Ordering A New Shaft
Inland Empire Driveline and Mustangs Plus keep ready-to-order driveshaft assemblies on the shelf for most Mustang applications. Inland Empire Driveline can make a custom driveshaft if you follow the proper measuring instructions on its Web site. Measure "X" from the rear axle yoke to the tip of your transmission tailshaft housing with the rear suspension at normal ride height. Allow "Y" distance for slip-yoke travel-normally around 1-1/2 inches of exposed slip-yoke from where the yoke meets the universal joint to tailshaft seal. Be specific when you order, including universal joint dimensions at both ends.
Another important thing to remember is to keep your driveline parallel, which means each end of the driveshaft (both yokes) should be parallel at all times. Odd angles will cause vibration and failure. Pinion and rear universal joint angle should be at the same number of degrees as the front universal joint for smooth operation.
Tube diameter depends on application. Here's how Mustang steel driveshaft tube sizing from the factory works:
| 2-3/4 inches: | Six-Cylinder |
| 3 inches: | Six-Cylinder |
| 3-3/8 inches: | Small-Block and Some Big-Block V-8 |
| 4 inches: | Heavy-Duty Big-Block |
Tube diameter and material thickness increase for aluminum shafts. Aluminum driveshafts aren't suggested for every application. Opt for one in a six-cylinder or small-block, while steel is suggested for big-block Mustangs. For those with healthy budgets and imagination, Inland Empire Driveline can build a composite shaft that's even lighter than aluminum. It also looks high-tech for your restomod show car.
Slip-yoke and bushing wear cause shaft oscillation, which can be felt as vibration as you modulate the accelerator. The only solution is a new slip-yoke and bushing. | 
When ordering a slip-yoke, measure precisely and be specific with your driveshaft shop. It's not always possible to get the exact length. Inland Empire Driveline, for example, will get it as close as possible, allowing for travel considerations. Most of the time, expect a slightly shorter yoke than original equipment. | 
Not all slip-yokes look the same. During the late '60s, Ford used this yoke/damper combination to soak up vibration. The damper works like your engine's harmonic balancer to absorb vibration and driveline twist. |
Another method of vibration absorption is the transmission damper. Not all Mustangs will have one. This damper hangs off the transmission tailshaft housing to take up driveline vibration. | 
To prevent driveline vibration, a driveshaft shop checks the shaft for runout (warpage and other irregularities) prior to balancing. Any distortion is unacceptable. A good driveshaft shop will know how to straighten a distorted shaft. If it can't be straightened, it should be replaced entirely, costing anywhere from $300 to $600 for a new shaft depending on size. Steel and aluminum cost virtually the same. Composite material is expensive, but it's stronger than steel and lighter than aluminum. | 
Driveshafts are dynamically balanced just like car tires. Inland Empire Driveline spins the shaft very fast, finds the light side, and welds weight to the shaft. Before welding, the shaft is spun with the weight tied in place to check for vibration. Remember, dynamic balancing isn't foolproof. Because driveshafts are subjected to stress issues, their dynamics can change after balancing. |
When power outdistances stock yoke strength, Inland Empire Driveline has solutions. Stock Ford yokes are made of cast iron (far right). The aftermarket offers steel differential yokes and transmission slip-yokes. When horsepower rises above 400, a steel yoke is needed for reliability and safety. | | |