I pull a 32' fifth wheel with my '02 2500. The truck is completely stock including the wheels and tire size. The hitch is a B&W with the Companion Fifth Wheel attachment. The hitch was installed per the manufactures instructions. The problem I'm having is the truck hops when backing the fifth wheel. This is not a new problem, it started when I purchased the trailer new in 2005. I have adjusted the companion and the tongue but it hasn't helped. Here's what I know:

1.the hop only happens when backing the fifth wheel, doesn't happen with any other trailers or loads even though I pulled heavier trailers. It should be noted that the fifth wheel is the only bed hitched trailer I pull.

2. It can be stopped by shifting into 4wd

3. The hop is created by the springs compressing and depressing to create bed hop and not wheel hop.

My questions is, is this relate to axle wrap? If so, would traction bars solve the problem?

Thanks for all of the input.
David

 

I have the same set up and never had that but what i get is once and awhile at low speed to avoid this i need to keep it in a lower gear and higher rpm. I do now the rear springs are starting to get tired after 350000k on them. As for backing up I have free wheel hubs and use low range it makes life a lot easier

 

Take a look at the rubber transmission mount on the crossmember. Try lifting the tailshaft housing of your transfer case- it should be rock solid. Sometimes the rubber separates from the metal and the rear of your powertrain is no longer properly dampened.

Your description sounds like axle wrap, traction bars can help a lot, but tend to mask other problems like cracked springs, damaged u-bolts etc. Sometimes the problem is also in the rubber bushings cotrolling the rear springs. If they are rotted out you get a lot of funny hops and wobbles from the rear, but since this comes on gradually you really get used to it and learn to drive around the problem.

About 2 months ago I fixed a 99 truck (QC SB 4x4 auto) that did not pass inspection because one rubber spring bushing was ugly- replaced them all with poly bushings from energy suspension and all the bucking and shuddering pulling and maneuvering trailers on gravel is gone.
Did the front control arms bushings a week later, now the truck is much nicer to drive than before.

Just my 2c

 

Just so I understand..... Your truck is "hopping"? Or is hop you're feeling the clutch grabbing upon engagement which is causing a hop or lurch? Because I cant understand why your truck would hop merely idling in reverse while connected to a trailer.

Also, do you have the CAD front axle or the non-CAD front axle?

 

Thanks AlpineRam. I will take a look.

Katoom,

The hop I'm getting is not the clutch grabbing. The symptoms show up anytime the truck is having to "push" the trailer, which means I can start off on a downward slope and get completely off of the clutch with no symptoms until the truck starts pushing up hill and the hopping begins. Once it starts all I can do Is come to a stop and shift into 4wd (high or low, makes no difference) and finish backing.

My truck has a CAD front axle.

 

Try disconnecting the trailer electrical connection and see if it still does it. I recently gave up on the factory integrated brake controller in my 2011 and installed a prodigy P3, the P3 is at least 10 times better but when backing up it applies the trailer brakes on/off/on/off and because of the B&W companion it is rocking the hitch simulating a hop, perhaps what you are experiencing, I have 3 other trailers but it only does this with the 5ver. The P3 has the ability to select the trailer brakes off when backing but only for a short period of time, as the controller is new to me I can never remember how to do it so I just persevere. What brake controller do you have?

 

Hmmm..... The hop is certainly odd since there should be no hopping whatsoever, especially with the weight of a 5th wheel pin resting on the rear axle. Besides, these engines run far too smoothly to cause a bucking affect under any situations unless there's something interfering, like as mentioned, trailer brakes dragging. There just isnt enough slop in the springs to cause the axle to wrap up and toss around to cause a hop.

Nonetheless, years ago I installed a 2 lo kit and I still consider it to be one of the best things I've ever installed. If you're unfamiliar with what that is, here's a couple links below, and I highly suggest you purchase it. BD makes one and so does Pacbrake, and they look to be the same. Install it and you too will find the 2 lo kit to be a HUGE benefit while moving your trailer around and it will save your clutch too. Something only for CAD axles too.

Differential Accessories - FRONT HUB 2-LOW KIT - BD ('94-'01, 4WD)

PacBrake 4WD 2 Wheel Low Kit 94-02 5.9L Dodge Cummins 12V/24V

 

I have had a Posi-Lock cable actuated CAD before on a few Dodges.
That system use no air lines or motors that like to fail.

2wd low is a cool feature for backing a trailer, even more so with a manual truck.

 

I am guessing it only happens when you are backing up hill, and I agree with you, it sounds like your springs are winding up, then releasing causing the "hopping"

I would talk to an RV trailer shop and ask, if it is spring wind up, it must be very common as would be the fix, if it isn't spring wind up, they have had to see it before and know the cure.

If you were in a hot rod, going forward, we would call it wheel hop, essentially, spring wind up and we use traction bars to eliminate it.

 

A lot of good advice, I have a few things to add: Check your driveshaft index- it's not possible to index the stocker incorrectly due to irregular splines, but it's such a serious issue if it's indexed incorrectly it's worth a brief look.

Sounds like typical axle wrap woes. 2wd low is very effective. I have my front axle controlled directly via toggle and vacuum solenoid. Works great- even with 3.55's and 35" tall rubber. But traction bars help too. Especially since it's not always practical to be in low range. I would do both.

I used galvanized erw pipe (respirator for the welding) with poly bushings between the u-bolt clamp plate and the frame. I did it initially because axle wrap was stuffing my drive shaft into the transfer case and damaging the seal, but it did help with axle wrap/wheel hop quite a bit.

As to smoothness of the vp44, I disagree. The vp44 reacts so quickly I think it can make things like this worse rather than better. I'm not sure I'm right about that though.

 

What I mean about "smoothness" of these engines is not pertaining to throttle response because yes, the throttle on these trucks is extremely sensitive and sometimes hard to hold steady on bumpy roads. But when moving a trailer or cruising through a camp park, I rarely even touch the throttle and idle "smoothness" is very smoooooth.

 

The B&W companion does have a history of "rocking" and in some cases bed damage has occurred. B&W will send you plastic filler strips to fill in the corrugations in the bed where the hitch makes contact. This provides a more rigid and stable platform for the hitch. B&W will supply the strips free of charge just contact them. I would like to know what brake controller you are using though. Are you using a double disc clutch?

 

is the hitch mounted to the bed only? if it s then that's the problem....it should be bolted to the frame!

 

The B&W companion hitch drops into the B&W turnover ball goose hitch which is rated at 33k lbs and attached directly to the frame. The companion is then torqued to 40ftlbs to draw the hitch down tight against the bed floor then the ubolts are torqued to 80ftlbs. The companion hitch is rated at 16k.

 

Just to follow up... B&W call center told me that the filler strips were plastic but.... what they shipped me is complete new feet for the hitch that have twice the surface area as the original ones, the new ones just attach over the original ones.This will spread the load over twice the area and might be worth a try for the "bucking" you are experiencing. Very impressed with their customer service.