Michael,
I think the mass moment of inertia of a circular hoop (steering wheel in
our case) about the turning axis is:
I = m * r^2 (mass times radius squared). So, if you weigh the wheels
and measure the radius - then you can plug in the numbers and see what
the difference is. Don't forget to divide by gravity to get from weight
to mass :)
If the wheels are close in mass, then a 16 inch wheel might feel better
simply due to the radius difference compared to a 15 inch wheel (radius
squared factor). More inertia, as you mention. On the order of 14% for
16" v 15" wheels of the same mass. If the original wheels have more
mass in the rim, then the percentage will be even greater.
I'll bet the vehicle dynamics engineers at DMH motor company had this
all figured out back in the day, along with the below mentioned 'grip
factor' :)
Potential solution: request Mike Lempert design more mass into the rim
of his wheels to bring inertia in line with original wheels. Joking !!!
Does the recirculating ball type steering box allow steering kickback,
where as a rack an pinion system will not? I think I read that
somewhere, sometime.
Dave M.
bored at work
-----Original Message-----
From: owner-healeys@autox.team.net
[mailto:owner-healeys@autox.team.net]On Behalf Of Michael Salter
Sent: Thursday, October 19, 2006 8:12 AM
To: WmsRbt@aol.com; smithn00@kitepilot.net; healeys@autox.team.net
Subject: RE: Lempert Steering Wheel
Oh Enlightened Ones,
On the subject of steering wheel weight I have always found that Healeys
with Woodrim wheels tend to exhibit more kick back than the originals. I
have recently realized that one of the reasons that I prefer driving
cars
with the original wheels is the lack of steering kickback. I suspect
that
this is attributable to the additional moment of inertia created by the
heavy rim of the originals.
Comments?
Michael Salter
www.precisionsportscar.com
-----Original Message-----
From: owner-healeys@autox.team.net [mailto:owner-healeys@autox.team.net]
On
Behalf Of WmsRbt@aol.com
Sent: Thursday, October 19, 2006 7:23 AM
To: smithn00@kitepilot.net; healeys@autox.team.net
Subject: Re: Lempert Steering Wheel
Ned,
By my estimate it should require exactly 8/7.5 ths, or 16/15ths more
force
to turn a 15" diameter wheel vs a 16" diameter wheel. Therefore the
15"
diameter wheel would require 6.67% more force tangent to the
circumference
of the
wheel to turn, all other things being equal. This of course discounts
the
gut satisfaction in gripping a beautiful wood trimmed wheel, which
probably
shaves some off the 6.67%. This is known to steering wheel engineers
as
the
"Grip" factor!
(By the way, I have a beautiful 15"dia Lempert wheel in the bag)
Robert Williams
BJ8
In a message dated 10/18/2006 5:17:12 PM Eastern Standard Time,
smithn00@kitepilot.net writes:
I may get one of his steering wheels for my BJ8. One of the choices to
make
is wheel diameter. My present wheel is 16" but it is difficult to spin
back
and forth in a gymkana (I almost think a "neckers knob" would be the
thing
to have for that type of racing). Would a 15" wheel be easier to use?
Your thoughts please,
Ned Smith
BJ8
near Chattanooga, TN
N34.89, W85.47
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