DIY frame rail reinforcement...
 

So I was thinking about FM's frame rail reinforcement...when a friend of mine showed me his. Aluminum rails out of computer server racks! Perfect width. Just cut to length, slip over rails, drill holes, and bolt up! (unless your rails are beat to s#*t like mine) So after some "massaging" in they went..cost me $18.00 in hardware...as opposed to $199.00. Here's a few pics:

Did they work well... can you feel any difference

Feels a bit tighter...but haven't really had a chance to push it..just finished about an hour ago.

Cool... Not bad for $18. Go test it out more

pretty cool, i'm wondering how sturdy those rails are?

They are pretty thick...I was standing on them while drilling holes....NO FLEX!!

Did you just bolt through the sides or did you bolt up through the floor as well?

thats cool, but the point of the FM rails is that they mount to the floor pans increase the stiffness along them.

Good idea though. if you mount some traverse reinforcement across those racks I am sure you will get a noticeable difference

Floor as well

Yes..thats the next DIY project:cool:

DId you drill up through the center of the frame rails to mount them to the floor?

Where did you get the rails? Do you have a part number or something?

might find them at Fry's

I might have to see where the closest one is, im not sure.

awwwwww dammit and here I had access to a bunch of those two post rack extrusions about a month ago. free. but didn't take them.

For reference:

FMs
http://www.flyinmiata.com/Store/images/13-69010.jpg

http://www.flyinmiata.com/images/mis...s/IMG_0046.jpg

I like this idea alot. Your gonna connect to two rails next right? What exactly from a shelf is that?

This makes me want to get two street sign posts and a sign to connect them both. I remember seeing a miata with a street sign under the car somewhere.

Vash-

I remember waking up once with a street sign stuck under my car....I think there was a mailbox and a trash can too:bang:

Very innovative, sort of I guess, great idea, I like $18 much better than $200.
I just might copy you here.

What exactly did that entail?
I can see some grinder work and perhaps some hammering. Was it that the rail was slightly wider than the track in the bracing, or was your rail uneven down it's length and you just smoothed it out.

How did you hurt your frame rails that bad in the first place?
What is the width of the rack you're using?

Do you think that these braces would "slip" over an unmolested frame rail?
What would be ideal is if the brace .001" wider than the rail and you would simply tap it up into place with a rubber mallet. Rigging up a crossbrace would be a really simple proposition.

Is there any dramatic difference in the undercarriage between the years. I know FM's brace is "universal", but is there anything to consider along those lines?

I've been wondering why more people haven't tried something like this. I was thinking about using angle iron on either side of the rail. Bolt them through the floor and to each other through the rail.

Hit the nail on the head here. While these aluminum rails might do something, they certainly won't provide the same rigidity as the FM rails. You really need a hat-shaped section in order to attach top the floor, rather than a C-shaped channel. Remember...the end goal should be closed sections.

closed sections are not subject to Lateral Torsional Buckling :giggle:. Damn structural engineering.

But yea, it needs to somehow hold to the floor. Incorporate some L brackets maybe

I see where you are going with this, but I think the fact that each "half" is tied together benefits you too much to not go with a couple of hat-shaped sections like the FM ones. Wouldn't be that expensive to have a metal fab place shear them up and put them in a brake for four bends. Plus, the will likely be lower weight as well, even without the cutouts on the FM ones. Hell, you can probably hole saw some holes if you want to lower the weight. They are probably saving 2 lbs is all. Bolted wide through the floor is key here.

Well, they are more resistant to LTB, but they can exhibit that failure mode, especially with highly slender, nonuniform elements. I can show you some photos of it happening if you like ;)

Good to see another structural engineer here. I do structural forensics for a living.

I believe you, lol. I was going off the frame rail lengths not being slender. I assumed their slenderness ratio would not allow LTB to govern.

also, you have a PM

Low + Speed bumps...mine look like a domestic violence victim.

Same here. The driver's side one is really bad.

+1 on the lowered vs speedbump problem.

Mine suffered when I tried to grind a curb skater style :(

ah screw you guys.... every week you disappoint me by making good shit from useless crap :/

kind of makes me want to hang myself for spending all that precious $$ :/

1. The massaging was a bit of hammering and a wire wheel. The rail was squished from previous owner probably using it as jacking points:bang:...also the rails had a whole bunch of spray undercoating on them (I shipped the car over from Hawaii)
2. Yes they would just slip over if they haden't been so bent outta shape. Light tapping with a rubber mallet worked on another miata that did same project.
3. Pretty sure the undercarriage is similar...the only thing to watch out for is fuel + brake lines.

Look into the test method FM did to quantify the stiffness increase from their rails (on their site I believe). Do the same test with your car. Compare results.