Chassis Rigidity beyond a roll bar...
 

I have been reading lately about "door bars". Preferably the Hard Dog door bars as seen here: http://www.gomiata.com/mim2dobaforh.html
I currently have a Hard Dog Xtreme Roll bar, which was the first thing I ever put in my car after I bought it. The Hard Dog door bars bolt right up to the lower mounts of my roll bar.
Questions:
Is this something that's going to be a real pain getting in and out of my car?
Am I going to wack my knees all day long and get pissed off?
Is it going to actually make a significant difference in chassis strength?
Is it going to interfere with my door panels or any other interior parts aside from maybe notching my carpet?

I also have been looking at the Frog Arms as pictured here: http://www.flyinmiata.com/index.php?...umber=13-71000
Questions:
Will these make a significant difference?
Seems like a lot of work (fender removal, looks like maybe some drilling, etc), but the cool thing is, you don't even see them.
I'm thinking door bars for sure, but frog arms???
Opinions/ suggestions...

Door bars make the biggest difference in my 2000.
Next was the FM butterfly+rails.
Then the shock tower bar.
Then the door seam welding.
Rollbar hardly did anything.
I don't have frog arms.

Go to youtube and search for my video "miata door bars ingress".

I have door bars in my track car and I am pretty sure they are low enough to not interfere with getting in the car. I never bang my legs on it. It's pretty much a no compromise mod.

Yes, they make an enormous difference, like change your sway bar set-up difference.

I'm definately buying the door bars...probably no frame rails or strut bar. I'd like to hear more reviews on the frog arms though.
Looks like the door bars mount to the lower roll bar mount. I assume I drill the floor for the front of the bars?
My car is a very clean setup. My roll bar looks like it came factory, and I hope the door bars will end up the same way.

why no frame rails? can't think of a single reason you wouldn't want them.
cheap, fairly easy to install, significant improvement, etc

Not a huge improvement if your current rails aren't beat to ----. Mine aren't, and I'd love them for jack points, but from what I've heard they're not a huge benefit with an undamaged stock rails. I mean they're a layer of steel over a layer of steel. Door bars box up the...door.

All speculation and rumor though of course.

It seems to me that the rails alone may not make a huge difference, by that the butterfly would make a significant change. Can anyone comment on that?

frame rails made a huge difference to my Roadster (original rails were in good condition), could immediately feel the difference even just reversing out of my driveway.
I had 16 sets made up locally for people, everyone happy.
https://lh5.googleusercontent.com/-U...0x600%255D.jpg

miata.net has 2 great threads on Boss Frog "Frog Arms":

1. http://forum.miata.net/vb/showthread...ight=frog+arms and

2. http://forum.miata.net/vb/showthread...ight=frog+arms

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.

I jacked up my car using the stock jack and the driver's side rear pinch point. Both back wheels came off the ground. I have no additional stiffening whatsoever, and both doors were open.

How much more do you need?

Anyone try the Frog Ribs? Second item in this link:

http://www.bossfrog.biz/Miata_Performance.html

Wondering how they compare to the Hard Dog door bars.

I've been wondering if anyone has tried a 'through-the-floor' subframe connector type set-up in these cars?
One could tie them in to the rollbar mounts and into the front frame-rails.

I like where the Blackbird rollbar mounts. (9th picture down)
I would think that it would be a better mounting place than the thinner metal of the floorboards.

http://blogs.insideline.com/roadtest...-roll-bar.html

Rails only, or butterfly as well?

I'm interested in adding stiffness for the times my hardtop is off, which is pretty much from April to October. I can get both wheels on one side off the ground from one jacking point with the roof off, so there's a decent amount of fore/aft stiffness in my car, but twisting flex is more noticable topless. That's why I'm curious about the butterfly itself (as opposed to just the rails), as it seems as though that piece would eliminate some/most? of the torsional flex.

How about stitch/tack welding the rest of the car? I did my door jams last weekend and want to do more. Such as the shock mount areas and behind the seat areas.

I only have the FM frame rails - MSMs have a lot of underbody stiffening and plates that would need to be removed to accommodate the butterfly brace.

With the frame rails in place, I don't have to jack the car up as high as I used to get both wheels off the ground so I know that they definitely add stiffness..

NAs and NBs in stock form have very little chassis twist prevention and was something that was addressed in the NC.

The biggest difference maker for me was the roll bar which addressed chassis-twist in a BIG way, I noticed the difference immediately when slowly turning right to exit the parking lot of the garage onto the street, the car felt completely different. I'd recommend a roll bar to anyone these days just for its chassis stiffening effects - the safety aspect and "cool factor" are secondary benefits as far as I'm concerned.

With my roll bar, frame rails, Frog Arms and Carbing 3pt front strut brace, I reckon I'm about as stiff as I can get without resorting to a roll cage. I can't fit the door bars though since I have MAZDASPEED seats which are wider than stock.

Good to know. :bigtu:

If I lift my 01 at one of the rear points, it will pick up 3 wheels. My rollbar is welded in, and the rear uprights go all the way to the frame rails in the trunk. It has sport bracing, but no aftermarket rails or door bars.

Your RB is obviously adding quite a bit, then. I do have a HT on mine, and all 4 latches are snugged down pretty tight. I'm sure it would twist/flex more without the HT.

Hustler, change them which way? Stiffer front/softer rear, or vice versa.

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.

i can't picture how 3 wheels can lift off the ground, especially if lifted from the rear...

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.

Plus these things just look sexy as shiz!!

https://www.miataturbo.net/attachmen...ine=1332538580

Oh, i forgot, the seats were a little bit of a PITA but i got them in.

Jack goes up, all wheels except for the one diagonal from the jack go up as well. I'll take a pic at some point. Car is loaded on the trailer now.

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.

ahh, for some reason i was expecting the other rear wheel to be planted. that makes sense now.

I have been away form Miatas for a while...Hadn't seen the door bars before. Those don't look bad at all. How does it effect the seat moving back and forth?

Craig

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.

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'm surprised you scored the 3 point brace so low. I have the exact same one and love it. But... you do have the MSM, but damn lol

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.

i guess you mean the backing plate. yea i have this on my STB and it made such an improvement over my old 2 pt

WTTFF????

If you jack up an unbraced car will it really arch like a mcdonalds sign?

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.

These 3-pt braces do come with a firewall backing plate that also attaches to the chassis:

https://www.miataturbo.net/attachmen...ine=1332906425

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.

wouldn't have mattered anyway since you already said you didn't notice any difference.

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.

blah

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?

Alternative is just welding some stupid piece of metal between the places where frog shiz bolts up. Not rocket surgery shiiiii

I use my strut tower brace to hold my turbo blanket on:giggle:

Garage Star is making their own version of the Frog Arms. Slightly cheaper

https://www.miataturbo.net/attachmen...ine=1336239944

Angle iron, a grinder and a cheapo flux core welder for ya... I didn't want to spend the money on something so simple either.

I've heard the quality of that stuff is sub par... That stuff is more of a road clubster product.

I tried welding once. Need to get back into it.

Start production on those! I'd take a set.

Considering their arms aren't even out yet, how did you hear that they were sub par quality?

I've gotten a few miscellaneous pieces from them and they have always been top notch quality. Because a person advertises on CR.net and not MT.net does not automatically mean they sell crap.

Yes it does.

More options and competition in the market will be a good thing either way.

^^ I second that. Anything that can drive down some of the prices would be a win for me. Just as long as the quality doesn't suffer too much, which I suppose is the Catch 22.

https://www.miataturbo.net/showpost....5&postcount=10

https://www.miataturbo.net/attachmen...0&d=1289973752

I'm not down with that angle iron type...I'd go for square tube anyday of the week though...

I'm gonna fab up my own version of "frog arms" and you guys will $hit yourselves.

Kinda thinking the same thing myself...

Yeah, cause those rigged up 1/2 assed versions of angle iron craps are embarrassing.

Lol, embarrassing for who? I'm perfectly happy with mine. It was dirt cheap, easy to build and I noticed a pretty big difference. At least it works fine on my craptastic street car. I definitely agree that it can be prettier, but I'll bet that your pretty version is only marginally better performing than my ugly version. I do like BBundy's solution though. Very elegant, lighter than mine for sure, and I really like the idea of the little welded reinforcement plate thing.

I'm just ---- about everything, weather it's under a fender where you can't see it, or not. I still know its there, so it should look good and perform to the extreme capabilities of what it can be.

Is that why you sport 16's? ;)

Ouch!