Webb Catalog

Brake Drum

Bolt (Mounting) Hole Sizes

This information is offered to eliminate concern regarding the hole sizes furnished in Webb

outboard mounted brake drums. These drums are those used in standard stud piloted or hub

piloted disc wheel applications.

Webb has elected to use a larger hole diameter on selected brake drums to provide

interchangeability across various applications and minimize the number of service part

numbers necessary for aftermarket replacement. This has resulted in additional clearance

being present when a larger hole is used in conjunction with a smaller diameter wheel stud.

EXAMPLE: 66884F BRAKE DRUM AS USED IN STUD PILOTED

AND HUB PILOTED DISC WHEEL APPLICATIONS

This additional clearance, when noticed, has caused some to reach the misconception that

the brake drum will not pilot properly or that there will not be sufficient surface area to

achieve proper clamp load.

As indicated in the above drawings, the drum pilot on the drum mounting flange is the

functional pilot which centers the brake drum relative to the axle centerline. The

clearance between the stud and the stud hole

does not

affect piloting.

However, should you have any questions regarding this information, please feel free to

contact our Sales or Engineering Department.

Disc Wheel

Disc Wheels

Pilot on Stud

Drum

3/4” (.75)

Stud

22mm

Stud

Disc Wheel Pilot

Drum Pilot

1.00” Dia.

Bolt Hole

1.00” Dia.

Bolt Hole

CLEARANCE

BRAKE DRUM AND ROTOR SERVICE INFORMATION

TROUBLE-SHOOTING: BRAKE DRUM BOLT (MOUNTING) HOLES SIZES