5
27
How to measure
stud standout
5-3
Stud standout is measured from the axle end mounting surface (the hub, for inboard mounted drums,
and the drum, for outboard mounted drums) to the first complete thread at the outside end of the
stud.
Stud located ball
seats are spherical
5-4
The nut seat for the stud located ball seat mounting system is a precision-machined
spherical surface. Cap nuts must be properly manufactured to assure correct seat-
ing. Never use one or two-piece flange nuts on a wheel designed with ball seats (see
Section 5-11).
Ball seat cap nuts may be obtained from your Alcoa Wheel Distributor.
Inboard mounted drum
Stud Standout
Stud Standout
Outboard mounted drum
Hub
Hub
Exposed
shoulder
Drum
Drum
Mounting
surface
Mounting
surface
First full
thread
First full
thread
Single and wide
base wheel, stud
located, ball seat
mounting
5-5
Front wheels are mounted as singles and require 1.8" (45.7mm) minimum stud standout. Most vehi-
cles have 1-1/8-inch studs on the front hubs. Alcoa single cap nuts, Part Nos. 5996R and 5996L, or
equivalents, should be used. Some front hubs have 3/4-inch studs. On these hubs, use Alcoa single cap
nuts, Part Nos. 5995R and 5995L or equivalents.
Disc Mate wheel spacers are recommended for use with Alcoa Dura-Bright
®
surface treated wheels to
protect the wheel contact surfaces from marring. Disc Mate wheel spacers are placed between the con-
tact surfaces of the Dura-Bright
®
wheel and the brake drum as shown below and on the next page.
Correct single mounting with
1-1/8-inch stud
located, ball seat mount.
1-1/8" Stud
Drum
Single Alcoa Aluminum Wheel
Disc Mate (when used)
Outer Cap Nut
P/N 5996R or L
(See 5-2, page 26)
Hub
1.8 inch
minimum
stud standout
Continued on the next page
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