Sharp Bouncing

[jeffreyduncan]

Morning.

I have a 2015 Chevy 3500 HD short bed, Crew with the duramax. It's setup with RS9000's in the rear (set at 9) and stable loads. Front shocks are Bilstein 5100. I have a Hellwig stabilizer in the rear. Truck is stock otherwise. No airbags.

I have a fairly heavy camper and took this setup out over the weekend for my first road trip. Everything went very well and I am generally pleased with the way it handles. However - I notice that I get an annoying fast bounce (I think from the rear). It's not a porpoise. It's more of a chucking. It happens a couple times per second it seems, when I am rolling over small bumps at highway speeds or over 40mph. It's not constant, and any larger bumps or dips are handled fine. It's more of an annoyance than a drivability issue.

I am thinking it's because my auxiliary springs are so pre-loaded with the stable loads. They are almost flat, but they aren't so flat that they touch the lower springs. i have maybe and inch and a half left. The truck sits nice and level though.

Would anyone have a suggestion to calm the sharp bounce and improve the ride?

I was thinking my options might be:

Add air bags.
Change the Bilsteins in the front for RS9000.
Install stiffer rear aux springs (SuperSprings).

Any insight would be appreciated.

[jeffreyduncan]

It definitely won't be. I'm probably slightly over. They are at 80 in the rear and I can't lower it. I could in the front. I'm convinced it's the Stable loads. Without them it rides like it should. They cause too much preload with my heavy camper.

[Ski_Pro_3]

I don't see any mention of the tires you are using. Especially the air pressure. You might want to try lowering the air pressure 5 psi at a time, starting with the front tires first.

If you discover the ride improves, the next step is to confirm your tire load capacity is still within limits with the reduced air in the tires.

[jeffreyduncan]

I wanted to update this thread with some information. I had the dealer fixing my slide out motor (replaced) and while he had it, I took the stable-loads off the truck because I was pretty much done for the season, and they give a harsh ride on the miles of dirt roads I drive. So the story is that I picked up the camper WITHOUT them installed, and the ride was amazing. No bounce whatsoever. So I am convinced that these stable-loads are root of the issue causing the bounce. As stated, they nearly flatten the helpers to near horizontal.

So my next move is to cut them down a couple inches, to retain some of the value they may provide in roll.

That's all.

Jeff

[jimh406]

trail-explorer wrote:
Skip the airbags, they will unload the suspension and make the ride even more harsh.

Obviously, this isn't always true. You do have to understand how they work though and use air bags to complement your suspension. Many of us are doing this using tried and true methods.

[trail-explorer]

Sounds road surface induced.

Skip the airbags, they will unload the suspension and make the ride even more harsh.

[Bedlam]

Although I ran Rancho 9000 series, I did look in to the Blistein's when I was shopping. The 5100's are dampened softer for off-road use where the 4600's are valved differently for heavy service use.

[jeffreyduncan]

Definitely not in my experience! Even without the camper on the back, and before I adjusted the rears, I noticed a considerable difference in the stiffness up front with the 4600's compared to the 5100.

[Garyl53]

I was told the 4600 and the 5100 (0-2" version) were identical other than the finish. Is this accurate or not?

[jeffreyduncan]

I wanted to report back after my trip with the new HD shocks up front. HUGE difference. I also backed the Ranchos down to 7 and had a full water tank. Tank was less than half on the ride home and as another poster said - not much difference. I think the main difference was the 4600's up front. I would say they cured the chucking by 98%. Thanks to those who pointed out I had the wrong Bilsteins up front!

[ab257]

Wonder if water sloshing in your tanks contribute to the weird bounce.

[jimh406]

I agree the 4600s are really good. My previous thread on the subject. https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28509858.cfm

[billtex]

Yes, I have to say the BS4600HD's really impressed me also. Great shock.
We pretty much always travel with full h2o (in front of axle). Try it and see how it feels.
You can always drain some...

Quite honestly, I feel no difference travelling with full h20 or not...

Report back after your trip.

Bill

[jeffreyduncan]

Just a quick update. I installed the 4600 series shocks and although I haven't had the camper on yet, I can certainly tell these are a stiffer shock than the 5100! Much nicer actually.

I'll report back after this coming weekend to let you know how they were with the camper. I have a 500 mile round trip ahead of me.

I am wondering if some water in the tank would get some more weight forward. I didn't have much if any water when I last made a trip. More GVW of course, but...

[rider997]

jeffreyduncan wrote:


Ok good info. I am happy to find someone with the same rig.

I'm aware of the weight on the camper. I did a lot of research. I don't have an on board generator but I have AC and probably won't remove that.

My bar also has three holes and I started in the lower recommended setting. So I can change that easily. I understand how you disconnect now - thanks.

My GVW is 11,500 and I thought for sure my rear axle max was 7050 and not 7500. The E rated tires I have are the 265/70/18 and are rated at 3525 each. Maybe you have a different tire size.

Either way I know I will be close to my limit.

In any case, I am hoping the 4600 series shocks will fix the issue. My truck would be a bit heavier than yours in the front with the Diesel I would guess.

You have tons of front axle capacity, so that shouldn't be a problem.

You're over the published rear axle capacity, but the axle manufacturer (AAM) seems to rate them significantly higher (> 10k lbs).

I currently have LT265/65R18 tires installed (GoodYear Silent Armor) with a 3750lb load rating. They decided to discontinue making those tires in that size. The stock tires were only rated at 3450lbs, and although they were LT tires, they were not 10 ply, and they were pretty sloppy handling.