Project 1949 Chevy Driveshaft - A Matter Of A Pinion

The next step was to machine the tube to the exact length, and put a small chamfer on the inner and outer end surfaces. The tubing was then cleaned inside to ensure no swarf or debris would be inside the finished 'shaft.

The machine included a hydraulic press that presses the weld yokes into the tubing. Rocky left this gap (arrow) to ensure perfect weld penetration.

Determining the tube length had to be 51 3/16 inches, he wrote it on the tube as a reminder then cut it to length. Inland Empire's aluminum driveshafts are manufactured from custom drawn 6061-T6 DOM aluminum tubes for consistent strength. Their products have passed Spicer's grueling dynamic reverse torsion testing, qualifying the company as one of the very few Spicer authorized aluminum driveshaft builders in the world.

With the rear weld yoke and U-joint assembly bolted to one of a number of special yokes manufactured for just such a purpose (remember, the rear U-joint is bolted to the pinion yoke in the car), the weld yokes at each end ready to be pressed into the tube, and the whole driveshaft assembly installed in a specialist machine, which looks like a very long lathe, a level is used at each end to ensure the U-joints are in phase with each other.

Welding aluminum requires absolute cleanliness, so the area to be welded is thoroughly prepared using a rotary wire brush on a bench grinder. Note the change in surface texture where it's been cleaned.

Once the welds have cooled, and still on the same machine, the driveshaft is spun up to speed to be balanced. A gauge at each end of the shaft informs the operator of what's required.

Re-installed on the machine, the 'shaft is checked for runout using a dial gauge at each end as well as in the center. Here's where Rocky's years of experience came in, as he knew exactly how to correct the slightest discrepancy.

Again, Rocky's experience came into play as he knew exactly how much weight to apply and where to apply it to perfectly balance the driveshaft. Weights were held in place with wire while the 'shaft was spun again, though they were in the right place first time!

The semi-automated MIG-welding procedure ensures strong welds every time. Adjustments are only made when different diameter tubing is used, as it'll rotate at a slower speed. And if you ever wondered how to attach a ground to a rotating assembly, here's how!