Boss Man

iTrader: (2)

Hello all,

I was trying to do my brakes the other day, when I noticed a lot of rust behind the rear wheels. I've searched on here and it seems this is a fairly common problem. The majority of people seemed to either fix it themselves or else get a new shell of a car. Are those my only two options? Is it not feasible to have someone fix this. I do not have a welder and my welding skills suck anyway.



Here is a closer view


Here is a view from the rear looking toward the front.


How bad is my car? To me it doesn't seem horrible, but I'm no expert.

Also, does anyone know of a good shop in the Cincinnati / Dayton, Ohio area I could take my car to?

Thanks!

Tobias

iTrader: (1)

Well, It's my opinion that any rust is bad rust. Eventually, that will eat through.
I JUST did the wheel wells on my car, and they were rusting in the *Exact* same spot as yours. You can find the pictures if you search for "Moose Jaw Build "

The rust in between that bracket thing, goes right into your storage bins. It's fairly common to rust there. If you cant poke through it with a screw driver, I guess it could wait for a bit longer - But the job gets harder the longer you let that rust, as it gets worse, and worse. I'd get on it right away.

kutukutu1

iTrader: (5)

i am fixing all ther rust on my car now and i got rust in the wheel wells as well, my car is past k, mine is about 3x as bad so ideally fix it while its small and not a big chunk. Grind all the rust down, buy some sheet metal and find a buddy with a welder that has decent skills. or go to harbor freight and get one of their welder and get some practice.

Boss Man

iTrader: (2)

Sorry if I gave the wrong impression. I DEFINITELY want to fix this.

I am just not sure how to, whether to try it myself or to farm out the work, or if this is a major problem for the car.

I do not like it, and my heart sunk when I spotted it, but I do not think it is affecting the structural integrity of the car, yet.

RX-7 Chris

iTrader: (19)

If it was me, I'd have someone take car of it as soon as I could. I have not welding skill so I'd have to have someone else to it. I would get it done sooner than later.

Boss Man

iTrader: (2)

I agree, Chris.

I'm not really sure where to take it. My mechanical does not weld and he said most body shops don't really do that kind of work either.

For those of you that took it somewhere, where did you take it and about how much did you spend on it?

Jibaro 12A

iTrader: (8)

I did mine myself, set me back about 80 bucks and a weekend.

ztfdrake61

I had my brother weld mine together, nice to have a union guy in the family, took an afternoon to get everything painted and sealed afterwards

LizardFC

iTrader: (1)

Mine was in as bad or worse shape - on rainy days, I would end up with a pool of water in the floor behind the seats! I used fiberglass to repair it. It was a messy process as I'd never used fiberglass before but it was inexpensive and will never rust again.

First off, you need to grind out every bit of rust. Leave plenty of deep gouges for the resin to bond to. Then use a rust dissolver (pink stuff you can pick up at any auto parts store) on all of the exposed metal. Not only does it eat up any leftover rust, but it leaves a protective coat. I used painter's tape to cover the holes from inside of the wheel well and applied my resin and glass to it from inside the car. The tape basically created a mold that could be peeled off when the resin hardened. Make sure you wear a respirator and set up a fan for ventilation. After you have a strong layer on the inside of the car, you can remove the tape and apply another layer from the outside. Then coat everything in a rust resistant primer or undercoating. In the end you should have a pretty permanent fix as fiberglass bonds very well to rough bare metal and will never rust.

It's been a few years and it's still holding strong. No puddles

kutukutu1

iTrader: (5)

there you go, no need for welding skills +1 ^^^^^

RX-7 Chris

iTrader: (19)

THe only problem with fiberglass is it isn't structural and I thought this was a structural part of the car.

GregW

Doing it right involves cutting out the rust, griding off the undercoating far enough from the point of welding and maybe some light bead blasting. Then, make up some patch pannels, apply weld through primer on both sides and weld in the new pannels. Then a nice coating of wurth undercoating.

Rust encapsulator and all that other stuff is temporary. Ive got cars my father restored 40 years ago, some things are temporary, some things are permanant (provided it never sees salt again). To do a good job you need either experience or a good aptitude in this area.

This thread should give you some idea of whats involved.
https://www.rx7club.com/old-school-other-rotary-63/video-log-restomodding-my-76-rx-5-cosmo-new-vid-jan-5-2023-a-923443/

LizardFC

iTrader: (1)

Fiberglass at the proper thickness is some really strong stuff. It's been used to make the bodies of Corvettes, race cars, and boats for decades. And I don't regard wheel wells as any more structural than a rear quarter, which I've seen repaired the same way.

purple82

Yes, yes, yes. This area of the car is subject to the loads of the rear suspension. You can't fiberglass it and you can't just fix the rust, you have to provide the structure that the chassis needs to support the suspension.

Just call around to body shops. You won't have any problem finding a shop that does welding restoration.

LiizardFC, you should seriously consider doing yours the right way. You can't support suspension mounting points with sheets of fiberglass.

LizardFC

iTrader: (1)

You somehow got the idea that I replaced the entire wheel well with fiberglass, which I did not. I merely filled in the holes left by rust, which is what Boss Man is trying to do. I've been driving and autocrossing the car for years since without issue, so I'm not worried. And I still insist that fiberglass in the proper thickness is strong and rigid enough to be used in this area.

RX-7 Chris

iTrader: (19)

This is what I was talking about.

renns

Keep a very close eye on that repair. I inherited a 1st gen a few years back that rusted in the bin area bad enough to cause the trailing link attach points failure. The owner elected to scrap the car rather than try to pursue a repair at that point. The metal in that area is definitely a critical part of the structure.

One problem with a fibreglass repair is that is tends to cover up what's happening underneath. If all is well-sealed and free of rust, that's great. But if rust starts or continues under there, it may go undetected until it's too late. I'd spend the money and/or time and weld proper patches to repair as GregW describes.

The doubler plate can be removed by carefully drilling out the spot-welds. Once that's removed, it'll be more clear what's happening underneath. Once the wheel-well sheet metal is repaired, a newly fabricated doubler plate can be welded into place, proper treated and sealed to provide better strength and longer life than the original.

Now if Mazda had only sealed that area properly from the factory we may have been able to avoid all this fun years down the road!

Boss Man

iTrader: (2)

Well I took it to a shop to have them look at it. They gave me a ballpark figure, which seemed reasonable to me, so I think I am just going to have them do it.

Thanks for the help, guys.

cshaw07

iTrader: (14)

what was their figure? im just curious

Boss Man

iTrader: (2)

Said it should be about $500. He did want to look at it more in depth before committing to anything though.

cshaw07

iTrader: (14)

woah! buy a good welder ~$360, a piece of metal ~$20ish learn to weld and fix it for under $500 plus you'll learn a lot and have a welder people ask me to weld for them all the time. I sucked at welding so I bought one just to learn, im pretty good at it now.

Boss Man

iTrader: (2)

It's a good plan in theory, but I think the reality will be more like:
buy a good welder ~$360
a piece of metal ~$20ish
add 220V outlet to my garage ~$50
find out I have no room in my electric panel so upgrade that ~$500
make a complete mess of my car then pray it is still salvageable ~FREE
take it to a professional so he can fix the original problem and my mess ~$800.

82transam

iTrader: (18)

$500 is very reasonable for a repair like that. I'll be interested to see how they do it...

cshaw07

iTrader: (14)

you shouldnt need a 220 welder for that. i bought a century 140amp welder (100% made and warranteed by lincoln) it came with 2lb spool, cart, regulator and hoses for gas, and it has a lincoln magnum 100L gun. Shipped to my house was right around $360. And i doubt you can mess it up THAT bad

RX-7 Chris

iTrader: (19)

I would have someone else do it. $500 seems like a good price.