Whenever you jump in your rig and go barreling down the highway or over your favorite flavor of off-road terrain, you’re asking a lot from the shafts and joints spinning rapidly underneath. Of course, we’re referring to the driveshafts that transmit our engine power to the axles. Every time these rotate, each U-joint speeds up and down in angular rotation while moving in an assembly of needle bearings and grease. These components should be checked on occasion and require periodic maintenance to ensure they don’t fail at the most inopportune time. Joints either come with or without zerk grease fittings. Those without are pre-lubed from the supplier to last the life of the joint. Those with a grease fitting should receive a squirt of grease from time to time. Driveshaft carnage comes in several forms. You can, of course hit a rock or other obstacle with the shaft and bend it, or severely scar it. But you can also destroy them (and cause other collateral damage) by having one that is too short or too long in your drivetrain. Whenever you lift or modify your rig you should consider the effects those suspension changes may have on the driveshaft angle and length, and you just might save yourself from broken parts. Those of us with solid front axles on (rear shackled) leaf springs often check driveshaft travel on the front axle to ensure there is sufficient spline length left engaged once the axle is fully drooped. However, a simple driveway check may not be sufficient to determine if you have adequate spline travel. On a vehicle with rear spring shackles on the front packs, the axle will want to droop down and move forward. When this is combined with a little throttle, the spring wrap induced by the front driving tires can stretch the packs down further, pulling the axle even further forward. This is when you’ll determine if your front shaft has sufficient spline travel. Neglected U-joints can lead to eventual failure. Typically, as a joint wears it will go from being well lubed and quiet to a drying joint that may give you warning by starting to squeak. Beyond this point, the joint wears metal-on-metal, and it will begin to develop looseness between the cross and the caps. At this point, a joint can come apart, leading to some serious drivetrain damage when it lets go. A quick way to check for joint play while on a vehicle is to put the axle on jack stands with the transmission in neutral and parking brake applied. Then simply grasp and wiggle up, down and rotationally, looking for any signs of looseness in the bearing caps (and in the splines while you’re at it).Neglected U-joints can lead to eventual failure. Typically, as a joint wears it will go fr Constant Velocity (CV) joints are more complex and have more points of movement and wear. Giving them an occasional shot of lube can prolong their life and save you from prematurely replacing expensive components.Constant Velocity (CV) joints are more complex and have more points of movement and wear. As driveshaft angle rises, wear rates increase. So expect shorter U-joint life whenever driveshaft angle is steeper, and check and lube the joints more often. If a driveshaft is too long and bottoms out at full suspension compression, you’re asking for trouble at the transfer case or axle pinion. When making suspension mods consider how the axle moves as it cycles and check your driveshaft compression/extension limits.As driveshaft angle rises, wear rates increase. So expect shorter U-joint life whenever dr By Jay Kopycinski Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!
