Wheel Wells

Wheel Well Fit Check

The wheel wells need to be placed on the frame and under the subfloor to prevent water thrown up from the road from rotting the subfloor. I was excited about installing the subfloor when I re-remembered this step. So I stepped back and went about fabricating new wheel wells.

The wheel wells for my Clipper were missing (along with most of the interior walls, etc. Based on internet posts I believe the original wheel wells were constructed from simple plywood boxes. The only remnants of those boxes was the outer aluminum wall that is riveted to the inside of the exterior trailer skin.

Remnant of Original Wheel Well

I had decided a while ago that I'd fabricate some new wheel wells. I really didn't want to use plywood boxes that would rot out fairly quickly because replacing them would mean tearing down the entire trailer.

I considered several alternatives but ended up designing a simple wheel well and ordering the metal pieces from SendCutSend. I'd considered purchasing sheet metal and cutting it myself, but after pricing in shipping, handling and waste it was going to be about the same price.

I ended up using 0.036" G30 galvanized steel which falls somewhere between 22 and 20 gauge. That's pretty stout for wheel wells and "the internet" said it was a much better choice than using aluminum because it's stronger. The G30 designation indicates how much zinc is deposited for corrosion protection (G30 is on the low end). I would have preferred G90 grade which has more zinc deposited for rust prevention but it was not available when I ordered. Later I'll talk to some additional efforts I made to prevent corrosion.

Laser Cut Parts from SendCutSend

Each radius of the wheel well is made of 3 identical cut pieces. The sidewalls for each wheel well are 2 identical cut pieces (6 and 4 total for the 2 wheel wells). I've found that ordering a quantity of 4 or more from SendCutSend is the "knee in the curve" for pricing so when possible I make design choices that allow for part commonality. In this case the wheel well is slightly taller than required (3" above the max axle loading deflection per Dexter) so that I could use a common design for the radius pieces.

I used my 36" straight sheet metal bending brake to make the appropriate bends. Of course I misbent a couple bends on the first one and had to hammer them back (which is do-able with steel) and rebend it.

Parts Bent into Shape For Assembly

For assembly I wanted to make encourage corrosion prevention. I considered a few options but settled on using galvanized steel "Tinners" rivets. These are flat head rivets used by "Tinners", ie sheet metal fabricators. I'd never heard of them before but they are available from Hanson's rivets and their distributors. I could find very little on the internet about their use. The sizing is odd compared to other rivets: they are sized according to the weight of 1000 rivets. I used a 1 1/4 lb rivet which is just under 1/8" diameter (Hanson Rivet part number TRSL01.25) which gives about 800 rivets per pound.

Small number of 1 1/4lb (1.25) Tinners Rivets

Drilling and setting these rivets is almost identical to the aluminum ones except they have a flat head vs a "universal" or "Brazier" head. I used a flat rivet set on my rivet gun. The lack of a domed head to center the gun was a little challenging but not much of a problem - fortunately no one will be able to see the few occurrences where the gun skipped off the rivet head.

As is my practice with the aluminum skin panels, I used Sikaflex 221 between the panel seams. So the process is clamp; drill, cleco, drill, repeat; disassemble; spread Sikaflex 221; reassemble with clecos; rivet removing clecos as you go. The Sikaflex makes it a little messy where it squeezes out but it's easy to clean up.

Wheel Well Assembly (1 of 4)

Wheel Well Assembly (2 of 4)

Wheel Well Assembly (3 of 4)

Wheel Well Assembly (4 of 4)

Once assembly was complete I sealed the inside seams with a liberal application of Sikaflex 221. Then I sprayed the inside with Rustoleum Professional Grade Rubberized Undercoating Spray. It took a can for each wheel well to accomplish the 2 recommended coats (wear a respirator!) I chose the Rustoleum product based on some YouTube comparison videos. It's not as thick as I'd imagined and I'm a little concerned about durability. I was hoping for something similar to bed liner. 

I also sprayed the outside of one sidewall on each wheel well. The outside of the sidewall will sandwich up against the inside of the trailer's aluminum skin and be riveted to it (it replaces the aluminum box side in the image towards the top of this post). The zinc coating of the galvanized steel should prevent dissimilar metal corrosion between the wheel well and the trailer wall but I thought an insulating coat of rubber wouldn't hurt.

Wheel Wells Drying after Undercoating

One last note. One of the sidewalls of each wheel well is not flanged. That sidewall will be riveted to the inside wall of the trailer. I left the sidewall long and plan to trim it to the shape of the exterior wheel well after I wove the shell onto the new frame. I did trace the old wheel well onto the new sidewall, but I'm not 100% confident of the final fit of the shell on the trailer so I wanted to leave myself some wiggle room.

Dry fit of the new Wheel Wells

Overall I was very happy with the way this subproject worked out. It was fairly straight-forward, not too time consuming, and reasonably priced (about $250 for materials).