If you're complaining that the rear tire, aka 85+lbs of mass, can rock and and forth with uneven road surfaces? that's totally normal. Either accelerate or slow down to break that rhythm.
If this is "normal" than this is a product I cannot live with. And yes, that is what I am talking about. The entire swingout "bounces" essentially forward and backward on stretches of concrete slab highways, and between 55-65 the oscillation is nothing short of violent. This isn't a little shake. This is a shake that you can thoroughly feel throughout the vehicle. And you can't always just slow down or accelerate out of it when you are in traffic that is moving at speed.
But you're mounting a big ass chunk of metal and rubber to a pivot point
Which is what this bumper setup was MEANT to do.
But should it be moving enough to cause vibration in the vehicle? I would imagine that if the latch is adjusted correctly for tension your spare tire carrier should not move much; additionally doesn't CBI reinforce the tire carrier with angled supports to reduce that or is it just box tube standing on it's own?
Agreed. It should NOT move this much. I have adjusted the latch several times from gorilla tight to normal tight and it makes no change. What does make a difference is taking the spare off. :/
Agreed. I also have to wonder if both gas cans were full when it happened.
No, this occurs both when they are full or empty.
How much lift do you have? Is the track bar at a down angle? If so the act of compressing the rear springs over bumps may be causing just enough side axle movement via the track bar to initiate the rear end wobble, which is then transferred through the sidewalls of the tires. I believe someone makes a drooped track bar for lifted rigs to offset this affect but I'm not certain. Blah blah blah, yada yada ya. I could go on but it's past my bedtime.
I have an Icon Stage 7 lift. So I believe it is about 2.5-3"s of lift. I am running their complete, top of the line suspension system.
I should also note, that I originally installed the CBI bumper before the lift. I had stock wheels and tires and I was running the stock suspension. In this configuration, I did NOT get the tire shake I get now. I installed the lift, and then promptly brought the truck into the dealer for an alignment and also to mount and balance my new tires on my new Level 8 wheels. The wobbling of the spare on the rear started immediately after this.
Which leads me to the experiment I tried today. I took the spare off and put it in the back cargo area. This definitely nearly reduced the bouncing effect on the highway. However, I did still notice a bit of bounce on the strtech of road that causes the problem. So my question is, is there something I can adjust on the suspension to reduce the bounce? Is it simply a matter of my raised center of gravity causing this? If so, I blame the Icon Suspension more than the CBI bumper.
you are just seeing manifested in your rearview mirror. Cause --> Effect.
It's more than just seeing it move. The entire vehicle bounces violently with the oscillation of the bouncing tire on the swing-out.
Also, More money does not always mean more awesome.
I understand that to a point. When you pay for a top dollar item, you expect top dollar performance. So if there is something that needs to be tweaked to make my suspension perform as it should, educate me.
Is the spare solidly mounted on the swingarm? it may seem that way because of gravity and weight, but just because you can't lift it, that does not mean that physics can't.
Yes. It is on there good. That said, I can reproduce the bounce with my hands quite easily while the vehicle is stationary. When it motion, the bounce is more pronounced, I will upload a video this weekend if I have the time.
My first reaction would not be the bumper. If you take the spare off and drive the same speed, are you still getting the shakes? if so; than the spare is not the issue for sure.
As I said above, I tried this today. Over the stretch of road the bounce was nearly gone, but I could tell that the rear end still had some bounce. However without the spare back there wobbling, the oscillation effect was almost nil. So again, this definitely could be a suspension adjustment issue that is manifested horribly in the bouncing spare on the swing-out.
The bumper WILL move back and forth along the long axis of the vehicle, so not right/left. I get this really bad (I have not tried it with my new dual swing arm) going up I5 to seattle. The roads are paved near Tacoma with a texture that causes some weird forward/back rocking that I have to either accelerate out of to break, or brake to break.
THIS IS EXACTLY what I am experiencing. And at least for me, this is unacceptable on such an new, expensive vehicle with such new, expensive aftermarket modifications.
I'd also make sure the tire carrier is mounted as low as you can make it, and make sure the latch is snug. The latch should go tight for the last 70 percent, and really chunk in to place. The U-bolt will stretch over time.
Yes and yes.
Hopefully that resolves it. But I'd try driving over the same roads without the tire, just to see if you have a bigger problem going on, the tire could just be a visual indicator, and not the cause.
See above.
Thanks guys, for your input. And suggestions on how my suspension might be tweaked to eliminate this would be most appreciated.
Bart
