Question: Will a roll bar (not cage) affect the stiffness of a chassis? If so, to what extent for...

*Autocross?

*Lapping?

I'm curious as my roll bar (not cage) will go in on Saturday

Thanks in advance, everyone :smile:

 

Anti-roll bars directly effect the roll stiffness of a vehicle, adding roll resistance, hence reducing load transfer per corner of vehicle. Through that mechanism, the front/rear roll resistance relationship is used to balance the handling characteristic of the vehicle; it is considered a fine-tuning device as its effects are relatively small.

 

Excellent overview! I autocross Sunday ...the day following its install (it's being installed for Solo I entry come Nov. 13). Having the roll bar add a touch of stiffness is much welcomed by me as that never did come to mind when considering/ordering it. Some's better than none. Thank you, FT@SELGP

 

Erik808 was asking about how by adding a roll bar to the inside of his MINI, he might get added stiffness to the chassis?

FT@SELGP answered with a comment about anti-roll bars which are the same as sway bars that we use front and rear to stiffen up our suspension and control understeer.

Back to the roll bar. First you must comply with the SCCA solo 1 rules on roll bar installation. You'd have to check with the company making your roll bar if they have designed the roll bar with chassis stiffening in mind or to offer protection to you in case of a roll over. The roll bar does add weight and cuts down on interior space and visibility so there are many tradeoffs. The larger the tube diameter and more triangles built into the design the stiffer it would be.

SCCA is more interested in providing rules to help with safety to Solo 1 drivers and I would think that rules would limit how stiff a design one could add to a car in order not to give unfair advantage. Plus that same car will get to drive in Solo II.

 

Precisely, minihune

One more thing ~ With the roll bar in the rear ...I'd think that it will balance out the distribution a tad (as stock's: 63% front; 37% rear). What do you all think?

 

Erik808,
I hope you had fun in Solo 1. You were going wheel to wheel in practice and out by your lonesome after lunch. 1 min 11 sec long course lap time and 98 mph at the end of the long straightaway. The timers were impressed by your MC. We watched you do some "late" braking before the hairpin turn. One other SCCA flag worker suggested you should have been allowed to run in the wheel to wheel with the two porsches and 240Z but I think he just wanted to be able to wave the blue and yellow passing flag more since he was bored he had not much to do with only a few cars on the track.

Your roll bar looks good. Nice install. Weight maybe less than 100 pounds? Just a guess. Certainly adds to rear weight and evens out the distribution.
Stiffness depends on design and attachment points. Yours goes more to the rear and passenger cabin floor so I think it may add to some stiffness.