Rocker Panel Rust and Related Issues

[WrenchTech]

I really like my horizon blue metallic 4Runner. I am wrestling with ideas about fixing the rust, but wondering if it is really worth it.

In addition to the rust in the rocker panels, it has some rust around the windshield, a small perforation in the back side of the driver side rocker by the rear wheel opening and some rust bubbles under the fender flare, down low on the leading edge of the driver’s side rear wheel opening. Also, The rear axle housing, particularly the sheet metal that covers the center of the pumpkin, is so bad that I am scared to open the oil filler plug for fear that the threads will rip out with the plug. I found out that Dorman makes a weld on replacement cover, But now I’m wondering if I want to expend the effort on an axle housing that is pretty rusty when I could get a western wrecking yard to sell me a rust free housing for $175 plus $110 shipping.

 

[tgreenwood75]

I think if you like the truck then just commit and keep it. The areas you have listed do not compromise the safety of the car so I think it is worth it. This is a car that owes you nothing and you enjoy so why not keep it around even if it's just a project.

I had similar rust on my drivers side rocker and it got ground down, tacked in some new material, bondo'ed over, and both rockers got a coating of Monstaliner or Herculiner, forget which but big name spray on liners. It has been 3 years now in Maine and Upstate New York, some of the most harsh possible climates for rust, and it is starting to resurface but I am confident I can keep it at bay with a wire cup brush, rust converter, and spray on bedliner.

I also have similar rust on the windshield frame. This summer I ground out everything visible. Used rust converting products and bondo on top with color match paint and clear. Cheap and quick, doesn't leak but I ultimately need to pull the glass to repair the lip which it rests on. I have a welder and will simply cut and weld some panels to repair it in hidden spots then redo my bondo and paint for the spots that are externally visible.

I had a pinhole in my diff cover that was able to be welded closed but I have seen covers worse than mine. If you have ongoing rust projects maybe pick up a cheap welder if you don't have one yet and tackle that Dorman replacement. If my patch & rust converter/paint don't stop future leaks I will need to cut mine off as well.

Doing all of these repairs would cost you a few weekends, but you would have slowed the cancer on your truck and it will cost only a few bucks in supplies. If you want pics of any of the areas I mentioned, let me know and I will send some along. If you feel the vehicle is safe, what do you have to lose!

 

[WrenchTech]

Thanks for the insight on your work. I am probably going to follow your advice and keep working on my current 4runner to keep it looking nice and running properly. In the meantime though I’m gonna be watching the salvage auctions with the hope that I can find a nice rust free unit with with some problems that I can fix that have nothing to do with rust.

I think if you like the truck then just commit and keep it. The areas you have listed do not compromise the safety of the car so I think it is worth it. This is a car that owes you nothing and you enjoy so why not keep it around even if it's just a project.

I had similar rust on my drivers side rocker and it got ground down, tacked in some new material, bondo'ed over, and both rockers got a coating of Monstaliner or Herculiner, forget which but big name spray on liners. It has been 3 years now in Maine and Upstate New York, some of the most harsh possible climates for rust, and it is starting to resurface but I am confident I can keep it at bay with a wire cup brush, rust converter, and spray on bedliner.

I also have similar rust on the windshield frame. This summer I ground out everything visible. Used rust converting products and bondo on top with color match paint and clear. Cheap and quick, doesn't leak but I ultimately need to pull the glass to repair the lip which it rests on. I have a welder and will simply cut and weld some panels to repair it in hidden spots then redo my bondo and paint for the spots that are externally visible.

I had a pinhole in my diff cover that was able to be welded closed but I have seen covers worse than mine. If you have ongoing rust projects maybe pick up a cheap welder if you don't have one yet and tackle that Dorman replacement. If my patch & rust converter/paint don't stop future leaks I will need to cut mine off as well.

Doing all of these repairs would cost you a few weekends, but you would have slowed the cancer on your truck and it will cost only a few bucks in supplies. If you want pics of any of the areas I mentioned, let me know and I will send some along. If you feel the vehicle is safe, what do you have to lose!

 

[WrenchTech]

Rock Auto has these Dorman brand weld on differential covers for about $45, but with shipping it comes to $57. I found one on eBay for $45 with free shipping. I ordered and it should be here sometime next week.

My plan is to take the axle out of the vehicle to de-rust the rest of the housing and get some black epoxy primer on it. And if I am going to be spraying that stuff I should probably spray some wheels like these...

 

[calebb]

My plan is to take the axle out of the vehicle to de-rust the rest of the housing and get some black epoxy primer on it. And if I am going to be spraying that stuff I should probably spray some wheels like these...

Love the color and glad you're gonna tackle some of the rust and keep it! I am in the same state with my 4runner, with rust in the same exact areas. Going through sections at a time replacing the sheet metal, in the future will have someone paint to match.

I also rebuilt my reared this past winter and went through a lot of planning of what paint to use. I ended up getting it sand blasted because it was out of the vehicle and only $100. The options that I saw that seemed to work the best in terms of longevity and actually preventing rust were epoxy, powder coat, and por15. I was going to do epoxy but I didn't have enough money and it was expensive, already had por15. And I'm glad I did because I por15ed my axle housing and epoxy primed my rear diff and backing plates and the paint is already coming off the diff. This could be due to human error though in my application, first time I ever used it. But I don't know where I could've gone wrong. The housing tho still looks brand new!

Also, I talked to a couple auto body guys about epoxy primer and you can't use it over rust at all. The rust will just come right back. You can't just wire brush it off and spray. So if you do decided to use it, be sure to get everything sand blasted so there's no chance of the rust coming back.

You can take a look at my housing if you want in my build thread. **Caleb's Limited build/repair thread - 98' Limited 4runner**

 

[WrenchTech]

I am finally starting to address the rocker panel rust. Last winter was really tough. I had the most amazing salt crystal formations growing on the decaying metal. It was reminiscent of the science projects we used to do back in my elementary school days where we grew amazing crystal formations from a process that involved borax laundry detergent.

So far I've just cut away the outer layer of sheet metal. This is my first look at the inside of the rocker panel structure. I can see a lot of places that I'm not going to be able to access to fully remove every last bit of rust. I think to do so I would have to be doing some kind of frame-off restoration and really disassemble quite a bit of the lower structure of the vehicle. I will do what I can with sanding discs and wire wheels and then I will get as much of the rest of it as I can with my little Harbor Freight sandblaster gun. Then I will give it a liberal coating of one of the urethane based rust preventative paints like POR 15. I haven't decided yet if I will try to make a new skin out of sheet metal to be welded in place, or if I will go through the process of making a simple mold so that I can make some fiberglass rocker skins which I will then bond to the door sill and the pinch weld flange. I would like to go to the fiberglass route because it will never rust, but I am thinking there are structural considerations related to preserving integrity of the floor pan that are best addressed with a welded repair. I would welcome input from people who have experience.

 

[WrenchTech]

Looking at the pictures I just put up, I can see that I really need to get busy cleaning up the frame, the suspension links, the sway bar, the gas tank skid plate and the axle housing. I hope my electric locking differential/ third member case will clean up. I know you can buy third member cases for the conventional differentials, but I have never seen a replacement case for electric locking differential. If there is such a thing I'd be happy to learn about it.

 

[tgreenwood75]

Likes like nice progress so far, the wirebrushing and cleaning is a tedious process but at least you still have all your metal in place!

I wonder for the rocker skin if you would be better off welding in new squarestock instead of making a perfectly contoured shape. It would look different but might be cleaner and stronger. The dogleg area would be the largest obstacle. I am imagining similar to how Jeep XJ guys replace their rockers. I could see it moving along pretty quickly with just a 12' section of 2x4 or 4x4 thin wall steel and you could fit it up with only an angle grinder.

 

[WrenchTech]

Likes like nice progress so far, the wirebrushing and cleaning is a tedious process but at least you still have all your metal in place!

I wonder for the rocker skin if you would be better off welding in new squarestock instead of making a perfectly contoured shape. It would look different but might be cleaner and stronger. The dogleg area would be the largest obstacle. I am imagining similar to how Jeep XJ guys replace their rockers. I could see it moving along pretty quickly with just a 12' section of 2x4 or 4x4 thin wall steel and you could fit it up with only an angle grinder.

Thanks for your input.

That’s an idea that I have considered, but then I watched Fitzee’s Fabrication YouTube channel. I am so in awe of the work he does restoring vehicles with metal parts he makes in his shop,that I feel that I should try to do an OEM style repair. He has an episode where he makes a 48” metal brake out of pieces of big angle iron. I’d like to try to make one as part of this project.

I have begun hood and fender swap as well. I just scored a pretty decent scoop hood and a pair of fenders with big flares. Now I need the flares for the rear wheel openings. I am probably going to buy some used doors that have the front part of the flare already attached. My driver side rear door has the beginnings of seam rust so I will take care of that at the same time, in addition to not having to figure out the complex system of attachment that Toyota used, which would require me to drill half a dozen holes in the door and then buy a lot of expensive Toyota dealership fasteners. I’m sure I will end up spending less just buying the doors from the wrecking yard with the flares already attached. The section of the flare that attaches to the quarter panel has a much simpler set up, and anyway, they are on the quarter panels, which you can’t just replace but undoing a few bolts.

I can't wait to spray a fresh coat of Horizon Blue Metallic (Toyota paint code 8N1) on all the paintable parts of the 4runner.

 

[D'arce]

I would welcome input from people who have experience.

When I did my rockers I cut one similar to how you did and it was a lot of work to get looking right. The whole weld is exposed and has to be ground down to a radius to match the factory look. The second one I did I pulled up the door seal and drilled out the pinch welds. One horizontal cut at the door pillar and the rocker fell off. The shape of your replacements I guess dictates where you cut. The Wolf part I used did not have a vertical rise at the pinch weld so I had no choice but to cut out in the open, so to speak.

The second one I used a rocker cut from a parts truck and the install was almost a joy it was so easy. Everything matched right up and took less than half the time. No hammering or tacking and bending to meet up. A bonus is it came with an inner as well, which is a royal pain to try and match with flat sheet metal.

If anybody is interested I can cut free the drivers side inner and outer off the parts truck, including the dog leg at the back. I have a wolf replacement I didn't use for the passenger with its matching dog leg...



My .02
D'arce

 

[Ron Burgandy]

i’d replace it with something considerably stronger than what the factory used, like square tubing. i’m gonna weld a 1” pipe on the outside to look similar to the factory radius and then use 11 ga plate to tie it back to the inner panel. takes a lot longer for rust to eat through 11 ga.


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