The brief
The A1 had given the owner two small clues, neither dramatic on its own.
The first was a faint clicking sound on slow tight turns. The kind of noise you would only catch if you had the window down at a junction.
The second was a grease patch on the floor where the car parked overnight. No bigger than a coin, but consistent enough that the owner had noticed it across a fortnight.
Those two together point at one thing: a torn driveshaft boot, leaking the joint's lifetime grease, and starting to let road dirt in.
Caught early like this, it is a small job. The boot replaces, the joint cleans up, and the shaft gets another full service life. Left for another few months, the grit working into the joint chews up the bearing surfaces, and then you are replacing the whole driveshaft, which is a much bigger job and a much bigger bill.
The diagnosis
Up on the lift, the underbody told the rest of the story. The outer driveshaft boot on one side had split along a fold line, and grease had been flung in a thin film across the underbody where the rotation had thrown it outward.
Road dirt was already working its way into the CV joint through the split.
We levered the joint by hand to feel for play and to rotate it through its full travel. No measurable looseness, and the joint moved smoothly the whole way through. That meant the joint itself was still serviceable, which is the result you want: it tells you the leak was caught in time.
So the call was boot replacement, full clean of the joint, fresh grease, and a careful look at the inner boot on the same shaft to make sure it had not gone the same way.
The work
Wheel off first, then the lower ball joint disconnected from the knuckle, which gives enough swing for the outer half-shaft to pull clear.
With the joint on the bench, we cleaned out the old grease and the road grit using a solvent wash. Then we inspected the ball cage, the inner race, and the bearing track for pitting or wear. Everything came back within reuse spec, which confirmed the early diagnosis.
New boot kit next. The new boot comes with a measured charge of the correct CV grease, which matters: too little and the joint runs dry in one spot, too much and the boot balloons and tears itself open from the inside. The right amount is the manufacturer's amount.
We pulled the new boot onto the shaft with its proper compression bands, reassembled the joint into the shaft, refitted everything in reverse order, and torqued the axle nut and the ball joint to spec.
The outcome
No clicking on tight turns at slow speed. No grease on the underbody. The boot seating cleanly and sealing properly at both ends.
We took it for a road test through a route with plenty of tight turns, since CV-joint noise shows itself fastest under low speed and full steering lock. The joint stayed silent across both lock directions.
The A1 went home with the driveshaft sealed for another full service life, and the joint saved from the much more involved replacement it would have needed if the leak had been ignored for another few months.
For the owner, this is the right outcome of paying attention to the small clues early. A low-cost repair instead of a high-cost one.