Restoration
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What do hot rodders, customized car builders, race shops and automobile restorers have in common? They all need to build custom-length driveshafts from time to time. Many project-car builders need specialized driveshafts if the part is out of production, or when mixing and matching oddball engine and transmission combos with non-standard chassis lengths. This also holds true for a front-engine project car with a shortened or lengthened chassis. Although you may get lucky and find a standard-length driveshaft that will fit, it is not likely to accept the heavy-duty larger-diameter U-joints that may be required to handle the power of high-performance engine upgrades.

Driveshaft Shopping
To see what is involved in building a custom driveshaft, we had one made up for a sports car in need of a shaft to join a Chevy small-block V-8 with a Borg-Warner T-10 tranny to a custom-built DeDion rear end (a type of independent rear suspension). When shopping for a driveshaft, be sure to choose a company with custom shaft experience. The good news is that custom steel driveshafts are not that expensive, generally running under $200 (if you require aluminum or carbon fiber, expect to pay more).


If you have a good driveshaft you will never notice it, but a bad one will be a nightmare. Vibration from an incorrectly balanced or assembled shaft will result in annoying noise and short U-joint life. Although anyone with a hacksaw and a welder can assemble a shaft, getting one right requires experience and professional equipment.

U-Joint Basics
There are three basic sizes of U-joints: 1310 (approx. 3-1/4" wide with 1-1/16" or 1-1/8" diameter caps), 1330 (3-5/8" wide with 1-1/16" or 1-1/8" caps) and 1350 (3-5/8" side with 1-3/16" caps). The 1350 is also thicker than the other two and is recommended for racing cars producing more than 400 hp. For high performance you will want heavy-duty U-joints, and for racing you need ones without grease fittings (which weaken the joint).


You can mix U-joint sizes at each end of the shaft but the strength will be limited to that of the weaker joint. A used driveshaft can be cut down, but only if it is in perfect condition (damaged shafts should not be repaired). When you assemble the joints onto the pinion yoke, torque the nuts to 17 lb.-ft. on 1310 and 1330 joints, and 20 lb.-ft. on 1350 series joints. Don't exceed these recommended specs because over-tightening can lead to premature wear. View the detailed steps in the Photo Gallery.


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Photo Guide

Pick a yoke that fits the U-joints you have chosen. Push the yoke all the way in, then pull it out one inch. Cars with independent rear ends (where there will be no plunge on the splines) only require about a half inch of pull-out.

Measure the length of the projected shaft between the centerlines of the two U-joints. If you have a live axle, support the rear end on jackstands or measure with the car on the ground.

At the shop, the tubing for the new shaft is measured to match the dimensions provided. For racing special thick-wall tubing should be used. You can also choose between 2-, 2.5- and 3-inch diameter shaft tubing. The larger diameter tubing is stronger, but first make sure you have clearance for it in your chassis and driveshaft tunnel.

The tubing is cut to length on a power saw.

The ends are dressed with a file to eliminate burrs.

A level is used to make sure the yokes are exactly parallel. The new yoke is tapped into place.

The transmission yoke is assembled onto its U-joint.

The driveshaft is chucked into a lathe and leveled.

A dial indicator is set up to measure runout on the shaft. A hammer is used to tap the yoke until the shaft runs true.

Once everything is aligned, the yoke is welded in place.

A U-joint is assembled on the rear of the shaft.

This strobe is used to check the shaft for balance. High-speed balance equipment allows the operator to precisely place a metal weight that will balance the shaft and prevent vibration.

The weight is spot welded onto the shaft. The placement of this is critical.

Tape is wrapped around the U-joint to keep the caps from falling off until the shaft is installed. This simple trick can save you a lot of time looking for dropped bearings.


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