CBI rear bumper swing out 'death wobble'

[LawnDart]

I admit that all swing arms have some wobble to them. It's inevitable. Steel or aluminum, it doesn't matter. I however, have worked for an offroad armor company who produced these kinds of expensive items and I know for a fact that what I've personally experienced from CBI's single swing arm compared to the products we made is excessive movement. If [MENTION=134155]bartvonwolf[/MENTION] is experiencing the same thing then I believe him. I paid over $2k for my bumper and while yes, it is a piece of art, I expected it to perform as good as it looks. I've since sold my rear bumper to fund other projects. I was not happy with it's performance.

Bottom line, there are many other bumpers out there that I've actually had hands on experience with and tested the movement of the rear bumper. Some have had no movement and some have minimal movement. I have yet to find anything that came in comparison with the amount of movement I experienced.

One thing to keep in mind is that in my video I was able to move it that much with one hand. If i had taken both hands to it you would have thought something was going to snap.

Mine definitely seems to move less than yours, and I have two hands on it.

Their design has improved, but I'm a believer that what the OP is experiencing is normal movement combined with an imbalance issue on tires or something is just tweaked in the suspension somewhere.

Outside of ONE very specific stretch of road, that tends to cause all cars I know to wobble like crap going up to seattle (not just rigs with tire carriers), my single swing arm and dual have been calm and chill.

 

[bartvonwolf]

excessive movement.

JWaldz, thanks for your words. I know some people have a greater tolerance for issues like this. But again, like you said and I said above, when you are spending this kind of money you expect an equal amount of performance. I commend companies like CBI for finding solutions on these modern rigs that don't really readily accept modifications the way old trucks do, however when you are charging a premium you have to make sure an adequate amount of R&D and testing is put into place before you start selling.

I am definitely going to get my tires checked, and I might call CBI (I think I did already, can't recall) and see if they can offer any additional pointers. If getting my tires rebalanced does not fix it, I think I am going to just take off the swing-out and finagle a way to get the over sided spare back under the truck, and keep the main bumper piece from CBI.

Thanks, all.

Bart

 

[wfo9]

OP, can you please update your sig and specify all your major mods... Tires, wheels, bumpers, suspension (springs rates...)

The sig is not there to brag or whatever, it is there to give people who are responding to you an idea of where you are coming from.

 

[bartvonwolf]

OP, can you please update your sig and specify all your major mods... Tires, wheels, bumpers, suspension (springs rates...)

The sig is not there to brag or whatever, it is there to give people who are responding to you an idea of where you are coming from.

Yup, sure, I normally have a nice sig, but I just haven't spent enough time here yet to make one. Plus, this site is blocked by my work firewall for some stupid reason, which is when I am mostly in front of the PC.

Bart

 

[bartvonwolf]

Sig added.

 

[wfo9]

Sig added.

OK that helps. You have a couple of things going on....

First the RTT and the swing out combined create a very high center of gravity in the rear of the truck. That is going to exaggerate any kind of side to side movement on a coil spring based suspension.

What rear springs are you running? Are they the overland/heavy version?

Also, on the level 8 wheels. Do you have the proper hub rings on them? I'm guessing they don't have the proper center bore.

 

[bartvonwolf]

First the RTT and the swing out combined create a very high center of gravity in the rear of the truck. That is going to exaggerate any kind of side to side movement on a coil spring based suspension.

The problem is NOT side to side movement. It is up/down or forward back movement. There is no "crabbing" effect or anything going on. I know how that feels with spring suspended rear ends.

What rear springs are you running? Are they the overland/heavy version?

They are the springs that came with the Icon Stage 7 suspension. They are HD coils as far as I know. My shocks are also adjustable and I have tried all the different settings for hardness/softness.

Also, on the level 8 wheels. Do you have the proper hub rings on them? I'm guessing they don't have the proper center bore.

Hub rings? I would think they have the proper center bore, these wheels are for Japanese Light Trucks. There are a lot of folks running them on their T4Rs.

Thanks,

Bart

 

[LawnDart]

Oh dude, first blush is you're not running the right springs. I have a feeling with the CBI bumper you're springs are highly compressed and I'd be running OME 898s or the Icon Expedition springs or whatever they call it.

Right now I bet what's happened is your rear setup is overloaded and any up and down road movement isn't being absorbed as well as it should. Combined with tires that MAY be out of balance what's happening is ALL of that movement is being translated into the rear most point, which is the tire carrier.

The stock springs were way underpowered for what amounts to like 350+ of rear weight with the CBI. I went 898s, and then eventually 897s when I did my cargo system/fridge/slider.

 

[3wbdriver]

If/when you shake your swing out is there noticeable play in the spindle bearings for the pivot? Is there any ability to adjust the tension on those like one would with, say, a front axle bearing? I know a couple of bumper makers use upper and lower pivot points for the swing out base. This would add a little more support for that point where the CBI uses a standup pin/spindle. Maybe the upper plate that spindle welds to needs to be thicker to give a stronger base with less ability to flex? Does flexing the assembly show flex in that area of the bumper around the spindle? If this is only occurring at certain road speeds and in certain road conditions you may simply be looking at a kind of harmonic value that you can only fix by changing your driving style in those specific conditions.

I'll openly admit I'm just throwing suggestions at the wall to see what might stick. All this thread is really doing is reinforcing my decision to just get the basic CBI bumper and opt out of the swing out setup. No need to quote or answer. I'm just trying to make helpful suggestions. I hope either you figure something out or CBI can make some suggestions.

 

[3wbdriver]

Oh dude, first blush is you're not running the right springs. I have a feeling with the CBI bumper you're springs are highly compressed and I'd be running OME 898s or the Icon Expedition springs or whatever they call it.

Right now I bet what's happened is your rear setup is overloaded and any up and down road movement isn't being absorbed as well as it should. Combined with tires that MAY be out of balance what's happening is ALL of that movement is being translated into the rear most point, which is the tire carrier.

The stock springs were way underpowered for what amounts to like 350+ of rear weight with the CBI. I went 898s, and then eventually 897s when I did my cargo system/fridge/slider.

I can also agree with this. You might look into these. The 52700 part number your kit came with has only a slightly higher weight rating. You have almost as much weight just in spare tire/fuel as you have in the bumper itself. Not even counting the RTT and whatever you throw in the back. These would probably be better for the load you have if you want to stick with Icon. Or LawnDart's suggested OME's would also be a good choice.

ICON 4Runner Overland Series 3" Lift Rear Coil Springs

 

[LawnDart]

I can also agree with this. You might look into these. The 52700 part number your kit came with has only slightly higher weight rating. These would probably be better for the load you have.

ICON 4Runner Overland Series 3" Lift Rear Coil Springs

You may not be getting any noticeable sag, but the springs are reaching the point where they're getting compressed and not absorbing shocks as well as they should, and that's being translated into up/down motion. Maybe that's the culprit, maybe it isn't and it's a compound issue.

But the stock Icons (I am using what amounts to the Stage 6) were way under powered.

It was mentioned you took the tire off and felt a similar result, just not as bad, which was a reduction in weight to the bumper, probably 80+ lbs. So you might be in that weight band right now where the springs are overworked.

Not trying to defend CBI here, not at all, I'm hoping we can identify the problem and work a solution for you.

 

[bartvonwolf]

Oh dude, first blush is you're not running the right springs. I have a feeling with the CBI bumper you're springs are highly compressed and I'd be running OME 898s or the Icon Expedition springs or whatever they call it.

So you are saying the springs the Stage 7 kit came with are not good enough? That sounds odd to me, since this is their top-of-the-line kit...

I know a couple of bumper makers use upper and lower pivot points for the swing out base.

The CBI bumper, iirc, has 3 bearings, two at the bottom and one at the top. There is no play there at all.

ICON 4Runner Overland Series 3" Lift Rear Coil Springs

I will call Icon and ask about these. What's another $300 at this point?!?!?

Not trying to defend CBI here, not at all, I'm hoping we can identify the problem and work a solution for you.

Yeah, and you know, I am not saying CBI made a bad product. I am just saying there is definitely something going on here, and the CBI bumper is where the problem is manifesting.

Thanks - Bart

 

[LawnDart]

So you are saying the springs the Stage 7 kit came with are not good enough? That sounds odd to me, since this is their top-of-the-line kit...

You're adding what amounts to 350lbs of weight to the furthest point of the vehicle, you're also using a RTT which is 100-150+ lbs. The springs that it comes with are intended for use with a 4Runner not carrying those things.

If they included HEAVY use springs with their kit what would happen is a stock weight vehicle would have such a stiff ride you'd basically destroy your spine.

When we installed the OME 898s before the CBI the back end stuck up nearly 2" higher than the front, and rode like crap. The weight of the bumper leveled the vehicle out, and made those crazy strong springs mellow out.

I think you've got a fundamental misunderstanding of how the suspension has to be planned out for the weight it's carrying. Your stage 7 (which is the same as my 6, just with the addition of adjustable dampening) was intended and built around a stock configuration weight vehicle. You're exceeding the weight of that performance envelope and you have to adjust accordingly.

My CBI bumper required OME 898s, which are 440lb springs. Once I put in the cargo system and tembotusk slider and ARB fridge I exceeded the weight of the 898s and had to step up to the 897s which are 660lb springs.

I hope that makes sense. If I had to guess you've got a combination of too much weight in the RTT *AND* CBI bumper, and MAYBE some balance issues with the tires, and it's all adding up to some crappy ride qualities that are more than just the rear tire carrier but the rear tire carrier is the most dramatic canary in a coal mine.

 

[bartvonwolf]

It makes sense, I am just confused as I thought the Stage 7 was designed as a HD suspension system to be used for overlanding, which is what the Expedition Overland guys used on their rigs, which is largely what I based my rig on. I figured, the Expedition Overland guys have the CBI bumper and the Stage 7 kit, roof rack with RTTs and all sorts of shit loaded in in the back, then this is the setup to go with.

In hindsight I realize that the Expedition Overland guys basically just made a giant commercial for Toyota, CBI and Icon so there may be other variables in their builds that were not discussed, and they obviously do not discuss any shortcomings or problems with their builds.

I understand the fundamentals of suspension dynamics, I just don't understand how I ended up with springs that are not meant for heavy loads and overlanding based on what I took away from the Expedition Overland guy's builds.

Thanks - Bart

 

[LawnDart]

You can't run HD springs in a stock weight vehicle. You'll end up with a rear end that's over sprung and that's bad. Really bad. The Stage 7 is not a magic bullet solution for expedition style builds and likely they did use a stage 7 but added the Overland springs but just said Stage 7.

No rear shock is going to carry all that weight you've dumped on there without an appropriately matched spring. You can't put an HD spring in the setup without the matching weight, nor can you put a non-HD spring in their without that weight.

One kit does not fit all, you're probably pushing some extremely heavy ass on there. My truck is almost 6300lbs, and going up to 6500 soon when I go long travel. Everything has to scale up to handle that weight.

Make sense?

Long story short, the icon setup is meant for stock weight vehicles, once you get into armor, winches, front and rear bumpers, everything requires that extra bit of adjustments because you're adding a TON of weight, well...almost.

It makes sense, I am just confused as I thought the Stage 7 was designed as a HD suspension system to be used for overlanding, which is what the Expedition Overland guys used on their rigs, which is largely what I based my rig on. I figured, the Expedition Overland guys have the CBI bumper and the Stage 7 kit, roof rack with RTTs and all sorts of shit loaded in in the back, then this is the setup to go with.

In hindsight I realize that the Expedition Overland guys basically just made a giant commercial for Toyota, CBI and Icon so there may be other variables in their builds that were not discussed, and they obviously do not discuss any shortcomings or problems with their builds.

I understand the fundamentals of suspension dynamics, I just don't understand how I ended up with springs that are not meant for heavy loads and overlanding based on what I took away from the Expedition Overland guy's builds.

Thanks - Bart

 

[GzTEP]

That's what I've heard. Why I won't be taking the plunge. Maybe a re design ?

 

[HOJeepster]

I get the same "death wobble" with my CBI. Only on conrete corregated highways when theres a seam every 10 feet.

I'm running Icon Overland Springs with custom Fox 2.5 with RR and DSC...so I doubt my rear end ain't up to the task.

I think its caused by the perfect harmony of cracks in the road. It happens right at 67 mph. Sucks...so I usually speed up or tap the brakes for a second to lose that momentum.

I've check all the bolts, etc...just seems to be caused by the overhand of weight back of the rear axle.

 

[3wbdriver]

So you are saying the springs the Stage 7 kit came with are not good enough? That sounds odd to me, since this is their top-of-the-line kit...

I will call Icon and ask about these. What's another $300 at this point?!?!?

Ask them what the weight capacity is between the 52700 that you have and the 52800. On the website what you have is a 2" lift and the latter is a 3" lift. But the latter spring has a much more detailed description including pictures. Hell for all I know they both have the same capacity and the only difference is in height. They just seemed to put in a lot more effort into describing the 52800 as an "expedition overland" spring, intended for loads like what you have. Maybe you can convince them to do a swap for your current springs since they didn't understand your requirements when you ordered the kit. If not and you decide to buy the heavier springs you shouldn't have any trouble moving the old ones in the For Sale thread. I've bought several pieces of gear that way from people who were upgrading to something else, including the Toytec springs I'm running in the back.

 

[wfo9]

I understand the fundamentals of suspension dynamics, I just don't understand how I ended up with springs that are not meant for heavy loads and overlanding based on what I took away from the Expedition Overland guy's builds.

Thanks - Bart

LOL, When I watched Expedition Overland I could not get over how poorly the 4runners appeared to perform offroad. Horrible builds IMHO. Big station wagons.... but it is hard to get anything that heavy to work well.

The springs have nothing to do with the stage... They include the same springs in all stages because they have no idea what weight you have on the truck. Its really tough with an overland build.. You have to decide when you want the truck to feel the best. Loaded down or daily..

Personally, I would ditch the swing out. It's not necessary at all.

 

[Dropzone]

Good luck, let us know if you get it resolved. I'm with you that it sucks to sink that much $ into your truck for it to be undriveable.

i

This is exactly why my off road truck is old. I will have less than $5k into when all is said and done.
Explore with a less expensive vehicle and have an econo daily driver.

I think the OP needs to have his rear alignment checked since the problems seem to have appeared having the lift installed