Doc

I recently went from simply a roll-bar to a full roll-cage. I ran one track event with everything BUT the top bar that runs across the top of the windshield installed… (I didn’t have the time to finish the last bar.)Everything seemed fine.

However, my very next event I ran WITH the top bar installed.

Now granted it was a bit cold that morning, probably the coldest morning I had yet to run however the car suffered from SEVERE over-steer! In fact, so much so that it resulted in a 360 traveling over 50 yards ending up in the wall. (OUCH!)

Unfortunately it began to rain and I had to run the next day in the wet. I disconnected my rear sway-bar all together and had my boost turned “all the way” down with about 10 lbs less air in the tires than I normally run and of course it did help, but… STILL tons'O'over-steer. Even in third gear going uphill and not too fast mind you… the back end was pitching out and just going straight was a handful too.

I haven’t’ had a chance to run the car on dry surfaces since then but even on the drive home the car seemed to be difficult to handle.

Is it possible the last bar on the roll-cage was enough to change my whole setup?

fletch.

Dude I think it was the cold tires and you jumping on it when Mo came out of 7.

Ahmet

No.

I would guess that you developed an alignment problem. Also, different tires behave very differently in varying conditions. Are your front tires the same as the rears (cept for size ofcourse)?
Ahmet

Tabor

Did you properly stress relieve the cage?

Doc

Over1g, Yes my tires are the same, Kuhmo Victoracers all around, and the were all brand new when I put them on. I've only used them once or twice before.

Fletch I'm still not sure about the coldness of the tires since I seem to recall jumping on it harder than I did that morning first time out and even in wet conditions such as Button Willow in the spring.

OK Tabor, you've got my attention. What exactly is, "stress relieving" a cage?

art

I assume that sterss relieving means making sure there is no preload, just like a swaybar.

Art

Tabor

I am no expert, but here it goes:

Whenever you weld metal together, stress can form. You need to relieve this stress through some method of heating/cooling. Your cage is welded, correct? It could be bending your chassie in some funny/not-so-funny fassion.

Doc

Actually my rollcage is a bolt in and there was no particular stress on the last bar as I bolted it in.

Maybe Fletch is right and I've got nothing to worry about, but I've heard it's common a full cage will make the chassis stiffer. I just didn't think it would make THAT much of a difference.