Really weird... My fontaine fifth wheel lifts up on the passenger front side. It's like the rails are worn out or something. I thought it was a worn sliding pin, but I pulled that apart and it all looks good. Even with the pin out, the drivers side is not loose (up and down) but the passenger side is. I was thinking of just ramming something in there, since I don't slide my fifth wheel anyways.

This could be the "clunking" sound I get when I bobtail. I don't notice it anywhere near as much with a trailer. But it is still there.

 

Just for clarification, it's the plate that lifts up. I noticed it lifted up when I put a shovel under the back of it to lift it up for grease.

 

It's the slider that's loose, correct?

Is this the slider where the "blocks" move outward away from the rail to unlock it?

Does the blocks have bolts thread into the outboard side? If so they are a tapered wedge type lock, and are adjustable by loosening the jam nut and turning the bolt out to tighten.

 

The blocks are solid, I had them out yesterday. The problem is where the "plate" (not the actual fifth wheel, but the plate underneath it) meets up with the frame. I just can't tell how to fix it without taking the whole thing off.

 

The plate lays flat on the top of the frame rails. Vertical (but upside down) L-brackets are bolted to the side of the frame rails, and then the plate is bolted to the L-brackets... no?

 

Well the plate can slide along the L-brackets, assuming we're talking about the same thing.

I'll take pics tonight if I do not go out.

 

The slider I'm referring to; the bottom half of the track is part of (or bolted to) the L-bracket. The top half has the 5th wheel pivot bushing boss.

The top half has a flange that kinda hooks underneath of the bottom half creating a sliding track... this type is very easy to determine what is worn.

This is not usually a wear point... if the slider was moved A LOT I could see it, or if it had been seized/frozen at one time and someone used drastic measures to force it to slide... otherwise, the track might be bent? Realistically, I'd have to see this to be of much help.

It certainly could be causing your clunking noise, though; get someone in the truck, leave the trailer spring brakes applied and get them to rock the truck back and forth while you watch the plate... look for the plate to lift and fall, or cock itself to one side, etc ... also, look for movement between the pick-up plate and the 5th wheel.