A clunk when you shift into gear or a vibration that comes on under acceleration in 4WD often traces back to a worn front driveshaft U-joint. On the 5th gen 4Runner the front shaft only spins in 4WD, so the joints can quietly seize from sitting dry. A single greasable U-joint is about $25; the whole shaft is around $300 if a joint has already failed and damaged the slip yoke.
Because the 4Runner is part-time 4WD up front, the front driveshaft sits still in 2WD daily driving and only turns when you engage 4HI or 4LO. That's a recipe for U-joints that rust and stiffen from disuse, then fail the first hard trail day of the season. The classic symptoms are a driveline clunk on engagement, a vibration that builds with throttle in 4WD, or a rust-colored powder around the joint caps from a dried-out, fretting bearing.
You can service the U-joint if the shaft itself is straight and the slip yoke is good — that's the cheap, satisfying fix. If a joint has already let go and chewed the yoke ears, you're into a full shaft. This is intermediate work that rewards patience: pressing U-joints without a proper press or vise setup is where people destroy a yoke.
A metric socket set and torque wrench, a U-joint press (a bench vise and sockets work in a pinch), snap ring pliers, and a grease gun. A Spicer greasable U-joint sized for the front shaft, or a complete OEM/Aisin front driveshaft if replacing the whole assembly. A pry bar helps free the shaft from the flanges.
1. Mark the shaft-to-flange orientation at both ends so it goes back in the same clock position (balance)
2. Unbolt the shaft from the transfer case and front diff flanges and remove it
3. Remove the snap rings and press the old U-joint out of the yoke
4. Clean the yoke bores, press the new joint in square, and seat fresh snap rings
5. Grease the new joint until clean grease purges from all four caps
6. Reinstall the shaft in the marked orientation and torque the flange bolts to spec
7. Test in 4WD on a quiet surface and confirm the clunk and vibration are gone
Press the joint in square — cocking it cracks a cap or galls the bearing and you'll feel it as a new vibration. Keep the needle bearings seated when you assemble; a dropped needle means a tight or notchy joint. Reinstall the shaft in its original clock position or you can introduce a balance vibration. And going forward, exercise 4WD periodically and grease the joint at service intervals so it doesn't seize from disuse again. If the vibration persists after a good joint, suspect a bent shaft and move to the full assembly.
A quality greasable Spicer U-joint is about $25; a press rental is free at most parts stores. A complete OEM front shaft runs around $300. A shop will charge $150–$250 labor to press a joint, more to swap a full shaft. The DIY U-joint route is the standout value here — most front-shaft complaints are one $25 part and an afternoon.
| Part | Vendor | Est. price |
|---|---|---|
| Spicer Greasable U-Joint (front shaft) | Spicer | ~$25 |
| Aisin / OEM Front Driveshaft Assembly | Toyota / Aisin | ~$300 |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.