Zero toe is good, 20 pounds is close but it probably feels good because you
have so much camber--something has to get that contact patch down on the
ground. Two possibilities: switch to radials--2.4 to 4 degrees is radial
territory. Bias ply Hoosiers have too stiff a sidewall to work like that.
Second, make the upper arm adjustable. I can send you a shot of Peyote's
upper arm if you'd like, but basically you replace the upper bushings with
heim joints. TR3/4 both suffer from a lot of camber gain and a lot of bump
steer. As the suspension compresses the camber increases. If you model the
arms and upright you can see how it happens. Lengthening the upper arm and
moving the pivot point inwards the same amount will decrease the camber
gain. Lengthening the arm more than you move it inwards will decrease camber
and reduce camber gain.
When you change any of these things you want to check your bump steer and
try to minimize it. Some of your tire wear might actually come from bump
steer--it toes the car in or out when the suspension compresses. Look in
Kas' book at page 211-214 for some ideas.
-----Original Message-----
From: owner-fot@Autox.Team.Net [mailto:owner-fot@Autox.Team.Net] On Behalf
Of Don Marshall
Sent: Monday, October 04, 2004 2:56 PM
To: FOT
Subject: Reducing negative camber
All, after a very successful weekend at Roebling Road but having used up the
inside third of a brand new Hoosier (left front, naturally), I'm about ready
to get serious about reducing the negative camber on my TR4A to see if it'll
handle just as well or better and maybe get better tire wear.
Normally I would remove some shims and be done with it, but this one gets
most or all of its ~2.5 degrees negative camber as a result of the springs
having been cut shorter rather than shimming, so there are none
to remove. It also appears that the upper A arm fulcrum pin may have
been reversed but I'm not sure about that yet.
It appears my choices are:
1) Replace the springs with longer springs to increase the ride
height and reduce camber and who knows what else.
2) Put spacers under the springs to effectively lengthen the
spring and pull out some camber without changing the springs or spring rate.
Anyone have an idea of what thickness spacer I'd need to eliminate a degree
of camber and what other effects this might have?
3) Have Uncle Jack add a section to the upper A arms to push the
tops out (opposite of the normal adjustment he does).
4) Turn the fulcrum pin back around if it's actually reversed.
Any other ideas would be welcome, preferably something that's easily
reversed if it doesn't help? The cars handles great and if excessive tire
wear is something I have to live with I'll do it but it seems to make sense
from all the previous discussions to try this. BTW, toe is zero and I'm
running 20 pounds air pressure in Hoosier Vintage TDs.
Aside to Henry. it wouldn't be the same without you. See ya at Road
Atlanta.
Thanks, Don
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