Durability Test - Fiberglass Fenders vs Steel Fenders

The steel fender came with mounting holes drilled in the proper location and even had threaded inserts in the factory location for bolting accessories such as the starter solenoid. The fiberglass fender didn’t come pre-drilled.

The battery was disconnected and everything unbolted from the fender. We needed to grind down some rust on the firewall and remove body grout to smooth out the mating surfaces.

The steel fender ultimately bolted on and fit flushly, but we had to trim a body seam on the firewall and the top seam on the fender where it meets the grille. The grille also had to be moved forward about half an inch to line up the front bolt holes—this could be production tolerances, or a tweak in our Jeep.

Using a piece of paper, a crayon, and the original fender as a guide, we made templates to drill the mounting holes in the fiberglass fender. Work carefully or you’ll wind up with a fiberglass coffee table.

Use masking tape to help prevent turning the holes into a hairy mess. It’s a good idea when working with fiberglass to wear gloves, unless you like itching.

Although we had to knock some more grout off of the firewall, grind the same firewall seam, and move the grille back about three quarters of an inch, all of our bolt holes lined up—amazing. We used washers to keep the bolts from ripping through the ’glass.

Cheesy. Although we may never have noticed this had it not been for the rocker guards, the fiberglass fender warped inward just rear of the wheel. We tried quite a few techniques to fix it, but just couldn’t get it to fit correctly.

We were amazed at how hard it is to actually hit something with the fender of a Jeep. After much perseverance we tagged a rock and crumpled the steel fender. The beauty about steel is that it can be bent back into place on the trail.

The fiberglass sustained way more pressure before cracking than we thought it would. It did crack, however, when we smacked it really hard, and then it ripped with a mild pull shortly after. Surprisingly, even in its ripped state, the fiberglass fender could still support Editor Cole Quinnell’s bulkitude.

Decisions, decisions. For those not into rockcrawling or who need to lighten their vehicle, fiberglass makes a sensible choice; however, we’d opt for the steel fender. We’re just too hard on our vehicles.

Say you live in the rust belt, you like to play eyesies- closies on the trail, or you just plain like to hit shopping carts in the local mall parking lot. The point is, when choosing replacement fenders you generally have two choices—fiberglass or steel. But how easy is each to install, how does each fit, and what is the survivability of each?

In an effort to bring you some answers we contacted Eagle Equipment and ordered up a pair of replacement fenders for a ’77 CJ-7. We photographed the installation of the steel fender on the passenger side and the fiberglass fender on the driver’s side, then took them out and bashed them for all they were worth. Here’s what we found.