The car is a Caterham Super Seven, exact duplicate of the Lotus Super
Seven, 1985 vintage.
The steering rack is moving from side to side, and worse, rotating.
I use the car for autocrossing and for open track events. I have sticky
tires and have measured the G lateral G forces at 1.25 gees, when the tires
were new.
The steering rack appears to be off a Triumph. It has the flanges at
either end of the rack. The pillow blocks (right term?) that attach the
rack to the frame are mounted just inside these flanges. This prevents
side to side motion. The clamping force of the aluminium pillow blocks is
supposed to prevent rotation.
Now all of this would be ok except for one small problem. There is a
universal joint at the input point of the rack, connecting the steering
wheel shaft to the rack. This universal has several bolts that allow the
universal to clamp to the shaft.
The problem: These bolts interfer with a frame member. What to do?
There used to be a couple of mm play in side to side motion of the rack
that occurs only under extrememe side stress. I fixed that by moving the
mounting holes on one pillow block out board to take up any slack left.
Now the rack rotates slightly bringing the bolts near the rack. I have
tried sanding the mating surface of the pillow blocks, to reduce the space
between the bocks to further clamp the rack. I fear too much clamping
force will deform the rack housing.
I guess I could cut a notch in the frame in that area, but the Seven is
minimal anyway and that might be the straw that breaks the camel's back.
Michael
(One of my fondest memories, BK, before kids, was associated with this
rack. I was at an open track event, and it shifted middle of every
session. My wife and I had it down in the pits. I would pull in, crawl
under and hold the bottom of the pillow block bolts. She would reach over
the top holding and loosening the top so the rack could be repositioned.
She is a mechanical engineer by training and trade and this was the only
time I could get her to work on the car!)
Michael Sands Kaleida Labs
(415) 966-0711 sands@kaleida.com
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