hopping while pulling hills

[TWhetten]

I pull a 25' 3-horse with a living quarter in the front, I don't know the weight but it is pretty heavy. When I start pulling a hill the truck has a slight "hop" in the backend, it is worse when the truck starts pulling real hard. What could cause this, do I need new shocks, airbags? I have never felt it in any other truck.

 

[jelag]

Could you be seeing the start of either carrier bearing failure or u-joint failure...

Both of these show up sooner when you tow... .

I have an 04 and when the rear end sat down real bad it would do that... . it also knocked out the rear oil seal to the transfer case 3 or 4 times... . we finally shortened the drive line by 5/8" and installed air bags which we check every time we connect a big trailer...

Our heavy trailer weighs in at 20K lbs and would set the back of the 04 down at least 6"... . what we felt was that the drive like would get straight and push the yoke into the transfer case... this truck (04) now has 245K miles...

Hope this helps... ...

One last thought is the hop related to the speed of the rotation of the drive line..... if so I'm guessing its one or more of the above... . I would describe it more like the wheel hop of a 4wd front end on a tight corner and it starts to bind???

 

[Gene Arnold]

You probably have a goose-neck trailer so this won't apply. However, if you have a hitch-pull with a weight distribution set-up, you may have too much tension on the chains. This lifts too much weight off the rear of the truck and allows the rear wheels to slip and could cause the jump. Just a thought.



Gene

 

[TWhetten]

thanks for the advice, I will check the u-joints and bearings

 

[Boondocker]

I've considered that this may also be a case of "axle wrap". The same as when launching empty, only worse when heavy. If so, then traction bars may help keep the driveline angles stable under torque. If you're overloaded and seriously compressing the springs, that needs to be addressed too, like with air bags.

 

[CBari]

This may sound odd but I experienced the same problem with my 03 with any heavy gooseneck usualy when starting of from a stop, but also climbing hills at low speed. I always though it was launch shutter associated with change in driveline angles as it only did it loaded. But last winter I spent a week driving around empty on ice and would feel the samething occasionally and to me it was like the limited slip differential was trying to engage.



I gave up worrying about it I figure when it get really bad it will break something and I will then know where the problem was.



By the way when really loaded heavy and starting on a hill I always put it in 4hi.

 

[TWhetten]

I bet it is axle wrap, it hops like axle wrap while playing in the sand, but not near as violent. You think that air bags will fix that? I would rather put on bags than traction bars.