SouthernSS – Combo Spring and Air Bag Setup (1 Viewer)

[Mr Chuck Norris]

I was about to do this on mine, then scrapped the idea for a couple reasons.

So yes, you leave everything connected and intact for the factory air system and just remove the OEM air springs. Install the coil conversion, run the factory lines down through the cut coil spring isolators, and plug them into the aftermarket bag. Then adjust the height sensors on the upper links to the new ride height.

I ran Airlift bags on my last 4runner and loved them. With the manual fill valve I kept them at the minimum 5psi and it wasn't harsh, just added a nice progressiveness to the rear springs and helped prevent bottoming. Then aired up to whatever was needed for the weight I was hauling/towing up to the max 35psi.

The issues with using the GX air system stem from the fact that the aftermarket bags are designed to be filled to 35psi maximum. The GX air compressor is not pressure regulated, it keeps pumping until the height sensors and computer tell it to stop pumping. Sensors not adjusted perfectly for the base ride height of your coil spring? Either the bags will have too little pressure and they can pinch/wear, but more likely they will get more than 35psi to hit your desired ride height. Same with carrying a heavy load. Same if you're climbing a hill and the truck's weight shifts to the rear. I have heard a few instances of the OEM compressor popping aftermarket airbags so I'm sticking with the manual fill valve for each bag.

 

[fourleggedfish]

I was about to do this on mine, then scrapped the idea for a couple reasons.

So yes, you leave everything connected and intact for the factory air system and just remove the OEM air springs. Install the coil conversion, run the factory lines down through the cut coil spring isolators, and plug them into the aftermarket bag. Then adjust the height sensors on the upper links to the new ride height.

I ran Airlift bags on my last 4runner and loved them. With the manual fill valve I kept them at the minimum 5psi and it wasn't harsh, just added a nice progressiveness to the rear springs and helped prevent bottoming. Then aired up to whatever was needed for the weight I was hauling/towing up to the max 35psi.

The issues with using the GX air system stem from the fact that the aftermarket bags are designed to be filled to 35psi maximum. The GX air compressor is not pressure regulated, it keeps pumping until the height sensors and computer tell it to stop pumping. Sensors not adjusted perfectly for the base ride height of your coil spring? Either the bags will have too little pressure and they can pinch/wear, but more likely they will get more than 35psi to hit your desired ride height. Same with carrying a heavy load. Same if you're climbing a hill and the truck's weight shifts to the rear. I have heard a few instances of the OEM compressor popping aftermarket airbags so I'm sticking with the manual fill valve for each bag.

Some solid points there, and definitely has me reconsidering also. Unless some l33t hax0r figures out how to add a pressure regulator which cuts off power to the compressor at a given psi rating, and then maybe re-enables the compressor after some time-out period, allowing for reduction in pressure as needed if say, over-the-hill and headed down the other side. I think you're right though, that compressor probably just inflates to a given height, regardless of pressure, or is set to not exceed some OEM bag pressure limit. How to make it smarter...? Automagic aftermarket bags would sure be nice!

 

[Mr Chuck Norris]

Some solid points there, and definitely has me reconsidering also. Unless some l33t hax0r figures out how to add a pressure regulator which cuts off power to the compressor at a given psi rating, and then maybe re-enables the compressor after some time-out period, allowing for reduction in pressure as needed if say, over-the-hill and headed down the other side. I think you're right though, that compressor probably just inflates to a given height, regardless of pressure, or is set to not exceed some OEM bag pressure limit. How to make it smarter...? Automagic aftermarket bags would sure be nice!

I was also really excited for the idea of load levelling airbags within coil conversion springs. But at this point I'm just going to gut all of the stock air system and hold onto it for a while. Besides the sensors and computer module, it's otherwise a very simple compressor and dump valve that pumps air into a small reservoir tank, and then into the bags. Pump more air to go up, dump air to go down.

A pressure switch could easily be plumbed into the air lines but who knows what the computer would think when it gets a dead circuit signal when the switch hits 35psi. I bet it would go into fault mode every time.

 

[fourleggedfish]

Yeah, here comes "all the lights" and limp mode.

Still hoping for someone much smarter than I to code it up on a Raspberry Pi so we can at least manually set pressure from inside the truck while rolling. I guess I could also just buy the aftermarket compressor/bag setup and be done with it. Or go full manual.

 

[Commander AJ]

I was about to do this on mine, then scrapped the idea for a couple reasons.

So yes, you leave everything connected and intact for the factory air system and just remove the OEM air springs. Install the coil conversion, run the factory lines down through the cut coil spring isolators, and plug them into the aftermarket bag. Then adjust the height sensors on the upper links to the new ride height.

I ran Airlift bags on my last 4runner and loved them. With the manual fill valve I kept them at the minimum 5psi and it wasn't harsh, just added a nice progressiveness to the rear springs and helped prevent bottoming. Then aired up to whatever was needed for the weight I was hauling/towing up to the max 35psi.

The issues with using the GX air system stem from the fact that the aftermarket bags are designed to be filled to 35psi maximum. The GX air compressor is not pressure regulated, it keeps pumping until the height sensors and computer tell it to stop pumping. Sensors not adjusted perfectly for the base ride height of your coil spring? Either the bags will have too little pressure and they can pinch/wear, but more likely they will get more than 35psi to hit your desired ride height. Same with carrying a heavy load. Same if you're climbing a hill and the truck's weight shifts to the rear. I have heard a few instances of the OEM compressor popping aftermarket airbags so I'm sticking with the manual fill valve for each bag.

Interesting point! I haven't towed anything yet but there have been many instances where the rear was loaded due to flexing over rocks on steep off road inclines. So far I haven't heard the compressor fire up at all and it has been well over a year. The bags are still plump full of air but I have no idea what the PSI is, it would be great to have a gauge for that. On a side note I did find out that the water from the wiper fluid tank will flow right out the rear wiper nozzle when going up super steep hills!

 

[EmotiveGoat09]

I recently did the 4runner coil conversion with 1" Eibach lift springs and threw the 4135 bags in my in my rig and my opinion is that they're too short. They don't do much until it starts squatting . Thinking about either ordering the coil-rite 6003 or 4108, does anyone have experience with either??

I want to wire this in to bypass the height sensor to manually control the stock compressor. Has anyone been able to find a wiring diagram for the harness going into the compressor?

 

[justcasey]

Sup guys. Anyone have any updates on this?
What to do’s and what not do’s? any regrets?

I’m leaning towards the Firestone (mated to eibach stage 2 kit and wheelers bump stops), using 6003 or 4108 instead of the 4135 since research shows people saying they’re too short. I too would “like” to run to OEM compressor since it’s a lot easier with a switch vs hooking up a compressor and then filling (as easy as that is too, but come on, a switch is much easier lol)

What I’m doing- well I’m not entirely sure if I want to use this to tow the street/track car to/from the track since its a 120’ish mile one way with some heavy steep hills to climb, but I would definitely like use a motorcycle hitch carrier to haul the R6 to the track with a loaded cabin as well, so a good amount of weight. And I won’t be doing this “often” so I don’t want to opt for heavy duty springs and risk the ride quality for a couple days out of the year.

Mr. chuck norris up there has a very good point though. it’s not entirely regulated and I guess you’re basically chancing it to over/under inflate especially while towing and not being on flat land. Its not something you want risk on whatever long or short adventure you’re taking.

I know a few have chimed in, but I want to see if there’s any updates for the people that have/had this set-up along with OEM compressor.

 

[Commander AJ]

Sup guys. Anyone have any updates on this?
What to do’s and what not do’s? any regrets?

I’m leaning towards the Firestone (mated to eibach stage 2 kit and wheelers bump stops), using 6003 or 4108 instead of the 4135 since research shows people saying they’re too short. I too would “like” to run to OEM compressor since it’s a lot easier with a switch vs hooking up a compressor and then filling (as easy as that is too, but come on, a switch is much easier lol)

What I’m doing- well I’m not entirely sure if I want to use this to tow the street/track car to/from the track since its a 120’ish mile one way with some heavy steep hills to climb, but I would definitely like use a motorcycle hitch carrier to haul the R6 to the track with a loaded cabin as well, so a good amount of weight. And I won’t be doing this “often” so I don’t want to opt for heavy duty springs and risk the ride quality for a couple days out of the year.

Mr. chuck norris up there has a very good point though. it’s not entirely regulated and I guess you’re basically chancing it to over/under inflate especially while towing and not being on flat land. Its not something you want risk on whatever long or short adventure you’re taking.

I know a few have chimed in, but I want to see if there’s any updates for the people that have/had this set-up along with OEM compressor.

So far my bags have been holding up great while being fully inflated the whole time after install. These things seem pretty dang durable! I used the 6003's and they fit perfect but I did not use the upper isolator if I remember correctly. Stock compressor works just fine and there are still no leaks after 60k of driving. Hope this helps!

 

[Mr Chuck Norris]

Sup guys. Anyone have any updates on this?
What to do’s and what not do’s? any regrets?

I’m leaning towards the Firestone (mated to eibach stage 2 kit and wheelers bump stops), using 6003 or 4108 instead of the 4135 since research shows people saying they’re too short. I too would “like” to run to OEM compressor since it’s a lot easier with a switch vs hooking up a compressor and then filling (as easy as that is too, but come on, a switch is much easier lol)

What I’m doing- well I’m not entirely sure if I want to use this to tow the street/track car to/from the track since its a 120’ish mile one way with some heavy steep hills to climb, but I would definitely like use a motorcycle hitch carrier to haul the R6 to the track with a loaded cabin as well, so a good amount of weight. And I won’t be doing this “often” so I don’t want to opt for heavy duty springs and risk the ride quality for a couple days out of the year.

Mr. chuck norris up there has a very good point though. it’s not entirely regulated and I guess you’re basically chancing it to over/under inflate especially while towing and not being on flat land. Its not something you want risk on whatever long or short adventure you’re taking.

I know a few have chimed in, but I want to see if there’s any updates for the people that have/had this set-up along with OEM compressor.

Personally... I would abandon the hitch moto carrier idea. I tried doing the same with my XR400 (260lb) on a Trackside carrier (60lb) and that weight cantilevered 2+ feet off the hitch of my old 4runner was enough to lift the front end 2 inches or so and made the steering scary light. I did this exactly once and then bought a 5x8 utility trailer to haul the moto.

As for bags, I have been very happy with my Firestone 4135 on ~1" of lift via Bilstein springs. Set up for manual fill though.

 

[EmotiveGoat09]

Sup guys. Anyone have any updates on this?
What to do’s and what not do’s? any regrets?

I’m leaning towards the Firestone (mated to eibach stage 2 kit and wheelers bump stops), using 6003 or 4108 instead of the 4135 since research shows people saying they’re too short. I too would “like” to run to OEM compressor since it’s a lot easier with a switch vs hooking up a compressor and then filling (as easy as that is too, but come on, a switch is much easier lol)

What I’m doing- well I’m not entirely sure if I want to use this to tow the street/track car to/from the track since its a 120’ish mile one way with some heavy steep hills to climb, but I would definitely like use a motorcycle hitch carrier to haul the R6 to the track with a loaded cabin as well, so a good amount of weight. And I won’t be doing this “often” so I don’t want to opt for heavy duty springs and risk the ride quality for a couple days out of the year.

Mr. chuck norris up there has a very good point though. it’s not entirely regulated and I guess you’re basically chancing it to over/under inflate especially while towing and not being on flat land. Its not something you want risk on whatever long or short adventure you’re taking.

I know a few have chimed in, but I want to see if there’s any updates for the people that have/had this set-up along with OEM compressor.

I ended up opting for the regular eibach springs in the rear and recently changed out the 4135 coil rite bag to the longer firestone 4108 kit [Coil-Rite Air Helper Spring Kit Rear 00-10 Chevy/GMC Tahoe/Yukon (W237604108)] and would highly recommend the setup.

The picture of the bag inside of the coil is the 4135 (short bag)

I do highly recommend running either the tall bags or the HD spring, the regular eibach is too soft for the heavier Lexus chassis in my opinion.
I've used a hitch rack for my dirt bike and towed a ski boat and the bags make a huge difference. I usually run 5-10 psi for daily driving and bump it to 15-20 for heavy loads and have been super happy with it.

 

[Commander AJ]

I ended up opting for the regular eibach springs in the rear and recently changed out the 4135 coil rite bag to the longer firestone 4108 kit [Coil-Rite Air Helper Spring Kit Rear 00-10 Chevy/GMC Tahoe/Yukon (W237604108)] and would highly recommend the setup. View attachment 2892385View attachment 2892386
The picture of the bag inside of the coil is the 4135 (short bag)

I do highly recommend running either the tall bags or the HD spring, the regular eibach is too soft for the heavier Lexus chassis in my opinion.
I've used a hitch rack for my dirt bike and towed a ski boat and the bags make a huge difference. I usually run 5-10 psi for daily driving and bump it to 15-20 for heavy loads and have been super happy with it.
View attachment 2892388

Totally agree with using the longer bags, the short ones just don't cut it. One thing that I did was countersink the bolt holes in the lower isolators so that the bolt did not rub on the lower portion of the bag. Pretty sure the bags are durable enough to withstand the abuse but I did it anyway.

 

[Mr Chuck Norris]

I'll also add that as long as the bags contact the coil conversion spring plate/puck at ride height, they are long enough. They don't need to be compressed at ride height. I have the Icon coil conversion hardware (aluminum puck surrounded by a poly isolator) and Bilstein FJ 0.9" springs and the Firestone 4135 is the perfect length to fit inside. Ride height is 1" higher than my stock airbag suspension which was set to factory specs.

 

[justcasey]

I ended up opting for the regular eibach springs in the rear and recently changed out the 4135 coil rite bag to the longer firestone 4108 kit [Coil-Rite Air Helper Spring Kit Rear 00-10 Chevy/GMC Tahoe/Yukon (W237604108)] and would highly recommend the setup. View attachment 2892385View attachment 2892386
The picture of the bag inside of the coil is the 4135 (short bag)

I do highly recommend running either the tall bags or the HD spring, the regular eibach is too soft for the heavier Lexus chassis in my opinion.
I've used a hitch rack for my dirt bike and towed a ski boat and the bags make a huge difference. I usually run 5-10 psi for daily driving and bump it to 15-20 for heavy loads and have been super happy with it.
View attachment 2892388

Nice!! I like it. Thanks for the info.

What did you do about airing up? OE compressor or manually filling?

 

[Mr Chuck Norris]

I ended up opting for the regular eibach springs in the rear and recently changed out the 4135 coil rite bag to the longer firestone 4108 kit [Coil-Rite Air Helper Spring Kit Rear 00-10 Chevy/GMC Tahoe/Yukon (W237604108)] and would highly recommend the setup.
The picture of the bag inside of the coil is the 4135 (short bag)

I do highly recommend running either the tall bags or the HD spring, the regular eibach is too soft for the heavier Lexus chassis in my opinion.

I've used a hitch rack for my dirt bike and towed a ski boat and the bags make a huge difference. I usually run 5-10 psi for daily driving and bump it to 15-20 for heavy loads and have been super happy with it.

Totally agree with using the longer bags, the short ones just don't cut it. One thing that I did was countersink the bolt holes in the lower isolators so that the bolt did not rub on the lower portion of the bag. Pretty sure the bags are durable enough to withstand the abuse but I did it anyway.

I'm curious - what issues did you both see with 4135 airbags that were alleviated with longer bags? What ride height are you both at in the rear? With the 4135, were they long enough to contact the top and bottom at ride height?

 

[EmotiveGoat09]

I'm curious - what issues did you both see with 4135 airbags that were alleviated with longer bags? What ride height are you both at in the rear? With the 4135, were they long enough to contact the top and bottom at ride height?

I haven't had a chance to figure out the stock compressor yet, the main issues I saw were figuring out a wiring bypass to the stock harness and running lines to a switch/regulator combo that would allow you to air up & down.

My main issue with the 4135 bags was when the suspension unloaded over a bump and compressed back down, it felt like there were two dramatically different spring rates when the bags would re-engage (felt like you were hitting a bump stop). Because the longer bags don't disengage when the spring extends, the rear feels much more linear when it compresses.

Hope that helps/makes sense.

 

[Mr Chuck Norris]

I haven't had a chance to figure out the stock compressor yet, the main issues I saw were figuring out a wiring bypass to the stock harness and running lines to a switch/regulator combo that would allow you to air up & down.

My main issue with the 4135 bags was when the suspension unloaded over a bump and compressed back down, it felt like there were two dramatically different spring rates when the bags would re-engage (felt like you were hitting a bump stop). Because the longer bags don't disengage when the spring extends, the rear feels much more linear when it compresses.

Hope that helps/makes sense.

That makes perfect sense, it's using the bags as another primary spring instead of a secondary load supporting spring. Sounds like it's working for your rig. Do the bags do much to alter ride height while unloaded? What springs do you have?

 

[justcasey]

Great info here!

Alright, definitely not the 4135 as it’s too short and does not fill in from top to bottom completely, like seen above in post #30.
4108 seems to be a great fit for the original eibach rear springs and Im sure other similar springs as well.

Couple screenshots from another fella on YouTube that also used the 4108 kit and shows how well it fits the eibach springs.
HERE for the video (@6:34).

I’ll be getting my suspension at the end of the month and will also purchase the 4108 kit and try figure out a way to use the oem compressor. I’ll come back with some install photo's and feedback!

 

[EmotiveGoat09]

That makes perfect sense, it's using the bags as another primary spring instead of a secondary load supporting spring. Sounds like it's working for your rig. Do the bags do much to alter ride height while unloaded? What springs do you have?

Exactly, perfect way to explain it.
They may have brought the rear up just a little bit but by taking out some of the sag from the softer coils (Eibach 1" lift springs for 00-10' FJ/4Runner & metal tech coil conversion) but I wouldn't count on them giving you any significant lift.

 

[justcasey]

That makes perfect sense, it's using the bags as another primary spring instead of a secondary load supporting spring. Sounds like it's working for your rig. Do the bags do much to alter ride height while unloaded? What springs do you have?

From what I understand, he has the standard rear springs that come with the kit.
THESE

Unless he has the upgraded springs which are rated for 250 or 400lbs according to their website.

LOAD-LEVELING SYSTEM (Rear) (For +250lbs of Added Weight)	AK31-59-005-02-02	Height Adjustable Rear Spring from 1.8" to 3.2" with 250lbs of added rear weight.		+1.8-3.2 in	$499.00
LOAD-LEVELING SYSTEM (Rear) (For +400lbs of Added Weight)	AK31-59-005-03-02	Height Adjustable Rear Spring from 2.0" to 3.5" with 400lbs of added rear weight.		+2.0-3.5"

Which makes me think if it’s worth it for me upgrade to the 250 or 400lbs.

On a daily basis, I think I’d have around 100lbs or slightly less of weight in the back (basic tools and a low-pro jack) and maybe other few items, I doubt this would make an impact on the standard springs since I assume they’re good for stock weight to 250lbs- and if I have more than 250 and I’m getting some sort of sag, then that’s when it’s time for some air.

Make sense? You guys think MD springs are worthy?

Edit: Scratch that, I might just go with 250lbs or higher as I’ll be adding some more weight like sliders, roof rack, and I always have my 1up bike carrier.

 

[EmotiveGoat09]

From what I understand, he has the standard rear springs that come with the kit.
THESE

Unless he has the upgraded springs which are rated for 250 or 400lbs according to their website.

LOAD-LEVELING SYSTEM (Rear) (For +250lbs of Added Weight)	AK31-59-005-02-02	Height Adjustable Rear Spring from 1.8" to 3.2" with 250lbs of added rear weight.		+1.8-3.2 in	$499.00
LOAD-LEVELING SYSTEM (Rear) (For +400lbs of Added Weight)	AK31-59-005-03-02	Height Adjustable Rear Spring from 2.0" to 3.5" with 400lbs of added rear weight.		+2.0-3.5"

Negative, these Eibach are what I'm running with these Firestone helper bags and this coil conversion kit.