Chassis Rigidity beyond a roll bar...
Joined: Oct 2011
Posts: 5,718
Total Cats: 830
From: Detroit (the part with no rules or laws)
I can't stress enough how much Boss Frog door bars + FM frame rails and butterfly brace did to my stock (r package)(now with RB sway bars) miata.
The improvement was monumental. At first i just had the frame rails and butterfly brace, and that made it pretty good. But after installing the door bars i could feel just pulling out of my driveway EVERYTHING was stiffened up. I also love my boss frog bars, they don't get in the way of anything. Everyone i let sit in my car say they don't even notice them. Even a buddy of mine that's over 6' 240lbs+ says he doesn't notice them.
Like i said, i highly suggest the combo.
The improvement was monumental. At first i just had the frame rails and butterfly brace, and that made it pretty good. But after installing the door bars i could feel just pulling out of my driveway EVERYTHING was stiffened up. I also love my boss frog bars, they don't get in the way of anything. Everyone i let sit in my car say they don't even notice them. Even a buddy of mine that's over 6' 240lbs+ says he doesn't notice them.
Like i said, i highly suggest the combo.
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Junior Member
Joined: Oct 2008
Posts: 219
Total Cats: 4
From: Southern CA
i can't picture how 3 wheels can lift off the ground, especially if lifted from the rear...
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Junior Member
Joined: Oct 2008
Posts: 219
Total Cats: 4
From: Southern CA
that said, i have frame rails, no x brace, and a HD sport bar. I'll be putting in the FM vmaxx track setup shortly, if there are any chassis issues i'll probably go door bars first then frog arms, as funds allow.
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The roll bar is welded to the frame rail. Pics of roll bar here:
https://www.miataturbo.net/general-miata-chat-9/i-have-disease-aka-miata-3-a-56401/
I'm not a fan of the bolt in door bars personally (roll cage nascar bars are a different story). I would stitch weld the seam around the door opening before installing bolt in door bars.
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Joined: Oct 2011
Posts: 5,718
Total Cats: 830
From: Detroit (the part with no rules or laws)
Probably about 85-90% of what it used to be. Passenger seat needs to be a few notches from all the way back due to the MS behind the seat. Drivers seat goes all the way back. I think i could have allotted more room on the seat side by installing them a little better. But the seats work nonetheless.
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On an NB, the ecu isn't behind the passenger seat anymore but the factory still puts in the bracket to limit that seats travel. It can be removed to allow the passenger seat to travel all the way back. The door bars won't affect fore/aft travel as they are parallel to the seats.
I have decided to man up and install mine. Just waiting for clear weather to do it on the flat part of my driveway.
I have decided to man up and install mine. Just waiting for clear weather to do it on the flat part of my driveway.
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Newb
Joined: Jul 2011
Posts: 37
Total Cats: 0
I have an MSM which had more chassis stiffening than most NBs to start with and here's my progressive chassis stiffening mods and how I ranked them (0 = no difference, 5 = most difference):
- MX5 Plus Twin Hoop Roll Bar with intergrated torque box (5)
- FM Frame Rails (2)
- Boss Frog Frog Arms (3)
- Carbing 3-point Front Strut Brace (0) - the stock MSM front strut brace is quite good
Frog Arms made a bigger difference than the frame rails but the fact that I can easily get 2 wheels airbourne when jacking up a corner indicates that the frame rails are doing a pretty good job of chassis stiffening.
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Elite Member
Joined: Jul 2005
Posts: 6,420
Total Cats: 84
Perhaps adding a large reinforcement plate to the attachment point of the 3 point STB, where it joins the firewall area, will spread the load and increase its effectivity. Popstoy on m.net did this and said it had a large effect.
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All-round "Good Guy"
Joined: Dec 2009
Posts: 1,036
Total Cats: 266
From: Brisbane, AUSTRALIA
As a said, the MSM OEM brace is quite good so I didn't really notice the difference. What I SHOULD have done was take the car for a drive without any front strut brace, install the 3-pt brace and do the same test. I sure that there would have been a noticeable difference then.
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All-round "Good Guy"
Joined: Dec 2009
Posts: 1,036
Total Cats: 266
From: Brisbane, AUSTRALIA
These 3-pt braces do come with a firewall backing plate that also attaches to the chassis:
Some people have questioned the validity of the 3-pt braces that simply mount to the firewall which is a valid concern because the firewall does flex - the rear bracket that also gets screwed into the chassis helps prevent this.
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Newb
Joined: Jul 2011
Posts: 37
Total Cats: 0
As a said, the MSM OEM brace is quite good so I didn't really notice the difference. What I SHOULD have done was take the car for a drive without any front strut brace, install the 3-pt brace and do the same test. I sure that there would have been a noticeable difference then.
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Joined: Oct 2011
Posts: 5,718
Total Cats: 830
From: Detroit (the part with no rules or laws)
That's one question people have, other questions are: "does the strut tower brace even do anything?" With a 4 link suspension, the only forces going into the shock tower are what is being absorbed by the strut, any lateral movement stays in the subframe.
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Is there any alternative to the Frog Arm product? I'm taking my fenders off (front clip already off for engine removal) and am going to Herculine the lips for rust/chipping prevention from our gritty roads and the occasional winter drive. I don't want to spring $250 so if there is a DIY frog arm that would be nice?
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Is there any alternative to the Frog Arm product? I'm taking my fenders off (front clip already off for engine removal) and am going to Herculine the lips for rust/chipping prevention from our gritty roads and the occasional winter drive. I don't want to spring $250 so if there is a DIY frog arm that would be nice?
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