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Discussion Starter · #1 ·
Hi all,
I'm following/reading this forum for some years right now, here goes my first post: I just got myself a (new) second hand grand cherokee summit 2016. the suspension feels really too soft. it bumps up and down and feels rather like a french Renault :(. before this summit i had an GC overland 2011 and the suspension felt like a ... GC! i was also driving last week an overland from 2016 and that suspension felt also like a GC.

is it possible one can adjust the parameters of the air suspension to get it stiffer? does my summit has a problem? is this normal behaviour for a summit 2016?

Thanks in advance for any help!
Regards,
Stefan
 

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IMHO, there should be a large noticeable difference between JGCs with the same suspension. There may be some differences and tires can also affect the feel, but not "extreme". Perhaps the vehicle you purchased needs to be looked at to troubleshoot what you are experiencing.
 
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No, that’s not normal. It should feel more stiff and “German sedan” feeling. There is no bounce after the initial compression with air suspension. Stability is excellent.
 

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Discussion Starter · #4 ·
Hi,


Thanks for both the replies. They both confirm my feeeling: 'there should be no bounce after the initial comression', certainly not two or three. I'll get back to the dealer and will post the result later.


Rgds, Stefan.
 

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Were the other two newer GC's you drove quadralift equipped as well or were they steel suspension vehicles?
Both of the vehicles he mentioned trying have QL standard if they are 4x4.
 
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Sounds like the shocks are shot.....
 
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Discussion Starter · #9 ·
Hi Steve,
Thanks for your reply, you MUST be right ... and i must be naive, i thaught that shock absorbing wit QL was done by air and not by the classic metal shock absorber as with spiral suspension (naive i aim!!). So now i'm sure one or more of them are bad. As i'm still in warranty (only 1,5 of the 4year and 33k km's) i hope jeep will replace them. I will let it know.
Again, thanks.
Stefan
 

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Hi Steve,
Thanks for your reply, you MUST be right ... and i must be naive, i thaught that shock absorbing wit QL was done by air and not by the classic metal shock absorber as with spiral suspension (naive i aim!!). So now i'm sure one or more of them are bad. As i'm still in warranty (only 1,5 of the 4year and 33k km's) i hope jeep will replace them. I will let it know.
Again, thanks.
Stefan
No problem, I hope that's all it is. I could be wrong, as it's has happened before haha.......but normally when the suspension just pogos like your describing its usually a bad shock, or strut cartridge.
 

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His location says Belgium. I wasn't sure if they had different specs than the US for various trims.
I did actually miss that... :eek:
 

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Discussion Starter · #13 ·
Hi,
some feedback: dealer was going to replace the shock absorbers under warranty. when i got my GC back, initially i thought it was a little bit better, after a couple of days i was again disappointed . My GC is bouncing is bouncing up and down, and even harder (very) from the left to the right. I also noticed that jeep only replaced the front absorbers ().


I did found a very interesting thread in the collegeau jeepforum explaining exactly the problem i have and explaining the potential cause being too low air pressure in the QL system, it even could be do to the fact that the closed system is filled with too much air instead of nitrogen gas, due to a leak. Air Suspension Pressure - JeepForum.com


i will contact jeep customer care europe for assistance tomorrow.


tbc.


Rgds,
Stefan
 

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Well, air is 80% nitrogen. While nitrogen is better because performance is more consistent as a single inert and stable gas, then a mixture, air does just fine because its mostly nitrogen.

Perhaps the QL suspension is different and more critical on the gas, but if that was true, I have trouble believing the system tops itself off with air.

Something being wrong with the system and causing it to retain too little pressure in the air springs.

Something else that wreaks havoc with consistent pressure in a system, if you get moisture in the system, the moisture can change pressures drastically and cause very inconsistent performance.
 

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Discussion Starter · #15 ·
Hi,


Time to give some feedback: my GC has been to the dealer 3 times, each time for more then a week, FCA has been 'diagnosing' and found nothing. All this time i'm asking dealer and FCA to give me feedback on how much pressure there is in my QL, so far no answer?! In the meanwhile bouncing get so hard it's getting dangerous to drive with, especially when loaded. 'loaded' means just getting 4x adult people in my GC … .


Now, I’ve just purchased the FCA software to start diagnosing myself and I immediately noticed that the QL 'system pressure' in normal mode (drive and normal height) is only some 100psi/7bar.


This 'system pressure' drops to below 2.4bar when loaded and lifting to offroad-2 level, when doing this I also get an error saying that compressor gets overheated. My guess is that the reservoir has not enough pressure and that the compressor must work much too hard trying to get the relevant pressure in the springs. THIS MUST BE IT no?!


I think the only thing to do is to refill the QL reservoir to 175 or 220 psi?!


Would very much appreciate if someone could/can confirm this?



Rgds,


Stefan

 

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The Air Bags are the springs, they fit in replacement of where the springs would go, the shocks are different for QL, but they are subtle difference, not radically different (likely to mount the air bag instead of the metal coil springs, or different damping rates since QL has varying spring rates).

The spring provide force as well as absorb and re-assert it, if it wasn't for friciton, when you went over a bump the car would bounce up and down forever.

The shocks do the damping, they just apply force in response to force and only proportional to force. The shocks are what limit the wheel to going up and down once and not continue to bounce.

So you're symptoms really sound like a worn out shocks.

There are a lot of threads on the QL talking about symptoms of worn out shocks. I did a little math with the specs, and it does appear if you're at the highest setting, you only have about ~1.5" of rebound in the suspension travel. Which makes me "suspicious" that if the vehicle spends too much time in that highest setting and takes any bumps at speed or big bumps at low speed, it will hit suspension travel limits, which is great way to damage the valves in the shock and render it useless.
 

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Hi all,
I'm following/reading this forum for some years right now, here goes my first post: I just got myself a (new) second hand grand cherokee summit 2016. the suspension feels really too soft. it bumps up and down and feels rather like a french Renault :(. before this summit i had an GC overland 2011 and the suspension felt like a ... GC! i was also driving last week an overland from 2016 and that suspension felt also like a GC.

is it possible one can adjust the parameters of the air suspension to get it stiffer? does my summit has a problem? is this normal behaviour for a summit 2016?

Thanks in advance for any help!
Regards,
Stefan
I purchased my 2016 GC Summit Nov 2019. And the others are right, mine feels very stiff. It is one stiff ride! Not loose or spongy at all. Hope this helps knowing I have the same car and sorry if yours is having problems. Being my 1st vehicle with air suspension that is a huge fear of mine.
 

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I had a 2011 Overland QL that was good. My 2017 trailhawk was very floaty, almost nauseating in the back seat. Replaced the rear shocks with bilsteins and it was better, but there is not an out of the box front replacement. basically gave up on it and was shopping other vehicles - then on a whim drove a 2020 TH, and it felt right, well damped, with good comfort - so it's in the garage now instead of a subaru or ford.

So if you can, maybe look for 2020 front suspension damper replacments.
 
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