Do I need the front wheel bearing dust cover? (missing)

I have had a long process replacing a wheel bearing on my 2002 Mazda protege 5. After taking the knuckle to a shop to have a new bearing pressed in, weeks later I am now ready to put the knuckle back in. (lots of cutting off of rusted parts, then finding replacements… very frustrating…). Now I look at the knuckle and I see that the dust cover is missing. This is a sheet metal shield that fits between the hub and the knuckle. It has a weird cutout shape with an opening for the caliper. How bad will it be for me to put this together without the “dust cover”? What is it for anyway? The old one was very rusty. Please help!

If the dust cover was only rusted on the OUTSIDE, there’s no problem.

Rust on the INSIDE means water and foreign material (dirt) has gotten in and is slowly eating away the bearing.

Actually, I no longer have the dust cover, the guy who pressed the bearing may or may not have it. This “dust cover” is really a large, about 10" diameter disc of sheet metal with a cutout where the caliper assy sits. It looks more like it protects the brakes than the bearing.

The dust covers are there to protect the brake components. I’d want to replace it.

Ok, I see now what you’re saying.

OK so it would be nice to replace it… but that means I have to get one, have the bearing pressed out, replace it, press it back… basically the guy who left it off and assembled the knuckle blew it. Also, the repair book says to mark the position of it before you remove it… so if I put a new one on I don’t know how to orient it. What I want to know is… how essential is this piece? What am I risking if I leave it off? Do the bakes overheat? There isn’t much “dust” around here, but lots of salt spray in the winter. Will I go thru rotors and pads quicker? It seems like such a flimsy little thing… how much can it protect?

This shield is meant to keep water splashing under the car from getting on the disc. If you have one disc unshielded you could get uneven braking under wet conditions until the disc got hot enough to dry off. If you have the bearing pressed out, you will probably have to have install a new one as the pressing brinells the races coming out (I may be wrong in your case).

Not having the part in hand, I am wondering if there is a way to cut a new shield to get it on; attach it to the knuckle; and then pop rivet stiffner plates to support the cut.

Anyway good luck on this.