We reserve the right to make changes in design or add improvements without incur-
ring the obligation to make such changes in equipment previously manufactured.

PARTS-SERVICE

GRAM

SUBJECT: DRIVE AXLE FLANGE STUDS - MAINTENANCE

This gram gives recommendations for maintaining a tight connection of the drive axle flange to
the hub. Four recommendations are given with each one numbered and explained.

1.

Keep Stud Nuts Tight
The importance of keeping the nuts tight can’t be over-emphasized. If the stud nuts loosen, the
studs may break or bend. Even if the nuts loosen without the studs breaking, damage can occur to
the connection. It may be impossible to keep the nuts tight without replacing damaged parts such as
the hub, drive axle, studs, nuts, and thimbles.

Check the torque of the nuts after 50 hours of operation when the truck is new or after the axle has
been removed and replaced. A table of recommended nut torques is below:

2

Sealant at Hub-Axle Flange
Do not use a gasket between the axle flange and the hub. A gasket may allow movement between
these mating surfaces. Therefore, use a thin Layer of Permatex t2 on the hub and axle surfaces.
NOTE: 1) The H30-60F uses an o-ring between the axle flange and hub. Therefore, do not use

Permatex on this unit.

2) The P60-80, H100-150F units have a metal flange around the axle stud bolt circle. This

flange is not a gasket. It supports the seal located on the inside of the hub. Use

Permatex #2 on both faces of the metal flange of the seal as well as on the hub and axle

flange.

C-G-10
DATE: March 23, 1971
MODEL: S20-30A,S125-

150A, H20-30E,
H30-60F H60-
80C,H100-150C,
P60-80A

TRANSMISSION &
DIFFERENTIAL

Unit Stud Nut Thimble Torque (Ft. Lbs-Lubed)

111805 17159 155480 60

S20-30A, S125-150A
H20-30E, H30-60F,
H60-90C

114825 17037 114827 75

P60-80A, H100-150C,
H110-150F

H150-250E

53664 15010 53559 90-110

C-G-10 -2- March 23, 1971

3.

Inspection of Parts for Damage
If the axle stud nuts are found loose or sheared, the hub, axle flange, or studs may be damaged.
Each of these parts are discussed separately:
a.

Hub
Inspect the stud holes in the hub to determine if they are egg-shaped. Replace the hub if the
holes are egg-shaped. The holes become out-of-round when the hub to axle flange con
nection is loose and the studs are bent back and forth. Figure I shows the design of the stud
hole. Note that the threads in the hub begin 9/16 inch below the face of the hub. The 9/16
inch unthreaded portion of the hole is to provide side support to the stud. This support
prevents it from breaking in the hub at the last thread. If the holes are egg-shaped, they will
not give support to the studs and the studs can break or loosen repeatedly.

b.

Axle Flange
The axle should be replaced if the tapered holes of the flange are worn oversize. Look at
the position of the tapered thimble when in-stalled in the axle flange. The thimble should
have a standout height when installed as shown in Figure II. If the axle flange hole is
oversize, the thimble will seat too deeply and allow the lockwasher to touch the flange. The
axle flange cannot be tightened adequately if the lockwasher touches the flange.

Be sure there is no interference between the lockwasher and the radius of the raised center
of the axle. See Figure II

FIGURE II - Illustration - Installed Thimble

FIGURE I - Hub with Stud

Standout Height

Unit
S20-30A, H20-30E
S125-150A, H60-90C
H30-60F

(X) Standout Height

1 1/8
1 1/16
1.0
1 3/16

1 1/2

P60-80A, H100-150C
H110-150F
H150-250E

Possible Interference

Standout Height of Installed
Thimble (No specific dimension
exists).

Thimble

Axle Flange

Axle
Stud

C-G-10 -3- March 23, 1971

c.

Stud
Replace all the studs if they or any other parts are damaged. The studs are so important
that they should be replaced if any problem of loosening or breaking occurs. Also, replace
the tapered thimbles when replacing the studs.

4.

Installation of Parts
a.

Stud into Hub
The stud should be screwed into the hub until the standout height (See Figure I) is equal to
the dimension listed for that unit in the table of Figure I.

The stud may back out when the axle flange nut is removed. If so, remove the nut from the
stud and install the stud correctly. Then, install the nut and tighten the axle flange.

b.

Use Correct Thimble
The thimble wedges between the stud and the axle flange. In doing this, the thimble forces
the flange against the hub and also locks the stud by a clamping action. Use only the Hyster
thimble recommended. If another thimble is used, it may not it the taper of the axle flange
and it may not close enough when wedged to clamp the stud in a locked position.

c.

Applying Torque to Nuts
The nuts must be torqued evenly. Raise the torque in small amounts until the required
torque is reached. Use a star pattern as in wheel nuts.

Interchangeability:

Not applicable.

Parts Stock:

Not applicable.

Effective Serial Number:

Not applicable.

Parts Reference:

Not applicable.