Went over a buddy's house whose a machinist and who has a lathe & milling machine.
Had him apart the stock fiero front solid brake discs, and remove/cut the hub down to fit within ..015" to fit the back of the Grand AM vented rotor.
My question to everyone is does the face of the old fiero disc (where the wheel studs stick out through, (now the actual hub) need to be machined/milled down as well?
Anyone know?
I know besides creating the new front hubs from the ol fiero front discs and milling them down to fit the back of the Grand AM vented rotor, that we also need to cut down the caliper carriers in 2 spots as well, but I'm not sure if the front of the hubs need to be milled down a little as well?
Hope someone who has done this mod or seen it done @ a local machine shop can chime in here.
and on here it says: "You might want to ask the machinist to remove the excess length from the face of the new hub to the back edge so it equals the depth of the Beretta rotor. While this is not necessary, it looks neater."
I've done the Grand Am brake modification on one of my cars. If I understand the question correctly, it is true that the wheels will protrude further outboard by an amount equal to the thickness of the Grand Am rotor mounting flange (3/8" if I recall correctly). That's because the inboard side of the new G/A rotor sits on outboard side of the old spindle flange, effectively spacing the wheel furher outboard. I've never heard of anyone milling down the thickness of either the Grand Am rotor or the old spindle flange to bring the wheel back inboard. First, I doubt there's enough material thickness to do this safely. Second, the offset isn't really noticable.
Here are the pics of mine. They were turned a little on the face to clean them up but not much. More for looks. During cutting one of them some metal jumped off and it had to be touched up and remilled. But they both work great
If you are turning the face.... Also can see if they can make it a Hub Centric for rotor. Hub Centric will stop rotor from being off center and mess w/ balance.
Take you rotor to machine shop... Don't need much... just a small lip to meet rotor's center. (Rotor's center hole has some bevel on backside because pilot meet flange face is rounded to prevent stress risers. See pic below.)
Turn face can, likely will, mess w/ rotor to clear dirt shield, caliper bracket, etc.
Dimension? Rockauto is your friend... 90 GA MOOG Part # 513017K Front Wheel Bolt Quantity=5 Flange Dia=4.921" <-- Proper Diameter so that any rotor will fit! Bolt Circle Dia=3.937" Bolt Size=M12X1.5" Wheel Pilot Dia=2.244" <-- Wheel Centric but don't care. Brake Pilot Dia=2.295" <-- Hub Centric for Rotor. Flange Offset=1.749" Hub Pilot Dia=2.894" Splines=33
(Yes, some turn the flange to fit inside rotor. Brake job = new rotor then new rotor's tolerance may not clear hub.) ------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
i did not turn the flange , just cleaned it up a bit .that is the face that your wheels have been riding against for years so unless your wheels have been wobbling there wont be a problem .
Guess I'll leave the face/flange of the front hubs alone then, with exception to IF I have some hubcentric rings made to keep the grand am rotor from moving back in forth around the studs.
Guess I'll leave the face/flange of the front hubs alone then, with exception to IF I have some hubcentric rings made to keep the grand am rotor from moving back in forth around the studs.
I'm having vibration issues with the new Grand Am Rotors-Calipers up-front swap.
I've re looked at everything and even after tighening the spindle nut to 12ft lbs (while spinning the rotor) and then backing off and re-tightening nut by hand, still the issue continued.
I even tried keeping the spindle nut @ 12ft lbs torqued, and that seemed to help a little, but still the vibration issues continue.
The problem is the slop in the fitment of the grand am rotor with the old machined front rotors/now hubs. There is too much play in the rotor with it not being centered. Add that the stock 14" fiero gt wheels don't center properly against the hubs and grand am rotors, and hence the vibration.
TheOgre is right. We need to properly center the grand am rotor around the fiero hubs. With that said we need to run hub centric rings around the od of the front hubs to keep the rotor snug. Might as well buy some hub centric rings for the wheels as well.
Looking @ Ebay now...tons of them on there. Just got to get the right sizes.
After swapping out my machined front hubs for a brand new set from the FieroStore, the vibration issues continued.
Finally found the problem. One of the front tires had a huge bubble form and part of the tire thread pop out and out of alignment as a result of severe dry rot.
Replaced tires/wheels with a different set of 15's and bam. Car drives like a dream.
Still can't believe this was the issue. It was hard to pin point because the tires didn't show this, until after a few times of driving, which cause the tire to finally start separating and deforming.
I'll try to post some pix. Very happy that it had nothing to do with my machined hubs : D
When you think it through it really makes sense that it was the tire, not the spindle.
I looked at my rotors carefully while preparing my car for winter.
There is just no way for the rotor to go out of balance. the studs poke through the rotor. Those holes are tight. The rotor can't move, not because of the spindle, but because of the studs. Sure there was a bit of a gap between the rotor central hole and the spindle, but it made no difference at all. Those lugs made it snug, and when torqued, the rotor is sandwiched between the wheel and the spindle. Absolutely now way for it to shift.
That was pretty much a red herring issue after all.
Yes... turning face will cause problems w/ clearance for shield, bracket, etc... just ignore that...
