2013 Ram 1500 Reg Cab Short Bed, Shaking coming from Rear.

[apeck5173]

Okay, So I have posted before as I was thinking it is the wheels on my truck. But I was wrong.

Turns out the dealer said it is because of my lift and the angle of the drive shaft causing the shake, He said to fix it I should get Adjustable trailing arms. The thing is, it shook in the rear before I lifted the truck.

Could it be the drive shaft is warped or out of balance? Should I try replacing the drive shaft? Or do the Trailing arms, or both?

I have the Rough Country 4inch lift.

 

[kurek]

Easy way to identify whether adjustable arms are the answer; get an angle gauge and check the pinion angle against the output shaft angle. Ideally with someone sitting in the cab just to eliminate variables. If the pinion and output shaft are within 0.5 degree of parallel then you don't need adjustable control arms. If they are not parallel that's very likely your problem.

 

[Wild one]

The regular cabs are notorious for having a tail wiggle .I had a buddy with a 12 that was scary to follow on the highway at 75+ mph,and that was at the stock height,the cure for his was aftermarket relocation brackets.I don't know if they'll do you any good on a lifted truck though. What happens is the arms don't run parrellel when you lower or lift one,and they'll consequently start trying to steer the rear-end,you have to get the locating arms back as close to parallel as possible to cure the issue.Has nothing to do with the driveshaft or pinion angles.

 

[apeck5173]

The regular cabs are notorious for having a tail wiggle .I had a buddy with a 12 that was scary to follow on the highway at 75+ mph,and that was at the stock height,the cure for his was aftermarket relocation brackets.I don't know if they'll do you any good on a lifted truck though. What happens is the arms don't run parrellel when you lower or lift one,and they'll consequently start trying to steer the rear-end,you have to get the locating arms back as close to parallel as possible to cure the issue.Has nothing to do with the driveshaft or pinion angles.

it just seems weird because it did this before I lifted the truck. Drives me nuts.

 

[apeck5173]

Easy way to identify whether adjustable arms are the answer; get an angle gauge and check the pinion angle against the output shaft angle. Ideally with someone sitting in the cab just to eliminate variables. If the pinion and output shaft are within 0.5 degree of parallel then you don't need adjustable control arms. If they are not parallel that's very likely your problem.

What Kind of gauge do i need to buy?

 

[kurek]

Any angle gauge is fine, like this thing for example or harbor freight has them sometimes super cheap. getting one is the easy part, sometimes it can be hard to find a perfect place to measure from on the truck.

Here is a video to help visualize the problem you're looking for, so you know what you are trying to confirm or rule out.

 

[Wild one]

it just seems weird because it did this before I lifted the truck. Drives me nuts.

Some do it even at stock height,there seems to be no rhyme or reason to it.You're by no stretch the first one to encounter a tail wiggle in a regular cab shortbox,the other thing they are bad for is axle breaking wheelhop.The longer wheelbase trucks don't have either issue as bad as the little short wheelbase rcsb's do.Search on here for posts by "Gary's Hemi" he went through virtually all the same issues you are experiencing.The only real cure is to get the locating arms back as close to parrellel as possible.When the arms run out of parrellel,they no longer travel in a proper arc,in laymens terms one arm basically gets shorter,and the arms then consequently try to steer or **** the rear end sideways under the right conditions.It's a cheap 4 link set-up under the 4th Gens that can cause numerous issues if everything isn't lined up in spec.You can check your pinion angle as Kurek stated above,but even if it's out of spec it won't cause your issues,but if it's way out to lunch,it's worthwhile buying a set of aftermarket adjustable locating arms and bringing it back to somewhat close.I don't know what's out there for kits to fix your issue with a lifted truck,but somebody should have a kit that should drop the front of the arms down .If you were lowered i'd tell you to buy Inez's relocation brackets,they move the arms down on the diff side,which is opposite from what you need though,you need to drop the front of the arms down on the frame side.
Search for Gary's posts in the lowered section

 

[brad_12]

Core 4x4 has real nice control arms.