Front Steer Axle Technical Training

Meritor Front Non-Drive Steer Axle

• The front non-drive axle is a solid axle system designed to support the weight of the front of the vehicle, provide a center point for the tire and wheel assemblies, and provide steering capability to the vehicle.

• Current Meritor front non-drive steer axles do not include suspension springs. The suspension springs are provided by the vehicle manufacturer.

“Easy Steer” Front Axle

• The term ‘Easy Steer” relates to the low friction composite knuckle pin bushings, made of acetate resin polymer. These bushings reduce steering effort and provide longer life.*

• *Bushing inspection and service is covered later in this program.

Model Identification

• Early Meritor steer axles

• Axle build information is indicated on the axle identification tag. The tag is fastened to the center front surface of the axle beam. There are four numbers listed:

•       Model number

•      Customer number

•      Serial number

•      Build date

• An example of a model number is; FF961 LX122.

Identification

• The axle model number identification plate is located on the axle center.

Model Identification, continued;

• Later Meritor steer axles

• Axle build information on the later Meritor axle is located on a similar tag as the early axle.

• The tag contains similar information except for the model number difference.

• An example of a model number is; MFS122015NX122

• This information is needed when ordering replacement parts

FF 961 Description

• The Meritor FF 961 axle is standard with bottle spindles for conventional wheel ends.

• Meritor supplies most axles to the OEM’s less brakes and wheel end equipment.

FF 961 Components

Typical axle components

FF 961 Inspection

• Refer to MM02, Lubrication and Maintenance Section.

• Use Table C to determine vehicle vocation

• Use Table D for lubrication, inspection and maintenance schedule.

FF 961 Inspection, Table C

FF 961 Inspection, Table D; Tie Rod Ends

FF 961 Inspection, Table D; Tie Rod Assembly

FF 961 Inspection, Table D; Miscellaneous Components

FF 961 Inspection, Table D; Knuckle Vertical End Play

FF 961 Inspection, Table D; King Pins, Draw Keys and Torque Requirements

• Measure end play by pushing/pulling on each side of the hub or drum while looking at the dial indicator.

• If end play is not within 0.001-0.005 inch, adjust the wheel bearings.

Wheel Bearing End Play InspectionWheel Bearing End Play Inspection

• The tie rod has right-hand threads on one end and left hand threads on other end.

Tie Rod InspectionTie Rod Inspection

Tie Rod Inspection• Tie rod threads must visible the entire length of the cross tube slot.

• Check tie rod movement by hand.

Tie Rod Inspection• Check for missing cotter pin.

• Check for damaged or torn boot.

Draw Key Inspection• Make sure draw key is installed

completely and the locknut is tightened to the specified torque. If the draw key is not installed correctly, the king pin and the axle center will be damaged.

• Tighten the draw key nuts from 30-45 lb-ft at the following intervals.

• After the first 6,000 miles of new vehicle operation.

• Every 36,000 miles of operation.

Knuckle Vertical End Play

• New or rebuilt axles, .001- .025 inch.

• In-service axles, .001-.065 inch.

King Pin Bushing Wear• Measure both upper and

lower bushing for wear.

• Replace both bushings if wear is greater than 0.010-inch.

• See MM2 for bushing replacement procedures.

• NOTE: When Easy Steer Bushings are replaced they must be reamed for proper fit.

Wheel Speed Sensor Adjustment

• The sensor must be reset each time the wheel end is removed to obtain he proper sensor-to-tone wheel gap.

• For sensor adjustment, push sensor in until it contacts the tone wheel. The wheel run-out will push the sensor back away from tone wheel for proper adjustment.

• See MM02 for sensor replacement.

• NOTE: If driver reports indicate the ABS light has been coming ON, and ABS diagnostics indicate the sensor gap is out-of-adjustment, check for possible wheel-end looseness as the cause.

Vehicle Pre-Alignment Inspection

• See MM2 for pre-alignment inspection.• Wheel and tire condition

• Front suspension condition (as shown previously in this program)

• Rear axle and rear suspension condition

Alignment Check, Toe

• Toe-in is when wheels are closer together in back than in front.

• Toe-out is when the wheels are closer together in back than in front.

Alignment Check, Toe• Steer axle toe is

adjustable to reduce wear to the leading edge of the tire and also to avoid road wander.

• Excessive toe-in wears the outside edge of tires.

• Excessive toe-out wears the inside edge of the tires. •Toe is adjusted in a static,

unloaded condition so that the tires will run in a straight line under a dynamic, loaded condition.

• Specifications

• Vehicle unloaded: 1/16” toe in.

• Most tire wear is caused by incorrect toe settings.

• See MM02 for procedures to measure and adjust toe.

• Toe adjustment is the responsibility of the vehicle manufacturer.

Alignment Check, Toe Alignment Check, Toe

Alignment Check, Camber Angle• Camber is the angle of the

tire in relation to the ground.• Positive camber occurs

when the distance between the top of wheels is greater than the distance between the bottom of the wheels at ground level.

• A small amount of positive camber is built into the axle beam and knuckle because camber changes with load.

• This results in a zero or neutral camber angle when the vehicle is operated at the normal load.

Alignment Check, Camber Angle; 1993 and later axles• Axle installed in vehicle.

• Left side (roadside) and right side (curbside):

• +3/16 degree to –11/16 degree

final reading.• TMC recommends; less

than ¼ degree either side.• The camber angle is not

adjustable. It is machined into both the axle beam and the knuckle.

Alignment Check, Caster Angle

• Caster is the tilt of the king pin center line when viewed from the side of the vehicle.

• The caster angle is the angle from the vertical position to the center line of the king pin. If the top of the king pin axis is toward the rear of the vehicle, the caster is positive.

Alignment Check, Caster Angle

• A slight positive caster creates a self-aligning action that helps to stabilize the vehicle after turning and it for driving straight ahead.

• Too much caster will increase steering effort or may amplify a shimmy condition.

Alignment Check, Caster Angle• Adjust caster according to

vehicle manufacturer’s procedure. Refer to vehicle manufacturer’s specification for caster angle.

• Generally vehicles with power steering are +2 to +4 ½ degree caster.

• TMC recommends; Left +3 ½ and Right +4 degree.

• Caster is the responsibility of the vehicle manufacturer.

Alignment Check, Ackerman Angle• When turning, the inner

wheel must turn at a greater angle than the outer wheel.

• This angle is the turning radius angle (often called the Ackerman angle).

• The angle is built into the design of the tie rod arms, the tie rod ends and the cross tube assembly to give the best possible road contact and to minimize tire wear during turns.

Alignment Check, Ackerman Angle

• If angle is not within specifications, premature tire wear will occur.

• Ackerman angle is not adjustable. Hard parts must be replaced to set the proper angle for a particular OEM and wheelbase.

Lubrication

• Refer to MM02, Lubrication and Maintenance Section.

• Use Table E for lubrication specifications.

• Use Table F for axle greasing intervals and specifications.

• Use Table G for wheel end oil change intervals and specifications.

Lubrication

Lubrication

Lubrication

Lubrication • King Pins

• Make sure the tires touch the ground. Do not raise the vehicle.

• Clean off all grease fittings prior to lubrication.

• Lubricate the pins through the grease fittings on the top and bottom of the knuckle.

•Apply lubricant until new lubricant comes from the thrust bearing seal and the upper shim pack.

• Tie rods

• Make sure the tires touch the ground.

• Apply the lubricant through grease fittings on assembly.

• Apply the lubricant unit new lubricant comes from the boot.

Lubrication ProcedureLubrication Procedure

Grease Lubricated Wheel Bearings• Remove the old lubricant

from all parts.• Discard seals.• Replace worn or damaged

bearings.• Force the specified lubricant

from the large end of the cones into the cavities between the rollers and cage.

• Pack the hub between the bearing cups with lubricant to the level of the smallest diameter of the cups.

Oil Lubricated Wheel Bearings

• Check the level on the cap. If the oil level is not at the specified level on the cap, remove the fill plug. Add the specified oil until the oil is a the correct level.

Diagnostics, General Items

Diagnostics, General Items

Diagnostics, Tire Wear

• Consult the TMC “Radial Tire Conditions Analysis Guide” for tread wear and tire conditions information.

Diagnostics, Tire Wear

• TMC “Radial Tire Conditions Analysis Guide” content example.• To receive a manual call 800 ATA-LINE and ask for item number T0121.

Summary

• This program has provided technical information on ArvinMeritor front non-drive steer axle, FF961

• Front axle product overview, inspection, lubrication, and diagnostic information was presented

• What additional information do you require that was not covered in the presentation?

• Questions or comments?

Where to Get More Information

• Other training sessions• Arrange with your DSM

• Maintenance Manuals• Technical Bulletins• Technology White Papers• Product Videos• Technical Library CD• ARM Web Site• Customer Service 800 535 5560• TMC Recommended Practices Manual• Vehicle manufacturer

www.arvinmeritor.com

• ArvinMeritor publications can be found on ArvinMeritor’s website at

www.arvinmeritor.com.

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