Icon RXT + King 2.5" = speedbump hell :(

Hey guys, sure as F didn't mean to start my build like this.. totally kills the mood to even create a build-thread... perhaps I will once this **** is over.

So anyway, got some kings w/adjusters (smooth rears, not bp), Icon rxt leafs at option 1. Every time I go over a speedbump the rear feels like it's smashing the road after goin over the bump. There's also a bit of a bounce over little imperfections which leads me to believe something's too stiff.

I also can't make the back bounce when "jumping" up and down on the bumper which is kind of absurd. Spare has been removed so that's an easy 45-50 lbs off the back... still, the back should be going up n down with me.

Adjusting compression didn't seem to help.

Shackles are torqued to 90 lbs-ft.

The front is absolutely fine and quite plush.

Is there some break-in period I should be aware of? Any help is greatly appreciated

And if you're wondering, yes, I'm willing to remove a leaf if necessary.

 

Did you torque the shackle bolts when the truck was on the ground, or up in the air? Needs to be the former, that’s the only thing I can think of. If I remember correctly, option 1 is a 30% softer spring rate than stock, so it shouldn’t be harsh…

 

(trying and failing not to look desperate by staring at the alerts icon)

Yes, bolts were torqued with truck on the ground.

 

Haha, I know that feeling!

Not really sure, but I’m watching because I was going to get some RXT’s soon. I know that I’ve read multiple people say that you can drive “through” speed bumps compared to over them with the icon leafs.
We’re the kings used - maybe they’re pressurized too high? Grasping at straws here

 

Brand new. I could reinstall the old shocks and see if there's a difference... good thing rears are easy.

 

I’d check the pressure in the shocks. More often than not they’re way over pressure. I’ve got my adjusters on full open and it rides like a caddy and soaks everything up.

 

Empty bed?

 

There's also a break-in period for the shocks but definitely check that pressure. Do you have the dial in the correct position?

 

Just a bedrug and a little dust.

There's a wrong position? I drove it fully soft and about 7 clicks firmer just to test. Didn't seem to change anything.
Currently I don't have a high PSI gauge so anything past 100 will give me the wrong reading.

Was not aware nitrogen pressure could cause this.

 

Definitely sounds like too much pressure. If you had the dial adjust to full open/soft you'd notice a difference.

 

Well, can't be too much pressure since one is at 100~110 and the other 50~60 (new gauge isn't super accurate) so that alone is reason enough to take one off. Can't have one cavitate... Now I'm gonna be paranoid about the front... Damnit.

 

Try swapping back to the old shocks for a day, if that does nothing it's time to look at the leafs. I'm leaning more to the leafs, maybe Icon or your vendor made a mistake. Leaf springs will soften a bit over time but not enough for what you describe to become comfortable.

What is the normal pressure for those rear shocks? I thought 150-200 was the norm. I also have heard lots of times that new shocks get shipped with low pressure but I've never heard of them being shipped with too much pressure. I don't think shocks have a break in period either, there's nothing to break in. It's a piston with shims on it that passes through oil.

 

How many miles have you driven it? Try putting a bunch of weight in the back and drive around for a day and see if the springs settle. I remember the Deavers on my Taco were super high and stiff until they settled.

I just put RXT's on the back of mine, but only have like 10 miles on them. They're still sky high, but not overly stiff.

 

Hmm sounds more like leafs after that pressure check. But I’ve seen 150-200 fill range is the norm.

 

Yes, 150-200 is the factory pressure.

So testing time.
Loosened shackles and eye bolts, removed shocks... So I wondered if shaking it from the bottom up would make it bounce freely... And it did. Next I get on the bumper and shake it again top down and got low enough to engage the bumps. Put shocks back on... Stiffness town again.

Something wrong with the shocks, can't shake it up or down anymore. It makes no sense, I can see them compress and extend when lifting the damn truck.

Unless they're valved insanely stiff for like track racing I see no reason for them to be like this

 

Did you get the shocks directly from King or another company?

 

Vendor, allegedly from King, but I'm starting to have my doubts.

 

Yeah to me sounds like it could have been valves for a truck carrying a heavier load. Reach out to the vender and ask them. It’s easily fixable.

 

Funny guy my vendor. Said another Tundra customer had the same issue and swapped for Tacoma rears, thats probably ok for stock leafs, but I'm not going to entertain that idea.

I get the feeling I'll have to get a race shop work on them, the bad thing is, I don't know how they ride other that stiff AF.

Bilsteins are back on until resolved... Such a bummer.

 

The bilstein fixed the rough ride?

 

If you aren't opposed to shipping, and that may be expensive from Mexico, maybe @AccuTune Offroad can help you.

 

That sucks man. If you have a shop you like call king and get what shims they recommend for the weight and what you plan to do with it. I know there are a couple places here in Southern California that will help you dial them in.

 

Also if you have a shop near by that can recharge your shocks then working on them is not that hard. Just cost money to get the nitrogen tank and regulator. I’ve rebuilt and re-valved my ADS rears and front to ride better for my needs.

 

Accutune will get you dialed in tell them your mods and weights they will valve it accordingly. We did my old mans built tundra and it was night and day difference

 

Pretty much, a smidge nicer than stock with the rxt's... 5100 have their own downsides.

Don't think I'd want to ship them, there's plenty of race preps and shops around that can do it, just gotta get the right one, AccuTune would have been my choice had things been different.

I'm not scared to try and revalve myself, I'd probably have to buy all the shim kits known to man just to be safe. Impractical. So race shop will likely be the first step if vendor can't make it right.

 

Skimming through this thread a bit, thanks for the tag.

Nitrogen pressure should be at 150psi for Kings. No you should not adjust nitrogen pressure to get you a smoother ride. You cannot check nitrogen pressure in the shocks with just any pressure gauge, it must be a screw on type that does not allow any nitrogen to escape. A smoother ride would come from different valving or spring rate change. King 2.5 shocks for Tundras come standard with Digressive pistons/valving. These tend to ride on the firm side. 99.9% of the time when we sell these shocks, we are swapping out pistons to a linear piston with progressive valving. This is a huge change in addition to our custom valving for your specific truck and its weight.

There is likely a few things leading to your stiff ride in the back. Lack of weight with the RXT pack is definitely one of them. You can confirm this by adding a bunch of weight in the rear to see. Shock valving would be next, and I am also questing the nitrogen pressure at this point if you have already tried checking those.

Hope this helps clear some things up.

 

You might get a parts order from me then, unless you open up a shop in Cabo next week

 

Vacation road trip!

 

I've got the exact same setup as you, King 2.5's with RXT on option 1 and having this setup for almost a year now I can tell you it wont get any better.
I think I have it worse as well being on a doublecab with less reward weight, the rear end jiggle over little bumps and potholes on the road is driving me insane.
I was waiting for the weather to clear up a bit (driveway mechanic) before I pulled a leaf out of the pack but reading this thread makes me think that isn't even the answer.

Monitoring this thread nonetheless, you are not alone!

 

If you have your old shocks, put them back on. RXTs are still an upgrade over stock even with OEM/5100's