Toyota-Lexus-Scion: Axles (front)/CV Joints and Boots
Toyota- Lexus-Scion: Axles (front)/CV Joints and Boots The front axles (and some rear axles with independent rear suspension) have flexible joints on the inner and outer ends of the axles to allow your wheels to get power smoothly even while going around corners or when going up and down relative to the vehicle.
A rubber boot encases each of the joints. This rubber boot is intended to protect the constant-velocity joint from losing its grease and from being damaged by water or road dust.
Eventually, after flexing through millions of rotations, these boots tend to crack and split open. When this happens, if the axle joint is still good, we routinely replace the boots and repack the joints with fresh grease. As long as the boots are intact, the original Toyota joints tend to hold up so well that I prefer replacing the boots to replacing the entire axle. When the boot cracks and splits open, the grease gets flung out and it exposes the joint to the possibility of being contaminated with water and grit which invites wear. Even in this situation, the joint can often be cleaned, relubed, and rebooted if it hasn’t been split open for too long. On original axles—even with 150k to 200k miles—I would routinely expect to get more miles out of rebooting the original axle than replacing it with an aftermarke one as long as the original axle hasn’t gone without grease.
If the joint has been damaged, then the entire axle needs to be replaced. When it’s the outer joint that is damaged, it tends to variously make a cyclic clicking, or knocking, or grinding, or creaking noise when going through sharp turns. When it’s the inner joint that is bad, most often the symptom will be a heavy vibration felt on straight line acceleration. When they’re available, we have a strong preference for using Toyota remanufactured axles. The only part that is being reused is the axle shaft. The joints are new and last as long as the original, which is far longer than can be anticipated from the aftermarket axles we’ve encountered—either new aftermarket or remanufactured. By way of example, we recently had a customer come in with both axles fully symptomatic and badly worn that had been replaced with non-Toyota parts at a major tire chain just a year and a half ago. They only had 26 thousand miles.
As the damage to the axle joint progresses, it can eventually impair your ability to corner safely. Although rare, in extreme cases it can even break. When the axle breaks, at minimum the car abruptly loses power to the wheels and won’t drive. Sometimes it can damage other surrounding parts. A friend of mine once had an axle break and it ripped loose his brake lines so that he simultaneously lost the ability either to accelerate or brake. He had just come down out of the Pyrenees Mountains—off a steep, winding road that ran along cliff’s edge—and out onto a level, relatively safe place to have it happen. Whew! Close call.
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