So here is what I have come up with... First off, I know it's not tires or pressure thats causing the rapid bounce. This is because i have run the stock load range E tires from everywhere between 50 and 85 psi and I have run all new Toyo AT tires that are load range D from 45 to 60 psi and it does not matter... the bounce is always there. So I'm almost certain that it's not the tires or pressure.... I won't rule out my shocks though. the Rancho 9000's that I have are approx 5 years old and they probably have 40K miles on them. So it could be that, but here is a question....
Is this rapid bounce only noticed on the crew cab long bed's or does it do it on all 05 and up super duties?

 

Cartmanea,

Thanks for the offer... I will let you know if I still need them a little later.

Phil

 

How can I tell if my Rancho 9000 shocks are bad? If I push them down on position 1 they compress fairly easy and will just sit there and not move back out, but if I try and push them down on position 9 they are much harder to compress, but they don't have much rebound? Is that right for these shocks?

 

If I were you, I would replace your shocks before I purchased the Sulastic part. You stated that you had 40K miles and 5 years of service from your current shocks. Depending on the "type" of driving, they may be worn out. If they are worn out, installing the Sulastic part won't help. So, the safe approach is to replace the shocks first, then see if you really need the Sulastic part.

By the way, did you truck bounce after you installed the first set of Rancho RS9000XL shocks?

 

The Rancho's were on my old 96 F350. When I sold it, I took them off and put them on my new 06 F350. I would say that the 06 bounced as bad or a little worse with the OEM rear shocks that were on it. The Rancho 9000 made a little difference, but obviously did not get rid of the problem. So maybe my 9000's are bad?

 

It's possible. The rear end of these trucks is pretty stiff though, so you get two scenarios when unloaded. Either the shock is under-damped and you get some bounce in the springs, or the shock is damped well or too much and you still get some stiff bounce in the tires because the springs don't give enough. If you plan on keeping the truck for a while and want it to ride a lot better, the '08 springs are a good mod. Unloaded have you tried going as low as 40-45 psi in the rear tires? I have Toyo ATs in 315/75r16, D-rated (50 psi) and run them 50 in the front, 40-45 in the back unloaded and it rides okay, still get a little bounce now and then in the back. I have Bilstein shocks too which are pretty stiff.

 

To me it just sounds like "normal" for a 3/4 ton or 1 ton truck. The springs in the back are stiff. You will feel every bit of every bump. I would try letting down the tires to 40 psi and see if that makes a difference. My next step would be to remove the third spring in the spring pack and regain your load capacity with an airbag system.

 

I keep hearing people talk about removing the thrid spring in the spring pack. First off is this even safe and second, third from the top or from the bottom? How will this really help? Does'nt the lower springs only come into play when you put a load on the truck? If i'm empty, these lower springs should'nt even play a role in the stiffness of the ride? Is this correct?

 

The spring pack just allows it to be a progressive rate. The further it squats the stiffer the springs get as more of the leaves come into play. You would remove the third from the top. It is perfectly safe. Te only spring connected to the truck and the axle is the top spring. Obviously you can't remove it. The others are just for load capacity. Removing that third one will make a huge difference in the stiffness of the ride.

 

Actually, removing the 3rd leaf affects the ride ride quality all the time as well as eliminating some of the progressive effect. It makes the longer leaf act "softer".
Let me see if I can explain it.
Each shorter leaf affects the flexibility of the leaf above it. The part of the longer leaf where the shorter leaf is present is not allowed to flex nearly as much as the part where the shorter leaf is not.
With the stock pack, only the outer six or so inches of the longest leaves are free to flex. Taking out the 3rd leaf means more like 10" are free to flex.
DIY experiment: Clamp a metal ruler to your work bench so most of it hangs off. Push on it 6 inches from the edge. Then push on it (same force) 10 inches from the edge. Notice how much further it deflects at 10"?
The shorter leaf is acting like the edge of the work bench, limiting how much of the long leaf is free to flex.

Did that make sense?

 

To the OP: It sounds like you don't regularly haul heavy loads if you are running load range D tires. You may be prime candidate to trying the leaf removal. If you don't like it, put it back.

Start by just removing the leaf and trying it out. Be aware the truck will sit lower - at least an inch lower due to the reduced spring rate. Headlight adjustment is likely necessary. The truck, when loaded, will also squat right into the overload springs much easier unless you add air bags to replace spring rate.
The last negative is that the rear axle will be able to "wrap" and hop easier. When I removed my 3rd leaf, I was expecting to have to add a traction/anti wrap bar of some kind as I have the tall F350 blocks and do a lot of off roading. But so far, I have not noticed hopping problems significant enough to add the bar.

 

Was your 1996 F350 a 4X4 and was it a dually? What about the 2006 F350... 4X4 and a dually? Rancho makes completely different RS9000XL shocks for these vehicles.

1996 F350:
Rancho Suspension: Upgrade Your Shocks

2006 F350:
Rancho Suspension: Upgrade Your Shocks

 

My original 96 was a 4x4 SWB not a dullie, and my 06 is also a SWB 4x4. I do haul atv's and pull an RV during the summer and hunting season, but the rest of the time, I use it to commute with in town. So it's a daily driver and camper puller on the weekends. So I don't know if I want to pull a leaf spring or not. I do have air bags... But I defenitely do not want to lower my rear end any more....

If I pulled a leaf, could I have a spring shop make a 1" spacer block to make up for the loss in height? Also, do I have to pull the spring pack completely off to take out the 3rd spring?

 

Then you have the incorrect RS9000XL shocks on your 2006 F350.

1996 F350:
Rancho Suspension: Upgrade Your Shocks

2006 F350:
Rancho Suspension: Upgrade Your Shocks

 

[quote=Elkoholic;9455082 My original 96 was a 4x4 SWB not a dullie, and my 06 is also a SWB 4x4. I do haul atv's and pull an RV during the summer and hunting season, but the rest of the time, I use it to commute with in town. So it's a daily driver and camper puller on the weekends. So I don't know if I want to pull a leaf spring or not. I do have air bags... But I defenitely do not want to lower my rear end any more....

If I pulled a leaf, could I have a spring shop make a 1" spacer block to make up for the loss in height? Also, do I have to pull the spring pack completely off to take out the 3rd spring?[/quote]


I would recommend replacing the rear shocks first. All of the old Ranchos I experienced were GROSSLY overdamped on the compression stroke. They would go into hydraulic lock and not allow the axle to move on high velocity impacts - like freeway joints. The only suspension left is tire sidewalls, and that is not a controlled suspension.

For your questions: Yes, you can put a thicker block and longer u-bolts to get height back. I'd suggest making the block longer (10-12"?) and conformal to the lowest leaf to minimize axle wrap issues.
You do not need to remove the entire spring pack.
I lifted (and securely blocked up) the truck off the frame until tire was a couple inches off ground. Remove wheel. Support axle with jack. Remove shock.
You're dealing with a lot of spring force now, so use extreme care and do not remove anything until you're sure load is under control!
Carefully loosen U-bolts and slowly lower axle until it is hanging a bit away from springs. Carefully loosen spring pack bolt. When everything (bolts, leaves, etc) is free from any tension, remove the u-bolts and spring pack bolt and just slide the leaf out the end. May need a little pushing with a hammer....
You will need to replace or shorten the spring pack bolt for it to fit back into the new shorter pack.
Carefully lift and tighten everything back up.