2012 Yukon XL Denali front suspension seems overly stiff

[dkad260]

I picked this up about a month ago, no complaints, however the front seems to ride a bit harsh over small bumps, the rear just floats.

The Yukon has 92K miles and when I purchased it, all four shocks/struts appear to be the original. I have replaced the rear with Arnott 2708 and that cured the extended bounce over bumps, wasn't bad but had an extra rebound or 2.

The fronts are still original, no warning messages, air compressor works as it should, tires are also new Defender LTX.

I did recently purchase a Tech 2 if that helps and I'm slowly getting familiar with it.

The ride height appears somewhat normal, RF seems a bit high but I'm not sure exactly what it should be with a decent load of fuel. One thing that comes to mind is the original owner had the 22" wheels installed when they took delivery, maybe the dealer programmed or set a higher pressure in the shocks? If that's even possible?

I get the fact a 22" will or can ride stiffer than a 20", but this seems different.

Ride height is as follows, with 3/4 tank of fuel, no passengers or cargo, key on and air compressor did run for about 3-5 seconds. Measurement taken from ground to bottom of wheel opening through axle center.

LF 35 1/4"
RF 36 1/4"
RR 37 3/8"
LR 37 1/8






Below is RR




Below is LR



Overall the ride is very smooth, the new tires made a world of difference over the Alenza's. This seems more than the bump compliance of the tires/tread, like stiff valving.

All input appreciated.

 

[gooffeyguy]

More than likely the front struts are your problem.

I just recently replaced my rear shocks with the AS-2708 and the pump with a Dorman. My rear air bladders were leaking. I still need to replace the front struts and I can tell/feel that it's gotten a bit rougher lately.

 

[dkad260]

More than likely the front struts are your problem.

I'm thinking so as well, but it does go against my line of thought of worn shocks/struts getting softer over time which made me think of the air system possibly being an option.

Can't argue with you on the fact they still have 92K miles so safe bet new would be an improvement.

Debating the OE struts over the Arnott, albeit a hefty price difference.

 

[gooffeyguy]

I've only seen passive struts from Arnott, which use a plug in resistor and eliminates the automatic ride control.

I'd probably go with OE on the front struts, unless someone else chimes in here with other options.

 

[kbuskill]

Just FYI... the front struts have absolutely nothing to do with the "air ride" portion of the rear suspension.

The AutoRide system (RPO code Z55) controls the valving of the rear shocks and front struts electronically. It stiffens or softens according to the terrain.

The Auto leveling system (RPO code G69) consists of the rear air shocks and the air compressor behind the drivers rear wheel well.

The AutoRide struts are known to get stiff when they age. I think this is perhaps a failsafe built into the design to keep the truck from leaning so badly in curves with worn out struts.

@iamdub unplugged his one time to check them out. Perhaps he will chime in with his results. I just remember him saying that they were scary soft when unplugged and he didn't recommend driving at high speeds or making fast maneuvers with them unplugged.

 

[dkad260]

Just FYI... the front struts have absolutely nothing to do with the "air ride" portion of the rear suspension.

I made a quick glance at the front suspension last week, and for some reason I thought there was an air setup on the front shock when I saw what looks like the height sensor and the larger protective boot...so my mistake.


Interesting about them getting stiff as they age, as the front end has virtually zero body roll on turns.

 

[kbuskill]

I made a quick glance at the front suspension last week, and for some reason I thought there was an air setup on the front shock when I saw what looks like the height sensor and the larger protective boot...so my mistake.


Interesting about them getting stiff as they age, as the front end has virtually zero body roll on turns.

Don't beat yourself up too much, you aren't the first to make this mistake.

The "height" sensor is for the AutoRide systems dampening control and the protective boot is basically a dust/mud shield for the strut.

 

[gooffeyguy]

I thought the height sensor in the front was for the autoleveling air rear, so it knew how much air it needed in relation to the front

 

[dkad260]

the protective boot is basically a dust/mud shield for the strut.

Yeah, the fact it somewhat resembles the look of the rear air shock membrane/boot threw me.

 

[91RS]

I thought the height sensor in the front was for the autoleveling air rear, so it knew how much air it needed in relation to the front

It is so the system knows what the suspension is doing so it can adjust the shock to control it. The rear sensors are also used for that but also used for the height adjustment. The same suspension control modules handles both functions.

The shocks on this body style can lock up just like the new ones but it is much less common. The best way to diagnose that is just to know what it is supposed to feel like and drive it but that's easy for me since I've been working on these since they came out in 07 so I've easily driven 100s of them. I will say that I put new front shocks on my Escalade just because I'm basically restoring it but I did not replace the front shocks on my Yukon which now have 188k miles on them and they feel about the same. These shocks are not supposed to "wear out" like traditional shocks do but I think they can still fail it just isn't as obvious when they do. I think the more important thing to replace is the springs, that made a huge difference and raised the front ride height 3/4." Unfortunately, they're discontinued. I always recommend the OEM shocks, I have the unpopular opinion around here of not being a fan of Arnott's shocks (the ones they put new bags on OEM shocks are probably ok).