What’s this piece for? (with pictures)

[CLudwig]

I'm new to this and full of silly questions.

What is that floppy piece of sheet metal behind the rotor. What is it called? What is it for?

Why does that screw stick out so far? The OEM wheel even has a hole it accommodate it but it’s clearly not a wheel support. Does this screw need to be modified for after-market wheels?

thanks.

[Divers]

A is the dust/dirt shield

B is the stud holding hub on.

[leftfield6]

B is as long as it is to help guide the wheel into place. The factory alloys have a hole that lines up with that stud.

[SergeantSavage]

Without part A you would likely have more mud/dirt splashed on the rotor, which would accelerate brake wear.

[CLudwig]

Perfect answers; thanks alot guys!

[kmead]

As stated the long stud does two things: holds the brake rotor on and its long so you can put the wheel on that long stud and then run the wheel bolts into the hub. It helps to position the long stud at the top to help hold the wheel.

Yes the long stud will interfere with many aftermarket wheels. Presuming you can find any. There are other bolts that can be substituted for them. Fiat made special low head bolts for this application. Your car likely has four of them already, others can be acquired at junkyards.

There are a few versions of the shield, some have a tipped out section that helps direct air into the brake caliper area. It is there to minimize the amount of splashed water onto the rotor. Which helps if you hit the brakes after an extended period of wet weather running you don't have to squeeze the water off the rotor before you get any braking.

[Tobi]

The TÜV in Germany made me remove peace A (gravel gard?) after I installed a bigger motor in my Opel Kadett so the brakes can get more air. I drove it like that for about 100000 miles and it seemed fine. I have been thinking about removing them from my Spider too.

Wikipedia:
TÜV=Technical Inspection Association. The German safety guidelines are among the strictest in the world, and getting a road permit for custom-built vehicles is said to border on the impossible.

[courtenay]

That stud hold the brake rotor on?? Doesn't look substantial enough to do that to me. When I had my '72 many years ago, there were two studs like that holding a spacer that went between the wheel rim and the hub in place as well as providing a convenient "hanger" for the wheels when installing them. When I put aftermarket wheels that didn't have holes for the studs, I simply left them off- which made installing the wheels and spacers kind of tricky. The disc rotors didn't fall off without the studs.

[Tobi]

That stud hold the brake rotor on?? Doesn't look substantial enough to do that to me. When I had my '72 many years ago, there were two studs like that holding a spacer that went between the wheel rim and the hub in place as well as providing a convenient "hanger" for the wheels when installing them. When I put aftermarket wheels that didn't have holes for the studs, I simply left them off- which made installing the wheels and spacers kind of tricky. The disc rotors didn't fall off without the studs.

The stud holds the bake rotor on till you have the wheel installed, after that the wheel/wheel bolts are holding the rotors. Yours didn't fall off because rust was probably holding them on.
Like Karl said, the studs can be replaced with some M10 or M8 bolts with a flat had and they will hold the spacer for an easier wheel installation.

[leftfield6]

Tobi is correct. "Holds it on" as in holds it on to keep it from falling on your foot while you have the wheel removed, not holds it on as in holding the rotor in place for braking forces. Your wheel lugs do that. The stud also helps to keep the brake rotor from moving when you are trying to put the wheel on and get the lug holes lined up right. Must be a euro thing, my VW Vanagon has the small studs as well.

[manoa matt]

As others have stated that screw works well with the stock steel rims and the "stock" alloy Cromadora rims as they have a hole or recessed area to accomidate the pin. However it appears your hub contains a metal or plastic hub centric ring. With the exception of a few manufacturers, most aftermarket wheels in a 4x98 wheel bolt spacing were not hub centric and need those rings to center the rim on the hub. Also most aftermarket rims did not contain a recessed area to accomidate the pin, hence the need to cut the pin off or find another bolt.

Whether or not you need that screw depends on what rims you decide to use on the car. Have those pins prevented the rims from fully seating against the wheel spacer? I would expect to see areas around each lug bolt hole where the rim was in contact with the wheel spacer, but do not see them in your picture.

[TX82FIAT]

those screws or studs identified as "B" also hold your spacer in place assuming you are using one with stock offset for the wheel.

[CLudwig]

And this piece?
The ring here makes it difficult to align the wheel for mounting. Cant it just mount directly? It fits better directly mounted, more bolt depth.

[manoa matt]

That's the hub centric ring I was talking about. What type of rims are you trying to mount?

[CLudwig]

That's the hub centric ring I was talking about. What type of rims are you trying to mount?

Ya that's what I thought, which confused me since the wheels are just 13" stock FIAT.
I took the wheel off to inspect the breaks, but I'm having difficulty remounting the wheel because the ring creates separation so that the bolts don't get good depth.

So is this needed? The wheel seems to mount better without it.
My guess is that the previous owner had custom wheels and put the stock ones back on before selling the car to me, but did not remove the hub ring.

By the way, my wheels have the hole to accommodate the pin so the ring is not necessary right?