I think I found the source of the groan...

[john baldwin]

Rear wheel bearing-drivers side.

Engine drop, trailing arm out, hydraulic press to remove outer race.
Looks like the inner seal on the bearing failed...it had deteriorated pretty badly. Major pitting in just that one spot on the outer race on the inside of the trailing arm.
On to the next side...

[DRACO A5OG]

Classic

[steely]

ya wouldn't of happened to recorded the sound, would ya?
good luck with that effort, and thanks for posting

[john baldwin]

Dan,
Sorry, no...all I know is that I could no longer drive the car...it had suddenly become such a low frequency, constant drone that it was hurting my head.
Do you suspect a bearing gone bad?
What's strange is that the drone started only when turning right, but then steadily progressed to the point where the noise was constant when driving straight ahead. Given that the pitting seen here was on the inside of the outer race, meaning the part facing the center of the car, I wonder if the lateral loads when turning right compressed the ball bearings against this pitted surface and caused the noise.
Anyway, will post pics of the passenger-side (starboard-side) bearing when that's out soon.
John

[porschenut]

John, did the frequency or volume of the drone increase/decrease according to speed? And, before it became constant, did it happen more often at slow speed or fast?

[john baldwin]

Dave,
The frequency didn't change, but the volume certainly did. IIRC, by 40 mph it was loud enough to be uncomfortable...with or without the top (Targa). Below 40, I didn't hear it so much, but suspected it was there.
Before the drone became constant, it happened turning right no matter what the speed.
Hope this helps...suspect you're facing a similar problem?

[Jdub]

Did this car sit for some time, in rainy or wet weather? Looks like a concentration of corrosives at the "bottom" section (4 to 8 o'clock) of a sitting bearing.

[john baldwin]

Jdub,
I suspect it did; 2 of the PO's (I'm the 4th) were located on the Florida coasts....(salt air?) The groaning in the turns has always been there; didn't notice it on the test drives (I guess I was too giddy with anticipation) and it didn't reveal itself when on the lift at PPI (rotating an unloaded wheel) or later when I had it up on another lift with a stethoscope on the trailing arms.

[Jerome74911S]

My left rear bearing is a bit loose, but no noise yet. Did you notice looseness before hearing the groan/drone? Mainly I groan as I look into my wallet when this stuff comes up. A bearing is only ~$40, but it adds up.

[john baldwin]

Jerome,
No looseness when I had it up on the lift...did the top and bottom rock test, all seemed tight. Just before this drop/ removal, I tested again, this time on jack stands and same result...all was tight.

I think what it comes down to is a lack of certain symptoms does not mean the bearing is healthy...just that it's failing for a different reason!

I was actually relieved when I saw the pitting you see in the photo...I was worried (due to the lack of the other classic symptoms) that the groaning can from somewhere else and all the effort to drop the engine, remove the trailing arms and press out the race was going to reveal a healthy bearing!

[john baldwin]

Outer race looks in fine shape...grease was ugly. Glad I pulled it anyway.
Softest Scotchbrite to clean up inside of trailing arm...FAG bearings should be plenty cold....warm up the TA with a torch and hope it just "drops in".

[rusnak]

I just did a rear wheel bearing replacement yesterday.

I must say, with the Sir Tools puller, it's an hour job from start to finish. A couple of pointers - make sure to support the outer race when you press the bearing into the rear trailing arm. I used a tiny bit of heat (200F) on the trailing arm, and froze the bearing. It pressed in with hand pressure until about half way. When you press the stub axle in, be sure to support the inner race. A large thick washer will do it, just be sure that it presses firmly against the inner race. Also, the SKF bearing seems to fit better than the FAG. I recommend the SKF for replacement.

You can remove and replace the "hat" (parking brake backing plate) with the springs and brake shoes all in one assembly. This saves you from having to mess with the 4 springs, etc. and possibly losing parts. Be dang sure to put the "hat" back on as well as the cover plate w 4 bolts before you press the stub axle back on. You must tighten the axle nut to spec. I forget what it is, maybe 400 lbs or so. I stand on the end of my 3/4" wrench handle, and with my body weight, get it really tight.

Edit: Do not use the hydraulic press for the stub axle installation unless you can support the inner race. I would use a threaded rod and some washers.