I need to replace the rear wheel bearing/hub assembly on my '99 EX (4-cyl) and looking at RockAuto, for example, I've many, many options:

1999 HONDA ACCORD Wheel Bearing & Hub Assembly

The Honda p/n is 42200-S84-C51 and the first (and least-expensive) one that matches is this Timken unit: More Information for TIMKEN 512178. There's a few less expensive options, but I won't go below the $50 mark (there's a Raybestos at $50.99). I'm not confident it's a match though since they don't cross-reference the Honda p/n.

Best to stick with the Timken unit I mentioned ?

Next is the spindle nut. The ones at RockAuto, none cross-reference the Honda p/n, 90305-S30-003, by the way, all say they're for the FRONT. Does RockAuto simply not have the rear spindle nut ?

 

I used a Timken bearing on my front knuckle of the TSX and have had no problems.

The front and rear spindle nut have different OEM part numbers, so there is probably a difference. You may want to buy this at the dealership. It looks like it will cost around $4.

 

Yeah, that's what I am starting to think as well (for the spindle nut).

I also went direct to Raybesto's website and input my car's details and it's saying p/n 712178 is their part (Wheel Hub & Bearing Assembly, Professional Grade; 4 Cyl; Rear Disc Brakes; 2 Per Car) and I can get that through Amazon for $46.33/ea. The Timken is even more at Amazon than from RockAuto.

Ever heard of Callahan or Detroit Axle ? $25 and $26 for their versions... Nah, never mind....

Timken is a very reputable bearing manufacturer. I used to work for a pump manufacturer and these type of pumps ran for decades. You only had to worry about two things failing: the shaft seal and the shaft bearings. We used SKF, Timken, etc as OEM parts.

 

It looks like the Timken part is $68 for your car. You will have to make the call for the $18 difference between the Raybestos and the Timken part. Ebay is another source, but you may get a cheap knock-off part too.

Here is a video on how to do the repair. This is for an Acura RL, but will be similar to your accord.

 

Doesn't look like to bad of a job. I certainly don't have a 32mm wrench/socket (pretty sure that's the size for my vehicle) but my son-in-law has access to them and has changed these before. Of course, with my luck, I'll have a similar seized-on bearing race like the buy in the video !

I also did the swerve test (roads were wet this morning so I was kinda gentle about it) and it seems like the noise occurs when I go left. That means it's the left-wheel bearing, if I'm not mistaken (the load is reduced on the right-rear when you go left, correct ?).

 

Wheel bearing noise can travel unexpectedly. The best way to pinpoint a bad bearing is to lift the car up and spin the wheels. For the front you can just get the front end up on jackstands and let the car idle in drive. Rears it helps to spin the wheel with an impact wrench. Then listen to each bearing using a long screwdriver or whatever to your ear.

Last time I bought a Timken front wheel bearing I opened the box and the part was marked NSK, which is probably Honda's OEM for the bearing.

nsk(dot)com/company/history/

 

I usually don't bash parts, but the Centric 406.40015E only lasted 6 months. Don't buy that one.
Also, I did see that you can test for the bad bearing by amplifying the vibration. Raise the wheel in question, and when spinning the wheel off the ground, test for vibration on the spring, the vibration of the bad bearing is transmitted up to the shock assembly.

 

What is "Centric" ? If it's one of the sub-$50 ones from RockAuto, I'm not even considering them.... It will be Raybestos, Timken, Moog, etc (leaning back towards the Timken at this point). It's $68 + almost $10 shipping from RockAuto or $76 with $0 shipping from Amazon.

 

And there's always a 5% discount code for RockAuto.

 

Timken is the best brand.
If it's not available, I would use MOOG
Advance Auto Parts has the Moog $75.99 - $20.00 with coupon code TRT25.
Pick up in store.