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blickcd 05-25-2019 11:18 AM

79 forward section of frame rail question.
I have nearly all of the belly skin off my trailer from the hitch back to the axles. My reason for doing this is I was pretty sure some outriggers had rusted and broken so I wanted to get in for inspection / repairs, and put a fresh coat of paint on the frame.

I'll digress and say that two years ago I did the same at the back to repair some rotted floor, ended up repairing all outriggers, and was glad I got in there when I did.

Back to the forward frame... While the rear frame rails are just an open C channel and easy to wire brush and paint, the forward ones have a reinforcing piece of flat steel, with a row of maybe 1.5" holes all the way down. This piece is welded to the top and bottom of the C channel perhaps every foot, making it a box tube in a sense.

Wire brushing and painting the exterior of the frame will be easy, but what have people done to get the inside cleaned and preserved? Blast out the loose dirt and rust with compressed air and then spray in POR 15?

Thanks in advance.

n2916s 05-25-2019 12:47 PM

I would do the exterior and then simply fog the interior of the tube with Corrosion X or Fluid Film.

blickcd 05-25-2019 01:50 PM

Thanks for the reply. I have never heard of either product, but am sure I can research them easily enough.

blickcd 07-13-2019 07:23 AM

Update: POR 15 and Fluid Film
7 Attachment(s)
I was able to come up with a spray rig to blow dirt and rust flakes out or the hitch A-frame and tough to access area of the boxed in frame rails where they meet the base of the A-frame.

This is a 3/8" plastic tubing which fits over the end of a compressed air blow nozzle, clamped in place, with the other end secured to an electrician's fish tape so it can be pushed inside the frame while you blast away with compressed air.

130 psi gets great results. The back end of the A-frame, where it butts against a cross member, there are holes in the cross member where you can insert the hose, and debris blasts out at the hitch coupler. Had to make a number of passes to get everything out.

I later modified this rig to spray Fluid Film inside the A-frame and that previously mentioned part of the frame rail.

First I bent the spray can straw at a 90 degree angle. You do this by inserting a solid copper wire into one end, placing near the flame of a plumber's torch for only a few seconds, and then bending with two pairs of pliers. After a short time for it to cool you can pull out the wire.

A hole just large enough to insert that straw is drilled in the plastic tubing, and the end of the straw is inserted, pointing downstream.

The open end of the plastic tubing was then welded closed by lightly heating with a torch and pinching shut with pliers. A number of small holes were drilled around the sides of the tube at that end, to become a spray head of sorts.

The rust proofing is a two-person job. One person inserts the tubing while the second operates the spray can and blow nozzle simultaneously.

Air pressure was reduced to a normal 95 psi for that and several passes were done to ensure a good coating. Also, it initially takes a while for the plastic tubing to fill up with Fluid Film and it to get all the way down to the spray head. It is thick stuff.

The frame rails forward of the axle, a C channel, are boxed into a square at the factory with flat steel, punched at regular intervals with large holes. The bent straw can be used to spray up and down inside those holes to coat the inside of the frame rails.

Total of 3 cans of Fluid Film used.

Also shown are a few photos of the POR 15 paint job. Use of that stuff is covered well by others. All I can add is that I wore a Tyvec suit, much to the amusement of neighbors, but was glad I did.

I also coated the bottom of the wood subfloor, outboard the frame rails with West Systems epoxy, which is why it looks darker.

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