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Discussion Starter #1
Hello - brand new to the forum here and a new Jeep owner, 2018 JK. My Jeep is "bouncing" or "bucking" when going down the road. This only happens on rough roads and is worse on the highway at higher speeds. On smooth pavement it's fine even at 70Mph. I just put a Metal Cloak 3.5 Game Changer lift on with Rock Sport shocks and 35 inch Nittos. Had it aligned and otherwise it drives fine. Tried deflating tires from 35 to 30 and that helped a lot but it's still worse than I would like it to be. It's a vertical "bounce" and when I am on a highway that is older and has small bumps every so many feet the Jeep gets to bouncing up and down every time I hit a bump. The constant bouncing is because there are constant bumps...in other words the Jeep does not bounce more than once after hitting 1 bump. But I am going down the road and my head is just bouncing - I am having to physically work to not have my body bounce around lol. I have stock bumpers and no side steps yet so it is a light ride. The rear coil springs are bending a little and I think I need a wedge to straighten those out but I don't think that is the issue. The front end does "appear" to sit a little higher, but I measured from ground to frame on both ends and it is close to equal. I am thinking if I put on heavier bumpers and deflate tires a bit more it may help out. I know it's a Jeep - but I have heard people say that their Jeeps ride better than stock even after installing a good quality lift...so this seems rougher than I would expect. When I drive these same roads with the family minvan the bumps are barely noticeable. Maybe I just need to get used to driving a Jeep haha! Any words of advice/ideas on how I can make this a smoother ride?
 

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Discussion Starter #5
I have a rcpt but no details on the alignment other than I did request they set the caster to 5 per Metal Cloak recommendations which they said they did. I forget what he said about Pinion. I need to go back and see if they have those records for me.
 

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I have a rcpt but no details on the alignment other than I did request they set the caster to 5 per Metal Cloak recommendations which they said they did. I forget what he said about Pinion. I need to go back and see if they have those records for me.
So you took it to a 4x4 shop that knows how to adjust control arms? Reason I ask is because I doubt a regular tire store will do that. They might have set the toe. So without a printout of the alignment there's know way to know if your caster is at 3 degrees or 5.

It might not hurt to go over the basics again. Loosen then torque control arms, track bar and shocks to spec. All with the Jeep on the ground and under load. Did they adjust the trackbar to center the axle?
 

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Discussion Starter #7
The shop does specifically do 4x4 alignments and came recommended from another local 4x4 shop. They did adjust the control arms to get the right angles for caster/pinion (they say) and centered the axles/steering and set toe. In speaking with the shop manager, it seemed like they were slammed that day and maybe he had one of the less experienced mechanics do the alignment under his direction, so that could be an issue. I will start by going back to the shop and see if they have the alignment sheet maybe was hectic day and he just forgot to give it to me. As soon as I get that I'll post it. - thx!
 

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A heavy rear bumper helped me, but 100# of something in the back and see it helps.
 

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One thing you may be feeling is the control arm angle. As you lift the angle gets larger(less flat) this angle results in the control arm transferring more force to the cab because it is less inclined to rotate.
If this is the case the options are accept it and live with it. Geo brackets, or convert to long arms.

Accepting and living with it can be made more comfortable by adding more weight to the jeep and bringing down the lift thus reducing the angle. (even more true if you are very light for the lift and sitting well above advertised height) It will also give more sprung mass for the unsprung mass to act on, resulting in less movement. You can also drop the tire psi so they play a larger roll in absorbing the impacts of a rough road.
 

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It's either shocks or bump travel. While deflating tires might help, that's masking the real problem. I have no problem running 38 psi cold on 35s in my JKUR on the roughest roads.
 

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Discussion Starter #12
One thing you may be feeling is the control arm angle. As you lift the angle gets larger(less flat) this angle results in the control arm transferring more force to the cab because it is less inclined to rotate.
If this is the case the options are accept it and live with it. Geo brackets, or convert to long arms.

Accepting and living with it can be made more comfortable by adding more weight to the jeep and bringing down the lift thus reducing the angle. (even more true if you are very light for the lift and sitting well above advertised height) It will also give more sprung mass for the unsprung mass to act on, resulting in less movement. You can also drop the tire psi so they play a larger roll in absorbing the impacts of a rough road.
I think it is running higher than 3.5 and my suspicions are that adding weight and dropping PSI will help. Thanks!
 

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What is Bump Travel?
Sometimes called 'stuff'. The amount of upwards axle travel before the bump stop hits (or less hopefully, the shock bottoms out). I've seen lifts with shocks that are too long and therefore many bump stop extensions are required. When you drive and hit a bump, if you do end up on the bump stop then it is very uncomfortable in the vehicle.
When I have done lifts I measure the wheel travel front & rear, side to side to tune the bump stops to the shock and any tire/fender contact. You want as much wheel travel as possible, even on road. I have 5.75" travel on the front with a 2" lift. I've seen 4" lifts with only 2.5" travel. Not good.
Anyhow it may or may not be bump travel, but it is a 5 minute job to measure the bump stop distances to get an idea if that is the problem.

It can also be the other extreme - reaching the downwards limit of the suspension (either by shock length or limit straps). If that happens you get a very choppy ride.

But my guess is shocks.
 

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I think it is running higher than 3.5 and my suspicions are that adding weight and dropping PSI will help. Thanks!
No steel bumpers, no winch, no aftermarket armor, yeah I guarantee you are higher than 3.5"

Incidentally when riding on a rough road do you hear a clacking sound?

And standing still can you slip a piece of paper/card between the top 2 coils of your spring? (you should not be able to) I just want to see if you have enough weight to compress them as they should be during normal operation. Those should only unload in a highspeed turn or when the axle droops offroad.
 

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Discussion Starter #16
Sometimes called 'stuff'. The amount of upwards axle travel before the bump stop hits (or less hopefully, the shock bottoms out). I've seen lifts with shocks that are too long and therefore many bump stop extensions are required. When you drive and hit a bump, if you do end up on the bump stop then it is very uncomfortable in the vehicle.
When I have done lifts I measure the wheel travel front & rear, side to side to tune the bump stops to the shock and any tire/fender contact. You want as much wheel travel as possible, even on road. I have 5.75" travel on the front with a 2" lift. I've seen 4" lifts with only 2.5" travel. Not good.
Anyhow it may or may not be bump travel, but it is a 5 minute job to measure the bump stop distances to get an idea if that is the problem.

It can also be the other extreme - reaching the downwards limit of the suspension (either by shock length or limit straps). If that happens you get a very choppy ride.

But my guess is shocks.
The shocks are new, long travel Rock Sport shocks from Metal Cloak that came with the lift so I doubt it's the shocks but maybe I'm not following you - how would I test for that? It doesn't really feel like anything is bottoming out...but again I'm new and have never actually experienced that.

So for the bump stop measurement....I measure from the top of the bump stops to the top of the spring and I should ideally have how much space for a 3.5 inch lift? I put basically 4" of bump stop pucks in front and back per recommendations of Metal Cloak install guide...maybe that's too much?

Thanks!
 

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Discussion Starter #17
No steel bumpers, no winch, no aftermarket armor, yeah I guarantee you are higher than 3.5"

Incidentally when riding on a rough road do you hear a clacking sound?

And standing still can you slip a piece of paper/card between the top 2 coils of your spring? (you should not be able to) I just want to see if you have enough weight to compress them as they should be during normal operation. Those should only unload in a highspeed turn or when the axle droops offroad.
I don't hear a clacking sound. I'll try the paper test and let you know!
 

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Measure the distance from the top of the bump stop extensions to both the bottom of the yellow factory bump stop rubber, and then to the steel collar that the factory rubber sits in. Same at the back. That gives you the distance to the factory rubber starting to stop the wheel travel and then total travel. In practice the factory bump stop rubber (I think it is urethane) is super squishy and does little to stop the upward motion on the axle.

Thinking about this more, if you are on the bump stops you'll see marks on the bump stop extensions.

When you really need to do with a lift kit is to assemble it without the springs, and then jack the axle one side at a time with the other side at full droop and then also with both sides jacked up as far as possible. Then look at clearances and shock length and set the number of bump stop extensions. I did the same kit (3.5" game changer) with different shocks on another JK and think I ended up at 3 spacers. Not sure if they are 1" high or not. But the ideal number is 0 to get the most wheel travel...

BTW the MC arms with those rubber bushings are great.

But why would it not be the shocks?
 

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Take your measurement vs this drawing and you will get how much lift you have right now. Also get the measurement of the current shock length and the distance from the perch to the bumpstop. Just to rule all that out.
 

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