Yukon Denali XL Manual Airbag Install Questions

[Foggy]

OK, so I ordered air helper springs/bags today.
Firestone shows the 4186 as the correct part to work WITH the
air suspension. I only plan on putting air in them when I'm towing
the heavy load.. I just want to "help" out my air shocks a bit.
Even though my tongue weight is well under the 1000 lb rating.
I noticed some greasy residue on my right shock.. The air bladders do
fill up and stay filled/tight. But I went ahead and ordered new ACDelco
oem repl shocks too.
I'll update on how the firestone air helpers work as soon as I get them installed.

 

[adventurenali92]

I will also disagree with @Rocket Man. I tow with air lift helper bags and factory rear air suspension on my 2006 denali xl. It has been work g for over a year with no problems. For the same reason that the OP is doing, I wanna help my rear air system and not over work it and keep my truck level. It’s incredibly stable while towing up and down the mountain and all the freeway travels. I’ve done it twice now. Once down and up the mountain. About to do it again Friday to take the boat off the mountain for winter storage.

 

[Rocket Man]

I'll disagree with my friend Mark here and say the Air Lift Springs will be fine if you keep the air pressure down and let the compressor and shocks do most of the work. Numbers wise, I think you need more tongue weight, at least another 100 pounds.

There are lots of GMT900 2500s around where I live.

I will also disagree with @Rocket Man. I tow with air lift helper bags and factory rear air suspension on my 2006 denali xl. It has been work g for over a year with no problems. For the same reason that the OP is doing, I wanna help my rear air system and not over work it and keep my truck level. It’s incredibly stable while towing up and down the mountain and all the freeway travels. I’ve done it twice now. Once down and up the mountain. About to do it again Friday to take the boat off the mountain for winter storage.

I was wrong, I forgot that they actually make some that are meant for this. I don’t know wth I was thinking.

 

[adventurenali92]

I will say this though! @Rocket Man is correct in his response about setting up the factory compressor to inflate the helper bags. It’s a good idea but unless you got lots of time and money, it’s not worth it. I bought a small 12V compressor from my local DIY store that says it’s good to inflate tires. Probably small car tires and not big LT truck tires like mine. But that’s ok. It’s a handy size and fits in the rear jack storage compartment with my factory tire iron and jack. Compressor will inflate my helper bags in about 30 seconds. And it plugs in to the 12V adapter in the rear tailgate area of my XL. So no need to find a regular outlet to use it. It’s a not a fancy custom setup where I flip a switch in the cab and bags inflate or deflate, but it works perfectly for what I need when I’m ready to tow the boat, and only takes an extra minute to get it squared away. Not a big deal.

 

[Foggy]

Everything all installed : 4186 firestone air spring helper bags, New OEM AC Delco rear shocks -air ride.
Disassembled and cleaned and painted all sorts of stuff under there.
The firestone kit does Not come with a T fitting. They assume you are
going to do 1 fill valve per side.. I did not want that for this application.
Ended up having to pull coil springs out to install air bags into them. PITA>

So far , on an errand trip today- pretty much rides normal- seems a little
stiffer in rear - due to new shocks I assume. I have min 10 psi in bags which does about nothing. I will be towing this weekend. I;ll put the 35 psi in them before I hook up the camper and see how it rides
and if the factory air pump for the shocks runs less as well.
I'll report back... OH, I also replaced rear pads/ rotors with upgraded
max towing stuff. Brakes were factory with about 30% left on pads and
no noticeable lip on rotors with 100K.
They "feel" a lot tighter now.

 

[Rocket Man]

Everything all installed : 4186 firestone air spring helper bags, New OEM AC Delco rear shocks -air ride.
Disassembled and cleaned and painted all sorts of stuff under there.
The firestone kit does Not come with a T fitting. They assume you are
going to do 1 fill valve per side.. I did not want that for this application.
Ended up having to pull coil springs out to install air bags into them. PITA>

So far , on an errand trip today- pretty much rides normal- seems a little
stiffer in rear - due to new shocks I assume. I have min 10 psi in bags which does about nothing. I will be towing this weekend. I;ll put the 35 psi in them before I hook up the camper and see how it rides
and if the factory air pump for the shocks runs less as well.
I'll report back... OH, I also replaced rear pads/ rotors with upgraded
max towing stuff. Brakes were factory with about 30% left on pads and
no noticeable lip on rotors with 100K.
They "feel" a lot tighter now.

Awesome.

 

[adventurenali92]

Nice job! Yeah the coil springs are a pain. My friend was lucky enough to get my bags in without taking them out. But he was it a struggle getting them in there. Lol. Should ride pretty well your hooked up to the trailer. I keep my bags at 15-20 psi when I’m not towing but have all my detailing gear in the back, and it rides really well around town. Let us know how it goes when you hook the trailer up!

 

[wjburken]

The firestone kit does Not come with a T fitting. They assume you are
going to do 1 fill valve per side.. I did not want that for this application.

I would be careful having the two bags tee’d together. When the bags are independent of each other, each side can absorb any additional load from bumps in the road or shifting weight because the closed system will momentarily increase in pressure and stretch the bag. With them tee’d together, if one side sees any additional load that is more than what is seen on the other side, the air will simply move to the other bag trying to find equilibrium. This can set up some weird harmonics in your suspension that you may not like, particularly if you get into a situation with trailer sway.

At the very least, make sure you have some flow control valves controlling the speed that air can exit each bag.

 

[Rocket Man]

I would be careful having the two bags tee’d together. When the bags are independent of each other, each side can absorb any additional load from bumps in the road or shifting weight because the closed system will momentarily increase in pressure and stretch the bag. With them tee’d together, if one side sees any additional load that is more than what is seen on the other side, the air will simply move to the other bag trying to find equilibrium. This can set up some weird harmonics in your suspension that you may not like, particularly if you get into a situation with trailer sway.

At the very least, make sure you have some flow control valves controlling the speed that air can exit each bag.

This^^^^^^. I definitely wouldn’t tee them together.

 

[Foggy]

OK, so here are my thoughts/results of the "helper" airbag install on
my 14 XL Denali. IT DID help the little bit of sag that I did have.
I put in 30 psi into the firestone bags, then hooked up trailer with
weight distribution bars.. Then started the Yukon... This order seemed to
help , rather than engine running the entire time.
The airpump definitely ran- but didn't have to KEEP running after hooked
up and leveled out..
The job was certainly a pita as I had to remove the coil springs to get the bags installed.. Of course I did a lot of cleaning, etc under there.
I put on the new ACDelco shocks - Z55 air ride .
The ride unloaded is a tiny bit stiffer with the new set of shocks unloaded.
Overall, I was really happy with what I did. I still need to to adjust my
Equalizer 4 point sway/weight dist hitch a tiny bit to fine tune...
But happy with the ride...
BTW, I did get the new upgraded rear brakes on too... Fronts will
be on soon. Along with the Edelbrock Etec SuperCharger and Kooks
Headers & Y-pipe with cats...
I could have used more power, so that should take care of that part.