Headache rack install ?

I've always seen a piece of mudflap or something rubber between the top of the frame rail and the headache rack. Not sure what its purpose is though.

 

U bolts from the bottom up - and on the bottom side where the U wraps around frame rail , I put a piece of aluminum block between bolt and frame.

I was told to do this to prevent the frame rail cracking. (?)

Piece of mat on the top side wouldn’t hurt, I never did this.

Jack with long piece of 4by4 up from the ground to help lift a little? They’re not too heavy when empty.

 

Yes good point. The u-bolt will actually bend the lower flange upwards over time. A block in that location helps keep the rail true.


Now that I think about it, the rubber is more than likely a barrier to prevent aluminum and steel contact as the paint will wear off the frame under the headache rack as the frame flexes. This is assuming its an aluminum rack of course.

 

I use an old piece of strap

 

The way it was explained to me many moons ago, the rubber mat is actually to prevent corrosion from occurring between the 2 different types of metal. Aluminum & steel don’t play well together when in direct contact with each other.

And here is the engineers scientific explanation.

“In severe environments, especially those with a high chloridecontent, attention must be paid to the risk of galvanic corrosion. Some form of insulation between aluminum and more noble metals (e.g. carbon steel, stainless steel, copper) is recommended”

 

And we have winner

 

It's the same reason why they usually have some type of material between an aluminum trailer and where the axle framing bolts to the aluminum frame.

Or the same for inner steel rims and aluminum outside rims. They usually have a felt type of pad so that they don't corrode. Makes for separating the rims much harder if you don't have the piece.

Also I think the rubber would also help so that ist can't move around. Adds a little more resistance so it can help same as using it under coil racks. So they can't shift

 

It's called Galvanic corrosion and you can read up on it. In a nutshell joining two dissimilar metals together causes a chemical reaction that causes corrosion to happen much, much faster than "normal"

Galvanic corrosion - Wikipedia

 

I had a galvanized pry bar i used to lock a barn door on a dump trailer and stored it in the lower tray of a aluminum headache rack, it would sometimes vibrate in that tray while the truck was shut down, had to wrap it in a rag so the metal bar wasn't touching the aluminum.