Don, my old TR4 that Tom now owns has the heim joints installed in the upper
control arms. The car runs Hoosiers Vintage TD's very effectively. Take a
look when we are all at Sebring in two weeks.
Bob
----- Original Message -----
From: "Bill Babcock" <BillB@bnj.com>
To: "'Don Marshall'" <marshall@nefcom.net>; "FOT" <FOT@Autox.Team.Net>
Sent: Monday, October 04, 2004 8:55 PM
Subject: RE: Reducing negative camber
> 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
|