Setting Proper Driveshaft Angles
To measure driveshaft angles and U-joint angles, start by lifting the vehicle either on a drive on style vehicle lift, or an axle contact style. This will keep the suspension under load and allow for correct measurement.
On your U-joints, the working angles may differ no more than 0.5° of each other; otherwise you will encounter speed changes that may prematurely wear out your bearings and caps.
To find the working angles follow these steps:
- Place an angle finder on the bearing cap and take note of the reading.
- Rotate the driveshaft 90° and repeat step one.
- Find the difference between the two readings and this will be that u-joint’s working angle.
Remember the variance...
Once you have completed that, you can move to the other U-joint and repeat steps 1-3. Remember, the variance between the two can be no more than 0.5°. If the variance is greater than allowed, shims can be used to remedy the issue. The angle of the rear U-joint can be altered by installing a tapered shim like these between the leaf spring and the axle. The front angle can be altered by adding or removing shims from under the transmission mount. Also, look to make sure the transmission mount itself has not collapsed, as this could cause a change in angle as well.
If you are running a 4-link suspension system, you can adjust the upper rear end links in or out to bring the variation back into where it needs to be. Make sure to adjust both the left and right equally, and doube check after you are finished to make sure the rear end is still square in the chassis.
