Front fender rust ideas

Coadster32

Coadster32

Member
Original poster
Supporting Member
Joined
Mar 18, 2024
Messages
42
Location
Connecticut
Last year, I cut out, and patched up the passenger side front fender rust issue. Didn't look terribly bad, until I started cutting into it. The hole was much bigger than anticipated, and learned about the double wall design that Jeep used. (IMO...seems pretty crappy by design with factory holes in them right in the wheel well). Anyway, it came out ok. I repainted, siliconed up the holes, and Fluid filmed the inside of the wheel well as a preventative measure. This year will be moving onto the other fender. Up front, this one doesn't seem too bad either, but who knows. I do know that I need to cut it all back, or it will be for nothing down the road.

I have thought about rubberized undercoating the fender-well, plastic lining the fender-well, things of that nature. Curious as to what others have done.
 
From my experience in every vehicle I've ever owned, rubberized undercoating is the devil. It dries, it cracks, it traps water. Everybody I've seen has pretty good luck with things like fluid film or oil undercoatings
 
  • Like
Reactions: pbeach
I didn't even know about the evilness of rubberized undercoating and sprayed teh insside of my fenders with it in the first summer I owned it. Luckily for me I sprayed everyting visible and most of what is hidden with Fluid Film before winter set in.

Almost immediately that undercoating turned as soft as the FF and pretty much stayed that way. It's been 6 winters and FF aplications now and it's probably been two years since I saw that black rubbery stuff.
 
Coadster32 said:
Last year, I cut out, and patched up the passenger side front fender rust issue. Didn't look terribly bad, until I started cutting into it. The hole was much bigger than anticipated, and learned about the double wall design that Jeep used. (IMO...seems pretty crappy by design with factory holes in them right in the wheel well). Anyway, it came out ok. I repainted, siliconed up the holes, and Fluid filmed the inside of the wheel well as a preventative measure. This year will be moving onto the other fender. Up front, this one doesn't seem too bad either, but who knows. I do know that I need to cut it all back, or it will be for nothing down the road.

I have thought about rubberized undercoating the fender-well, plastic lining the fender-well, things of that nature. Curious as to what others have done.
Click to expand...

I can personally say rubberized undercoating is a frame killer, so think about what it'll do to thin sheet metal. My grandfathers 2013 Avalanche frame looks like it's 30 years old because of the amount of rubberized undercoating he used to use because the undercoating shop he took it to every fall made bank off of it and told him it was some anti-salt miracle. Fluid film will creep and move around as rocks hit it as it's just lanolin. Rubberized undercoating doesn't creep or chip, it starts to crack up and acts as a "sponge" that traps water, salt, dirt against the frame and just makes shit worse. Never use rubberized undercoating. I'm dreading chipping all of that garbage off of his frame this summer, but what needs done, needs done. Just don't use it. It's doing more harm than good. There's really good videos on YouTube that are Exhibit A of why you should throw that can of rubberized coating in the trash.

Now, to answer your question, when the rust on my front fenders started eating through I just cut them off with a grinder and installed tube fenders. If your Jeep is a rust bucket and you don't care too much about poor fitment and have two people, Barricade Offroad or Smittybilt is a budget option. Not recommending either, I'm just saying that they are cheaper and good enough if you're just trying to hide rust. The rust is likely going to keep coming back because of just how garbage that double wall design is. If you already found big holes, I would recommend replacement. A lot of people have rust free OEM fenders out there on eBay and marketplace. I found a set, in my Jeep's color, for $300 rust free a couple weeks ago. That's a really good deal, but they're out there.

The 4 bolts that go into the tub, the bottom 1 or 2 like to snap off or the rivnut likes to spin out. So keep a few on hand if you go that route.
 
I've posted this before and I think it's worth doing again now that it's been about 3 yrs. since I did it.

I replaced my front fenders with factory style originals. The previous ones had rotted through in usual spots ... the horizontal flat areas on top. I could clearly see that the new ones were not well primed between the underside of the fender and the top side of the panel that I believe is meant to be a stiffener. From memory the gap between the 2 is about 1/4" and there were 2 rows of adhesive. It's basically a rust trap.

I removed the panel on each fender, sealed various edges and then primed and painted them as normal. I use Fluid Film and this area gets a coat annually.

I drive my LJ year round through the worst of winter so it gets a fair bit of abuse. I don't think these panels are needed at all.

20-07-21 1.JPG


20-07-21 2.JPG
 
Last edited:
  • Love
Reactions: Granite
PCO6 said:
I've posted this before and I think it's worth doing again now that it's been about 3 yrs. since I did it.

I replaced my front fenders with factory style originals. The previous ones had rotted through in usual spots ... the horizontal flat areas on top. I could clearly see that the new ones were not well primed between the underside of the fender and the top side of the panel that I believe is meant to be a stiffener. From memory the gap between the 2 is about 1/4" and there were 2 rows of adhesive. It's basically a rust trap.

I removed the panel on each fender, sealed various edges and then primed and painted them as normal. I use Fluid Film and this area gets a coat annually.

I drive my LJ year round through the worst of winter so it gets a fair bit of abuse. I don't think these panels are needed at all.

View attachment 510665

View attachment 510666
Click to expand...

Some say it's for sound suppression, others say it's for structural rigidity. It's likely both, but there's not much structure once it all goes brown lol.
 
cooper32 said:
Some say it's for sound suppression, others say it's for structural rigidity. It's likely both, but there's not much structure once it all goes brown lol.
Click to expand...

I figured they might be for rigidity but I hadn't heard about sound suppression. On both counts, I haven't noticed any difference at all. Kind of funny if those were their priorities over RUST! :giggle:
 
  • Love
Reactions: Cooper Smith
Granite said:
I’m at the point where I’m just shopping for new fenders. These seem good enough:
https://www.carparts.com/details/Je...m_campaign=20238272333&gad_source=1&gclsrc=ds
Click to expand...

I bought the same set at Christmas time because they had some discount codes.

They look decent for the money. Sitting in the shed for future use.

The chances for us from NH and MA to find rust free OEM ones is going to be slim to none. When the day comes to put them on I will do what @PCO6 , did cut that rib right off.
 
  • Like
Reactions: PCO6 and Granite
DB04RedJeep said:
I bought the same set at Christmas time because they had some discount codes.

They look decent for the money. Sitting in the shed for future use.

The chances for us from NH and MA to find rust free OEM ones is going to be slim to none. When the day comes to put them on I will do what @PCO6 , did cut that rib right off.
Click to expand...

Occasionally they will pop up on marketplace there is a guy in southern NH that parts out jeeps often. I am needing to replace my driver's side for a second time soon going to follow the @PCO6 method also.
 
  • Like
Reactions: DB04RedJeep and PCO6
I had the luxury of cutting out the rust from the same spot on the opposite fender this past summer. I went single layer on the repair, and used fluid film after prime/paint the underside. Crappy designing there for certain.
 
Top Bottom