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Discussion Starter · #1 ·
I currently have a harddog rollbar and Im looking into some more chassis stiffeners.
What is everyones opinion on the best route to go. I have a 91 miata with no underbody braces.

Im thinking about a front underbody brace and fm frame rails, then eventually harddog door bars, Everyones Opinion is appreciated, Thanks
 

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Discussion Starter · #3 ·
Id like to, but money and ground clearance are also issues. Btw I know of the front and rear brace, but what is the third??
 

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I have the following braces on my car:
Harddog SS Hard Core DD
FM Butterfly Brace
Power Plant Frame Brace
Racing Beat Front Brace
Racing Beat Rear Brace
OEM Mazda Strut Tower Brace (10AE)

The FM Butterfly has an amazing effect.
If you mount it all the way up there is no ground clearance lost.
 

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I absolutely love my 3point autoexe strut bar, tightened the front sooo much, car feels great.
I also have FM rails, and HDHC roll bar, and stock 99 braces.
 

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Discussion Starter · #7 ·
anyone gone from a rollbar and extended it to a cage???, hows the increase in rigidity feel??
 

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Add the FM rails to your roll bar and you should feel the difference immediately. You could up the ante to the full butterfly brace if you want, but I'd bet that the FM rails will make more difference faster than almost anything else.
 

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anyone gone from a rollbar and extended it to a cage???, hows the increase in rigidity feel??
I did, 4pt hardcore then later added front section via welding.

dont waste your money on those overpriced metal bars that fm sells

get something that actually can save your life too

 

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Arent we talking about a street car here? Hitting your head on one of the roof bars without a helmet would be much worse than not having them.
 

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Discussion Starter · #11 ·
half autocross, half nice weather car, its not my daily. I think Im gonna go with the racing beat braces, then Im gonna prolly get door bars. Even though driving around with the top down and having a cage would be badass.
 

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I would definitely recommend getting the Cannon rear brace over the RB one. The RB piece is flimsy sheet metal and doesnt really fit correctly, IMO.
 

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I have a '91 also. When I added slightly stiffer shocks and springs my tired old chassis couldn't take it any more and it rattled like crazy. I didn't want to spend a ton of money just yet as I didn't know what I wanted to do with the car overall so I installed the Flyin' Miata rear subframe brace made by Skip Cannon. I feel this part is a little more sturdy than the RB version and I like it better than the later factory crimped tube braces because it picks up two additional points creating a more rigid box. I also added the Racing Beat front subframe brace which is a very nice cast aluminum piece. It's mounted with 4 strong bolts in an attempt to minimize twisting. Both braces helped quell my vibrations and made the car much more tolerable over bumps.

The biggest bang for the buck is probably a 4- or more point roll bar as you get additional stiffening around the open sides of the tub plus added safety in the misfortunate event of a rollover. To visualize why a roll bar works so well at stiffening a open car take a plastic cup and squeeze opposites sides of the rim together. See how easy the cup bows? If you put a stiffener in there the cup would remain cylindrical. Same thing goes for the big opening that is your passenger compartment.

Many people have reported success with just FM's frame rails w/o the center butterfly section. Too bad you missed out on FM's deal of the day a month or two back as they were selling an earlier version of the frame rails that weren't compatible with the new butterfly middle section for cheap.

Next you might consider shock tower braces. People report varying levels of effectiveness on these so you pay your money and take your chances. A 3-point brace is probably better as it braces against the firewall. Triangles are strong.

At this point it becomes a matter of diminishing returns where you add more weight to the car and spend more money for smaller and smaller increases in stiffness. You could seam weld the chassis, weld in additional support bars for your roll cage, install fender braces, add later style firewall gussets, etc. Be sure to pick up the latest copy of HyperRev to see a wide assortment of chassis stiffeners available today.
 

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heres a pic of the door bar

omg thats the dumbest thing I have ever seen

more saftey...nope

stiffer...nope

less money in your pocket...yep
How do you figure?

I'm skeptical of the safety in a side impact, I see getting pinched being pretty easy... but having driven Eddie from Adrenaline's Civic before he sold it, the doorbars DEFINATELY make a difference in stiffness.

I want to do a set in my car, but I want them way lower than that. I don't want anything that can crush my leg to be right next to me.
 

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omg thats the dumbest thing I have ever seen

more saftey...nope

stiffer...nope

less money in your pocket...yep
How do you figure?

I'm skeptical of the safety in a side impact, I see getting pinched being pretty easy... but having driven Eddie from Adrenaline's Civic before he sold it, the doorbars DEFINATELY make a difference in stiffness.

I want to do a set in my car, but I want them way lower than that. I don't want anything that can crush my leg to be right next to me.
well since it doesnt make a triangle is not as stiff as it could be. its really low and has a bend in it with no support... it would do nothing for a crash, except maybe mousetrap like you said. I think it would add *some* stiffness but I would say less than just the fm rail braces. a 6point should look something like this

the pic sucks but you get the idea, straight bar from the joint to the floor
 
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