I am swapping roll bars with the person who purchased my old Miata (they didn’t like the diagonal) and I plan on powder coating it before reinstalling (black). While researching things to do while bar is out, I have come across a few pictures of Miata's with a couple additional braces running centered from the top of the roll bar to the top of the windshield. I have a few questions:

1. Will this help noticeably with vehicle rigidity? I have no qualms about adding 10 lbs of metal to alleviate some of the body flex. I was looking into door bars, frog arms, and frame rails. How would it compare to these?
   
2. Is this something that must be done with the bar in the vehicle? It doesn’t make sense to powder coat the roll bar if this job is done after the bar is installed (mismatching coloring with new bracing/welds). Does the soft top fit back on? Is it welded or bolted to the top or bottom of the windshield frame?
   
3. I currently run in SSM in my local SCCA auto-x region. I know the frame rails and other braces would bump me out of that class, but would this?
   
4. Does anyone have any opinions after having this done to their car? Regrets, things to do differently? Cost? Pictures?

My car: 97 with Old School Sebring and additional this and that’s. It is my DD during the summer and the wife and I like to take a couple three day weekend road trips with it. I plan on attending a track day or two at Miller Motorsports Park this summer. Drive to auto-x events, which I do for fun. I am not top 10 pax competitive (mostly among friends).

 

yes
yes
yes
1-guy with a mariner blue car

 

Thank you for the quick reply, but was looking for a bit more detail.

 

Flipsidecustoms

Watch your noggin if you plan to drive on the street....thats the only reason I'm not going to cage my car....

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That's very badass!

 

Looks cool as hell, but I just know I'd take a hacksaw to it the first time I smacked my head on it.

 

You're going to put a big moment on those welds for the top bar if you ever do roll it over. There isn't much strength in the windshield and it will still want to crush. Seems like a good chance the top bar would break too.

 

I highly doubt that. Since its boxed in there is a far less chance of total collapse. The load will be distributed across the roll bar and the windshield. Only way its breaking is if it gets thrown off a building (as long as it has a full strength weld)

 

Maybe if there was a hoop welded alongside the windshieldframe where this bar would connect. Make it real close to the frame and remove the trim pieces so you can get it welded in properly. This will allow you to still use the latches and it wont be so intrusive. Then you're only a few pieces of tubing and some doorbars away from a full cage.

 

i agree... thats just going to add a point load to the middle of the windshield frame and crumble the windsheild.

 

I was planning on doing this to my car as well! mainly to get rid of the vibrating of the window thingy (that **** annoys the **** out of me when the top is down!

 

+1 Looks like the worst designed roll bar I've ever seen; but what do I know, I thought building a splitter from plywood sounded like a good idea.

 

Examine the first picture

Then examine the second


I agree there is a better design but its far better then just a roll bar.

 

What door bars are those in the red car? ^

 

Kirk Racing.

 

I can't see how in a roll over those bars wouldn't just fold down into the cabin. That would be a really bad day if those bars came down onto your shoulder.
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To me it looks like an unsuccessful attempt to bridge the gap between roll bar and roll cage. It may work better than I think; but I don't like it and would rather just have a well designed roll bar.

 

I agree. In a mild roll over, I could see it working. but in a catostrophic crash, those bars could be curtains to the driver. They could literally spear the driver. I would never put that in my car, unless there were test results that would prove it was beneficial and safe. Assuming that system is safe is ridiculous.

 

That setup looks like it would cost as much as a full cage.

 

I don't completely agree with your stress analysis of it. Any force in the connecting bar will get brought back straight to either the windshield or the roll bar. It is still the same basic scenario. It might add a little strength, but if the car rolls, the windshield is still collapsing.