Berreta brakes

[2ML67]

My Fiero has the Berreta brakes all around, I have had them on the rear before with no problem but this is the first time with them on the front.
I am finding that at high speeds I am now getting vibrations right up the column, this problem was not there before the upgrade. Any one else had similar troubles or have any ideas how to cure it. Have already had alignment checked and rack is also ok, all four tires have been rebalanced and still the vibration persists. No I am not talking about massive speeds basically any thing over 160km/h and it gets scarry. Dan

[FieroBUZZ]

No I am not talking about massive speeds basically any thing over 160km/h

 

The only thing I can think of is that when the rotor is mounted onto the machined hub, it is slightly out of round.  Does it seem to be 1 side or equal?

[aaron88]

Could be bracket fatigue.  The bracket may be vibrating now causing a wheel vibration.  Set up a garden hose with one end in various locations where you suspect the vibration may be coming from and listen to the other end while you brake.  The shorter the hose the easier to hear.

Aaron

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P.S. I finally got me brakes, but now I need rims and tires, not to mention a tonn of other stuff.

[FieroBUZZ]

I read that as it vibrating while driving at speed, not while braking.  Could be wrong though.

[2ML67]

It is vibrating at speed not braking. Put front brakes back to stock then test drove, no vibration all the way up past 190km/h (factory speed limiter). Put Berreta brakes back on and problem has returned. Basically slight vibration starts at around 100km/h then worsens with speed becoming scarry at around 160km/h. Double checked wheel bearings and there is slight free play when rotor is put on machined hub before bolting on rim. Dan

[aaron88]

It’s now quite obvious now that you have a problem with the mounting brackets.  They aren’t stiff enough or not mounted close enough to parallel with the rotor.  The pads are catching (on an angle) on the rotors and causing a vibration, at least in part because your brackets are mounted too far out from the spindle to be rigged enough.

New pads may fix the problem temporarily.  Residual pressure valves may also work (2 lb).

Aaron

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[2ML67]

Took the hubs down to a machine shop to have them checked and they found one of the hubs is so far off it shook the machine. The guy said who ever did the turning down of the rotors screwed up. Got him to turn me down another set and will try this afternoon to see if that fixes the problem. Dan

[FieroBUZZ]

Do I get a prize?   

[2ML67]

Installed new hubs and took her out, problem solved ran her up to the limiter and no vibration. Dan

[aaron88]

If the rotors had too much runout, why was it okay at first?  That's odd, but problem solved so... cool.  Didn't know you had to have your rotors turned down.

Aaron

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[FieroBUZZ]

To install Beretta/GA fronts, you need to machine off the rotor from the Fiero rotor/hub.  The hub then is fit into the hat of the new rotor (like most cars).  Evidently the hub had been machined into an out of round state.