I own a 2002 3500 Dually with factory overloads, and Rancho RS5000 5 speed shocks (older version with 5 settings)

When towing my 7500 lb. dry weight Jazz 2780 5th wheel large bumps cause some occasionally hard bumps in the rear. I figured the suspension was bottoming due to poor rebound damping ability of the shocks, however today a shop advised that it may simply be the factory overloads coming into contact as their supposed to. Dialing up the shocks to their max setting helps a bit, but the ride is harsh with much more chocking translated back into the truck. (Lower settings ride very nice, but offer very little in compression rebound damping in towing conditions)

My first attempt at a remedy was to install 5000 lb. air springs in the rear. At about 35 psi it does seems improved, but large bumps still cause an occasional hard stop type of feeling in the rear. (Sort of porpoising effect and 1-2 hard stops in the suspension...like it bottoms out)

My next attempt will be to install a set of newly acquired KYB MonoMax shocks to see if they perform better. (Have had good luck with KYB and Bilstein both in truck and RV applications in the past)

This shop I visited today said they have had good luck installing larger jounce bumpers to allow the factory overloads to come into contact with the springs sooner.

Would appreciate any experience or insight that I might gain from others here that have addressed this issue....

Thanks!

 

I have heard that removing the overloads all together with air bags is a nice, adjustable ride. I'll let you know how it goes since I just got 5k bags myself, haven't installed yet.

My springs are sagged pretty good, empty flatbed puts them about 1-1/2" off the overload springs. So it actually rides real nice with about 1k lbs in the bed, but empty is harsh.

 

I'll be anxious to hear how it works out for you.....

I don't believe my overloads are even engaged when I hook up. It doesn't seem to sag the truck's rear suspension at all, although I never thought to look at the overload engagement.

A test removal of the overloads shouldn't be that difficult, but I think I'm gonna mount up the KYB's first.

Update: More research finds many suggestions to extend the bump stops by larger aftermarket model or spacers to engage the overloads earlier. This was also suggested by the shop I visited today, as it apparently sets the overloads in motion sooner and smooths out the engagement. (Reduces the harsh impact of engagement)

My problem is not leveling, sway, or handling other than the harsh impact of what I now suspect stems from overload engagement from large bumps. Anxious to hear more from anyone who has improved on this phenomenon with modifications....

 

Air bags.....

Shocks don't support weight, just cushion it, and wear out over time.

A good set of airbags will stabilize and support the ride.

 

As mentioned in my original post I've already installed a set of 5000 lb. airbags. (Air springs)

I just washed up from installing two rear KYB Monomax shocks. The Rancho's were SHOT! They were easily compressed by hand, so I suspect that was the majority of my problem right there.

Going out for a test ride now....

Update: HUGE SUCCESS!

I've had good results with both KYB Gas-adjust and Bilstein on a number of applications before, but this is my first experience with the MonoMax model. I'm a big fan....

Fantastic control of unsprung weight of the dual rear wheels. Yes...it is stiff, but not harsh. I'm extremely pleased and can't wait to tow to see how it acts. Based on what I experience so far I anticipate that a lot more control and less harshness if/when the overloads are engaged over large bumps.

I'll update when I get a chance to hook up and tow/test.

 

I was thinking the air bags would be the solution, but since your shocks were bad, that's why they didn't help. Glad you got it all working!

 

Sweet! I love when things go right!

I had Rancho 5500's on my F-100 prerunner back when, they didn't seem to last very long IIRC.

Shocks are a wear item, good catch.

 

Ive got the 3" leafs on mine and the truck handles like crap no matter what I do with the shocks. Its all in the spring rage versus the empty load weight.
Ill be going to soft-ride leafs and air bags when I can. Fed up of banging around like an empty school bus.