19psi

well, they are, but IFS is just inherently weaker than a straight axle. when i worked at lexus, i remember replacing 2 front diffs on the 100's. ring gears just shattered from driving on a dirt road. of course the customer might have been doing more than that and using way too much throttle....never had any problems on the old straight axle 80 series though or the rear axles on any series for that matter.

Hoser

IMO, the front diff is really the only notable component on the 100 that was not overbuilt. It's a compromise between ride comfort/handling vs strength. I've driven a 105 (straight axle 100) and I'D be fine with its ride comfort. Others might not.

motohide

Overbuilt, yes to a certain extent. Like drift cars on the track the same idea applies here. That is, the LSD's and lockers as well as shafts and joints, and teeth on a diff/transmission can take well in excess of the sheer horsepower and torque these moden V8 and turbodiesel trucks can render on them. That isn't really the issue. However, with the advent of AWD and VSC systems electronically doing the traditional job of locking and unlocking as well as additing brakes to spinning wheels, the actuation is much more busy and repetitive in the department of lock/unlock cycles. What happens is that sheer inertial mass of flywheels and heavy tire/wheel suddenly engaging and disengaging is like taking a jackhammer to the drivelines on really rough terrain that does have grip in engaged tires and not on floating tires. This driveline shock is what really kills the joints and gear teeth on modern AWD systems like those on the GX and LX.

With fully engaged air locked or manually locked TRUE locked up 4WD, the constant lock/unlock cycle is non existent and the only driveline shock is from the driver inputs and the engine power. So the axles and gears can survive a much more even shock, and none of the busy hammering that the electronic systems give on these extreme loads and terrain.

motohide

Oh excuse me, what I meant to mention with analogies to drifting cars, is that driveline shock is similar when pro-drifters kick the clutch repeatedly with high grip road tires... That kills the drive-train much more often than crazy power those high strung turbocharged engines make. Flywheel inertial forces being much more the death force, than the sheer power output.