates the leverage point on the front axle, causing the axle roll to become even more dramatic. Enough force or pressure can be applied to fire the front block out from between the axle and the spring. This will result in loss of steering and frontend control, which may have a tragic result for you and the vehicle.
Some argue that welding the front blocks to the axle can eliminate the block from shooting out, and in their mind it's a safe fix. True or not, when you raise the spring perches higher on the axle you place a greater amount of force on the spring. The springs are now working harder to control the vehicle's vertical and lateral movement and can cause the axle to travel unpredictably, cause spring deformation, and also raise the leverage point on the axle. Sure, you won't shoot the block out, but instead the entire axle will wrap violently under the vehicle. Simply put: Don't run front lift blocks.
Welding front blocks or building...
Welding front blocks or building tall perches creates a high leverage point that creates more stress for the leaf spring. This diagram illustrates the forces the vehicle encounters during cornering (shown turning left). The lateral force is now intensified as much of the vehicle's leverage is placed high above the axle. Axlewrap during acceleration is also compounded.
This diagram illustrates the...
This diagram illustrates the forces the vehicle encounters during braking. The front lift block sits in a high-pressure area and as a result could easily be ejected from between the spring and the axle resulting in complete loss of control over the front end. This only intensifies as tire sizes become larger due to greater leverage.
The only thing worse than...
The only thing worse than having one block in the front is having two! Not only has this truck raised the leverage point by creating a taller perch, but having a loose block resting between the spring and the perch is a recipe for disaster. Seventy percent of your vehicle's braking power comes from the front. Although the blocks here are only a few inches tall, they can easily distort the leaf springs and become deadly projectiles. Another note to mention is welding anything cast is terribly difficult and requires a skilled professional welder to lay a solid bead. So don't do it!