Ok so I did the grand am front brake up finally finished it take it for a drive down the highway and woah. Vibration is terrible wheel shake like a mofo. I used the stock hubs cut the fiero rotor off and installed longer studs using h3 hummer ones. I read something that lose the centric ring on the hub do they sell insert ones I can order to install or do I have to make my own? [img]http://images.fieroforum.co m/userimages/pontiacfierokid1985/C06C9CB9-25A3-4796-AA96-5AAA61EDF308.jpeg[/img]

[This message has been edited by pontiacfierokid1985 (edited 02-02-2021).]

Were it me, I'd:

Jack it up and put the front on stands, wheels off
Spin each wheel and see if there's play (like grab the tire at 3 and 9 o'clock and wiggle). If so, I'm thinking your wheel bearings aren't tightened enough / properly.
If instead they drag, I'm thinking the bearings are too tight (which is surprisingly easy to do), or maybe the rotors are warped (be odd since they're new, but could happen)
Might also be grabby calipers or pads, but guessing they're new too?

Oh oh, you lubed the slide pins on the calipers, right?

Also, your second pic has a typo in it (remove the space from fieroforum.co m so it's just fieroforum.com.)

-- A

[This message has been edited by dremu (edited 02-01-2021).]

You could have up to 2 issues.
1. Rotor off center from hub. Rotor pilot is a larger ID than the wheel pilot and there is no rotor pilot on the 84-87 front hub (never was a need since the rotor is cast into the hub). This allows the rotor to sit off-center as it is tightened between the wheel and the hub.
2. Wheel off center from hub. With the added rotor hat thickness on the 84-87 front hub, you lose the majority of the wheel pilot area under the rotor, which leaves very little for the wheel to center on (especially since the leading edge is normally tapered). Depending on type of wheels and how they are tightened, the wheels could be off center which will make a large imbalance issue.

To address #1, you can use some 1/4" wide strips from an aluminum can to wrap around the wheel hub to center the rotor (don't cut yourself - they will be sharp!).
To address #2, with the wheel elevated and all lug nuts loosened, gently snug by hand all the lug nuts, then snug using a small ratchet, then snug them to about 40+ lb/ft. Then lower the car and finish the torque sequence. Doing the small snugs with the wheel unloaded, allows it to more precisely center on the cones of the lug nuts.

When I did the brake upgrade on my Fiero, I used method #2 mentioned above to center the wheels on the hubs. It would last for awhile, but eventually the wheels would get knocked off-center.

The problem took care of itself when I bought aftermarket wheels, and centering rings for them. The centering rings had a nice crisp edge which was able to (just barely) catch the lip on the hub. That was enough to keep the wheel centered.

I doubt anyone makes a centering ring for stock Fiero wheels with the Grand Am upgrade. So that would have to be a DIY project.

I’m honestly looking into getting 17 inch scion TC wheels for my fiero but I’m just wondering if this is going to have a vibration also I know I need to open the center bore on the tc wheels since they are smaller I believe but they do share the 5x100 lug pattern just as Fiero’s do.

Even if you replace the wheels, you need the centering rings to properly locate the rotor to the hub.

The wheels self center due to the conical shape of the lug nut and the lug nut pocket in the wheel.

quote Originally posted by pontiacfierokid1985: I’m honestly looking into getting 17 inch scion TC wheels for my fiero but I’m just wondering if this is going to have a vibration also I know I need to open the center bore on the tc wheels since they are smaller I believe but they do share the 5x100 lug pattern just as Fiero’s do.

Yes, they're 5x100mm, just like the Fiero. But the hole for the hub is smaller, so it needs to be bored out. If you can get a sharp edge on the hole after you bore it out, then it should be able to (just barely) catch the lip on the hub. And that will keep the wheel centered. That said, I haven't done the Scion wheel mod before. So I don't know if that's feasible. Worst case scenario, you have it bored out even larger, and use centering rings.

quote Originally posted by Blacktree: Yes, they're 5x100mm, just like the Fiero. But the hole for the hub is smaller, so it needs to be bored out. If you can get a sharp edge on the hole after you bore it out, then it should be able to (just barely) catch the lip on the hub. And that will keep the wheel centered. That said, I haven't done the Scion wheel mod before. So I don't know if that's feasible. Worst case scenario, you have it bored out even larger, and use centering rings.

Ok so found these wheels instead and found out that you don’t need to open the center hole on them to mount them I need new tires anyway so why not go bigger 16 inch and I’ll be able to store my stock cross lace rims and have the cleaned up later if I ever want to mount them again

New wheels or not, you should use centering rings when installing the rotors on your front hubs.

quote Originally posted by olejoedad: New wheels or not, you should use centering rings when installing the rotors on your front hubs.

I feel like I shouldn’t have to center the rotor since I had the fiero hub turned to fit the grand am rotor over the fiero hub. I mean it was snug when I was installing the rotors over the hubs. Where could I fine centric rings for this then? I’m seriously about to drop the hubs off to a machine shop/welding shop to have a lip welded on the centering ring on the hub

You absolutely need to center the rotor. I gave the easy method to use above.

Welding on the hub is a very bad idea. They are cast iron and welding will lead to fracture.

A Speedi-Sleeve might work to take up the slack, though I haven't tried this.

For the brake project on my Fiero, I got front hubs from Brian Sanburn (sluppy123 on the forum).

He makes the hubs from scratch, so when you order, you tell him what rotor you have, and he makes the hub to fit the rotor without play.

There needs to be adequate clearance between the inner diameter of the rotor hat and and the outer diameter of the hub, to allow for easy rotor removal in the future.

Centering rings of various sizes are available online and at tire stores.

Edit to add....

When removing the rotor from the stock hubs and turning the OD of the hub to fit the new rotor, the Fiero hub must be chucked using the inner machined face for the bearing race to assure concentricity.
If the hub is chucked on the outer surface, the hub may not run true.

[This message has been edited by olejoedad (edited 02-09-2021).]

I tend to agree that the hub and rotor need some "breathing room" for heat expansion / contraction, and rust buildup.

Here's an "outside the box" method I used to center the Grand Am rotors on my hubs. I found wheel studs where the shank (the unthreaded portion) was longer than stock. So the shank protruded into the brake rotor. The holes in the rotors needed to be reamed out, to fit. The wheel studs are Dorman part # 610-376. I don't remember offhand, but want to say I used a 9/16" drill bit. If you go this route, you may want to double-check that.

quote Originally posted by Blacktree: I tend to agree that the hub and rotor need some "breathing room" for heat expansion / contraction, and rust buildup. Here's an "outside the box" method I used to center the Grand Am rotors on my hubs. I found wheel studs where the shank (the unthreaded portion) was longer than stock. So the shank protruded into the brake rotor. The holes in the rotors needed to be reamed out, to fit. The wheel studs are Dorman part # 610-376. I don't remember offhand, but want to say I used a 9/16" drill bit. If you go this route, you may want to double-check that.

I used lugs from a h3 hummer as I did on all my Fiero’s this is the only one that has been giving me this vibration problem. I’m gonna get regular style lug nuts that fiero originally came with these cars. I have some weird chrome style and feel like these could be a problem also.