2018 RAM 3500 with factory rear air suspension VOILENT REAR AXLE HOP

[DonFitzwater]

I should have been more detailed in my initial description of the issue (which intellectual mechanical sleuths need in order to give an informed opinion) which I love about this site and why I respect and appreciate the time that people give and the info that's shared by all of you...... Let's see if I can do a better job

-3500 dually 8' bed extended cab all tires (yes the crappy NEXON brand that came stock) inflated to psi recommendations on door
-heavy duty tow package 4:10 axle w/factory air suspension
-truck unloaded all 3 times issue occurred, and at random, impossible to predict
-approx. speed 50-65
-solid surface road
-NOT a series of bumps nor tractor trailer breaking bumps
-Severe and Violent axle "wrap or bounce" when I hit one sharp short bump, I'd say like 1.5" that definitely starts in the back and works its way up to the front (picture a tuning fork type action) which last time rendered my steering useless. Braking did not help, I was at the mercy of the truck until it decided it was done and lasted I'd say 10-12 seconds.
Now I have driven All types of trucks over the years I am a CDL-A holder and I drive many different types of commercial trucks in the Fire Service (I mention this only to stress that I'm not using the word VIOLENT lightly) The last time sacred the hell outa me. Like I won't let my wife or two boys drive the truck, which is totally unacceptable for a new truck. To be clear, Im not describing residual suspension hop from a stiff unloaded leaf pack.
I suspect the air bags are exaggerating this action. Maybe the system is OVER/UNDER inflated or a poor batch of leafs that rely too much on the air suspension, maybe the shocks are bad and are overwhelmed. Dodge says nothing noticeable, all is fine can't help because problem can't be duplicated

-only thing I know to do is to enlist my boys to rig up their GO-PRO cameras underneath, aiming at the axle and hope for the best

TFucili,I did as you suggested and called FCA today, I am also gonna write a letter and send it certified

so now that you all hopefully have a better picture....thoughts anyone??

I watched a video on YouTube recently that a Ford owner posted since his dealer couldn’t duplicate the concern. He had inside and outside video footage. Let’s just say that Ford had him fixed up in short order.

 

[mwilson]

Packing piled up in one shock so it binds while it's twin is doing what it should......that would create an interesting situation on a bump...with air bags....??

 

[AEdelheit]

Interesting situation, using the GO-Pro to try and catch it on video is a good next step. I will be very curious to see the outcome.

 

[sag2]

Something isn't adding up here. It sounds like you have something similar to death wobble. If that's the case there should be a specific spot and I guarantee if it actually happened you'll remember exactly where it is. Unless you show the dealer where it occurs exactly they'll never be able to determine whether or not they actually repaired the problem if they find one.
Doing anything else is just a waste of time.

 

[TCDiesel]

OP... Its unlikely to be relate to the rear of the Truck, More likely to the front.
The Ram System has height sensors and is completely dedicated to the height, its not like each sensor is a valve that reacts to height with continue source of air like big trucks.

Bad rear shocks would cause hop , bouncing, it would not create violent hopping.

Self-leveling, just could not react that fast.

 

[AH64ID]

Self-leveling, just could not react that fast.

Nor does it adjust at those speeds.

 

[TCDiesel]

Nor does it adjust at those speeds.

Yep ,the 1500 has Aero-mode and drops the vehicle to that level its a slow process, the same goes for changing form Aero to normal, once it changes to that level it stays their until commanded to change. the 2500/3500 systems are even more dedicated to stationary heights.

Any level change requires Pump activation.

 

[BIG HIPS 3500]

I will hook up GoPro cameras tomorrow and do my best to recreate the action, if i’m successful in in catching it on video i will post it for sure. I will also keep this post updated with any new interactions i have with FCA

 

[Cummins12V98]

Run 35psi rears unloaded. Factory shocks are good and besides Bilstein does not make a replacement.

Run truck in ALT ride mode ALL the time!

LOVE my Factory Rear Air Ride!!!

 

[AEdelheit]

Nor does it adjust at those speeds.

It doesn't react that fast but still ramps up air pressure and rebound force much faster then traditional leafs or coils.

Run 35psi rears unloaded. Factory shocks are good and besides Bilstein does not make a replacement.

You wont realize how much rebound valving the stock shocks are lacking until you put on good shocks, There are many other brands other then Bilstien , Fox Makes a good OE replacement shock,

 

[EZeis]

Run 35psi rears unloaded. Factory shocks are good and besides Bilstein does not make a replacement.

Run truck in ALT ride mode ALL the time!

LOVE my Factory Rear Air Ride!!!

I left my truck in alt trailer height and had no difference in ride quality.


Earl

 

[AH64ID]

I have noticed that my truck will stay in ALT ride height after the payload is removed, but it’s not at ALT ride height. Due to lack of payload it sits like it does in normal ride height, but once I load it back up it drops again.

 

[Cummins12V98]

Mine sets low compared to non air trucks. It stays low with or without a load in ALT.

As far as shocks go the OE are nitrogen and of good quality. I replaced the fronts with Bilsteins with a small improvement. My rear rides fine. I have had two RAM owners ride in mine and are amazed at how nice it rides.

Does anyone know for a FACT that rears are made by anyone besides OE?

This whole issue sounds like part of the puzzle is missing here.

 

[AH64ID]

Mine sets low compared to non air trucks. It stays low with or without a load in ALT.

Mine appears to sit lower as well, in normal or ALT.

Next time I’m loaded heavy enough for ALT I’ll take some measurements.

 

[JR]

Fox Makes a good OE replacement shock,

For stock ride height? or lifted trucks?
I'm about due for a replacement set but have not found much for a stock truck that excites me.

 

[AEdelheit]

For stock ride height? or lifted trucks?
I'm about due for a replacement set but have not found much for a stock truck that excites me.

Yup for stock height and lifted, we work with Fox on some of our shocks and they have changed the valving strategy in the last few years , much better then they used to be and a lot of rebound that really helps with the stiff leafs. https://www.ridefox.com/subhome.php?m=truck&make=Ram&model=3500+&year=2018&position=ALL

 

[GrantP]

Just a warning on the Fox 2.0 front shocks. The upper stem actually threads into the shock body and can come loose leaving you with a disconnected shock rattling around. It happened to me twice, even after using thread locker and of course I was a long way from home both times that it happened. I trashed them and went with King 2.5's and they not only don't fall apart but the ride was also much better. Personally I think the design of the threaded stem on the Fox 2.0 is complete garbage.

 

[Cummins12V98]

Mine appears to sit lower as well, in normal or ALT.

Next time I’m loaded heavy enough for ALT I’ll take some measurements.

Both pics in ALT, both bed heights the same. Pin weight is 5,700# and RAW is 9,750#. Yes even in standard ride mode mine rides lower than regular sprung trucks.

I am 55" to top back corner of bed to ground.

 

[AEdelheit]

Just a warning on the Fox 2.0 front shocks. The upper stem actually threads into the shock body and can come loose leaving you with a disconnected shock rattling around. It happened to me twice, even after using thread locker and of course I was a long way from home both times that it happened. I trashed them and went with King 2.5's and they not only don't fall apart but the ride was also much better. Personally I think the design of the threaded stem on the Fox 2.0 is complete garbage.

They do thread in true however Fox corrected that issue , we saw that issue alot about 2 years ago but once they fixed it we have not seen a single issue with them and thats over a year ago.

I personally have King 2.5s, there great shocks but majority of people wont spend $2200+ on a set of shocks. A 2.5" shock has alot more surface area and tuning ability so ya it will ride better then a 2.0 but for people that only drive on road / light off road the IFP's do work very well for the cost and still ride much better then stock.

 

[lpennock]

Mine appears to sit lower as well, in normal or ALT.

Next time I’m loaded heavy enough for ALT I’ll take some measurements.

With 4200lb of truck camper in bed the Alt mode is 1-1.5 lower than the normal mode. Unloaded I don't see any difference. The one time I tried to go to Alt mode when unloaded I got a message about not enough weight to go to Alt mode. When I have been in ALT mode and then unloaded the camper I didn't get any messages.