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FWD issues

2012 Mazda5 Touring; 2016 Mazda3 Sport
So, we've been having some fun learning experiences working through the FWD system on our 2012 "5", replacing things that look bad, and will hopefully eventually fix the annoying noise that got us tearing into the thing in the first place. Not terribly relevant, but I'm super irritated at having invested $20,000 on a brand new car that's now (at 75k miles) needing repairs like any other aging car, but considering that my '87 Colony Park ($4000 used in 1997) puked its transmission at 85k original miles and 10 years old, and I was never able to change the spark plugs on my '90 Cutlass Calais International Series ($3000 used in 1996) because they were permanently seized to the head at 90k miles, maybe that's not entirely justified. The 5 still drives great aside from needing (I'm 95% sure) camber/caster adjustment, which the dealer failed to perform when I had it aligned there a while back. I just saw someone selling adjustable lower balljoints, which might be a more convenient option than offset bolts or even camber-only alignment plates .........

Anyway, The ongoing noise is kind of a whirring/buzzing that is consistent with road speed and not related to steering or throttle input.

The first bad part I found was the left front wheel bearing, which was not surprising as I had bought used complete spindles when I did the brakes two years ago and couldn't get the rotors off. (Maybe I could have cut the rotors off? Too late now.) The wheel bearing had lots of play, so we bought a new hub/bearing kit at NAPA and changed it out. Had to chase down my local machine shop, which had relocated since I'd last needed them, and $60 for pressing the bearing hurt a bit, but it was done and our problem was fixed!

Or not. It kept up, and even seemed to gain a floppy tone. An inspection looking specifically for noise found noise coming only from the right inner CV boot, and I found grease escaping from both inner CV boots. I just got around to replacing the boots last week (big thanks to the guys on the What Are You Working On thread!), so now it's all fixed!

Or not. The noise is now more of a pure whir/buzz/whine. Now I'm wondering about the intermediate shaft bearing, and also figuring I should do the right front wheel bearing for good measure, since it probably has the same miles as the left front that was floppy. Unless an inner CV joint is bad despite looking fine on the bench, these should be the last two pieces to the puzzle unless there's something weird in the transaxle.

I was distressed to find that the intermediate shaft bearings are very hard to come by, but then I found this thread:

as well as these sources that claim to sell intermediate shaft parts:

Parts Geek

Anyone have experience with these sources?

If anyone's worked on the intermediate shaft, was removing and replacing the bearing something you could do with hand tools, or did it have to be done on a hydraulic press?

Any random advice for working on FWD stuff? My only previous experience living with FWD long term was with our '03 Cavalier, which when we traded it was well on its way to rusting in half without anything up front looking questionable except for some weeping from the axle seals.
2010 Mazda 5 Sport
This is the way I always look at these kind of things: If everything looks ok underneath for the important stuff like wheel bearings, etc. Fluids all look good, no leaks...just drive her until something breaks. :)

I've driven many a car a lot of miles with a weird sound. Usually something gets worn to the point you find it.

If it really bothers you, I'd roll it into a shop and pay a diagnostic fee and see what they say.

I do think a sound like that is going to be a bearing of some sort.
2012 Mazda5 Touring; 2016 Mazda3 Sport
So ..... any input on Parts Geek or Zoomzoomnationparts?

Any experience on whether intermediate shaft bearings are a benchtop job or require a shop press?
Ottawa, Ontario
17 Mazda 6 GT
I don't really know the Mazda 5, but if I'm not mistaken, it was a joint venture with Ford, so the underpinnings should be the same as the C-max, no?
Maybe you can search for parts under the Ford banner?
2012 Mazda5 Touring; 2016 Mazda3 Sport
The only C-max sold here (that I've ever been able to find out about) was the high roof five seat hybrid. The UK market Grand C-max seems to have been very similar to the 5, and could be a parts source, provided it was offered with the same 5 speed automatic transaxle. That would take a little research to verify ....

The Fusion and Focus, along with the 6 and 3, are very popular here, but at present I have no exact interchange info.
2012 Mazda5 Touring; 2016 Mazda3 Sport
And we're back working on it!

To recap, last summer/fall (2020) I noticed a whirring noise while driving and replaced the left front wheel bearing. Then it seemed there was a slight floppy sound, and I found that the inboard CV boots were leaking a bit of grease, so I replaced them. Whirring noise continued.

Fast-forward, and as of a couple weeks ago (Sept. 2021), the whirring had progressed to a very noticable grinding noise that even my mostly-deaf mom could hear, that very clearly went away (or at least changed) with maybe a couple of degrees' steering input to the left. Just last week I replaced both left and right drive axles and the right front wheel bearing.

So ... both CV axles (drive axles) and both front wheel bearings are all new.

Good news: the grinding sound is gone. Bad news: There's a slight shudder when accelerating, that turns into a loud TAP-TAP-TAP-TAP-TAP sound when lifting off the gas. Sound gets a little quieter when completely off the gas and when coasting in Neutral. Symptoms persist everywhere between 30 and 70mph.

As of maybe an hour ago, inspecting from underneath with the transaxle in both Neutral and Park, there's no noise from any of the CV joints or the carrier bearing, slight scuffing sounds from both front brakes (as I would expect), and a sloppy klunk from the diff when changing wheel direction

Thinking it might be time to pay an actual mechanic to do some digging and tell me what's wrong.
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2012 Mazda5 Touring; 2016 Mazda3 Sport
So! Turned out the culprit was the new left axle!

A user at grandmarq.net told me to Google complaints about new bad axles from the supplier I chose. I bought my axles from NAPA, and I found mixed reviews for their stuff on various message boards. Some people have had great luck with their axles, and others have found them the least reliable of any brand.

Since I actually replaced the left axle first, then ordered the right axle and bearing for delivery the next day after finding it hadn't fixed the grinding, I just went out and swapped the original left axle back in. The grinding is still gone, and so is the clunking! (y)
2012 Mazda5 Touring; 2016 Mazda3 Sport
I will be taking that advice into account in the future.

One more question for now: Any experience with a new CV joint shuddering a bit for a while and then smoothing out?