MERITOR WHEEL BEARING
ADJUSTMENT SYSTEM FOR
THE AFTERMARKET
®

OPTIMAL WHEEL BEARING ADJUSTMENT.
LONGER TIRE LIFE AND MORE TIME ON THE ROAD.

Meritor and Temper.
Together to Provide a Superior Bearing
Adjustment Solution.
With more than 100 years of axle-manufacturing
experience, Meritor has consistently brought advanced
axle technologies to the marketplace. Whether
designing and manufacturing from the ground up or
partnering with another industry leader, our goal is
to provide fleets and end users with products that
deliver maximum operating efficiency and premium
performance. And now, Meritor Aftermarket is teaming
up with Temper® to offer Doctor Preload® and TemperLoc® spindle nuts – a superior bearing adjustment
system for wheel-end management, longer tire life and
less downtime. That’s an idea that really does drive results.

“I’m a firm believer in the Doctor Preload and
Temper-Loc nut system. It’s helped us cut
recap use by one-third over two years and
reduce inside tire edge wear-out by 90%.
Our wheel ends run truer and run longer.”
Russ Van Beek, Heyl Truck Lines
Akron, Iowa

“I use the system on roughly
100 trailers and it’s keeping
preload on the wheel bearings.
It has been a good addition
to my fleet.”
John Herbst, Owner, J&R Transport
Dickeyville, WI

Founded in 1969, Temper is a leading engineering
and manufacturing company in precision assemblies
and equipment for industrial products. The company
introduced its first product – Temper Load Rings – in
1970 to offer better bearing adjustment for a wide
variety of industrial applications. Today, Temper
continues to pioneer technologies that provide complete
solutions for heavy vehicle applications, including the
Doctor Preload and Temper-Loc bearing adjustment
system.
Doctor Preload and Temper-Loc bearing adjustment
system is designed and manufactured in the U.S.A.

“Setting the proper pre-load can’t be
anything but good. That’s why we’ve
invested in Doctor Preload and Temper-Loc
spindle nuts. I’m glad I spent the money
on this system and it’s working well on all
my trailers.”
Brock Ackerman, K & B Transportation
South Sioux City, Nebraska

“We believe in the product and it’s doing exactly what
it promised to do – keeping a consistent preload on the
wheel bearings and contributing to good-to-better tire
wear. The system has been a valuable addition to our
maintenance operation. On our two most recent orders
of new trailers, we insisted that the OEMs install
Temper-Loc nuts, which puts us on the right track
with properly managed bearing settings.”
Roy Hegland, Fleet Maintenance Supervisor, Midwest Motor Express
Bismarck, ND

Better Bearing Management Through Preload.

Load on bearings, including preload, is measured in
“pounds-force” or lbf. SAE recommended practice
J2535 stipulates the optimal settings for drive and
trailer axle wheel bearings to be between 500 and
1,000 lbf, and between 250 and 500 lbf for steer
axle wheel bearings. With these settings, bearings,
seals and other wheel-end components provide
maximum performance.

Optimum wheel-end management begins with optimal
wheel bearing adjustment. According to the Society
of Automotive Engineers (SAE), the optimal setting for
wheel bearings is a light preload.
What is preload? Preload is simply defined as a
measured “tight” bearing setting in which all of the
rollers in the tapered roller bearings are kept under
a slight force, or load. This preload condition keeps
vibration and angular movement in the wheel end to a
minimum during operation, reducing potential bearing
wear and other wheel-end problems.

Without preload, there is space or “clearance” between
the bearing components and the bearings are said to
have end play (also referred to as a “loose” bearing
setting). Excessive end play can result in extreme wear
on bearings, spindles, tires, and wheel seals. It can also
cause anti-lock braking system (ABS) faults.

IMPORTANT WHEEL-END PERFORMANCE GAINS

INCREASING
Wheel-End Performance

Doctor Preload setting range
(SAE J2535)

Conventional practice end play
(degraded performance)

0

PRELOAD
Pounds

.004

END PLAY
Inches

.008

.012

.016

Optimal Preload with the Doctor
Preload Tool.
Doctor Preload, when used in conjunction with
Temper-Loc spindle nuts, is the ideal wheel-end
bearing adjustment solution. The system sets the
bearings to precise preload settings with a quick,
simple, reliable and repeatable process.

Features and Benefits:
n Measured, precise, repeatable settings to optimal
preload for more time on the road
• Improved tire life
• Optimal bearing, spindle and wheel seal life
• Decreased ABS faults
n Adjusts wheel-end bearings to meet SAE J2535
recommended preload settings

Specifications
Doctor Preload Tool
Part Number

Use with Temper-Loc Nut

Axle Spindle
Application

MER415005

MER614723

TP Trailer

Meritor (TP), Dana, Eaton (P22), Fruehauf, Propar

TN Trailer

Meritor (F, H, RL, RQ, TK, TKL, TKLD, TL, TLD, TN, TND, TO, TQC, TQD)
Dana Spicer (D20, D21, D22, DD22, K21, K25,K30)
Eaton (C, C2, CD, CD2, CE, ESA225J, EST, EST225J, EST230J, ETA230C, ETA225D,
ETA225J, H23L, H25R, HCE, HJ, HJE, LA15, T18C, 20L-77, 22L, 22R, J, JE, JH, 23L,
23R, 25R)
Hendrickson (HN)
Ingersoll (A22T)
Standard Forge (A25, A26, 17,000 lbs, 18,000 lbs trade)
Meritor (F, H, RL, RQ, TK, TKL, TKLD, TL, TLD, TN, TND, TO, TQC, TQD)
Dana Spicer (D20, D21, D22, DD22, K21, K25, K30)
Eaton (C, C2, CD, CD2, CE, ESA225J, EST, EST225J, EST230J, ETA230C, ETA225D,
ETA225J, H23L, H25R, HCE, HJ, HJE, LA15, T18C, 20L-77,22L, 22R, J, JE, JH, 23L,
23R, 25R)
Hendrickson (HN)
Ingersoll (A22T)
Standard Forge (A25, A26, 17,000 lbs, 18,000 lbs trade)

MER415003*

MER614743

Axle Applications

MER415084

MER614743

TN Trailer with
Aluminum Hubs

MER415002

MER614836

FF Steer

Meritor (FD900, FD901, FD961, FE900, FE903, FF900, FF901, FF921, FF931,
FF932, FF933, FF941, FF942, FF943, FF944, FF952, FF961, FG941)
Spicer (1100S)

MER415347

MER614837

FE Steer

Meritor (FE931)
Eaton (EFA12FA, EFA12FA, EFA13FS, E12001, FE931, 12K, 13.2K)
Ford Sifco 12K
Ford 6K

MER415004

MER614973

R Drive

Meritor (TR), Eaton (P22), Ford, Rainstar

* Note: Not compatible with Conmet aluminum hubs for TN trailer axles. Contact our Customer Care team for more information.

Precise Positioning With Temper-Loc
Spindle Nuts.
Temper-Loc precision single-locking nut system
provides bearing adjustment with pinpoint accuracy;
each Temper-Loc nut is manufactured to ultra-tight
machining tolerances. The nut system sets optimal
wheel-end preload maximizing tire life and vehicle
uptime. With its unique chamfered mounting face,
Temper-Loc is the exclusive spindle nut used in
conjunction with the Doctor Preload bearing
adjustment tool.

Features and Benefits:
n Heat-treated nut face for superior strength
n Fingertip control retainer ring for ease of placement
and positioning
n EasyView™ verification of positive locking

Specifications
Temper-Loc
Nut Assembly
Number

Replaces
Stemco
Number

Replacement
Retainer Ring Number

MER614723

447-4723

MER614743

447-4743

MER614836

Axle Spindle
Application

Thread
Diameter

Threads
Per Inch

Tool Socket Size

Outer Bearing

MER644723

TP Trailer

3.480”

12

4-13/16” - 8 point

HM518445 / HM518410

MER644743

TN Trailer

2.625”

16

3-3/4” - 8 point

HM212049 / HM212011

448-4836

MER644836

FF Steer

1.500”

12

2-1/2” - 6 point

3782 / 3720

MER614837

448-4837

MER644837

FE Steer

1.500”

18

2-1/2” - 6 point

3782 / 3720

MER614973

449-4973

MER644973

R Drive

3.250”

12

4-3/8” - 8 point

580 / 572

Six Simple Steps. Countless Benefits.

1. Attach Doctor Preload tool to end threads of the
axle. Use a sweeping motion to guide the load arms
around the locknut while engaging the key locator
in the keyway. Engage the thread with two turns of
thread with the end of the axle.

4. Finger-tighten the Temper-Loc nut against the
bearing; align the closest dot on the nut to the key
locator indicator mark.

2. S
eat the bearing rollers. Tighten T-handle
to load the bearings until the gauge
pointer is in green “Roll In Zone.”
Roll the wheel three revolutions.

5. Remove the Doctor Preload tool.

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3. To set the bearings, loosen T-handle slowly until
gauge pointer points to “Set Drive/Trailer Axle” or
“Set Front Axle” accordingly.

6. Install the Temper-Loc nut retaining
ring and check for correct retainer
installation.

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