[Healeys] collapsible column

[allen c miller jr]

In February I drove a 2010 Toyota compact head-on into a truck tractor parked
in the slow lane of Jamaica's only limited access highway. Even at moderate
speed (30-35 mph), the front end was pushed back to my ankles. Thanks to
modern 'progressive failure' technology, I walked from the crash with shoulder
and lapbelt burns and chest bruises from caving in the collapsible steering
column. As soon as I walked off the plane, I began designing a collapsible
column for my 100M racecar, a project that had been in the left brain phase
for two years, but never got off the sketch pad. A week later I finished CAD
plans and perspective renderings, sourced parts, and took a BJ8 high ratio
(12:1) box to Don Breslauer in Connecticut, a noted custom fabricator with
extensive racing team experience. He tweaked the design and worked out the
fabrication issues. The next day later I took home a ready-to-mount box. Even
with the prototype, my savings were 60-70% over the costs of sending a box to
England for conversion, given shipping and the currency conversions.

I'd like to share my plans with anyone interested in converting from the "Sir
Lancelot" model Healey steering column to a modern design collapsible model. I
have no financial interest, just a desire to improve the odds of others
getting the same break I got in February. The design is based on fitting a
stock $79 Borgeson 1DD:0.75DD collapsing tube to a big Healey box. Total parts
are around $200.

1. the near ends of your stock column and outer tube are retained from the
firewall back to the wheel, along with the stock clamping mount is preserved.

2. any model big Healey box BN2 to BJ8 can be converted without a loss of
trafficator function; the only change is that your trafficator is fixed to and
rotates with the wheel. Horn and turn signal inputs are picked up under the
dash cowl with electric motor brushes contacting bronze bushings mounted over
nylon isolators.

3. in addition to the stock clamp mount under the dash, the column passes
through the inner firewall box section on a ball swivel joint. both mountings
resist the intruding column on catastropic impact.

4. the column passes through the swivel joint and joins a section of 1.125" x
0.20" DOM tube  (same o.d. as the Healey outer column tube). this in turn
joins a Borgeson 1"DD:3/4"DD collapsing tube that will fail 6"-7" on impact
against the firewall.

5. the 3/4"DD tube is mated to a short stub section of the Healey worm gear
coming out of the box. the stock worm gear retains its roller bearings and is
further stabilized inside a short section of the stock outer tube an custom
turned oil-impregnated nylon flange bushing. I packed the box with bearing
grease in place of the original oil, but an oil-sealing felt setup like stock
could be made.

6. The three weld joints are made with custom turned billet plugs rose welded
to the tubes and run full precision welds around the joins. Don's work nears
perfection. Precision welding around billet turned splices made for a
stronger-than-stock column, with less than 0.01" of axial rollout. Installed,
the only conspicuous part of the column (between the firewall and the carbs)
appears stock, with essentially the same o.d. as the original 1-1/16" Healey
tube. The stock firewall blanking plate is kept for cosmetic appeal (or you
can mount the swivel ball joint to it for better impact resistance if you
don't mind seeing the swivel joint on the engine side)

Please email if you'd like drawings and narratives. If someone will host on a
web server, I 'll be glad to upload the drawings. I can put you in touch with
Don or will gladly chat  with your local machinist by email.

Allen Miller
BN2M