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Driveshaft FAQ

Can I make my driveshaft stronger?

Yes. There are several ways to make a driveshaft stronger.

  • Increase tubing diameter. Bigger tube OD = stronger driveshaft.
  • Increase tubing wall thickness.
  • Increase U-Joint size.
  • Switch from greasable to non-greasable U-Joints.


Call one of our driveshaft experts if you need help determining how to make your driveshaft stronger.


Yes. You can upgrade to an aluminum driveshaft. Aluminum driveshafts weigh approximately 30 to 40% less than steel.  The lighter aluminum material allows for longer driveshafts since there is less mass in the center of the tube to whip at high speeds. 

Conversion U-Joints are used when you need different caps on each side of the ujoint.  For example, if your driveshaft is 1330 series but your rear end yoke is 1350 series. Action Machine offers conversion U-Joints that have 1350 Series on two caps and 1330 Series. When measuring a Conversion U-Joint, be sure to measure across the the U-Joint in both directions (with the caps on and fully compressed) and measure all 4 cap diameters. Also note which sides our outside clip and which are inside. Refer to our easy-to-follow U-Joint Measuring Guide to for more information on how to measure U-Joints or call us for help.

Yes. This is common if the transmission or rear end has been modified. If you think that you have 2 different sizes on the same U-Joint, you might have a conversion U-Joint. Refer to our U-Joint Identification Guide to determine what you have.

Yes. To shorten a driveshaft, we remove one weld yoke, cut the tube to length, re-weld the yoke and then balance the driveshaft.

To lengthen a driveshaft, both yokes are removed, new tube is installed then welded and finally the driveshaft is balanced.

Either option will save you at least 50% versus the cost of purchasing a complete new shaft. All you have to do is ship the shaft to us and we will handle the rest!


 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
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.
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.



Driveshaft out of Phase
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.
Worn or Broken U-Joint
Check for movement. Check U-Joint trunions (ends) for any uneven wear.
Wrong Size U-Joints
Check OEM specs. Use Measuring Guides to check driveshaft and yokes for proper fit.
Driveshaft too Long
Call us to review your set up. Solution could be to install 2 Piece driveshaft.
Worn Slip Yoke or Spline
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.
Lack of Grease
Where applicable, make sure that ALL U-Joint caps and slip yoke accept grease. Follow lube interval recommendations.
Driveshaft not straight or out of balance
In most cases, straightening and balancing will solve this problem. Worst case scenario is that the driveshaft tube would have to be replaced.
Balance weight fell off.
Balance driveshaft.
Torsional and/or inertial excitation
Straighten tube and balance driveshaft.
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.



Driveshaft too Long
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.
Driveshaft not Straight or out of Balance
Straighten and balance driveshaft.
Lack of Lubrication
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. 



 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.


There are a lot of variables when dealing with an angle problem. Ideally your transmission and pinion should be parallel to each other in both the top and side views.  The front and rear ujoint should have the same ujoint angle within 1 degree.  Avoid any ujoint having more than 3 degrees of operating angle.  Call us with any questions.

Glossary of Common Terms


 Bearing Plate

A retainer plate fixed to the back of a round bearing used to position the bearing in the yoke.

A procedure in which the distribution of mass in a rotating body is
checked and altered where necessary to ensure that vibration does not occur during operation.
Ball Seat

 A full or segmented angular contact bearing located in a socket that supports and centers the ball stud.

Ball Stud
A yoke generally used in CV applications which incorporates a stud onto which a ball is mounted.
Failure that occurs when the static forces between two curved surfaces in contact result in local yielding of one or both mating members to produce permanent surface discontinuity. Example: Needle roller indents on a u-joint trunnion or trunnions.
Cardan Universal Joint
A non-constant velocity universal joint consisting of two yokes connected by a cross through four bearings and driveable by external sources.
Center Support
A rolling bearing element surrounded by rubber, mounted in a bracket
configuration used to mount the support to an outside structure.
Centering Socket Yoke
A yoke assembly that functions as a self-aligning bearing and provides support and a means of centering in double cardan universal joints.
Companion Flange
A flanged member that attaches a driveline to drivetrain components,
typically affixed by some bolt-together method.
Critical Speed
The speed at which the rotational speed of a shaft coincides with the
natural vibration frequency of the shaft, causing a dynamically unstable condition.
Cross and
Bearing Kit
Drive member with four equally spaced trunnions in the same plane and four bearing cups with attaching parts. Also referred to as a universal joint kit or u-joint kit.
Cross Hole
A through hole located in each ear of a yoke used to locate a round
Double Cardan
Universal Joint
A near constant velocity universal joint consisting of two trunnion type Cardan universal joints whose trunnion yokes are connected by a coupling yoke or H-yoke with internal supporting and centering means.
An assembly of one or more driveshafts with provisions for axial
movement, which transmits torque and/or rotary motion.
An assembly of one or two universal joints connected to a solid or tubular shaft member.
Driveshaft Length
Center to Center
The distance between the outermost universal joint centers on a
Drive Train
Term used for the unit of all components from the Transmission to Rear differential. Also referred to as Power Train.
One of two projecting parts of a yoke symmetrically located with respect to the rotational axis.
End Yoke
A yoke which attaches a driveshaft to another drive train component such as the transmission.
Flange Yoke
The yoke which attaches the driveshaft assembly to a companion flange.
A protective shield used in front of and behind the bearing and rubber on many center supports and end yokes.
Failure that occurs when two sliding surfaces are subjected to such a
combination of loads, sliding velocities, temperatures, environments, and lubricants, that massive surface destruction is caused by welding and tearing, plowing, and gouging. Example: Bearing cup/trunnion end galling on a cross and bearing kit.
A double yoke which connects the two halves of a double cardan
universal joint.
Half Round Yoke
Cross Hole
A semicircular hole located on the end of each ear of some end yokes and used to locate a round bearing.
The central part of a yoke used for attachment to another member.
Inside Lock-up
Term referring to either a cross and bearing kit or a yoke that utilizes a snap ring seated in a groove in the bearing cups and located inside the yoke ears to retain the kit in the yoke.
Joint Angle
The angle described by the intersection of rotational axis of the input and output members of a universal joint and measured on the same plane described by these areas.
A sound and vibrational deadening material added to the inside surfaces of a tube.
The dimensional distance between the two retaining surfaces in a
driveline component used to locate the bearing surfaces.
Stub Shaft.
A short shaft, generally splined, used in applications requiring more than one driveshaft. It mounts through the center of a support bearing and allows an additional driveshaft component to be fixed.
Outside Lock-Up
Term referring to either a cross and bearing kit or a yoke that utilizes a retaining ring in a groove near the outside edge of the yoke ear, rested against the outside face of the bearing cup.
The relative positioning of the universal joint yokes on a driveshaft or driveline.
Retaining Ring
A removable ring used as a shoulder to retain and position a round
bearing in a hole.

Ring Groove
Round Bearing

The surface used for positioning a round bearing with a retaining ring.
Consists of a round bearing cup with needle rollers designed to ride on a trunnion.
A flexible member which prevents the escape of lubricant and the
entrance of foreign matter.
Slip Movement
A permissible length of axial movement.
Slip Stub Shaft
A short, machined shaft, generally splined, which, when used with a slip yoke allows axial movement.
Slip Yoke
A yoke which allows axial movement.
Snap Ring
Strap Bearing Clamp
A semi circular device that conforms to the bearing profile holding them in place in half round and some DC yokes.
Swaged Tubing
A tube with one or both ends having a smaller diameter then the middle section.
Swing Diameter
The maximum diameter of the circular path described by a rotating
universal joint.
Thrust End
The end of a cross trunnion used as a thrust surface.
Total Indicator Reading on a specific point thru 1 revolution of a shaft.
Torsional Damper
A mechanical device, generally an inertia ring, attached to a drivetrain
component by means of a rubber inner ring to minimize driveline vibration in addition to balancing.
One of four projecting journals of a cross.
The tubular connecting member of a driveshaft.
Tube Diameter
The outside diameter of a tube.
Tube Yoke
A yoke with a piloting hub for attachment of a tube.
A clamping bolt with two parallel threaded legs used to retain a round bearing in certain end yoke designs.
Universal Joint
A device which can transmit torque and/or rotary motion from one shaft to another at fixed or varying angles of intersection of the shaft areas.
Wall Thickness
The measurement between the inside and outside diameter of a tube.
Weld Yoke
Same as tube yoke.
Wing Bearing
A member with a key and projecting wings used as the bearing base and positioning the thrust end of a cross trunnion.
Yoke Shaft
A one piece member designed to incorporate a tube yoke, tubing and stub shaft. It is used in close-couple applications and eliminates the need to use tubing.
A lubrication fitting, usually threaded into a driveline component that will allow grease to be injected into the component, but does not allow grease to escape.