Custom Hitch, Original Flatbed Removal

My truck came with a commercial style hitch:

It is a little hard to see in this picture, but it hung down way too low for my purposes and was also very heavy duty. I decided it needed to go, as did the flatbed.

I chose to get rid of the flatbed because it:
-Was elevated very high off the frame and I want things as low as possible.
-Dropped down in the back, as you can see
-Totally restricted up-travel of the rear suspension
-Had a headache rack that would have been in the way
-I found someone to buy it for a decent price.

The guy I sold the flatbed to got the hitch as well.  In hindsight, I may have been better off leaving the hitch on there and cutting/welding it to suit my needs.

Regardless, he got the flatbed and the hitch assembly.  This left the end of my frame rails a little beat-up, with junk welds from the people that installed the flatbed, some rough grinding/cutting from the flatbed buyer, and a rusted out rear cross member.  The rear cross member, which also serves as the rear mount for the diesel tank, had a valley in it that held moisture and rusted through in some places.  This is the only significant rust I have found on the truck.

I decided to take out the cross member and replace it with a new one that would also serve as my new hitch system.

Easier said than done.

Plasma cutters are not fond of chassis coatings, they are not so great at being used on a vertical surface, and when you are using them with a plastic fuel tank within inches.......they are not the ticket.

To get the rear cross member off I had to grind some welds from the hitch installer and then drill out, I think, 12 rivets that Ford used to secure it.   Don't quote me, but I think I used a 9/16" bit after center punching the rivets and drilling a pilot hole.  You are near 9/16" steel when you have the frame itself and a rivet head on each side.  I tried air chisels and hammers and in the end drilling was the only way, mostly upside down.

Drilling metal upside down sucks, holding the drill in the air, hot metal shavings flying around.....glad to be done with that.  Buy a full face shield, and apron, and welding sleeves if you are going to try it.  I recently bought a set of step drill bits at Harbor Freight, so they are probably junk, and they work great. They would not be the best for drilling stuff this thick, but they would get you to the half way point easily. 

Once I got that sucker out, I began to build my custom hitch which would serve as:

-A regular hitch, 2.5" receiver
-An adjustable bumper mount for when the camper is on/off the truck
-A winch mount
-Part of the system holding the rear most brackets for the spring flatbed mount.

I used a huge hunk of 3/8" thick steel tube that was, pretty sure, 5"x3", must weigh 50lbs. Add to that 3/8" plate for the ends and two 2" receivers and one 2.5" receiver.   This picture gives you the basic idea:

 The larger, middle, receiver is to serve as a normal receiver would, the two smaller, outboard, receivers will serve as a bumper mount or winch mount.   I'll be making a winch mount that has the two 2x2 pieces of steel that plug into those receivers.  The same receiver set-up will be in the front bumper, so I can move the winch front to back.  

After welding and paint (2 coats POR15, 2 coats Rustoleum truck bed liner) it all looks like this and you can see my shoes are grey.   I tack welded everything and then had a pro finish it up.  The thickness of the material and critical nature of the welds trumped my manly motivation to do it myself.

Here is the hitch installed (terrible picture):

The hitch is bolted to the frame on each end with three 9/16" Grade 8 bolts and one 1/2" bolt that runs vertically and passes through the frame twice.  So, essentially 5 connection points per side.  I sleeved the portion that the 1/2" bolt runs through so that moisture could not find its way into the main beam of the assembly.   There are two holes that are tapped 1/2", 13 tooth, into the bottom of the hitch.   This is where the "skid plate" that holds the fuel tank bolts into for the rear connections.  I had to buy news bolts, the factory ones were an odd thread I could not match a tap to.  I did not use Loctite on these, but it would not hurt.  Use a lock washer at least.

Before installing the hitch I ran compressed air through it to dry out the inside.  Before I installed the fuel tank bolts I stuck the red straw on the WD-40 can into the holes and blasted away in all directions, hoping to give the inside an oily coating should moisture ever find its way in there.  This is one of the few times somebody probably used WD-40 for one of the intended uses.

As I mentioned earlier, the rear ends of the frame were hacked up all the welding and grinding they had seen.   The original owner of the truck sprayed some type of chassis coating on the truck.  I needed to protect the ends from corrosion.  The trouble was that some spots had paint, some chassis coating too, and there are lots of rough edges.  After considering a few options I decided to clean the ends as best I could, although not trying to get to bare metal.  I used Simple Green and plastic brush after first using a wire brush.  I got it all decently clean and then sprayed it with Eastwood Anti Rust

This products is basically a black (I think you can get amber too) wax/tar/goop coating.  It is not rubbery and I see no way, as is sometimes the concern with rust protection coatings, that water could get behind this stuff.  It is not a rubber coating, like a tool handle, it is more as if you smeared a hard grease over metal.   I have not had the truck out in the elements so I cannot speak to the long term effectiveness, but it went well, looks good and it seems like it should work.


It was a nice option to cover over rough metal that was painted in some spots, bare in some spots, and covered with a similar product in some spots.  I overlapped the spray onto the sections of the frame that had pristine coating on them, so I have good continuity of coverage.   I did 3 coats, each with about 24 hours dry time.

Hopefully, in the terrible picture below, you can see the nice coating it gave.  It does not really run, that is how uneven my frame rails are.   I do not recommend this coating for applications were it will be rubbed, impacted, etc.  It does not seems like a very tough coating, although decent.  The corrosion protection is the selling point.

Chassis Brackets for Spring Mounted Flatbed

I originally had intended to make a 3 point mount for my camper, similar to a Unimog's.  This type of mount eliminates the transfer of twist in the frame to the truck bed, or the camper on it.  It is important to protect the camper from twisting, the chassis flexes quite a bit when on uneven ground, so that cabinets stay fastened, walls don't crack, doors don't jamb, etc.  It also allows the frame to flex freely, which supplements the suspension.

After being educated by the group at Expeditionportal.com, I decided to use a spring-based mounting system.  I basically decided to copy what the M35 (Duece and a Half) uses.

The basic advantage over a 3 or 4 point system is that the load is spread over the entire length of the frame, and it is probably easy to build a spring system than a 3 or 4 point system.   Having the load spread over the entire length of the frame is needed for the truck with lighter and/or not boxed frames. (This is all relative of course and the F-450 has a huge frame by many standards)

To replicate this system I purchased angle iron, actually steel, 5"x3" and 1/4-5/16" thick.  I cut it to the necessary lengths, added extensions where the frame had the depth to allow it, drilled holes in the plate that allowed me to use existing holes in the frame, painted them, and bolted them on.   It took WAY longer than it should have, as everything seems to do.  I was able to fit six mounts total, 4 of them with room for two springs and 2 of them with room for one spring.

I used Grade 8 hardware all around, in 7/16, 9/16 and 3/4", all in 2" length.  You can see in the picture above how the bolt in the upper right corner is smaller, I was able to use all existing holes in the frame which preserved the paint, the strength, my time and drill bits.   The frame is 8" deep at this point, so I welded a 3" plate on.  This bracket, along with one just like it on the other side, are directly behind the cab.  

For the two brackets in the middle of the frame, which each have room for one spring, I had to get a little creative.

I used the same angle steel and welded on a 1/4" strip of steel, with a 3/8" spacer at the end, and bolted it up within the leaf spring perch.   Because the leaf spring perch is not as deep as the mount springs, I will need to cut one down and will probable try to fit a small section of spring above the angle steel that will come off of the flatbed structure.  Again, I used Grade 8 hardware and existing holes, with one 3/4" bolt into the frame and a 9/16" into the cross member.


For the rear most brackets, I incorporated them into the custom hitch that I built.

These got 3 x 9/16" bolts.





For all the hardware I used a lock washer and in some cases I also used a lock nut.

The brackets were coated with two coats of POR15 and two coats of Rustoleum aerosol can truck bed liner.   I am not happy with the coatings and will speak more about that later, it may be my fault.

One "trick" I used to mark the holes on the plates, for drilling, was to clamp the plate to the frame in the final position.  I then took a socket that fit just exactly in each hole that I wanted to mark.  I then dipped the end of the socket in spray paint, with the longest extension clipped in the socket.  I then pushed the socket through the existing hole in the frame and make a nice circle of orange spray paint that was centered and let me drill fairly accurately.  All of my hardware is 1/16" smaller than the hole it is in, to allow a little bit of wiggle room.  The hole(s) in each bracket for the spring bolt to bass through are 3/4", the bolt itself will be 1/2" or 5/8".