What are these pins for?

They are a hookey locator pin that you really do not need. They do help to hold the rotor to the hub not because they are required but to take slack out of the system and allow you to not have to take the slack out of 2 parts during assembly. In a way to idiot proof a process. There also is dirt and debris around and that can interfere with proper clamping forces of wheel to hub. So if you pin the rotor you keep dirt out of the hub rotor interface and only have the rotor to wheel interface to make sure you keep clean. But that's easy because the can see that interface. You can't access the hub rotor interface without removing the caliper. I guess that's more than you ever wanted to know about those pins.

13mm wrench. Leave them unless you have a reason to not use them. For example there are aftermarket wheels that do not have the wheel face cutouts for those pins.

 

Good info. Something else new to stick in the brain. Thanks Carl.

Robb

 

they aren't really necessary if you are handy with positioning your wheels for mounting. Or if you have a locator tool aka, threaded a wheel stud. but then removal leaves a hole so I'd leave them alone especially since these are the rears and would allow water to get into the parking brake assembly. What a mess!

 

Fiats have the same set up, but Alfas and De Tomasos seem to go with the studs protruding from the hub with lug nuts to secure the wheel. The lug nut design seems superior to me. Not sure why Ferrari and Fiat would go with their method. It certainly slows down wheel installation.

 

They also keep the disks from rotating on the hubs. They keep the holes on the disks aligned with the threaded holes in the hub. They also keep the disk tight to the hub in the case that your lug nuts would become loose. Needed? Depends on how you define needed. You will find them, or something like them, on just about every car with disk brakes as well as drums. Some don't have the wheel alignment pins and are just set screws which hold the disk or drum tight to the hub.

 

Just a note, if you go with spacers ( I have Hill on my car ) you need to remove those fasteners to fit them.

 

Hijack- on 355 rotors, what is the rubber nub between the lug holes for?

 

It's the same thing just fancier. A little bigger to help you line up the wheel easier.