Hey everyone, just making this post so people on google can easily fine this.
I've owned my 2011 RDX SH-AWD since 2013, it currently has around 200,000 km on it. Hondata tuned since 100,000 km.

For the last few years I've had a mystery vibration during acceleration that no shop has been able to diagnose. Based on my research it seems the bearings in the axels go bad and vibrate during acceleration but seem fine during a visual inspection. The part numbers are as follows:

Drive Shaft Left: 44306-STK-A01
Drive Shaft Right: 44305-STK-A01

Replacing both of these fixed my issue. Car feels 10 years newer!

 

If you still have the old axles and inspect the inner joint cups you'll find one or more pitted areas, this is a spalling failure and what causes the axle(s) to vibrate. It's usually just one axle causing the vibration but you can't determine which axle unless you disassemble the inner joints and inspect. It's possible an externally mounted camera viewing the axles during driving may help detect which side is the problem. The vibration isn't an up/down vibration it's a sideways force on the axle as it rotates type vibration. The tri-pod bearings in the inner joint that slide within the cup as the axle rotates get stuck in the pitted area like a detent and put a sideway force on the axle.

 

At what speed was the vibration, and how severe is it? Does it get worse when you are turning/on ramp?

I think I have the same issue, and the shop I took it too thinks it's early bearing failure.

Would hate to replace the bearings to not solve the issue. But not sure if it's the axle or not.

Interestingly the dealer replaced my axle around 110KM under warranty; it was in the shop for something else but they replaced this on their own without me complaining about it.

Car now has 240KM however, so I guess it could have failed.

 

Thanks for info! Mine is starting to shake during higher speed only on gas