Hello,


I´m new to Fiats.


Today I tried replacing the rear brake rotors on a MY 2005 Stilo 5-dr diesel, with no success.


The rotor was rusted stuck onto the hub. (quite common situation) I started tapping it with a light hammer. Still stuck, so I continued with a 16 oz hammer.


The rotor was still stuck to the hub, but the hub got dislodged on the wheel-bearing. This surprised me greatly.


I would have expected the axial movement of the hub on the bearing to be positively restricted, at least well beyond the forces stemming from a 16 oz hammer swung in the confined space in the wheel-well and under the car.


I managed to tap the rotor and hub back into place, and the car seems drivable with due care.


Does anyone know how the hub / wheel-bearing are attached to each other, please? Is it just a friction-press-fit., or is it positively fastened?


(I can´t tell from the parts-catalog drawings, which only show the hub as a unit, supposedly including the wheel-bearing.)


I know it is the hub / wheel-bearing interface that was upset, and not the wheel-bearing / rear axle, because of the wobble of the rotor when spun before I tapped it back into its correct position.


Any advice would be greatly appreciated, thanks.


David
Lund, Sweden

Can't explain the hub loosening but the best way to get a rotor off is to hit it with a "dead blow" rawhide hammer. Ordinary hammers just tend to bounce off. A Thor number 2 hammer is suitable.

jim cooper said:

...the best way to get a rotor off is to hit it with a "dead blow" rawhide hammer. Ordinary hammers just tend to bounce off. A Thor number 2 hammer is suitable.

Click to expand...

Thanks, that´s good advice for thomping a stuck rotor off the hub.


David

David, Are you sure the hub itself was loosened? This seems unlikely. I would say you partially moved the rotor when you hit it so that it sat unevenly on the hub ( I assume you removed the two small locating screws on the face plate before you started hitting the rotor?). In any case, remove these screws and then give the rotor a firm hit with the dead blow hammer. The rotor may be rusted to the hub but the area of contact is quite small, about the thickness of the rotor itself.

Hello jim,


Thanks for the reply!

jim cooper said:

David, Are you sure the hub itself was loosened?

Click to expand...

I´m positive the hub moved axially on the wheel-bearing.


Initially I too thought it was next to impossible. I too thought the disc had moved on the hub.


However I did observe the hub surface as visible through the lug-bolt holes in the rotor. There was at all times zero separation between the flat end surfaces of the disc and hub. Thus to my bewilderment I´m sure the hub and disc moved in unison, unseparated.


As I kept hammering away at the disc, the disc and hub moved together axially (with considerable axial run-out at the periphery while rotating, which is why I know it is the hub-to-bearing and not the bearing-to-axle interace which was upset, as the latter would move and tilt the plane of rotation while not causing run-out), all while chunks of rust came off from behind the hub.


At first I thoght that was material from the hub-to-disc interface caming loose. Now I realise it most likely was the remains of the hub-to-bearing retention interior circlip, or its correesponding inside radial groove in the hub, or both, that appeared.

jim cooper said:

... ( I assume you removed the two small locating screws on the face plate before you started hitting the rotor?)...

Click to expand...

Good advice! I did have those locating screws removed. (Forgetting to remove the rotor retaining screws is a mistake I´ve already made, and learned from, before.


Thanks,


David