Stefan MegaDork
2/12/18 2:44 p.m.

Dad loves his Miata.  He's always wanted one since he sold his Elan back when the kids arrived.  Not sure why he waited so long, but it finally arrived a couple of years ago.  Its a slightly used and loved 99 in BRG.

So aside from general maintenance (driveshaft, motor mounts, brakes, timing belt, front main seal *twice* with the second time resulting in pulling the motor), the only improvements so far had been a Harddog bar prior to hitting TNiA last year.

After that event, some Koni's, sways and springs from FM were ordered.

At TNiA, he'd had a rear brake caliper bolt come out and take out a wheel on the last session (damned lucky he made it back to the pits with it considering it happend on the back straight at about 100mph).

So when the FM sale came up at the end of last year, he jumped on a set of frame rails, butterfly brace and shock tower/master cylinder brace.

I drop by to lend a hand over the weekend, start to prep the car by removing the seats, folding the carpet back, put it on jack stands, etc.

Then we see take a close look at the frame rails:

Yeah.  That's not supposed to be like that.

The exhaust and one fuel line all had corresponding scrapes or slight kinks.

How we missed it when we were under the car previously, is annoying to say the least.

So now the fun begins; how do we want to repair this?

We decide to try pulling the rails back down a bit with a slide hammer, especially since we have the frame rail braces to install, so their resulting ugliness would be hidden and strengthened.

Other thoughts including using the plasma cutter to cut them out and replace them with donor pieces from somewhere or some steel C-channel.  The proximity of the fuel lines and the lack of skill with the tools led to simply de-mangling them as much as possible, installing the braces and getting on with life.

We built a small plate to fit into the largest hole in the frame rail, threaded for 3/8-24 and got to work on the driver's side rail with the slide hammer by drilling some extra holes and moving the plate along.  We eventually tied a string to the plate to help pull the plate forward and back after struggling with lining it up.

Used a drill to finish the hole to the proper size for the tap, the initial hole was created with proper tooling.

The above is where we got to Sunday afternoon before we called it.  Dad will keep working on it during the week and I'll drop by next weekend to lend more hands and hopefully work on the passenger side.

ultraclyde PowerDork
2/12/18 2:56 p.m.

Your post title describes every automotive project I've ever started.

that's some serious frame bash. Can you do that from improper jacking on a Miata? Kinda seems like it was off roaded badly.


Professor_Brap Reader
2/12/18 2:58 p.m.

thats pretty impressive frame damage!

NOHOME UltimaDork
2/12/18 3:04 p.m.

The way I would want to do this is to weld some 5/16" or so bolts to a piece of tin, say 1" square 18 gauge, then the piece of tin gets welded to the crushed cross-member at about the same spacing that you drilled the holes.


Then I would get a long piece of stout angle iron and jack it up under the crushed rail so that the bolts can go though matching holes. The angle would be supported on each end by the stouter-than-frame-rail sub-frames.


I could then  tighten nuts on the bolts to put a controllable force on the pull. when done I would buzz the bolts off and just leave the small plates on the frame-rail.

The rails on the Molvo were a bit crushed but not that bad. I ended-up chopping up a few 2x4" square tubes in order to clad them in 1/8" steel. NOW I can jack the car up from them.

Stefan MegaDork
2/12/18 3:05 p.m.

In reply to ultraclyde :

Yeah, I'm guessing it was high centered on a curb or a log or something.  Not sure how you'd do that on a Miata without there being more signs of damage, but there you are.

I don't think you could damage the frame rails like that using a jack to raise the car.  They aren't that heavy (after working on his A4 Avant and all of our Turbo-Dodges before that, this thing is a whippet!)  He has the rubber puck adapter to lift it from the outer seam, but the car sits on jack stands with them under the frame rails without issue and their surface area is smaller than the jack.

Adrian_Thompson MegaDork
2/12/18 3:05 p.m.

So do you think that damage was there when he bought the car, or was it a result of an off caused by the brake issue at TNiA?  And while we're at it, what the heck is TNiA?

Stefan MegaDork
2/12/18 3:19 p.m.
Adrian_Thompson said:

So do you think that damage was there when he bought the car, or was it a result of an off caused by the brake issue at TNiA?  And while we're at it, what the heck is TNiA?

TNiA = SCCA Track Night in America.

There was no off, the car started making a scraping noise, so he backed out of it, found the brakes were essentially not there now and coasted from the back straight through the "esses" and into the pits where the tire finally went flat because the bolt had gone completely and the caliper cut a groove through the inside of the wheel.  At that point the car was stuck since it wouldn't roll very well and we had no spares with us.  Took until the next morning for a tow truck to bring it home.  He replaced the rear calipers and bolts and also drilled them all (front and rear) for safety wire.

Damage was there when he bought the car, I think our unfamiliarity with the underside of the car was the main reason we missed it until now.  I may have even noticed it when we were replacing the driveshaft or when I helped pull the engine, but I don't know for sure and it doesn't matter in the long run.

APEowner HalfDork
2/12/18 3:48 p.m.

I've never seen a Miata that didn't have the frame rails bashed flat in at least one spot.  To be fair my Miata experience is limited to Spec. Miatas and the sad, cheap castoffs that Spec. Miatas are often built from.

NOHOME UltimaDork
2/12/18 4:16 p.m.

Armored frame rails

You can see the tabs where I was going to mount the transmission cross member. Then came plan b.


Rodan Reader
2/12/18 5:07 p.m.

Watching with interest... my '99 has some rail damage, but not nearly that bad.  Looking forward to seeing what you can do with it.

wlkelley3 UltraDork
2/12/18 7:29 p.m.

Also watching with interest. My (wannabe) BRG 99 has similar damage. I thought maybe a big C-clamp and puller might get things back in shape. C-clamp to straighten out and puller to "persuade" the metal where to go. Want to put in a set of those frame rails but automatically puts the car in a Mod class autocrossing so not going down that path. Pretty sure improper jacking is most likely the cause. Mine was damaged before I got the car and I admit to probably adding to it before I figured out what was happening and learned a better way to jack the car.

dculberson UltimaDork
2/12/18 10:51 p.m.

Once the FM frame rail reinforcers go in, the stock frame rails won't be doing much. Just mash 'em out of the way any way you can.

Stefan MegaDork
2/13/18 11:34 a.m.

In reply to dculberson :

Yep, the instructions even say as much.  Ours were mashed bad enough that there wasn't a way to mash them out of the way without pulling them back out far enough to sort of beat them into submission.

I suspect this will be finished just in time for this brief period of sunny weather to go away in exchange for another cold snap/freeze just to mess with everyone.  Welcome to the PNW!

Brotus7 HalfDork
2/13/18 6:08 p.m.

It sucks when you find a gems like that.  Looking forward to seeing the fixed product - and now I want to look under mine to see if I'm similarly afflicted. 

SIde note: What kind of mill does your dad have?  Looks like a good size bench top column unit.

Stefan MegaDork
2/13/18 6:18 p.m.

In reply to Brotus7 :

It’s a pretty good sized freestanding mill, about 2000lbs from what I remember.  He’s been working on converting it and the large to CNC.

The more I think about it, I wonder if the damage could be an over-zealous tow truck operator?  Or perhaps a tow dolly mishap?

Crackers Dork
2/13/18 8:02 p.m.

If you can weld tabs to the corners with a bolt hole in them, you can use a section of chain and a 4x4 to pull those rails back out pretty easy. 

It will still take some hammering, and probably both in unison. 

In the past I've used a bottle jack to apply force while I hammer, but you have to get pretty creative. 

Vigo UltimaDork
2/13/18 10:16 p.m.

That looks like slide hammer work to me. 

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