PTC News March 2015

Monday, March 9, 2015

Experiencing Continuous Rotor Pulsation Problems?
The Source of the Problem Could be the Hub Flange

The hub flange is ground zero for pulsation problems. Any runout in the
flange will be magnified by the rotor. But, when do you replace a flange, stub
axle or an entire hub assembly unit? Verifying the answer requires some
basic math and a micrometer.

 All flanges have some degree of runout. This is why there are tolerances in the service specification and in manufacturing. A flange may have up to .005" of runout and the bearings may have zero end play. It is impossible to see damage with the naked eye. This is why carefully measuring with a dial indicator as part of a brake job is important.

What are the Most Common Causes of Hub Flange Runout?
• A flange can be damaged by curb strikes or pot holes
• If a hub or bearing is over torqued, it can damage the flange and cause runout. It can also damage the bearings and the axle shaft.
• Pitting and corrosion where the rotor mates to the flange can induce runout.
• The flange can be damaged by excessive and uneven lug nut torque.

Suggested Replacement Guidelines
As a rule of thumb, if runout is greater than .005" for a light vehicle, then it’s a sign that the flange may be damaged or out of specification and further corrective action must be taken. If all attempts have been made to correct runout and it can’t be brought below .002" or recommended specification, then you should replace the hub assembly or wheel bearing hub unit.

PTC Hub Assembly Key Advantages:
• OE design, fit & function for easy installation
• Metallurgy testing eliminates metal fatigue
• ABS sensor testing eliminates connection problems
• Improved dimensional end testing to ensure end play meets OE standards & controls noise


Click here for a PDF copy of the March Newsletter