Cause | Solutions |
Wrong U-Joint Size | Inspect driveshaft, rear end and transmission yokes for U-Joint sizes. Use the How to Measure Guides to help you. |
Improper Lubrication | Make sure that all 4 caps on U-Joint accept grease. Also be sure to follow the proper greasing frequency guidelines. Generally,… |
Improper Installation
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Inspect snap rings to be sure they are properly seated. Check U Bolts and strap kits. Over-torquing U-Bolts will crush the caps and not allow the roller bearings to operate properly. |
Worn Yokes |
U-Joints caps should have a tight fit in the yoke. They should not spin.
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Excessive Torque | |
Improper Phasing | Most driveshafts are built with the yokes at each end of the tube aligned in the same position. If the transmission yoke ear faces the side and the rear end yoke ear faces up, then the driveshaft could be phased wrong. Multi Piece driveshafts usually have all yokes aligned for best operation. Rephase driveshaft and balance. |
Driveshaft too long or too heavy | Change to a 2 Piece or aluminum driveshaft. |
Driving conditions too extreme for driveshaft | Increase driveshaft strength. See how to make your driveshaft stronger. |
U-Joint quality too low for application | Off Shore / Generic U-Joints should be replaced with Heavy Duty U-Joints. |
Improper Driveline Angles | For most cars and trucks without a CV joint, try to maintain U-Joint operating angles at between .5 and 3 degrees max. |
Causes
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Solutions
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Driveshaft out of Phase
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Most driveshafts are built with the yokes at each end of the tube aligned in the same position. If the transmission yoke ear faces the side and the rear end yoke ear faces up, then the driveshaft could be phased wrong. Multi Piece driveshafts usually have all yokes aligned for best operation. Rephase driveshaft and balance.
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Worn or Broken U-Joint
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Check for movement. Check U-Joint trunions (ends) for any uneven wear.
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Wrong Size U-Joints
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Check OEM specs. Use Measuring Guides to check driveshaft and yokes for proper fit.
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Driveshaft too Long
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Call us to review your set up. Solution could be to install 2 Piece driveshaft.
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Worn Slip Yoke or Spline
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Slip yoke and spline should have very little torsional rotation. Also, the slip yoke should move smoothly and evenly over the spline. The coating on the spline, if it has it, should fully cover the spline. If worn, we can help by replacing the slip, spline (or both if required) and then balancing the driveshaft.
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Lack of Grease
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Where applicable, make sure that ALL U-Joint caps and slip yoke accept grease. Follow lube interval recommendations.
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Driveshaft not straight or out of balance
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In most cases, straightening and balancing will solve this problem. Worst case scenario is that the driveshaft tube would have to be replaced.
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Balance weight fell off.
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Balance driveshaft.
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Torsional and/or inertial excitation
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Straighten tube and balance driveshaft.
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Modified Vehicle | Sometimes things like lifting a truck swapping out a rear end can lead to vibrations – and it is all about the ujoint angles. If the ujoint angles are changed from stock, you may now have uneven ujoints at the front and rear of the shaft. You may need to shim the carrier bearing on your 2 piece shaft or shim the axle to bring the axle nose up or down. |
Cause
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Solution
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Driveshaft too Long
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Bigger tubing OD is stronger so upsize tubing. For example go from 3 to 3.5″ OD tubing. Another option is to switch from a steel to aluminum driveshaft. Driveshaft weight and RPM can cause them to flex up and down like a jump rope as they spin faster and faster. The lighter aluminum shaft has less mass in the center compared to the same length of steel driveshaft – therefore the aluminum shaft does not flex like the steel shaft and runs smoother. Final option if there are no other options is to install 2 Piece driveshaft.
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Driveshaft not Straight or out of Balance
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Straighten and balance driveshaft.
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Lack of Lubrication
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Car and pick up truck greasable ujoints should be greased every 3,000 to 5,000 miles. Be sure grease purges out of all 4 caps. Slip yokes on 2 piece drivesahfts should be greased at least once per year. Inadequate lubrication leads to component failure and vibrations.
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Cause | Solution |
Driveshaft too Long | Install 2 Piece driveshaft. |
Driveshaft not Straight or out of Balance | Straighten and balance driveshaft. |
Lack of Lubrication |
Grease U-Joints and slip yoke as needed.
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