Fred Williams
Brand Manager, Petersen’s 4Wheel & Off Road
Three years ago we showed you Axletech’s bolt-on portal boxes for Dana 60 and Corporate 14-bolt axles (Aug. ’09). Since then we’ve been wondering whether they would ever go mainstream. Were they too far out for the average off-roader? We recently had a chance to drive a four-door Jeep Wrangler JK with portal axles nearly identical to what Mopar will soon be offering from your local Jeep dealership. Simply put, they work.
A portal axle is designed with a gearbox at the end of the axlehousing that drops the wheel centerline below the axletube centerline for additional ground clearance. The Mopar/Dynatrac/Axletech portals offer 5 inches more ground clearance than stock.
The idea of a portal axle is simple. At the end of each straight axle is a gearbox that raises the axletube so it is above the centerline of the wheel. These gearboxes also multiply the gearing, in this case by 1.5. So with a ring-and-pinion ratio of 4.10 you get a final drive ratio of 6.15 along with 5 inches of lift. This is about perfect for 40-inch-tall tires under a Jeep JK.
As we go to press, Mopar (the parts division of Chrysler/Dodge/Ram/Jeep) has announced that it will be selling these axles for $12,500 for a front (PN P5155670) and $11,000 for a rear (PN P5155671). That is $23,500 for two complete, bolt-in axles, not pocket change by any means. However, this includes 5 inches of lift as well as gearing and lockers, almost obviating the need for any suspension upgrades.
We got behind the wheel of a four-door with the axles under it to determine if living with portals is realistic.
PhotosView SlideshowWhat We Discovered
We drove the Jeep on the road, where it tracked and acted as good as any Jeep Wrangler on 40-inch tires. The weight of the big tires was obvious, but the 3.8L V-6 and automatic transmission could get us up to speed as quick or quicker than other JKs we were wheeling with. We expected gear whine from the four-gear portal boxes, but there was more tire noise. The brakes (Wilwoods) reacted perfectly and could slow or stop the Jeep just as normal, even on steep inclines off-road.
The lack of speed sensors in the portal boxes gave our early-model (pre-’12) JK a plethora of dash warning lights and no speedometer, so we would like to see sensors added. We understand speed sensors are mandatory on the ’12 model with automatic transmission. We checked the speed via handheld GPS and were amazed how 70 mph felt smooth and controlled.
Off-road the stock suspension worked great until the weight of the heavy axles and big tires overcame certain components, especially the shocks, which faded quickly. The factory link arm bushings will not last long with the added leverage of the portals, so those and upgraded shocks will add cost to the already startling $23,500 price tag.
The Jeep was not a Rubicon and as such had only a 2.72:1 low range in the transfer case, but combined with the 6.15 final drive of the portals, it worked great with 40-inch tires. The tires did rub ever so slightly at full stuff and turn, but the differentials only scraped a rock once in a whole day of rockcrawling. We are told the axles will include ARB Air Lockers and a 4.10 ring-and-pinion and come ready to bolt into a Jeep JK.
The additional cost of eight-lug wheels (all the portals are eight-lug) and tires is considered a wash since few JK owners would be comparing to a Jeep on stock rims and rubber. However, the high-backspacing wheels are hard to find and demand a premium price in the 17-inch sizes.
Adding portals will require links and shocks for any real off-road use, and factory driveshafts will need to be upgraded as well, again increasing price. The benefits are ground clearance and gearing, but we would suspect a final price of about $30,000 for newly geared and locked ProRock 44 front and ProRock 60 rear portal axles, driveshafts, better links and shocks, and wheels and tires on top of the price of a stock Jeep JK. It’s not cheap, it’s not for everyone, but we know there are Jeepers who have and will spend twice that on their Jeeps.
