Seven Notes, Part 2

by Joe Nepsa

Well, now that the handling is greatly improved because of our bump steer adjustment, we thought that a little safety would be nice. Just look at the steering shaft. A six-foot long x 3/4 inch diameter hardened steel rod aimed directly at the driver’s chest. No room for an airbag so our first thought was to adapt a Lotus Elan/Triumph collapsible steering shaft to the Seven. (Gee why didn’t he tell us about this last time.)

The (we’ll call it Elan) Elan collapsible steering column is comprise of: 1) an outer tube with splines at one end to connect to the steering wheel hub and a cutout at the other end; 2) the steering shaft, which fits inside the outer tube, has one end splined that connects to the rack via the flex joint and an 8 inch long flat cut at the other end and, 3) a clamp that is semi circular on one side and flat on the other side. In simplest terms, the steering shaft fits inside the outer tube and, through the cutout in the outer tube, the clamp is positioned so that the flat clamps down on the steering shaft flat, thus locking the shaft and tube together while allowing the steering shaft to slide inside the outer tube upon impact.

The first thing we needed was, well, an Elan steering shaft assembly! (I believe the Caterham cars have collapsible shafts, so you may be able to obtain one of these.) We actually needed one steering shaft and two outer tubes. The Elan steering shaft is several inches shorter than that of a Seven and we thought it would be much easier to extend the tube by cutting and joining two outer tubes together rather than trying this with two steering shafts. Given the length of the steering shaft and location of the flat, the trick here is to position the cutout in the outer tube so that the clamp does not foul (worthwhile English word here) the brake union or brake lines. Both of which just happen to be in the spot where you would like the clamp located.

The best location for the clamp is about seven inches forward of the foot box steady bracket. The clamp should be positioned near the top end of the inner shaft flat and centered in the outer tube cutout. This will allow for some adjustment in the steering wheel location and for maximum travel of the shaft inside the tube. Temporarily connect the shaft to the rack. Measure from the proposed steering wheel location to near the top of the shaft flat. This is where the center of the cutout will be located. Cut the outer tubes at a angle. This will make it easier to weld them together as well as providing a very strong joint, as opposed to trying to ‘butt’ weld these together. Also remove the turn signal cancellation ‘tab’ at this time. When finished welding, check the inner shaft movement in the tube to ensure that the welding didn’t leave any spatter that may interfere.

You may wish to replace the steering shaft and steady bracket bushings at this time. These are readily available and inexpensive. Now install the steering shaft assembly, by sliding it from the inside through the bushing and steady bracket then connect it to the flex joint and rack. Next install the clamp making sure that it is sitting squarely on the shaft flat. Just for good measure replace the two bolts and properly torque them. Try at least grade#5 or better. Be sure that the bolts are long enough to fully engage the threads in the clamp and threaded enough so as to not bottom out when tightened as AN bolts will. Also check the setscrew, actually an Allen head, and the large nut on the clamp to be sure these are tight. You may need to re-center the steering wheel by adjusting the outer tie rod ends. Double check all the flex joint and clamp bolts to ensure they are tight; and the steering wheel nut.

Now we’re all set for the test drive!

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