bump and bucking - Diesel Forum

truckdrivindave · 08-14-2007, 08:23 PM

A friend got a 5vr I think a 30 ft 5vr weighing in at close to 9k.

Hitch installed by dealer

When he hits a bump on road the 5ver bucks his truck

truck is a dually extended cab

5ver has been raised and lowered to no avail at the king pin

5ver is not loaded since he just bought it.

What would be causing it??? [img]/ubbthreads/images/graemlins/smokin.gif[/img]

jetskier · 08-14-2007, 09:01 PM

This is common when the trailer axles are too far forward. I get bucked when I tow my 31' fifth wheel. You can load up the front of the trailer to keep the pin weight higher than the rear to reduce the effect. I like to think of it like a teeter totter. When you hit a bump, the trailer bounces and then rocks back and force until the energy of the bump is dissipated through the suspension and hitch. This force is felt both horizontal and vertically in the truck.

An aftermarket pinbox seems to be the ticket. I've heard that the Demco Glide Ride remedies it almost completely. As soon as the budget allows, I'm going to order one.

There are other boxes, but I don't have the links.

karmikacres · 08-14-2007, 10:49 PM

What year is your friends truck? There is a TSB for bucking (tsb 07-6-9). I had the tsb done, and it cured my bucking beast.

Mike

bootcreekranch · 08-16-2007, 12:43 PM

Any idea of what they did? I pull a 31' LQ trailer and sometimes it about beats us to death. Seems like certain bumbs at lower speeds (35-45mph) trigger it. Was yours anything like that? MY 2000 did the same thing but even worse so I was hoping this one wouldn't have the problem but it does just not as severe. I have added Ride Rites and may have helped some but the backseat passengers really get beat up. It doesn't do it with my lighter GN trailer so must have something to do with the added pin weight. Calling Ford now and thanks for calling the TSB to our attention.

truckdrivindave · 08-16-2007, 07:26 PM

I dont know/ origionally I thought it might be where the 5th wheel sits whether it need to go forward an inch of the axle. But if the trailer is bucking the truck as it hits a bump. Its got to be the trailer....Maybe it needs shocks...

I was hoping someone here might have an idea but it seems it is not a common problem.....So I dont know...... [img]/ubbthreads/images/graemlins/smokin.gif[/img]

Flywheel · 08-17-2007, 08:58 AM

It is a common problema nd has to do wither with trailer geometry or loading (or a combination).

Some folks ignore it. Others upgrade with shocks from either Monroe or Dexter. Others do something with the hitch. THey make air ride hitches for this.

My GN has a tough time hauling my little tractor (about 4000lbs) with shredder - but it will haul the heavy tractor no problem, and empty it is fine. Or if I remove the shredder...so in my case - loading is critical.

I am thinking of fabbing up some shocks just to see - but am runnning onto problems witht he slipper spring set-up.

If you have eye-to-eye springs, Dexter also makes a shock absorbing equilizer that is supposed to help - it is pretty new - check out the Dexter site.

JoeF350 · 08-17-2007, 02:29 PM

Put a 5th Airborne hitch pin on your fiver and the bucking /bumping,chucking WILL be gone. Our KZ Montego Bay 5ver came with this hitch on it. It is a smooth riding trailer. I will NEVER have another trailer without a 5th Airborne.

Joe

bootcreekranch · 08-17-2007, 03:03 PM

According to Ford the TSB is a flash on the sensativity of the accelerator. They feel when the bucking starts it is accentuated by footpedal being bumped. I'm also told that the professional rodeo people are removing the overload spring and installing air bags to stop this problem and after the flash that will be my next step as I already have the bags on.

RLDSL · 08-24-2007, 01:23 PM

My 5er makes my truck buck bad on concrete interstates with expansion joints. Here in Arkansas, they've switched almost everything to blacktop so it rides pretty nice, but a couple of months ago we went across texas and back across Oklahoma and what's left of my spine was so messed up i spent 4 days in bed.

I broke down and scavanged a passenger air seat with a fore aft isolation slider out of an International cabover semi and rigged that thing in. No more backslap and I can barely even feel speed bumps now. Something real handy for me since my spine is almost completely fused together, so my back cant absorb any of the bumps like most folks.

I put just a rocker seat on the passenger side. The kids don't seem to mind the ride in the back, they're still spry enough where it's all fun to them, but I do see airbags in the future.

----Robert

Old_Machinist · 08-27-2007, 07:48 AM

I haul both 5th wheels and gooseneck horse trailers. I notice the bucking, if you are talking about the "front to back" tugging you get to be much worse with the gooseneck. Part of that is the 5th wheel hitch has a little bit of give around the kingpin but that gooseneck is a 3 foot long lever with very little play on the ball and that 3 to 4 ft lever is being used by the trailer to pull on the truck. Does a pretty good job at times also. Have seen quite a few 5th wheels people have converted to goosenecks that end up shaking the front part of the camper to pcs due to the leverage of the solid, straight pipe of the gooseneck.

frunky · 09-07-2007, 09:49 PM

I just installed the 5th Airborne last weekend. Pulling a 26 ft 5vr that weighs 7660 loaded for extended travel, except all water/holding tanks empty. Pin weight calculated to be 840. That's only about 10-11%. I know it should be higher, and probably adds to the bucking, but that's the way it is. I load heavy stuff forward under bed as much as possible. The trailer is nose high also, but hitch is set to lowest setting, and pin box is set to highest setting, so am stuck with that.

The bucking is real bad with my 05 250 with camper pkg (overload spring on rear axle). The Dodge 2500 I had previously had much better ride towing, but harsher ride solo. The 250 just about beats us to death, and I was afraid something was going to break, either the hitch or the pin box. The 5th airborne helped immensely. I still have to fine tune it by moving the airbag forward as they suggest when you have a lighter pin weight (Their are 3 pin weight positions; light, medium, heavy.) Next month I'll try it and see if that helps even more.

I'm considering removing the overload leaf on the truck and see if that helps even more. If it squats too much, I'll add the Firestone airbags, but the Dodge 2500 didn't squat too much so it will probably be alright.

Anybody else remove their camper option overload spring?