5th Gen 4Runner Rear Air Bag Suspension Lift Installation and Overview
I think we all enjoy working on our 4Runners and as we keep adding stuff to our favorite rigs, things start to get heavy. It may start with new bumpers, drawer systems, winch, dual battery systems and we wind up with a rooftop tent, spare fuel storage containers, water – and I can’t forget all the recovery gear. See a recent article on all the recovery gear I use from time to time. All that weight starts to add up in the 4Runner.
Air lifts are great for owners who want to level their truck, maintain a comfortable ride, and take less stress off the suspension when towing or when carrying additional weight in the 4Runner.
The added weight into two categories
- Always on the truck
- Only on board when wanted or needed
For the first category, the only real fix is an upgraded suspension with heavier springs. I am very happy with the suspension I have installed given I have a new front bumper, winch and dual battery system in my 4Runner.
The 2nd category has been a challenge for me. When off-road or camping, I’d like to carry a lot of extras with a recent addition of a rooftop tent all that can add up to over 400 pounds (probably a lot more). I didn’t want to upgrade the springs and found another option.
Introducing the Air Bag Suspension Kit
Although new to me, air lifts and air bag suspension kits have been around for a long time. They are typically used to help adjust the rear ride height when towing but can also help with the 2nd type of added weight that I’m concerned about.
There are many articles on how to install them and folks who have installed them swear by them. One other common consensus in the forums and around the Internet was after installing the Air Lift system and it performed. Many people say it was the best $100 upgrade they’ve done.
An air lift is relatively inexpensive and also easy to install on your own. I agree it was inexpensive and fairly easy to do since I had help from my sons and a car lift.
Air Lift 60809 1000 Series Rear Air Spring Kit
Here is what I used to install the kit on my 2015 T4R Trail Edition
- Air Lift 1000 Series: Check Price
- Anderson Metals 57001 Brass Hose Fitting: Check Price
- Kingston Brass Mini Ball Valve Lever: Check Price
- Wire Loom 3/8 inch: Check Price
- Wire Loom ¼ Inch: Check Price
The air lift kit is pretty complete with bags, enough tubing, spacers, Schrader valves and all the required extras to put it together (clamps, zip ties). You can add wiring loom to help protect the tubing, but it’s not mandatory.
You can benefit from a soapy water solution in a spray bottle and a reciprocating saw with a long flexible blade (more on that later).
If you don’t have access to a lift you will need a jack, jack stands, and wheel chocks to lift both rear wheels up.
Air Bag Suspension Kit Installation
The first step is to read the installation manual that came with the Air Lift kit. It’s a great kit if you have a 3rd or 4th Gen 4Runner but Air lift does not have specific instructions for the 5th Gen. After reading through a few posts, I was able to find the right kit and understand the one modification I had to do in order to make it work in the 5th Gen. I’ll explain the difference down below.
Next, Lift the car so that both rear wheels hang with suspension and springs extended. With the wheels off the ground, I had more than enough clearance to perform the next steps.
The image below is from the Air Lift Installation manual and here is the main difference when installing in a 5th Gen. As I mentioned earlier the manual is geared towards older 4Runners and they have a set up with an internal spring bumper with 5 sections and they recommend to cut the bottom 4 sections leaving just one on top of the spring:
On my 5th Gen, the Bumper looks like the image below with only 4 sections. I found mixed reviews on how much to cut so I took a middle ground and cut off the bottom 2 sections.
I used a reciprocating saw with a long flexible blade and cut the sections between the extended spring coils. I then pulled out the cut section.
Here too, I found different opinions online. Some folks found it very easy to cut, just like I did, while others found it too difficult and wound up taking the coil out altogether.
If you do go that route, the Installation guide has specific instructions on what to do to remove the spring.
Once the bumpers are cut and with the spring still extended I was able to squeeze the bag in between the coils. A little spray of soapy water helped, but I found it a lot easier than I thought to get the bag installed. It’s up to you how you orient the Bag, but I found it easier to install the bag with the barb pointed down. There is an existing hole in the base of the spring housing so threading the air tube was much easier from the bottom.
After the Bag is installed, slip the provided spacer between the bag and spring base. It may help if you use some double-sided tape to keep the spacer on the base or Bag. Here too I found mixed suggestions on whether to tape it or whether it was needed at all. I opted to install it and tape it to the bag.
With the spacer and bag installed, thread the tube up through the bottom, place a clamp on the tube and attach to the barb on the bottom of the bag. Here too a little spray of soapy water helps. Make sure to attach and secure the clamp close to the bottom of the bag. I was surprised at how much room I had to play with to get the tube positioned.
Please note: I started on the Driver’s side since I wanted the Schrader valves positioned closer to that side. Once you attach the tube, try to find the best route to your desired position. Here too, the installation guide is very specific about leaving enough slack and zip tied to a suitable spot (I followed the brake lines).
Once you’ve found a route that suitable for you, you can cut the tube. Once cut, you can add the wire loom up through the spring base – your option. Repeat on the other side
Finished on One Side
Once done, you should have the two sides looking like the graphical representation below from Air Lift’s Installation Guide. This shows how the bag and spring fit using the provided spacer. Here’s what it looks like on my 5th Gen. And one more look, a little further out.
Here are some photos of how I routed the tubes and where I zipped tied using what looked like suitable tie points for me. I basically went up and across on both sides until the tubes came together.
I attached the Schrader valves through the lip behind the bumper. The material is sturdy enough to hold the valves with the supplied hardware and instructions provided in the installation guide.
And that’s it. It was not a difficult modification but there is one more option I’m debating. You will notice I kept the bags, tubes and Schrader valves separated. The main benefit of this set up is that I can adjust each side at different PSI in case I have an uneven load.
The other option is to have both bags and tubes connected by the provided “Y” Barb adapter so that you can just have one Schrader valve and keep the pressure even. From what I found on the web, there are pros and cons to both setups.
The separate configuration will not interfere with the action of the anti-sway bars minimizing any body roll while on the pavement (along with the added benefit I mentioned above). The combined setup will provide better articulation when off road by allowing air to move between the bags and providing slightly better articulation between wheels.
I went with the separated version (two valves), but if I find any issues I will add the set up below that will give me the option to change the set up with the flip of a valve. Close the valve and you keep the bags separate; open the valve and you link the two.
- Anderson Metals 57001 Brass Hose Fitting Adapter, 1/8 inch Barb x ¼ inch NPT Male
- Kingston KMBVM Series Brass Mini Ball Valve, Lever, ¼ inch NPT Male & Female
Plus plumbers tape and two “ T “ connectors from Home Depot.
I’ve been using this mod now for about a week off road and on the pavement at highway speeds with no issues. I have not added the Roof Top Tent yet, but I can see a benefit when fully loaded with all my other “stuff”.
- Do not over inflate the bags – limited to 35 PSI.
- Keep at least 5 PSI at all times. Any lower pressure and you risk damaging the bags.
- Check pressure regularly and make sure you check for any leaks before you go on the road.
- I have not found much of a difference in ride between 5 and 15 PSI. Over 20 PSI, I start to feel a little harder ride, but not so much that I have to dial it back.
- My ride height did not change, but there is less sag under heavy load.
The First photo set at 5psi 2nd set at 35psi. I can’t see the difference but much stiffer ride at 35.