Rear End Shudder

[Wellsp]

When I accelerate up a hill the rear end of my truck starts hopping usually around the 60 mph mark. The last time this happened, I was towing my 26' travel trailer over Mt. Hood Pass. I decided to conduct a couple of experiments. I pulled over and disconnected the Edge EZ Power chip. On the next hill I accelerated to the 60 mph and no shuddering. OK maybe it's a power/torque issue. So I reconnected the chip and disconnected the towing stabilization system to put more weight on the rear end. At the next hill I accelerated to 60 mph and again no more hopping. I pulled over the reconnected the towing stabilization system and took off. The hopping was back on the next hill. Any ideas?

 

[RustyJC]

I know this sounds crazy, but the first thing I would do is run the truck over a scale with the trailer and weight distributing bar(s) attached. It sounds like you have the weight distributing bars pulled too tight, unloading the rear axle.



There is an ad that shows a car pulling an Airstream TT using one vendor's weight distributing system - the rear wheels are off the car, and the rig is still sitting level. In other words, the weight distributing system is capable of holding the rear of the car off the ground!



Just a thought... .



Rusty

 

[Bob Horrell]

Rusty hit the nail on the head. I used to work in the industry and this problem was more common than you might think. It was especially noticeable on a dirt road where the rear wheels would really lose traction.

It sounds like your rear tires are breaking loose and then grabbing thus giving you the shuddering feeling. Another way to check this is right after climbing an hill where the shuddering takes place, pull over and feel the rear tires. If they have been slipping and grabbing the tread will feel pretty hot. You can compare the heat on the front ones with the heat on the rear ones. The rear ones will almost always feel a little hotter but not by a large amount.

When installing the load levelers, how much does it raise the back of your truck? Try reducing this by half and see if that doesn't stop the shuddering. One chain link adjustment can make a big difference, especially if your trailer isn't that heavy.

Hope this helps.

Bob