I've seen the heim joint upper a-arm modification before, very nice. I
thought about doing this on my TR4 but was warned that it was not
considered "vintage legal".
Perhaps we need a group opinion on this modification.
Richard Hone
TR4 TR6
> ----------
> From: Bill Babcock
> Sent: Wednesday, June 3, 1998 5:54 PM
> Cc: 'Amici Triumphi'
> Subject: RE: K & S Alignment/Sharing Information
>
> I've done a great deal of work on my front suspension. No secrets, I
> just don't have all the measurements and calculations at hand. The
> primary problems is that if you project the roll center for the stock
> suspension it winds up around five feet underground. It's considered a
> good thing to have the roll center for front and back in the same
> plane
> (or at least close). Since the roll center for the rear wheels is the
> centerline of the axle (fixed axle) there's a lot of funny forces when
> the car turns.
>
> I modified the upper arms to add adjustable heim joints instead of the
> stock bushings, and offset the pivot point towards the engine on the
> spring box by about an inch to raise the roll center. The adjustments
> allow me to change camber (though it also changes the length
> relationships of the arms) and change caster slightly by shortening
> one
> arm more than the other.
>
> I haven't done any real tuning since the initial setup, but the
> handling
> difference is remarkable.
>
> I also fiddled with the control arm height to reduce bump steer.
>
> I'll make a bunch of measurements and pass them on ASAP. I wasn't very
> scientific about the design, other than modeling the roll centers on a
> computer. But it's working very, very well. It's a whole new car.
>
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