harsh ride from fifth wheel

[scaleman155]

I recently purchased a used 1992 carraige 32ft fifth wheel.  It weighs approx 12000lbs loaded.  I tow with a 1997 f350 crew cab dually with a 7.3 powerstroke.  Here is the problem.  It { the truck } rides horrible now.  I am experiencing a front to back lurching{?} motion at highway speeds { and slower }.  I understand from what I have read that this is common with heavier trailers.  The truck is riding suprisingly level and is just barely on the overloads.  My question is this, would a replacement pin box such as the trailair or 5th airbourne help this problem.  Since the truck is not sagging, I can't believe that airbags would help.  It feels as if the truck and the trailer are working against each other.  I previously towed a smaller 5000lb fifth wheel so I have never had to deal with this problem before.  Has anyone here experienced the same problem and if so what was the solution?  I'm not opposed to changing the pinbox, but I want make sure I am on the right track before I spend the $$$ .  thanks for the help

 

[Carl L]

Could be a number of things.

1.  Road surface:  concrete interstates can get rhythmic wear in the road surface that cause any trailer to buck badly.  The only cure is slowing until it begins to be tolerable until the pavement improves.

2.  Trailer imbalance:  a trailer, any kind, need to be weighted towards the front so that the pin weight is sufficient to stabilize the tow.  A fifth wheel needs 15-20% of the trailer weight on the pin.  Weight behind the axles can quickly destablize a trailer.  Try moving as much weight forward as you can.  If your fresh water tank is ahead of the axles, travelling with a full tank is an easy way to do this.

Trailer shocks may help, but then again may not.

If I were you, I would get the trailer, as loaded to travel, weighed as soon as possible and determine the pin/hitch weight -- see our library for the procedure.

 

[scaleman155]

I wondered about the shocks as they look original and are prob worn out. I plan on getting it  weighed soon. as far as re-distributing weight there isn't much that I can change .  the fresh water tank is behind the axle.

 

[BruceinFL]

I have a Trail-air pin box and it is wonderful. A great improvement over none.

 

[Carl L]

I wondered about the shocks as they look original and are prob worn out. I plan on getting it  weighed soon. as far as re-distributing weight there isn't much that I can change .  the fresh water tank is behind the axle.

Now there is some brilliant design.  Yeah, if the shocks were original equipment and you are having your problems by all means replace them.

To see the Trailair that Bruce recommends, click HERE.

 

[2006F350]

Different trailer, essentially the same weight. We got rid of the Lippert 1621 pin box and went with the TrailAir. Man oh man, what a difference. It went from driving a truck with a load in the bed and towing a heavier load to driving a truck with a load in the bed and I hardly feel the trailer behind as most of the shock of uneven roads, cement cracks, etc is absorbed by the air bag and shock absorber in the TrailAir. Best $928 (installed) investment made.

The only draw back I've found is that I get mesmerized watching the shock absorber move up and down - fixed that by turning my inside rear-view mirror up, and the headliner of the truck isn't near as interesting, so I don't watch it. Actually though, it is really amazing to see the shock absorber in action as then you realized just how much bouncing, jerking, etc was being transfered to the truck.

Another air box is the 5th Airborne and I've stories both directions as to which is the best at absorbing chucking and pitching. The main difference from what I have seen is the trailair pivot point is behind the pin where the 5th airborne pivots up and down ahead of the pin. To my way of thinking, the trailair is the best design as all chucking etc is actually 'felt' behind the pin box  so very little is actually felt at the pin. The front pivot still puts the chucking over the hitch so it can't help but to still transfer some of that movement down to the hitch.

Larry

 

[tvfrfireguy]

On our first snowbird trip to Arizona last year, we made the mistake of taking I-5 south out of Sacramento.  The right hand lane had huge chuck holes and we ended up losing our heat pump (suction line to compressor broke) and the replacement was $850.00.  I now have a 5th airborne pin box and what a difference.  I have no idea which pin box is the best but if one was that much better than the other, they would probably be out of business.  I installed it myself.  My Alpenlite had only four bolts.  You will need a torque wrench.  I too had the chucking problem and the 5th airborne pin box lived up to it's billing.  Dave 

 

[scaleman155]

thanks for all the input. sounds like a replacement pin box will go to the top of my want list.  In the mean time I'll try to do some re-arranging to help the ride as much as I can.

 

[dirtdr]

me and my business partners have identicle new vision 41 foot toy haulers. the only difference is he has an air ride pin box (not sure what brand) and i have the standard stiff box. His tow vehicle broke down and I had to tow his 5er with my truck ('08 F-450 pickup) about 500 miles to get him home. This was a good 'apples to apples' comparison, as both rigs weigh the same, balance the same, etc. I noticed that the ride of the TRAILER seemed to be significantly smoother, but the TRUCK was like it was touring around empty - very rough compared to my solid pin box.

For me, if i was worried about the trailer getting banged around too much, i would get the air ride pin box, but it made the truck ride way to rough for my liking.

 

[2006F350]

Not quite necessarily 'apples to apples'. When we changed from the solid to air pin box, I actually had to adjust my hitch because the trailer rode too high - even though it was installed according to directions and measurements taken before and after.

About the only way the truck should have been effected the way you mention is that either it was riding nose high or the air bag way over inflated. Your statements have me a tad confused. First your truck rode like it was empty, then it rode rough.

A rough ride from an air pin box would almost indicate the air bag was not inflated or not inflated enough. Ride like empty - are you saying that it didn't feel like you had any weight at all in the truck? Then the trailer was not level, but nose high and the pin weight was too little.

I've pulled the same trailer with the same truck both with a solid pin box and the TrailAir. No way on this plant would I even go back to a solid pin box. It is easier on the trailer, easier on the truck and much easier on the passengers.

If I had my way (which obviously, I do not), there wouldn't be a fiver roll off the assembly line anywhere that did not have an air pin box installed.

Larry

 

[dirtdr]

both trailers are 4000 pounds weight on the pin. There was definately weight on the truck, but when hitting bumps and frost heaves on the highway, the TRUCK would jump and bounce similar to the way it does when empty- although the trailer seemed smooth.

like i said - all else was equal - total weight within 200 pounds, same ride height.  Air bag inflated to recommended ride height. the only difference is that the air ride pin box extended the pin forward about 10 inches from mine.

just my impressions of it, thats all. Take it or leave it

 

[2006F350]

Sorry, didn't mean to come across as doubting you, was just confused by the apparent conflicting statements. Now I understand what you refered to as riding like it had no load.

With a solid pin box, the 'bounce' would have to overcome the full weight of the pin, so most of it would have been absorbed by the truck suspension. The air bag is pressured up to compensate only for the pin weight, so an sharp upward movement by the truck could actually compress the bag quicker than the truck suspension which allowed the the truck to 'jump'. That extra 10" forward in pin placement played a major roll in this also (like putting a 10" cheater pipe on the end of breaker bar for more leverage).

The road must be a pretty bad to cause that situation. Out of curiosity, do you know why your friend exteded the pin out 10"? That is putting a lot of extra stress on the trailer frame that it probably wasn't designed for.

Larry

 

[dirtdr]

he tows his rig with either a freightliner century class single axle highway tractor (long hauls) or for short hauls he has a f-350 short box. the new vision toy haulers have a large overhang off the front, so he purchased a manual slider fifth wheel. after forgetting to slide it back once (and denting the cab of the truck), he opted for the air ride pin box which was 10" longer than the stock one. this enabled him to turn without sliding the hitch back, as a bonus it has an air spring in it.

 

[scaleman155]

I am still wondering if it doesn't have enough weight on the pin.  everythingin the trailer stays put and when I go over railroad tracks it actual rides smoother than my old lighter trailer.  I expected the truck to sag more when I bought it but like I said earlier, I just barely sets on the helper springs. Up till now I have only towed 2 trips on I70 in Ohio about 200 miles each.  That road , while not great , is not that bad. I guess it's more of balance issue.  I'm kinda worried about extra wear and tear on my truck more than any thing.

 

[Carl L]

I am still wondering if it doesn't have enough weight on the pin.  everythingin the trailer stays put and when I go over railroad tracks it actual rides smoother than my old lighter trailer.  I expected the truck to sag more when I bought it but like I said earlier, I just barely sets on the helper springs. Up till now I have only towed 2 trips on I70 in Ohio about 200 miles each.  That road , while not great , is not that bad. I guess it's more of balance issue.  I'm kinda worried about extra wear and tear on my truck more than any thing.

Quit guessing.  Weigh the trailer and the truck.  Your pin weight should be around 15-20% of actual tralier weight.  We have the procedure in our library.  Click HERE.