Author: Scott Wilson - swilson@off-road.com August 1999

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30 degree Ramp When preparing a vehicle for rock crawling, wheel travel should be one of the biggest areas of attention.  Significant wheel travel will allow the vehicle to keep all four wheels on the ground while going over very challenging terrain.  Keeping all of the wheels on the ground translates to safer wheeling, more maneuverability, and a more stable vehicle. Our 88 4Runner project vehicle is being built with trails like Rubicon in mind, so wheel travel is an important consideration for me when deciding how I will build the vehicle.  In 1986 Toyota began selling all of its pickups and 4Runners with IFS (Independent Front Suspension).  Previous model years have solid axle suspension front and rear.  While providing superior on-road handling and greatly improved comfort levels over washboard roads and broken pavement, the IFS offers little wheel travel.  When four wheeling a Toyota with IFS through difficult terrain, lifting a front wheel is common, and often unavoidable.  When Toyota began using IFS on the front of their trucks, in addition to wheel travel, component strength took a small hit.  To save space Toyota used a 7.5" differential instead of their proven 8" design.  A smaller diameter ring gear translates to a weaker ring gear, so 7.5" failures are more common than 8" failures.  The axles from the straight axle design are replaced with smaller diameter axles with flanges for the CV axles to bolt to, and the birfields are replaced with CV joints.  Having the flange break off the inner axles and having CV joints break are common failures for Toyota IFS trucks. The only locking differentials currently available for the Toyota 7.5" assembly are the Detroit EZ Locker and LockRite. These lockers are both automatic lockers.  Having an automatic locker in the front axle of your truck will limit maneuverability any time you're turning in 4WD because it reduces your turning radius.  I have always wanted an ARB locker in the front of my truck for the improved maneuverability and reduced stress on the front axles,  but since a 7.5" ARB is not available, that was never an option.  With a Toyota straight axle in the front, the front and rear axles are each using 8" 3rd members and many more lockers are available in this size, including the ARB. Toyota IFS is by no means 'weak'.  Depending on your driving style and choice of terrain the Toyota IFS truck may serve you very well.  My IFS 4Runner served me without failure for nearly three years.  My choice of terrain was constantly becoming more aggressive and I knew that I would soon run into the failures that come with pushing the IFS too hard.  The Toyota straight axle design offered more wheel travel and the axles have a lower failure rate.  I weighed the performance differences between the IFS and straight axle and I decided to make the switch. On my last 4 wheeling trip before the axle swap I was climbing one of the waterfalls on Tank Trap (Hollister Hills trail made famous by the yearly Tough Truck Challenge) when I broke the flange off of one of the inner axles.  I began backing the truck out of the trail in 3wd and only 5 feet from the trail head I broke the opposite side CV joint. A humorous end to the IFS components.