Help chasing pulsing groaning sound Topic is solved

[LAV70R]

First time I’ve heard of this: three and a half hopefully easy questions:

(1 & 1.5) I take it there’s no way to find out if this is indeed the issue without opening the transmission—is that correct? Similarly, replacing and shimming the new bearing requires installation from the j side as opposed to externally correct?

(2) You might have hit the nail on the head: the wub wub sounds are at a much lower frequency than the wheel rotation—if the outer race is indeed spinning, then it would rotate at a fraction of the speed of the inner race… does my logic align with yours?

(3) Finally, would this problem be consistent with the sounds/ I rations only occurring when the driver-side of the car is under load (assuming it’s the driver-side axle bearing in the transmission that’s no longer shimmed)?

Thank you so much in advance!

As Vova indicated, it cut could be the worn splines in collar slave + angle gear.

In my case it was a slack in transmission's final drive / differential preload. I got rid of it only by rebuilding the transmission. Over time / miles preload shims get crushed into transmission's case, the free play lets the axle walk away and become non-coaxial so lightly. This puts load on one spot of the bearing race, it finally picks up and grinds through the case, accelerating wear and wub-wub-wub noises.

I saw another AW55, with twice less miles, and it had the first signs of the spinning bearing race. The transmission guy who made dozens of them, said it is a very common problem. They all do it, just give it enough time.


Screenshot at 2025-07-31 09-24-37.png

[vtl]

Imagine the differential that can tilt away. The final drive teeth no longer make a good contact, you get a bad differential noise.

Also this affects the B4 drum, it is tilted vs the B4 drum brake. B4 servo piston now has to travel more in order to engage the brake, and that's why 2-3 and 4-3 often feel delayed and soft, sometimes even with the engine flaring.

[LAV70R]

Solved! Despite the problems happening on right turns, after replacing driverside lca, bearings x2, and all tie rods and end links, I started looking for a new angle gear but replaced the passenger side front wheel bearing—and it drives like new again!