Drive Shaft Games: Fun & Education

Hello,
I would like to hear your opinions on this.
Vehicle: Audi 80 B4, year 1994, 1.9L engine, front-wheel drive, drive shafts with internal tripod joints.
Both waves are noticeable and audible when the vehicle is stationary and the steering wheel is straight.
- Longitudinal play,
- Rotating game,
- the right wave also has some radial play.
It's clearly visible on the right side, and just starting to appear on the left. I moved the waves laterally with one or two hands. I haven't been able to access the gear side yet.
Complaints during driving: Steering instability when driving straight at speeds of approximately 40 km/h or higher, with a "pulsating" sensation when turning slightly. The steering wheel slightly drifts to the right with this "pulsation." Steering instability around 100 km/h. No or minimal vertical play.
The mileage for both drive shafts is 360,000 km. I replaced the boots on the inside and outside approximately 50,000 km ago, and re-greased the bearings at that time. I can rule out a manufacturing error (such as a faulty coil spring on the outer joint or incorrect torque).
In both longitudinal and rotational play, it's likely that both outer joints would be damaged.
To check the internal joints, I thought about checking the shaft and housing against each other at the transmission flange for play, as they are supposed to have some axial play. But does it still make sense to leave the internal joints in place?
hg
Herbert.

In my experience, tripod joints usually last forever. I have never had a defective tripod joint in the workshop, not even in Passats and Audi A6 models with mileage exceeding 400,000 km. Even in the 1998 A6 with currently 518,000 km, the original ones are still in place. However, the outer ones are already on their second set.

"Thank you!"
So, the first step is to simply change the direction of travel to the outside, while of course checking the inside.
"On my Passat, they lasted longer."
hg
Herbert.

Based on the error description, I would suspect a problem with the inner joint.
Try swapping the orientation of the inner joints (right to left and vice versa). It's a bit of a makeshift solution, but it might help with troubleshooting without having to spend a lot of money right away.

Hi Herbert, assuming I wanted to keep the gearbox for a longer time before having to replace all the joints one by one, I would get 2 complete drive shafts, which would cost me the same as 4 individual joints. But that would be a great solution in the long run.
When disassembling, you would need to clean the individual joints after removing the seals and grease, inspect the edges in the ball track, then determine which joint is the cause of the problem and only replace that one. This would be a more cost-effective approach.
After a pulsating sensation, there's a cracking sound in the steering when turning and accelerating.

Hi,
Thank you again for the answers.
"@ Goettman - Yes, for constant velocity joints on the inner side. However, it's not really possible with tripod joints, as the shaft is a single unit. You can technically remove them (the repair kit includes the inner cover and retaining ring), but then you'll be mixing the joint components from the left and right sides. It won't improve anything by doing that."
I'm going to check the prices for a complete axle and the outer joint separately, but I didn't want to completely ignore Michael's experience. This Audi is in excellent condition, the first owner, and the goal is to reach 500,000 km. I'll never find another car like this again.
hg
Herbert.

Hi,
Here's the complete status after inspecting the inner joints (the vehicle is still on its wheels and aligned straight). Checking for play is a bit more difficult here, as it involves considering the axial and tilt play of the flange shafts.
On the left side, there appears to be some play or looseness in the ball joint (it's not entirely clear). On the right side, there is no noticeable play, but I couldn't grip the joint as firmly because the heat shield wasn't removed.
The gameplay on both sides is similar to what was described earlier.
My conclusion:
Axial play in both waves, rotational play on both outer sides, radial play on the left outer side: outer joints are defective.
Playing joint, inner left side: also defective.
Or am I wrong?
@Goettmann - You already mentioned an internal joint in response to my first message. What led you to that conclusion?
Thank you for your help.
Herbert.

Hello,
Finally, here is the repair report.
After disassembly, the right side bearing showed noticeable play in the outer joint, with almost a grinding sensation. In my opinion, it was moderately worn. When shifting the inner joint under pressure towards the load side, a slight unevenness was felt.
The left wave had a small amount of play on the outside, only slightly worse than the AT wave. The inner joint was the same as the right one.
Since I needed the car to be drivable again immediately, I bought two new tie rod ends before removing the old ones, and of course, I installed them. The steering issues at low speeds are largely gone.
In retrospect, a reliable inspection of the shafts is only possible when they are fully assembled. If there is no time pressure, one can then decide to only replace the clearly defective joint, depending on the planned remaining operating life.
hg
Herbert.