Steering alignment

[haustrup]

When I fitted my Lotus replacement galvanized chassis som year ago I
didn't find any information concerning the shims needed for the
steering rack, even if should have been stamped or written on the
chassis.

As the steering does feel a little strange in some situations I would
like to have an alignment made.

Can anyone tell me how this is checked or meassured to find the
correct alignment?

Regads
Steffen
Denmark

[Martin_StuartUK]

The problem caused by incorrect shimming of the steering rack is bump steer
- in other words, as the wheel rises in reaction to a bump, there will be a
steering reaction due to incorrect geometry on the steering rack.



It is reasonably easy to knock up a DIY rig to measure bump steer yourself,
using a couple of dial gauges. If you would like details, e-mail me off list
and I will scan and send you a diagram. If you do have bump steer, I would
suggest that your best bet is to speak to someone like Andy Widnall at
Spyder Cars to see what rough guidance he can give you on the size of shims
required to correct the problem, though to an extent it will need checking
and correcting by trial and error.



Otherwise, any race car set-up specialists will be familiar with the problem
of bump steer and should be able to check and correct the alignment for you.



Martin

[mikecauser]

I think it was supposed to be written with a felt-tip pen on the
chassis. I've definitely seen such markings on new chassis.



The quick, but not cheap, way would be to go to a shop specialising in
racing cars, eg Formula Ford. The cheap, but not quick, way is to
attach a laser pointer to the wheel, remove the spring/damper unit, and
work the wheel through its travel with different shims under the rack.
An ability to think about linkages in 3 dimensions helps a lot here.


Mike
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[fasterbyelan]

Steffen,

When I bought my replacement Lotus chassis the shim sizes were engraved
on the rack mounts. The galvanising does however make it difficult to
read and it can be missed under certain light.

The chassis was bought from Chris Neils who, when asked about the
availability of shimming steel, claim it was not required - I never have
had much confidence in them since!

Karl