King pin replacement on trailer? What do you recommend?

Stronger and Stronger get it from the trailer manufacturer. You don't want to have anything less. To much depends on that piece of steel.

 

That is a good question. I always used standard plate. Hardened plate does not cost a lot more. It would wear longer.
The frame work above the flat plate takes all the weight. A flat plate sheet will not take much weight.

 

I agree with @BoxCarKidd. Mild steel plate is ok. Its whats under it that counts.

 

In all my years, and all of it in the salty midwest, and literally HUNDREDS of trailers, I don't ever recall someone replacing a pin. Oh sure, there some that were pretty worn, but I think that's one of Gods toughest things, a 5th wheel pin. What's the deal?

 

I have seen plenty. Worn out pins, cracked and rust jacked plates

I bet over half the mechanics in the country have ever seen a pin gauge, much less used one on a DOT.

Owners usually scrap trialers when they see the estimate. I have fixed a few.

 

replaced a few on our trailers over the years. Do it at the dealer or reputable shop. Too much is riding on it to cheap out.

 

Usually by the time the plate was shot, like someone said, the trailer wasn't worth repairing. Trailers aren't exactly rare.

 

The older trailers used 1/4 thick plate. Most newer and heavy spec are using 3/8. Doesn't have to be hardenened. Standard mild is all they use. Hardened steel will destroy a cast fifth wheel surface like a hardened hammer and actually becomes brittle over time. If the pin is a weld in It will be easier to just cut it all off and replace with a new pin with it. If you go thicker plate then what is on it get the proper length pin. They make different shoulder lengths to compensate for the bolster depth. Also it is a great time to custom set the pin depth from the nose. If it is too deep like a lot of older trailers you can move it toward the nose or vice versa.
One custom thing my wife’s uncle used to do at his trailer repair shop on a dedicated o/o trailer was offset the pin a little to the side by 1/4 ,1/2 , or an inch to compensate for the tractor drive axles being offset to one side a little. Made better tracking.
You can actually see this on older trucks. Hook to a trailer and it may overhang to one side more. Usually the right side. Sometimes by 2 inches! This was common on Peterbilt Air Trac and Air Leaf in the 70’s and 80’s.