Joe Perez

iTrader: (8)

Fellow rust-belt dwellers, I need some advice. I'm relatively new to living in places where they throw salt on roads intentionally, so I didn't grow up learning this sort of knowledge from my father / uncle / catholic priest.

Although I now own a dedicated winter car, my NB is showing the effects of having been driven through seven fairly brutal winters. It's perforating in what I gather to be the usual places:







I don't really care about the cosmetic aspect. What concerns me is the specific location of the rust- it's happening at what, from external observation, would appear to be the most highly-stressed points of the unibody.

So, is this nothing to worry about? Or is there going to come a day when I hit a pothole and the car just breaks in half like in a cartoon? Not that the roads in Chicago resemble the highway between Kuwait City and Basra on the morning of Feb 27, 1991...

Is there anything which can be done to halt the spread which does not involve a cutting wheel and a welder?

I don't care about making it look pretty, merely about wringing as much useful life as possible out of this car. The oily & spinny bits are still in great shape.

I am aware of the existence of various elixirs such as POR-15 and Eastwood Rust-converter / Rust-encapsulator. But I have no knowledge of their efficacy, nor can I imagine how to get them into every little nook and cranny. (Maybe I'm not imagining right.) I have zero faith in my ability to go unscrewing the fenders and whatnot without breaking every single bolt down there.

Am I over-thinking this? Are the parts which actually matter from a structural perspective buried sufficiently deep that they're probably fine? I've seen photos of Miatas which have been cut in half through this area, but that doesn't really help me understand which parts are bearing most of the stress, and how protected they are from the elements when not cut in half.

patsmx5

iTrader: (16)

Gee Emm

It's a long time since I have seen rust like that here. We never put salt on roads because our winters are not snow/icefests, I don't think even in our snowfields salt was used. But coastal areas used to be a problem, so structural rust was a thing in cars that live(d) close to the sea., though not so much these days because of increased rust protection.

Based on that experience, I'd say that there is more rust than you can see. How bad, is the car structurally weakened, you'd have to open it up and look. I'd get one of those cheap inspection devices that plug into your computer (phone?) drill a hole, and have a stickybeak - take photos, record video, and get someone who has relevant experience to advise you. If you decide it is still driveable, then the rust converters etc will keep the rot under control in the short term, but they don't restore strength already lost,

damir130

All miata's look like that over here. Have never seen one break in half, even when stressed in the hands of morons. So you're probably ok.

Having said that, once the rust gets that visible from the outside then all the inner construction at the rear will no longer be there. Poke around the front of the rear wheel-well, you'll probably find some holes held together by underseal. Thats typically the originof the sill rust.
Might want to check the front frame rails at the crumple zone too (near the arb mount), high probability that that will be gone too. Those might be important in a head on collision, so don't crash into stuff too violently.

ohnoitisnt

Im from the south UK. Welding rusty mx5's is the everyday here for a garage that wants the work, because any corrosion within 300mm (or something) of a suspension mounting point fails the yearly inspection (the MOT) and we salt our roads every winter.

Ive seen a few really rotten ones out on track and they seem to just work. Never seen or heard of parts coming off even in the really bad ones. Yes i think youre overthinking this :-) That said i agree that looks like it wants addressing now before it becomes a chop and weld job. Ive never used a rust converter (most of the crap i play with is too far gone by that point) but its what id be considering.

Wire wheel on the grinder and then rust convert, primer, colour match rattle can, drive

rleete

iTrader: (21)

While your car probably won't break in half anytime soon, it's too late to save it. Yes, the tin worm is hard at work inside as well as what you can see, but it will take a while to seriously compromise it.

Patmx5's solution is probably the best for extending the life of the beast. Not much to do except drive the hell out of it and enjoy it while you can.

x_25

My NB is worse, and I have an NA parts car that is missing the jack points back there it's so rusty. They still stay in one piece with no issues.

That said, the amount of rust you can see is typically 1/3rd the amount of rust there is. That's already into a cut and weld job. If you don't care about looks, cut those sections out, cut out any non solid rust, wire brush any flakey rust, then rust coverter (naval jelly or ospho) and paint. Then rivit/pannel bond something over those spots and send it.

Scrambles

iTrader: (7)

Hi Joe,
Having owned and repaired a rusty NB from Chicago I'm concerned about the condition of your frame-rails based on the way those rockers look. Mine were so rusty the front sway bar mounts were nearly sheared off (and I had less rocker rust than you).

Here's what I was dealing with:
https://www.miataturbo.net/meet-gree...8/#post1062193

Joe Perez

iTrader: (8)

Kinda what I figured.


What poking around I've done hasn't reveled any majorly compromised spots in the frame rails, bulkheads, etc. I'm sure there's some in there, but at the surface layers, only what I'd consider to be the outer skin if fully perforated.

Lots of surface rust on the underwise, but no actual bubbling that I've found.



So long as it's a gradual process, I'm ok with knowing that the car is eventually going to die.

Or... and hear me out here: Maybe it's an "ignore it and just go on with life" job, which sounds like way less work to me.

rleete

iTrader: (21)

As we say at work: NGP. Next Guy's Problem.

Efini~FC3S

iTrader: (4)

Burn it










Burn it with fire!!!

Padlock

You've got absolutely nothing functionally to worry about as long as your cool with the aesthetics... my college turbo'd "winter beater" NA6 from years past was well beyond what you're showing and I still ran this car at local AutoX events in the summer. Never ran into a structural issue (which is kind of the beauty of the PPF/Subframe design). You could physically stick your fists into the quarter panels, the doors still shut nicely, and I didn't notice any obvious signs of abnormal chassis flex. The car ended its life with me as a bare unibody shell being delivered to the scrap yard. I simply got sick of wrenching on rusty stuff once I graduated and had money to toss at something nicer...

Joe Perez

iTrader: (8)

Thank you for this.

I don't race this car, it's just my fair-weather commuter. And since I live in the city, it's somewhat rare that I get to exceed 30 MPH.

I'm going to continue blithely ignoring the problem.

huesmann

iTrader: (1)

It might be too late for that!

x_25

If you keep it out of the salt it will progress rather slowly. You will want to stop the rust and add paint if you are going to drive it in the salt with any regularity. It will accelerate very quickly anywhere the underlaying rust has flaked the paint off.

hornetball

iTrader: (4)

When the doors stop closing correctly, you'll know it's time. It's sad to see an old friend go like that though. I remember those Basra road strikes.