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Chassis stiffening - which parts are good?

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Old 06-20-2009, 02:48 PM
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Default Chassis stiffening - which parts are good?

Everyone seems to have differing ideas about what the good items are as far as chassis stiffening goes. Rather than just bolt on everything on the market (like the jdm Honda guys seem to love to do), I'd like to use as few parts as possible so as to keep expense and weight down. My car's a '93, so it didn't come with much bracing in the first place. I already have a rollbar and a hardtop, and I am not going to put a cage in this car.

Some of the pieces I can think of off of the top of my head:

frame rail reinforcements
butterfly brace
front subframe brace
rear subframe brace
triangle brace
f/r shock tower brace
f/r LCA brace
underfender brace ("frog arms")
PPF support
door bars

That's all I can think of. See? Which to choose?
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Old 06-20-2009, 03:12 PM
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all of the above lol I'd like to get some rails, then some subframe braces I already have roll bar and front shock tower brace
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Old 06-20-2009, 03:42 PM
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Having over half of those, I would have to say the ones I would stick with would be roll bar, door bars, frame rail brace and frog arm. I would also like to see what seam welding would do, cheap (or free) and fairly easy. I wish I could start over and do it right. I view this car as sort of a trainer car to learn what works best, and what route to take to my ultimate goal. If I could do it again, I could do it for half the cost and twice as good. I would start with seam welding, add roll bar, door bars, and frog arms and be done (if it were an R package and already had the sub frame braces, if not, add those too).

My frame rail braces helped a good bit, but not the wow factor I hoped for. I would imagine the butterfly section would help a bunch. From what I have heard, door bars are also a best bang for your buck part. Frog Arms seem like they would work well too. I will be trying them out very soon. Decided to put the turbo on hold yet AGAIN so I could make my car more comfortable for daily driving (reduce cowl shake and all of the shuddering over bumps). So suspension and chassis will be getting more attention.
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Old 06-20-2009, 03:49 PM
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there's a group buy on the boss frog fender reinforcements...

id also check out boundary engineering for the frame rails... two great braces for under $300 shipped.
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Old 06-20-2009, 03:57 PM
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Forgot about the seam welding. IIRC "The Pass" has seam welded some and is local. Maybe I'll give him a shout..

Where can door bars be purchased anyway?

Thanks for the feedback dudes, keep it coming.
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Old 06-20-2009, 05:34 PM
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Bethania for door bars. I just installed my frame rails last weekend and Im pretty happy with the difference. I think with better front and rear sub frame braces and a 3 point tower bar in the front it should be stiff enough for my liking.
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Old 06-20-2009, 06:01 PM
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I've got the FM frame rails, HDHCDD bar and the door bars. Seats bolted to the floor with back braces clamped on the HDHC and a front shock tower brace. They all made small changes, the door bars made the biggest single improvement without a doubt.
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Old 06-20-2009, 11:01 PM
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I wish so much that I could overlook the bar in the hip factor with the door bars. I know that any side impact in our cars would be bad, but adding a hardened steel bar next to my hip just makes me uncomfortable on a daily driver. Would really love to though, just can't. I may feel more comfortable with racing seats, which will probably find their way into my car soon.
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Old 06-20-2009, 11:13 PM
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Originally Posted by NA6C-Guy
I wish so much that I could overlook the bar in the hip factor with the door bars. I know that any side impact in our cars would be bad, but adding a hardened steel bar next to my hip just makes me uncomfortable on a daily driver. Would really love to though, just can't. I may feel more comfortable with racing seats, which will probably find their way into my car soon.


I've been thinking about that and I think that if you were hit that hard on the side to cause the bars to actually hit you then you might have more than that to worry about. Can someone measure how far the bar is from the outer skin of the door? Without being next to my car I'm thinking about 10"s. I could be wrong but with that kind of impact Id be more worried about head neck injuries.
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Old 06-20-2009, 11:34 PM
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Originally Posted by levnubhin
I've been thinking about that and I think that if you were hit that hard on the side to cause the bars to actually hit you then you might have more than that to worry about. Can someone measure how far the bar is from the outer skin of the door? Without being next to my car I'm thinking about 10"s. I could be wrong but with that kind of impact Id be more worried about head neck injuries.
Well what I worry about more is not the bar hitting me from bending, but me hitting the bar. A car hitting you in the side is going to make your car move to the side, and your body will want to stay where it is... which means... bar to the hip. At least the door hitting you would be more spread out. Like I said, I think I would feel better having a race seat with high side bolsters to protect me.
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Old 06-21-2009, 09:04 AM
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I padded my door bars up with SFI foam and they are on the outside of the race seat. I was more concerned about my legs since they can come in direct contact with the bar, hence the padding.
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Old 06-25-2009, 11:52 AM
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I have a HDHCDD, door bars, carbing trans brace, beatrush triangle brace and beatrush STB. That's it. No factory bracing.
I've tried the butterfly brace w/ frame rails, frog arms, factory bracing and ppf brace.
If you want less weight for less money and the same stiffness, run the door bars instead of the butterfly brace.
Frog arms are nice, but I don't need them with the door bars.
The trans and triangle brace seriously reduce drivetrain movement and i have superpro diff bushings. Throttle response is seriously improved and drivetrain movement is very minimal.
The PPF brace is a good mod for horsepower cars. The PPF will bow under heavy torque loads and the brace does a good job of reducing all of that flex.
The beatrush STB is pretty.
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Old 06-25-2009, 12:27 PM
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Originally Posted by levnubhin
I just installed my frame rails last weekend and Im pretty happy with the difference. I think with better front and rear sub frame braces and a 3 point tower bar in the front it should be stiff enough for my liking.
I finally jumped on the bandwagon and ordered frame rails from Boundry. My new miata has crazy cowl flex when I removed the HT a few weeks ago. Hopefully battles it a little.
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Old 06-25-2009, 12:40 PM
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BIggest improvement is from the door bars.
2nd is teh FM butterfly.
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Old 06-25-2009, 01:17 PM
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Iv'e driven Johnfag's car and holy **** you feel connected to it. My car feels how a nascar looks on a road course.
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Old 06-25-2009, 04:42 PM
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Originally Posted by Braineack
I finally jumped on the bandwagon and ordered frame rails from Boundry. My new miata has crazy cowl flex when I removed the HT a few weeks ago. Hopefully battles it a little.
I think you will like them. They surely helped me out a lot with cowl shake, but there is still a lot left too, so don't expect a miracle from them. I think the butterfly section would improve the effects by a lot, but I'm scared to get them because of fitment and making new rattles for myself.
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Old 06-25-2009, 08:26 PM
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Wait, how is seam welding cheap or free? I would imagine it would be by FAR the most expensive and labour intensive. Or do I not know what seam welding is....
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Old 06-25-2009, 08:35 PM
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I think you definitely want to call Emilio at 949 and Brian at Good-Win-Racing and get their take if you're gonna spend any serious money.
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Old 06-25-2009, 08:47 PM
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Originally Posted by Dr. Nick
Wait, how is seam welding cheap or free? I would imagine it would be by FAR the most expensive and labour intensive. Or do I not know what seam welding is....
Because it only costs you time and labor if you do it yourself.
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Old 06-25-2009, 09:02 PM
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^ yup.

I wouldn't be doing all of the crazy "rotisserie" welding, just touching up some of the spots around the windshield frame and doors, possibly the floor beneath the carpet.

I haven't heard of the Carbing trans brace, and google got me nowhere. Pics?
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