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Weak JK Axle Housing?
Q: My July copy of 4 WHEEL DRIVE & SPORT UTILITY MAGAZINE (catchy title by the way) arrived in the mail today, so I immediately locked myself in my man cave to begin devouring all the tasty tidbits contained therein. Anyway, as usual, I read Phil's 4Word first. There he casually mentions, "We didn't know the front end had a weak housing yet," referring to Jeep JKs. Jeep JKs like mine.
Can we please get a little more information? What is it that's weak about the front housing? What does one do about it, short of a Currie 60, and what sort of off-roading exposes the weakness in the front housing? Whatever you can tell us would be appreciated. And now on to Page 15, "Big Red." I hope you can tell how much I enjoy your magazine. Warm regards.
Vancouver, BC, Canada
A: David, thank you for your question, and we're very glad you enjoy the magazine. We have talked about the JK's weak front axle housing in a few tech articles in the past year, so that is why Phil didn't go in to great detail about it in his July 2010 4Word column. The short of it is yes, the JK front axle housing, including the Rubicon Dana 44 housing, is weak and prone to bends and cracks when subjected to heavy and sometimes even mild use.
This may not be as big an issue for those running stock suspension and tire size, but it greatly depends on how you use your rig. Difficult trails and hard use will take its toll; driving around town and hitting fire roads likely won't. Either way, there are methods of protecting the housing from breakage that won't break your wallet.
Off-Road Evolution [(714) 870-5515, offroadevolution.com] offers its C2 Front Axle Reinforcement Gussets and its EVO 44 Magnum sealed axle sleeves to protect the housing from cracking or bending. The gussets are manufactured from 3/16-inch laser-cut and CNC-bent steel plate and are designed to add strength to the front axle inner C steering knuckles. The gussets are a direct fit to the JK Dana 30 and Dana 44 axles. The EVO 44 Magnum sealed tube sleeves provide double-duty protection, making the factory axle housing 30-percent stronger and also adding a double seal to further prevent debris from entering the axle tubes. Both Off-Road Evolution kits are also offered for TJ front axles.
In addition to Off-Road Evolution, many other manufacturers have begun offering JK axle gusset and sleeve kits, including Teraflex, Poly Performance, TMR Customs, Mt. Logan Off-Road, Die-Tech Off-Road, and others. Thanks for writing.
Toyota 4Runner Gears & Skidplates
Q: I own a 1992 Toyota 4Runner with all the usual stuff on the motor: header, cam, and cold-air intake. I also put on some heavy-duty torsion bars, coils, and some 31-inch tires. I'm looking to put a locker and maybe some gears in it. I have always heard that with 33-inch tires you need to run 4.88 gears. But what happens if you are only running 31s? I totally understand lower gearing for off-roading, but what will it do to me on the highway? At 65 mph, I am turning about 2,700 rpm with the stock gears. What will the 4.88s do? And how much will that help pulling hills at highway speeds? Then, is there any way to give my 4Runner a tummy tuck? The fuel tank is a big concern of mine. It's always banging on stuff. So is the transfer case. Any help you can provide is appreciated.
A: Coop, your 4Runner uses 4.10 gears stock, which should provide ample power for most driving situations. If you make a move to 33-inch tires I'd suggest 4.56 gears. The 4.88 gears paired with 33s will give you great low-end gearing for trail use but will be too low for comfortable street/highway use. What will the lower gears do? You likely noticed a slight drop in acceleration when the 31-inch tires replaced the OE fitment. Lower (numerically higher) axle gears will improve acceleration and help out in hill climbs, especially when taller tires are installed. Be advised that your top highway speed will come at a higher rpm. For example, you indicated that you run 65 mph at 2,700 rpm with 4.10 gears and 31s. If you kept the 31s and installed 4.56 gears you'd run 65 mph at about 3,200 rpm. A move to 33s and 4.56 gears puts you at 65 mph at about 3,000 rpm.
Concerning skid plates and belly pans for your 4Runner, check out All-Pro Off-Road [(951) 658-7077, allprooffroad.com] and BudBuilt [(828) 572-1202, budbuilt.com]. I wasn't able to track down a fuel tank skid plate for your model 4Runner but All-Pro offers a stout transfer case skid plate and crossmember, and BudBuilt has IFS skid plates and full-coverage belly pans. Hope this helps. 'Wheel on.