Gaining the Ultimate Raise
In readiness for my epic 2018 adventure, I upgraded my suspension with Ironman 4×4 Foam Cell Pro shock absorbers Performance coil springs before installing a MCC 4×4 Accessories steel rear bar with dual wheel carrier. The added weight caused the rear of my Prado to sag and the nose to rise, making the vehicle unsafe on the road due to the headlights being too high. I needed a solution that would be simple to install, have the strength to handle the conditions than I planned to cover, enhance the ride, provide the ability to lower the rear if I removed the wheel carriers and raise the rear when I was packed for a trip.
I reached out to Polyair Spring and they were happy to supply me with their new Polyair Ultimate Air Bag Kit. The Ultimates are constructed using high-density polyurethane making them stronger and more durable allowing a working range from 5PSI to 60PSI. They also promised to fix my sagging bum problem, improve my ride and more importantly correct my headlight issue. I was keen to try the Ultimate Air Bag Kit and was excited when they were delivered to my door.
Having used Polyair Red Series airbags in my 80 Series Landcruiser, I knew that the easiest way to install them was on a hoist. Andrew Cassar at Ontrack 4×4 was ready to sort the install for me and within a couple of days, I was photographing the Prado to provide a base height before heading to OnTrack 4×4.
The guys at OnTrack 4×4 really got stuck in and completed the install in just over an hour. It was a simple job, at least on my Prado. The prep work of attaching the airlines to the Ultimates and then covering them with protective corrugated tubing was the first step. Next, the bump stops were removed, and the airbags slid into the coil springs.
OnTrack 4×4 made the install look easy
We then decided where the best spot for the valves would be before the MCC rear bar was taped before the holes were tapped, pre-drilled and then a step drill bit used to make precisely sized holes. The holes were then touched up with some black anti-rust paint before the valve stems were installed. The final step was to run the protected air hoses from the top of the air bags to the valve stems, keeping well away from the exhaust and leaving some slack (to prevent any damage during axle movement).
Once everything was bolted up and tidied up with cable ties, the Prado was lowered, ready for some air. We started at 20PSI before adding 10PSI at a time to get the ride height correct, finally settling on 40PSI.
Before and after shots show how impressive the change is
With 40PSI as my benchmark, I enjoyed an improved ride, making long driving stints easier to manage. On the corrugations in Diamantina National Park, Plenty Highway, Hay River Track and Gary Junction Road, I was amazed by not only the smoothness of the ride but also the reduction in the stress on the rear suspension. The Ultimates matched perfectly with my Ironman 4×4 Pro Springs. The Gary Highway was savage, with severe corrugations, washouts and rocky sections but the Ultimates improved the rough ride thanks to their progressive spring rate.
Having survived the Talawana Track, including a detour into Karlamilyi National Park I thought my rear end was still sagging a touch. The airbags were still sitting at 40PSI, but I think that my Ironman 4×4 suspension had settled after the tortuous kilometres I had covered. I added another 10PSI to take them up to 50PSI and kept them at that rate to places such as Karijini, Cape Range, Francois Peron and Kennedy Range National Parks, Dirk Hartog Island, Yardie Creek Track, Gibb River Road, Kalumburu Road and Mitchell Plateau and the track in and out of Purnlululu. When I started crossing the Simpson Desert on the Madigan Line, the airbags were still at 50PSI.
The Madigan Line was a real test for the Ultimates, with the western sides of the dunes severely cut up by a group towing camper trailers who were a day or two in front of us. My rear end would bounce around severely, sometimes both rear wheels getting airborne as I crawled up the dunes. I played around a little with the Ultimates, dropping them down as low as 20PSI to see if it would help. As I changed the pressure each day, I ended up back up at 50PSI as that level was the best option for the conditions.
Polyair Springs did provide me with the Ultimate Air Bag Kit free of charge, but that it no way has influenced my thoughts on this product. They really have delivered on their promise, performed without a problem and I really do rate them highly.
Driving over 24,000km, I really gave the Ultimates a hard time, with corrugations, cut up sand dunes, rock crawling, water crossings, washouts and heavy weight. My body roll was reduced, especially noticeable around roundabouts and didn’t move an inch when the camper trailer was hooked on. I am seriously impressed with these new Ultimate airbags, they are definitely one of the best modifications I’ve made to the Prado and recommend them to anyone who is looking at fixing up a saggy rear end.
For more information on the Polyair Ultimate Air Bag Kit, check them out here
For more information on Ironman 4×4 suspension, check them out here
For more information on Ontrack 4×4, check them out here
Hi Glenn. What was the protective corrugated tubing you had fitted over the airbags. The airbags do not come standard with this.
Hi Greg, thanks for getting in touch. The corrugated tubing came with the kit from Polyair. It is the sealed variety with no split. https://www.polyair.com.au/ultimate
I hope this helps.