So I had my rear fenders rolled about two years ago and was quite happy with the results (no more chewing through tires at auto-x!). However, I recently discovered a potential problem with getting your fenders rolled: the V created by bending them up creates a place for dirt and road salt to accumulate, and I can't be sure it caused it, but I noticed a small rust bubble at the rear corner of one of my fenders when I washed my car for the first time after this winter (that had a ton of salt on the roads).

I plan on sanding down the area as best I can, spraying it with POR 15 and possibly filling in the V with some sort of flexible material/glue/sealant that will seal out all future water and debris.

I can't imagine I'm the first person this has happened to, but I don't remember reading about it before on here, so I thought I would let others know. If you have dealt with this before and have tips on repairing it, let me know what you did!

 

It doesn't surprise me one bit. When you stress the metal, any undercoating of paint will more then likely pop right off. Like you said, some accumulation can occur which only helps promote more rust...I'd be surprised if you're the only one seeing this problem...

 

I had rolled fenders on a Toyota Celica (78 22RE, 5speed, 3Gen Supra Rims, lowered 2 1/4" inches all around) -

They had filled the inside of the V with what looked like J-B Weld - (thinking about that now, that had to have taken a lot of it) (the car had a custom paint job too - which was done after the fender rolling...)

If I ever have rolled fenders again, I'd probably use some type of body filler, or epoxy based product that can fill in that space.

 

Improper rolling of fenders causes this.

If you use a heat gun and a professional roller, the paint will not chip and still protect the fender. Using a baseball bat on a dirty unprepped surface will surely cause this problem down the road.

 

They used a heat gun and proper fender rolling tool. The paint is fine everywhere I can see (ie no "stretch" marks in paint). I don't see how one method of rolling fenders would be better than another in this regard as they all accomplish the same thing (creating a V).

 

You don't want to create a V, you want the piece flat against the fender. Our quarter panels are thick as hell and it takes a lot more work to get them flat. It took a lot of pounding to get mine to flat ( prior to paint).

Some individuals cut the piece of completely and file it smooth. This is a better option but requires more work.

 

HMMMMM I take my comment back.

I just figured there were people out there that put a flush fitment on the rear.... had scrubbing then decided to roll their dirty fenders, with a wooden bat with no heat...... thus chipping the paint..

 

That would make sense, wouldn't it?

Since I'm doing this with no intention of repainting the car, I need to keep paint intact.....I would consider cutting it but I feel like that has a chance of cracking paint in places that I wouldn't want.

So if I'm going to fill in the V, would I want to use something like bondo/body filler or something like silicone sealant?

 

I think you need to get the area dry then... perhaps a quick dry silicone sealant, as bondo will not be the same color (grey white)...... and silicone will not be as noticeable under the car.

 

Masking tape and spray paint. Worked for me. Can't see it from the outside but I sprayed every which way up in there.

 

Spray paint? You mean like the 3M underbody rust inhibitor?

 

I don't think color matters as nobody can see inside the V....

 

yeah i was pissed rolling cracked my paint AND i still rubbed... so i tried to cover it a lil with anti-rust, but am sure i will see it someday.

 

Agreed!! I've rolled the fenders on my last daily mitsubishi and 7 years after I did, still in good shape, no rust. You must do it right.

 

I heard of rust forming from rolled fenders mostly from water/dirt getting jammed into the crack and keeping the area moist.

I would seal the inside lip with sillicone or that rubber underbody coating.