I have never owned a convertible before, I honestly would prefer a hardtop, but I found a 09 MCS R57 with lower miles, in better shape and for a better price then the comparable hardtops in my area, so thats what I got.... I know that losing the roof and its pillars creates different and increased stress on the chassis during load shift such as turning braking or going over uneven roadways.... To me Torsional and longitudinal rigidity would be the obvious places to suffer when losing the additional points of contact from A,B, and C pillars connected by the roof. so my question is in the R57 cooper S unibody frame, where specifically the chassis need to be reinforced to compensate for these forces? Im not opposed to losing having the convertible capability, like a targa top or a cage that I can mount a top to. I want the car to have to have similar stability as a hard top but with the extra bracing found in a convertible and I want to know what options are available, preferably ones that add minimal weight that don't cost more then the car.

 

I have one of these on my hardtop, and I notice the difference when going up driveways and similar things. The car lifts the front and rear wheels evenly when jacking the car on the front lift point. I also have a NM strut brace on the car, but don't notice much difference with this. The X-brace is recommended, and installs in about 15 minutes.

I understand that there are additional braces undercar on the cabrio.

http://waymotorworks.com/tsw-xbrace-r56-r55-r57.html

Mike

 

Like Mike said our X brace and a strut bar are the most cost effective options to stiffen it up without a major change to the car.

 

 

You have to cut the panels, or at least drill holes them them, but it's not really meant for the panels.

 

Also understand that you give up about 1-1/2" of ground clearance with the x-brace, especially under the center of the car where there is a bump to clear the exhaust. With stock suspension, in the center of the car, I could drive over a baseball, but would hit a softball. For me, it was worth the trade off of stiffness vs. ground clearance. When I modded the suspension I didn't go too low.

I remove the brace during winter, because it sounds really painful hitting ice chunks right under my feet. Even with this 'hassle' of removing it, I'm a big fan of the X-brace.

Have fun,
Mike