All,
About a year ago, I replaced a driver's front wheel bearing (the whole hub assy.) with a new-in-the-box part. A week ago, I needed to remove the hub to install brake ducts, and opened the bearing seal cap to find alot of grease flung all inside the space between the cap and the bearings (about an inch deep).

Then I looked, and while the rear of the bearing (the rear that rests against the spindle flange) is sealed, the inner race (under the cap) isn't... you can see the ball bearings exposed.

I opened the passenger side, which is a factory original, and the race inside the cap is indeed sealed, just like the backside... and as you'd imagine, there's alot less grease flung out from centrifugal force, even though it's 100k and 15 years old instead of 5k and 1 yr.

So, I bought two brand new ones from Ray at Malloy, and they're unsealed too! Did Mazda cheap out and stop using a bearing seal? If so, no wonder they don't last after you fling all of the grease out of them.

 

Here's the comparison... note the bearing sheild visible in the old hub, and visible bearings (no sheild) in the new

 

I see no difference. There is no need for an outer seal, the cap does that job just fine.

 

^^^^

Do you mean you see no FUNCTIONAL difference, or no ACTUAL difference? There's clearly a sheild in the first photo, whereas i've circled the visible ***** in the 2nd.

There's about an inch space between the bearing face and the cap, so the centrifugal force flings the grease off of the bearings, and into that 1" worth of space.

 

It's an interesting question.

Generally speaking, bearings need a lot less grease to function 100% than it would appear. In fact if you retain a whole lot of grease in a bearing the temperatures will go way up. (Which is why packing a bearing with grease is not about getting as much grease in there as possible) As long as there is SOME grease in the bearing during operation it should be quite happy.

So while I can't comment on the intent of Mazda's design and apparent change in bearings, I can say that if there is still some grease in the bearing itself you have little reason to worry.

I do have a question though - in both pics it looks like I can see some rollers. Is that true?

Dave

 

So pack in some more grease. might be messy, but if it is all sealed, the you are good to go.

 

I replaced both front hub assemblies about 5 years ago at about 100000 miles, the bearings were sealed just like the original ones.

 

^^^^

They must've changed it... cheap bastards... they SHOULD be sealed.

 

Well, the year old one (not pictured) already has a little wiggle like the 100k mile one, so draw your own conclusion.

What do you mean "rollers"?

 

This might be a dumb question, but is there a way to reuse the original bearing assembly?

I was planning on doing new front bearings in the next month or so.

 

About a month ago I had a ticking noise coming from both front wheel bearings. both were w/o front seals, just rears. was surprised about how little grease was packed in, there was no mess on the nut side either.

There isn't much one can do with a ticking bearing, replace it or wait for it to fail. I chose to wait but I thought it a good idea to pack grease in it by pressing two rubber chair leg glides (the kind typically found on crutches) sandwiching in some grease between the bearings. When I was done, I found more drag on the vehicle from the extra grease. the car also pulled to one side, I probably did not apply equal amounts of grease. It did stop the ticking for a couple of days, but its back. Likewise the pull went away too. I suppose the grease is flung about under the cap.

Interesting that too much grease can slow the vehicle down and cause pull, I didnt think about retaining heat.

re:rollers, I think he means the needle bearings.

 

Peter, I think it would be easier to see if the axle nut in the first photo was removed. The flange on the nut is covering the seal.

 

The flange actually isn't covering the seal... it's the same diameter as the inner bearing race.... the seal is the flat peace of metal running all the way around that I circled (it's like a flat ring)... it is partially obscured with all of the old burnt up grease though...

 

Called Ray at Malloy back, and he confirmed that Mazda DID change the design. His drawing shows a washer behind the spindle nut, but he didn't think it would be large enough diameter to retain grease. My hubs (factory original or new) have no washers whatsoever. Anybody else have 'em?

He's calling Mazda Tech to see what's up.

 

mine had large washer, probably sufficient for sealing grease.

only one wheel is clicking.

 

You should always have a washer in between the bearing and the axle nut to keep the bearing seated in the race of the hub. Proper torque is very critical of that bearing nut to prevent premature wear on the bearings.

 

^^^^

Actually, I talked to Ray again later, and there is no washer for the front. Only the rear.

 

Sorry, I wasn't clear. I meant that I see no difference between the two photos AND that I don't see a need for a seal anyways.

Most of the wheel bearings that I take apart don't have an outer seal, they just have a bunch of grease packed in and a cap on it.

Are you replacing the bearings because they get slop in them? If so, you probably just need to tighten them. I made the same mistake with my FC.

A method that I find very effective is to tighten the hub bolt snug, then give the hub a few rotations. Repeat tightening, then spinning until you can not take out any more slack (using medium/light force on your ratchet). I'm talking ~15-18 ft/lbs.

 

Well Peter you could just buy some big *** washers and cover over the open end.
Seriously though you could take some measurements and see if you can just find the correct size bearing with the cover elsewhere maybe not through Mazda. I am sure it's a metric standard.

 

Yup, I could, as I gather they are a standard size, but then there would be the small matter of extracting the old ones, and pressing a new sit in. I don't think that's a hammer and screwdriver job... they were put in with a press.

 

If you can't see the difference, sorry, but you need to look closer. You'll note that in the "new" pic I actially circled the individual ball bearings that are visible. In the "old" pic, there are no ***** visible, because they are covered with a metal sheild just as they are on the outside.

In terms of just "packing it full of grease", The pocket of the hub is rather deep. You'd need to fill it up with half a can of grease such that the spindle nut and shaft themselves were litterally submerged in grease. I'll try to take a picture of the used "new" one I have, but basically, after a year, all of the grease is out by the cap rather than in the bearing race, and the thing doesn't spin as smoothly as a brand new one... no surprise.