Flyin' Miata frame rail reinforcement

[kyle.bowker]

I finally got my FM frame rails installed tonight. I don't know why every project I tackle seems to take twice as long as it should (based on others' reports) but WOW! what an improvement. For reference, my Miata was built 11/90 and the only other chassis bracing is the RB front subframe brace and FM Skip Canon rear subframe brace. My car is much more "planted" feeling and more solid. Like others have said, my car now feels 15 years younger. I should have done this years ago. Everything seems to work better and my suspension seems to work more smoothly. One of the best parts is how I can use the frame rails as jacking points so no more driving up onto tiny homemade ramps so I can fit my low profile jack underneath the front subframe. If you have a NA and have not done this mod then go out and do it now. It really is worth it and for the price there are few better ways to spend your money.

http://www.flyinmiata.com/index.php?dep ... r=13-69010

And for the record, I do not plan to upgrade to the center butterfly section as it is a royal pain to install and remove for servicing the transmission or exhaust system. Plus I think it is a little too exposed for me. I saw some nasty carnage on a Miata where the front of the butterfly section got caught on a manhole cover. It wasn't pretty.

[ferris]

thats awesome ... congrats on the install

This has been on my list of to-do's for awhile now. I have been looking at the other alternatives to FM. I still do not have a good handle on which frame rail set is best for the money. I would also want to do the butterfly section as I don't really street my car and its already too low for potholes, speed bumps or anything other than the highway and a parking lot.

How long did the install take? Any tips for an easier install?

[kyle.bowker]

AFAIK there are two options: Flyin' Miata and Boss Frog. The Flyin' Miata version is the only one that works with the FM butterfly brace section. I like what Boss Frog has been doing with respect to V8 Miata swaps but I've been buying from FM for so long they are usually my default choice.

FM is stainless steel and uses stainless steel hardware.
Boss Frog appears to be powdercoated mild steel and uses Grade 8 hardware.

I like the FM rails and feel that the stainless steel fasteners are more than strong enough in this application. So again, I tip my hat to FM. The Boss Frog are cheaper so if a few bucks makes a difference to you then they would be your choice.

You will have to remove both seats and the sill plate, unbolt the lower seatbelt anchor and fold back the carpet and the insulation. Unclip the hard brake and fuel lines from the chassis so they float and are easier to manipulate. Install the frame rail, align it as far forward as possible, drill a hole, clean up the hole with a deburring tool, fasten the nut and bolt, repeat 20x. Then un-install the frame rails and clean both the top and underside with wax and grease remover, prime, paint and apply rubberized undercoating. Allow to dry. Re-install the frame rails and tighten all 20x fasteners (an electric impact driver and a helper would have sped this process up greatly. Reaffix the hard brake and fuel lines. Some people do get more creative when re-routing the hard brake and fuel lines beneath the car. I don't like how close the re-routed lines are to the bolts protruding through the frame rail and I hope the floating rubber isolator will help prevent rub through but I may engineer a more elegant solution. Re-install the carpet and seats.

[ferris]

Thanks for the information.

I never read too much about it, but how do you re-route the fuel/brake lines. Does the kit come with lines, do you buy more line or just bend the existing lines.

Do you have to do anything about bleeding the fuel line, or just the let car stumble for a second once restarted. I guess this would be a good time to change the fuel filter (I am assuming the fuel filter is like the one on my passat, directly in line with the hard fuel line.)

I am not worries about the carpet ... its mostly removed from my car and in the dumpster awhile ago. It was moldy, took too long to remove properly and replace properly so it ended up in the dumpster.

Where did you get underbody spray ... I never used this when I installed my 6-pt harness and have been meaning to do this before my floor starts to rust.

[kyle.bowker]

The hard brake and fuel lines are normally attached to the unibody via two brackets. Because the frame rail mounting bolts now occupy the same space as the hard lines you must slightly relocate the lines by modifying the two brackets (hammer them flat) and attach them to the frame rail using two self-tapping screws. This leaves them a little more exposed as they are not tight up against the bottom of the floor and I feel like the frame rail mounting bolts are still precariously close to the hard lines.

I got the 3M professional rubberized undercoating in a spray can from AutoZone. It was like $10 and it's very messy so wear eye protection and crappy old clothes you don't care about.

[JoeTR6]

I like the idea of stainless steel for this application. It's a harder material than mild steel, and I'd be a little worried about corrosion. Of course, the stock frame rails will most likely rust away before anything you add will.

My 1990 Miata had the Cannon rear brace and the Racing Beat front subframe brace. Both did a remarkable job of reducing the shakiness of the car. The front brace is only $100 and is a simple install, so I'd recommend that if you don't do the full butterfly brace.

Now let's see how that car does at an autocross, Kyle.

[motomoron]

I installed the chassis rail and butterfly bracing while doing the "replace every single worn item w/ new and better" service on my early '90 NA.

Bearing in mind that it went from totally hammered suspension and bushings to all new everything at the same time - the manner in which the bracing "un-aged" the chassis was very gratifying. It's a ~solid~ little car now. I wasn't too worried about the butterfly brace catching stuff - my Sprite is WAY lower and M3 is pretty low, and they don't drag on much. Plus it'll protect the shiny new stainless steel hi-flow cat and FM exhaust from speed bumps.

I recommend FM bracing highly. Hell, I recommend FM anything highly.

[ButtDyno]

FWIW, I had the cheapest shock tower brace available (Greddy/Trust) for my '93 and I felt it made a really noticeable improvement in how the car felt over bumps (i.e. it did not feel like it was going to rattle to pieces). Something to check out, IMHO, since it sounds like that is still unbraced. I always wanted to try the FM stuff to see how it felt.

[kyle.bowker]

I installed a Hard Dog Hard Bar Sport roll bar today and it made the biggest incremental difference out of all the braces so far. I can't imagine driving an old Miata without all the bracing I have. Next step is complete disassembly and seam weld....