Project 1949 Chevy Driveshaft - A Matter Of A Pinion

Another type of sliding joint is shown here, used commonly in driveshafts for cars with hydraulic suspension, which see a large discrepancy in 'shaft length at upper and lower suspension travel limits.

Inland Empire Driveline can supply 1350 forged steel pinion yokes, precision machined for a perfect fit and forged and heat treated for maximum strength. These U-bolt-style yokes are specifically designed for Spicer 1350 use, and are available for a variety of rearend applications.

The U-bolts should not be over-tightened. In fact with a bearing cup diameter of 1 1/8 inch, such as mine, they should be tightened between 14 and 17 ft-lb. Over-tightening them will cause drag, leading to vibration.

Once I'd installed the RideTech ShockWaves and could set the suspension at "full drop", it became apparent that the pinion yoke very slightly interfered with the rear of the trans tunnel (arrowed). It's shown here in the "fully raised" position with the new driveshaft held in place with tie-wraps, as I didn't have the correct size U-bolts at the time.

When I originally lowered the Purple Pig while it still had a closed driveline, I raised the transmission tunnel as high as it would go without affecting the stock rear seat base.

Luckily, I only had to raise the rearmost 6 inches of the tunnel to provide clearance for the pinion yoke and weld yoke on the driveshaft, the remainder of the shaft easily clearing the tunnel on "full drop". As the rearmost section is behind the rear bulkhead, the stock seat base will still fit! With the tunnel modified I can now fit my finger between the yoke and bodywork with the rearend on the bumpstops.