Dealing with crushed "Frame Rails" on your Miata

[Pyr0monk3y]

When I bought my Miata the frame rails were absolutely crushed. They were so badly crushed that the floor pan was bent and bulging inside the passenger compartment. It looked like someone just threw a floor jack under the car and didn't even look before they picked the car up. It's a miracle the fuel and brake lines weren't crushed.

These frame rails are paper thin. They are not jack points and they add barely any strength to the car. Really, the only thing I can figure they are strong enough to do is reinforce the floor pan. It appears like 2 engineers had an argument. One wanted a light chassis and the other wanted a stiff chassis. They compromised.

Luckily, several companies sell a solution/upgrade to fix this problem. I went with Flyin' Miata's rails however there are a number of other companies that sell similar products. I went with Flyin' Miata because they routinely have "group buys" where they sell 30 or so sets of rails at one time at a lower price. Also they offer a butterfly brace that offers even more reinforcement to those whose cars are compatible.

I'll apologize in advance for the bad photos, it's hard to get good lighting on the underside of a car.

Here's what I had to work with:

http://i.imgur.com/W2Ea2Mk.jpg

http://i.imgur.com/2KQrnaa.jpg

Start by arranging the fuel lines in a way that you wont bend or break them. They're kind of in the way, but they're flexible so it's not too bad.

http://i.imgur.com/hc2apG1.jpg

Tools: Big hammers, pry bars, chisels, pliers, and a 10mm wrench (for the fuel line brackets). The steel bar is there to assist the pry bar.

http://i.imgur.com/Sa3pGX1.jpg

Use the chisel or pry bar to get the flattened rail away from the floor pan. Then grab it with the pliers. Were just bending the old rails out of the way. You could cut them off if you really wanted, but bending them is easier.

http://i.imgur.com/YXwcB3o.jpg

Once you've bent the rails away from the floor pan, use a ball peen hammer to deal with any bulges.

http://i.imgur.com/GCxlXUw.jpg

http://i.imgur.com/wyZ402V.jpg

Things should be looking a little better now.

http://i.imgur.com/DIPsqCi.jpg

If you're worried about rust, hit any bare metal with some paint.

http://i.imgur.com/XxOxaMQ.jpg

Now repeat on the other side, then apply whatever aftermarket frame rail solution you opted for.

http://i.imgur.com/UKZ35ns.jpg

Done.

The car is a lot stiffer now. I immediately noticed the difference when I left my driveway. The ride is smoother and there is less vibration. Even if your Miata isn't a track car, this is a worthwhile upgrade.

[wannafbody]

Good work

[Agent☣Orange]

Nice job Pyro! Thank you much for your great post and pictures. Hell of a good start on mazdaroadster.net

[atank]

Very Nice Job!

[etikoner]

I can't believe i still haven't bought a set of frame rails lol.

[tsingson]

You have a lift in your driveway? If so, let's do my frame rails man. Just kidding. Excited to see the car in person tomorrow night.

[Pyr0monk3y]

You have a lift in your driveway? If so, let's do my frame rails man. Just kidding. Excited to see the car in person tomorrow night.

Indeed, my dad and I built a 34x46 garage in our backyard 2 years ago. Complete with 2 post lift, air conditioning, running water and internet. It's basically just a big man cave.

Don't get your hopes up, I'll be there but my car is nothing special. Just a beat up Miata.

[tsingson]

My hopes are that we get more enthusiasts to come out to the meets. All car makes. I have a friend that autocrossed his RSX and he is starting to come out. I have a set of Boss Frog frame rails that I need to install. Just didn't want to install them on my back. My NB is nothing special either man. Just another NB.

[JLBMX5]

I have the only special Miata. Oh wait its not special its red only the most mass produced color lol

[CDPHOTO]

Do you think my frame rails are saveable?

http://i1150.photobucket.com/albums/o607/ChrisDaleyPhotography/2013-06-30155038_zpsd24f3204.jpg (http://s1150.photobucket.com/user/ChrisDaleyPhotography/media/2013-06-30155038_zpsd24f3204.jpg.html)

http://i1150.photobucket.com/albums/o607/ChrisDaleyPhotography/2013-06-30155029_zps6b8e873b.jpg (http://s1150.photobucket.com/user/ChrisDaleyPhotography/media/2013-06-30155029_zps6b8e873b.jpg.html)

http://i1150.photobucket.com/albums/o607/ChrisDaleyPhotography/2013-06-30155021_zps4349e13c.jpg (http://s1150.photobucket.com/user/ChrisDaleyPhotography/media/2013-06-30155021_zps4349e13c.jpg.html)

[BoBo]

If I were you I would just have it cut and install a new floor pan reinforcement rail. Or you can leave them because the real frame rails are on the side of the car. But because bent floor pan rails are ugly it's just better to have them cut out. Like this one:

http://www.youtube.com/watch?feature=player_embedded&v=fxjXK3gEG10

It should be cheap to due at a muffler shop and have it shot with an undercoat. You could use a 25lbs dumbbell to push the bulge on the floor pan. It worked on my mr2 before, just tap the bulge little by little until it's flat.

[Pyr0monk3y]

Just bend or cut them out of the way enough to install the new rails on top of them. Make sure to paint any bare metal, once the rails are on it will be a pain to fix any rust that forms underneath them.

It looks like your car is pretty low. You probably wont like new aftermarket frame rails since they rob you of a little ground clearance. You'll have to raise your ride height 1/4-1/2 inch. But, you gotta do something. I'm shocked your fuel and brake lines aren't smashed.

[CDPHOTO]

If I were you I would just have it cut and install a new floor pan reinforcement rail. Or you can leave them because the real frame rails are on the side of the car. But because bent floor pan rails are ugly it's just better to have them cut out. Like this one:

http://www.youtube.com/watch?feature=player_embedded&v=fxjXK3gEG10

It should be cheap to due at a muffler shop and have it shot with an undercoat. You could use a 25lbs dumbbell to push the bulge on the floor pan. It worked on my mr2 before, just tap the bulge little by little until it's flat.


That is a great idea!! Thanks BoBo! I really like that plan over the frog rails. some 1x2 thick wall square tube would be way cheaper and be just as strong. I have a welder. The hard part would be cutting off the old rails. I really need to get a plasma cutter.

[BoBo]

^No problem glad to help. I wish I knew about miatas having a weak frame rail sooner.My miata frame rails on the passenger side is perfect, except the driver side, it's pushed up a bit, but I managed to drill a hole on top to slip a bolt and hammer the rails down. Whereas, my infiniti has frame rails are much stronger and you can use it as a jack point.

[wannafbody]

Some states require the factory frame rails to pass inspection. So cutting them out totally isn't always a good idea.

[BoBo]

^ It shouldn't be the case with the miata. The real frame rails for the miata is located at the side of the car where by the rocker panel. I don't know why a crushed floor pan rail would matter with state inspection. I doubt people could tell the difference once you replace it with a new rail like the one on youtube and just spray it with undercoat. But yeah some states have weird car laws, I heard you can't even lower your car in some states.

[Pyr0monk3y]

^ It shouldn't be the case with the miata. The real frame rails for the miata is located at the side of the car where by the rocker panel. I don't know why a crushed floor pan rail would matter with state inspection. I doubt people could tell the difference once you replace it with a new rail like the one on youtube and just spray it with undercoat. But yeah some states have weird car laws, I heard you can't even lower your car in some states.

Good point but unless they're an engineer or a miata enthusiast it's unlikely that the inspctor will know that it's just a floor pan component. To someone who doesn't work on miatas it looks like a poorly designed frame rail.

[BoBo]

Good point but unless they're an engineer or a miata enthusiast it's unlikely that the inspctor will know that it's just a floor pan component. To someone who doesn't work on miatas it looks like a poorly designed frame rail.

Whoever does the inspection should know what their doing.I'm lucky I'm in California, places with the snow belt like the Midwest where people use salt, it can take out an under body in 5 years. I just got a quote today, and my local shop is only asking for only $150 if I really want it done. The bodyshop might charge more. But my frame is not even that bad.That is like the main thing I hate about miatas. If it weren't for the weak floor rail, things would be much easier. I will post a picture later.

[CDPHOTO]

Here in Oregon we dont have a state inspection. Just has to pass emissions. The motor and trans will be coming out sometime after this heat wave passes the NW. I figure that will be a good time to mess with the frame rails since there will be no weight in the nose of the car. I will be taking pictures every step and I will post a follow-up when I'm done.

[BoBo]

Here in Oregon we dont have a state inspection. Just has to pass emissions. The motor and trans will be coming out sometime after this heat wave passes the NW. I figure that will be a good time to mess with the frame rails since there will be no weight in the nose of the car. I will be taking pictures every step and I will post a follow-up when I'm done.

It's weird in Norcal, it just started getting hot a week ago, and summer is almost over.Maybe global warming. Are you getting a 1.8 swap? shoot for the early 1.8 with a 99 head. That should give you a tiny bit more power, but in general 1.6 & 1.8 is the same slow motor. I was gonna buy fm rails, but I'm waiting for the heat to die as well. Keep me posted on your pics of the rails.

[Martin]

[temporary thread jack] Just curious - what's the high temperature during a heat wave in Oregon? [/temporary thread jack]

[kung fu jesus]

73 degrees

[Martin]

lol

[CDPHOTO]

[temporary thread jack] Just curious - what's the high temperature during a heat wave in Oregon? [/temporary thread jack]

Well today it was around 80... last week though we hit 100 two days in a row. With 70% humidity... it was kinda miserable.

[charchri4]

Here in Oregon we dont have a state inspection. Just has to pass emissions. The motor and trans will be coming out sometime after this heat wave passes the NW. I figure that will be a good time to mess with the frame rails since there will be no weight in the nose of the car. I will be taking pictures every step and I will post a follow-up when I'm done.

This is what I did with mine and it worked pretty well. It's cheap and you could use smaller box or rectangle material to be lower.
http://jimsmiata.blogspot.com/2013/02/todays-adventure-welding-upside-down-on.html
http://2.bp.blogspot.com/-ZwvCOn1mR0E/URE0FcMZ0gI/AAAAAAAAADE/uiQqIdrFhMU/s640/frame.jpg

I did end up welding them in from the top later on.
http://1.bp.blogspot.com/-u27mbFdEZN8/UZo7qRliYJI/AAAAAAAAAwo/qT8CI21HTHk/s640/5+20+13+6.jpg

A couple more shots of them at the bottom of this post
http://jimsmiata.blogspot.com/2013/05/the-mother-of-all-transmission-mounts.html

[BoBo]

^ wow that looks clean.

[Cap]

What type of fasteners hold the frame rails in place? Are they simply a thread cutting hex head screw?

[Pyr0monk3y]

no, it is a nut and a bolt through the floor board. You have to pull the carpet to install.

[Zoomazoomzoom]

Hey sorry to resurrect this old thread . I had flattened frame rails on my 92na and I ended up using pry bars and a air hammer using the chisel attachment the longest time of straightening was waiting for my 2gallon air compressor to refill the tank so the air hammer had full scfm.

http://i886.photobucket.com/albums/ac67/g-woods/92%20Miata/4CC0A644-0708-4A2B-9329-6B87BC31D691_zpsdt3lntgt.jpg (http://s886.photobucket.com/user/g-woods/media/92%20Miata/4CC0A644-0708-4A2B-9329-6B87BC31D691_zpsdt3lntgt.jpg.html)

http://i886.photobucket.com/albums/ac67/g-woods/92%20Miata/AE8A3C4E-F318-44B4-A918-48AA166CDA87_zpsxw9sh8s1.jpg (http://s886.photobucket.com/user/g-woods/media/92%20Miata/AE8A3C4E-F318-44B4-A918-48AA166CDA87_zpsxw9sh8s1.jpg.html)

http://i886.photobucket.com/albums/ac67/g-woods/92%20Miata/07B2623A-85E2-493F-A5A9-73EE6D25CF0E_zps07xsahtm.jpg (http://s886.photobucket.com/user/g-woods/media/92%20Miata/07B2623A-85E2-493F-A5A9-73EE6D25CF0E_zps07xsahtm.jpg.html)

http://i886.photobucket.com/albums/ac67/g-woods/92%20Miata/6511D448-B22B-48FA-852A-81B970858B79_zps3w80osjr.jpg (http://s886.photobucket.com/user/g-woods/media/92%20Miata/6511D448-B22B-48FA-852A-81B970858B79_zps3w80osjr.jpg.html)

http://i886.photobucket.com/albums/ac67/g-woods/92%20Miata/B55681D0-81AB-4E11-BC4C-17A6836D36BA_zpse8bzjaoq.jpg (http://s886.photobucket.com/user/g-woods/media/92%20Miata/B55681D0-81AB-4E11-BC4C-17A6836D36BA_zpse8bzjaoq.jpg.html)

http://i886.photobucket.com/albums/ac67/g-woods/92%20Miata/661D5A36-D9A1-47AC-A02E-C0D305BED919_zps9swhkldb.jpg (http://s886.photobucket.com/user/g-woods/media/92%20Miata/661D5A36-D9A1-47AC-A02E-C0D305BED919_zps9swhkldb.jpg.html)

[Stealth97]

looks worse now..

[Cxmoney]

you need some frame rails.... lol

[WASABI]

looks worse now..

I don't think so. I would like to see a few more pictures with better lighting. The next step I would do, would be to repaint and undercoat the rails. Then look into aftermarket frame rails. They cover your existing rails and add additional rigidity to your car.
http://www.mossmiata.com/Graphics/Products/Large/909-411_1.jpg

http://www.topdownmx5.com/images/framerail/DSCF0457.JPG

They are easy to install, inprove your ride, and would be good piece of mind.

[charchri4]

+1^^ Bending them back down is fine but it does nothing to put the lost strength back in them and after being crushed once they will crush much easier the next time. Either cap them with like the photos above or if you want the cheap way out I have 12 bucks into mine a couple of posts up.