GTM roll cage modifications and race car build log

[crash]

I'm just going to think out loud here for a minute, so please, if my train of thought is incorrect, then point it out...

2800 LBS car

Roughly 40/60 split front to rear weight distribution.

I'll get conservative and estimate 1400 LBS in rear.

Two tires, so weight is divided by two...700 LBS.

Data shows over 2 Gs of lateral loading.

Therefore back up towards the 1400 LBS in dynamic loading. Probably higher as when side loads increase the inner tire does less work(usually) than the outer tire.

Granted that upper and lower arms take most of this load. Still, one would be "hard pressed" to develop a test rig that will apply 1400 LBS of load to the rear suspension.

Now consider the fact that we used to be able to see it move by using our legs to push on the wheel...

Conclusion? The rear suspension is going to move and flex in a dynamic way under the loads we are now producing.

Also I believe it is imperative to look at the rear suspension system dynamically and to maybe start with something closer to 1/8 toe in, but also to see where it goes when loaded. A 1/16 toe in is pretty light, especially considering that would be 1/32 per side.

In general, the cars I have raced have been very sensitive to toe adjustments. The GTM appears to be no different, and a wider tire just exaggerates the situation because of the distance between the hub and the outer edge of the bigger tire. Moving the upright away from the tire centerline may even exacerbate this issue.