1

Rotor serviceRotor serviceOn car brake

latheOn car brake

lathe

2

Rotor runoutRotor runout

• Rotor runout [wobble] causes pedal pulsation and vibration during braking.

• Beside irritating customers it can increase stopping distance.

• Excessive runout can also lead to premature pad failure.

• There are two causes of rotor runout:– Warped rotors– Bent hubs

• Rotor runout [wobble] causes pedal pulsation and vibration during braking.

• Beside irritating customers it can increase stopping distance.

• Excessive runout can also lead to premature pad failure.

• There are two causes of rotor runout:– Warped rotors– Bent hubs

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Hub flange runoutHub flange runout

• Hub flange runout is the warp and distortion of the rotor mounting surface on the hub.

• Hub flange runout is the warp and distortion of the rotor mounting surface on the hub.

• The wheel studs make measuring hub flange runout difficult and impractical.

• The wheel studs make measuring hub flange runout difficult and impractical.

4

Hub flange runoutHub flange runout

• Rust and scale that build up on the hub flange and the rotor mounting surface also contribute to runout.

• When the rotors are removed during brake service and repositioned on the hub runout may increase due to the scale and rust wedged between the mounting surfacing.

• Rust and scale that build up on the hub flange and the rotor mounting surface also contribute to runout.

• When the rotors are removed during brake service and repositioned on the hub runout may increase due to the scale and rust wedged between the mounting surfacing.

5

Cleaning the Hub FlangeCleaning the Hub Flange• Always clean the mounting

surfaces with sandpaper or a buffing wheel when servicing rotors.

• Always clean the mounting surfaces with sandpaper or a buffing wheel when servicing rotors.

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Hub flange runoutHub flange runout

• One of the prime causes of warped hub flanges is over torquing the wheels when installing lug nuts with an air wrench.

• A torque wrench should always be used when installing wheels.

• Hubs can also be damaged by road hazards – hitting potholes and curbs or in collisions.

• One of the prime causes of warped hub flanges is over torquing the wheels when installing lug nuts with an air wrench.

• A torque wrench should always be used when installing wheels.

• Hubs can also be damaged by road hazards – hitting potholes and curbs or in collisions.

7

Video linkVideo link

• Rotor runout• Rotor runout

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Torquing lug nutsTorquing lug nuts

• Specifications for lug nut torque can be found in AllData.

• Specifications for lug nut torque can be found in AllData.

• Typical lug nut torque is around 80 ft/lbs.

• A ½” drive impact wrench applied to a lug nut for 1 second will apply about 120 to 150 ft/lbs of torque.

• Typical lug nut torque is around 80 ft/lbs.

• A ½” drive impact wrench applied to a lug nut for 1 second will apply about 120 to 150 ft/lbs of torque.

Micrometer type torque wrench

Single digits

Tens

9

Rotor runoutRotor runout

• Rotor runout is primarily caused by heat.

• Uneven heating of the rotors under severe braking loads can cause the metal to distort.

• Over torquing lug nuts is another factor.

• Incorrect setup when resurfacing rotors can also cause runout.

• Rotor runout is primarily caused by heat.

• Uneven heating of the rotors under severe braking loads can cause the metal to distort.

• Over torquing lug nuts is another factor.

• Incorrect setup when resurfacing rotors can also cause runout.

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Total runoutTotal runout

• When the rotor is mounted on the hub the warp of the rotor is combined with the runout of hub flange.

• This is called ‘total runout’.

• When runout is measured with the rotor mounted to the hub the measurement is called ‘total indicated runout’.

• When the rotor is mounted on the hub the warp of the rotor is combined with the runout of hub flange.

• This is called ‘total runout’.

• When runout is measured with the rotor mounted to the hub the measurement is called ‘total indicated runout’.

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Maximum indicated runoutMaximum indicated runout

• Most manufactures set the limit of total runout to .003”

• Most manufactures set the limit of total runout to .003”

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Factory rotor / hub indexingFactory rotor / hub indexing

• Accurate runout measurements are made on the rotor and hub.

• The hub and rotor are indexed in a position that minimizes total runout when assembled.

• Accurate runout measurements are made on the rotor and hub.

• The hub and rotor are indexed in a position that minimizes total runout when assembled.

• Some manufactures index the rotor to the hub during assembly.

• Some manufactures index the rotor to the hub during assembly.

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Indexing rotor to hubIndexing rotor to hub

It is a good practice to mark one stud on the hub and the corresponding hole in the rotor with paint so that the rotor can be reinstalled in the same position as it was installed at the factory.

It is a good practice to mark one stud on the hub and the corresponding hole in the rotor with paint so that the rotor can be reinstalled in the same position as it was installed at the factory.

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Runout and rotor resurfacingRunout and rotor resurfacing

• Resurfacing the rotor on a off-the-car brake lathe will return the rotor to zero runout but if the hub is bent or distorted the rotor/hub assembly will still have unacceptable runout.

• Floating rotors – rotors that slide off the hub as soon as the caliper has been removed – should be machined on the car using an on-the-car brake lathe to insure that the total runout of the rotor/hub assembly is minimized.

• Resurfacing the rotor on a off-the-car brake lathe will return the rotor to zero runout but if the hub is bent or distorted the rotor/hub assembly will still have unacceptable runout.

• Floating rotors – rotors that slide off the hub as soon as the caliper has been removed – should be machined on the car using an on-the-car brake lathe to insure that the total runout of the rotor/hub assembly is minimized.

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Rotors with hubsRotors with hubs

• Non driven wheels that are supported by tapered roller bearings are either integrated one piece rotors that are cast with a hub, or 2 piece assemblies where the rotor is bolted to the inboard side of the hub flange.

• Non driven wheels that are supported by tapered roller bearings are either integrated one piece rotors that are cast with a hub, or 2 piece assemblies where the rotor is bolted to the inboard side of the hub flange.

One piece cast iron rotor with bores for wheel bearing races

Rotor is bolted to hub assembly

Hub with wheel bearings

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Resurfacing rotors with hubsResurfacing rotors with hubs

• Integral hub and ‘bolt on’ hub rotors can be resurfaced on or off car.

• Since the adapters for the off car brake lathe center on the bearing races the rotors should have nearly zero runout after cutting.

• Integral hub and ‘bolt on’ hub rotors can be resurfaced on or off car.

• Since the adapters for the off car brake lathe center on the bearing races the rotors should have nearly zero runout after cutting.

ArborCone

Adapter

ConeAdapter

Silencer

Spacer

Nut

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Two piece rotor and hubTwo piece rotor and hub

• Once the rotor is bolted to the hub the two pieces should never be separated for resurfacing.

• If the rotor has to be removed to replace a broken stud or wheel bearing the rotor / hub assembly should be indexed to ensure they are reassembled in the same way.

• If a new rotor is being installed it should be resurfaced after the hub is bolted to the rotor.

• Once the rotor is bolted to the hub the two pieces should never be separated for resurfacing.

• If the rotor has to be removed to replace a broken stud or wheel bearing the rotor / hub assembly should be indexed to ensure they are reassembled in the same way.

• If a new rotor is being installed it should be resurfaced after the hub is bolted to the rotor.

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On-car brake latheOn-car brake lathe

• Most manufactures specify or require their dealers to have and use on-car brake lathes.

• Most manufactures specify or require their dealers to have and use on-car brake lathes.

• Resurfacing the rotor while it is attached to the wheel hub is the only way to insure that the rotor runs true – without wobble.

• Resurfacing the rotor while it is attached to the wheel hub is the only way to insure that the rotor runs true – without wobble.

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On-car lathe - componentsOn-car lathe - components

• Electric motor serves two functions – – Drives the rotors via the wheel hub.– Drives the cutting head feed .

• Cutting head – More compact than the cutting head off car lathe to

get into tight spots and to fit inside wheel well.

• Center support – Allows the motor and cutting head / motor assembly

to be flipped 180o so that the rotors on the other side can be resurfaced.

• Telescoping / Parallelogram linkage – Allows the cutting head motor assembly to be raised

and lowered a few inches while keeping the center support centered on the wheel axis.

• Electric motor serves two functions – – Drives the rotors via the wheel hub.– Drives the cutting head feed .

• Cutting head – More compact than the cutting head off car lathe to

get into tight spots and to fit inside wheel well.

• Center support – Allows the motor and cutting head / motor assembly

to be flipped 180o so that the rotors on the other side can be resurfaced.

• Telescoping / Parallelogram linkage – Allows the cutting head motor assembly to be raised

and lowered a few inches while keeping the center support centered on the wheel axis.

20On-Car brake lathe componentsOn-Car brake lathe components

Electric motor

Cutting head

Wheel adapter

Center support

21On-Car brake lathe componentsOn-Car brake lathe components

Control panel

Manual feed wheel

Trolley

Center support

lock

Center support

Power switch

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On-car lathe - componentsOn-car lathe - components

• Wheel adapters – Connect the hub flange to the drive motor– Adapters are available for nearly all 4, 5 and 6 bolt

in a variety of bolt circle dimensions.

• Trolley– Supports the weight of the entire lath assembly.– Allows the lathe to be moved from one bay to

another.– Mounted on casters so that the unit to be

accurately positioned under the vehicle.

• Control panel– Motor on/off switch, indicator lights and runout

display

• Wheel adapters – Connect the hub flange to the drive motor– Adapters are available for nearly all 4, 5 and 6 bolt

in a variety of bolt circle dimensions.

• Trolley– Supports the weight of the entire lath assembly.– Allows the lathe to be moved from one bay to

another.– Mounted on casters so that the unit to be

accurately positioned under the vehicle.

• Control panel– Motor on/off switch, indicator lights and runout

display

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Task #1Task #1

• Refinish rotor on vehicle; measure final rotor thickness and compare with specifications.

• Refinish rotor on vehicle; measure final rotor thickness and compare with specifications.

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Shop safetyShop safety

• Keep hands away from moving parts.• Keep the floor area where you will be working clear

and unobstructed.

• Keep hands away from moving parts.• Keep the floor area where you will be working clear

and unobstructed.

• Safety Glasses must be worn at all times.

• Never wear loose fitting clothing when working with power equipment.

• Never use a piece of equipment or extension cord with a broken ground pin. The ground pin is a safety mechanism that prevents injury or death by electrocution in the event of an electrical short in the equipment.

• Safety Glasses must be worn at all times.

• Never wear loose fitting clothing when working with power equipment.

• Never use a piece of equipment or extension cord with a broken ground pin. The ground pin is a safety mechanism that prevents injury or death by electrocution in the event of an electrical short in the equipment.

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Vehicle setupVehicle setup

• Raise the vehicle to a height where the center of the wheel is about belt buckle high.

• Grab the tires and wiggle the tire top to bottom to determine if there is any play in the wheel bearing. If the wheel bearings are adjustable tighten the adjustment until there is no free play. Non adjustable bearings will need to be replaced if there is any free play.

• Remove the brake caliper. Hang the caliper using safety wire to prevent damage to the brake hose. Make sure the caliper is not in contact with the rotor or CV joint.

• Raise the vehicle to a height where the center of the wheel is about belt buckle high.

• Grab the tires and wiggle the tire top to bottom to determine if there is any play in the wheel bearing. If the wheel bearings are adjustable tighten the adjustment until there is no free play. Non adjustable bearings will need to be replaced if there is any free play.

• Remove the brake caliper. Hang the caliper using safety wire to prevent damage to the brake hose. Make sure the caliper is not in contact with the rotor or CV joint.

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• Since the adapter will bolt to the outboard surface of the hub it should be cleaned with a buffing wheel or sandpaper.

• Since the adapter will bolt to the outboard surface of the hub it should be cleaned with a buffing wheel or sandpaper.

Vehicle setupVehicle setup

• Measure and record rotor thickness. It will require close to .020” of material to be removed in the cutting process.

• Measure and record rotor thickness. It will require close to .020” of material to be removed in the cutting process.

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Electrical connectionElectrical connection

• Do not use a drop light to power the lathe. • If an extension cord is needed, use one that

is less than 25 feet in length and 12 gauge or lower.

• Do not use a drop light to power the lathe. • If an extension cord is needed, use one that

is less than 25 feet in length and 12 gauge or lower.

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Remove caliper and anchor bracketRemove caliper and anchor bracket

• Removing the anchor bracket may be necessary to allow the lathe to be positioned inside the wheel opening

• Removing the anchor bracket may be necessary to allow the lathe to be positioned inside the wheel opening

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Video LinkVideo Link

• Tool setup procedures• Tool setup procedures

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Lathe setupLathe setup

• If the calipers are mounted at the front, start on the passenger side. If they are mounted at the rear, start on the drivers side.

• This insures that you will be making your initial adjustments with the lathe in an upright position. You will be using it upside down when you move to the opposite side.

• Check to make sure the cutting tips are installed correctly.

• If the calipers are mounted at the front, start on the passenger side. If they are mounted at the rear, start on the drivers side.

• This insures that you will be making your initial adjustments with the lathe in an upright position. You will be using it upside down when you move to the opposite side.

• Check to make sure the cutting tips are installed correctly.

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Select the adapterSelect the adapter

• Select the proper adapter to fit the bolt circle.

• Select the proper adapter to fit the bolt circle.

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Mount the adapterMount the adapter• Mount the adapter drum to the adapter plate using the vehicles lug nuts.• Mount the adapter drum to the adapter plate using the vehicles lug nuts.

• If the lug nuts have integral wheel cover retaining washers you will need to use universal lug nuts to retain the adapter.

• If the lug nuts have integral wheel cover retaining washers you will need to use universal lug nuts to retain the adapter.

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Do not use an impact wrench!Do not use an impact wrench!

• The adapter nuts need to be snug. Use of an impact wrench can warp or possibly break the adapter.

• The adapter nuts need to be snug. Use of an impact wrench can warp or possibly break the adapter.

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Snug up the lug nuts by handSnug up the lug nuts by hand

• Hand tighten the lug nuts

• Hand tighten the lug nuts

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Install silencing bandInstall silencing band

• For best results use a weighted silencing band.

• For best results use a weighted silencing band.

36

Video LinkVideo Link

• Mounting the machine• Mounting the machine

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Align the lathe to the hub axisAlign the lathe to the hub axis

• Position the lathe next to the hub and align the unit until the threads of the drive motor shaft align with the adapter.

• Position the lathe next to the hub and align the unit until the threads of the drive motor shaft align with the adapter.

• Lower the vehicle until the center of the adapter is at belt buckle height.

• Lower the vehicle until the center of the adapter is at belt buckle height.

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Connect the drive motor to the adapterConnect the drive motor to the adapter

• Tighten the center screw knob to secure the motor drive flange to the adapter.

• Tighten the center screw knob to secure the motor drive flange to the adapter.

Center screw knob

39

Connecting the lathe to the adapterConnecting the lathe to the adapter

• Align the motor to the adapter and tighten the center knob

• Align the motor to the adapter and tighten the center knob

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Adjust the cutting head positionAdjust the cutting head position

• The cutting head slides latterly on a dovetail. Position the cutting head so that it is centered on the rotor.

• The cutting head slides latterly on a dovetail. Position the cutting head so that it is centered on the rotor.

Cutting head

position lock

Dovetail

41

Cutting head aligned with rotorCutting head aligned with rotor

• Once the cutting head is centered on the rotor tighten the lock lever.• Once the cutting head is centered on the rotor tighten the lock lever.

42

Preliminary adjustment of cutting headPreliminary adjustment of cutting head

• Loosen the lock on the cutting tips then back off the adjustment knobs until the tips are far enough apart to pass over the rotor.

• Loosen the lock on the cutting tips then back off the adjustment knobs until the tips are far enough apart to pass over the rotor.

Cutting depth lock

lever

Cutting tip adjustment

knob

43Reposition cutting head Reposition cutting head

• Used the manual feed knob to bring the cutting tips to the center of the rotor.

• Used the manual feed knob to bring the cutting tips to the center of the rotor.

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Plug in the machinePlug in the machine

• Do not use an extension cord longer than 25 ft• Do not connect to a powered drop light

• Do not use an extension cord longer than 25 ft• Do not connect to a powered drop light

• The machine should be connected directly to a 3 pin 110 volt outlet.

• The machine should be connected directly to a 3 pin 110 volt outlet.

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Power switchPower switch• The power switch is above the control panel.• The power switch is above the control panel.

• The yellow ‘Ready’ indicator light will illuminate when there is power to the lathe.

• The yellow ‘Ready’ indicator light will illuminate when there is power to the lathe.

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Auto compensationAuto compensation

• Push the ‘Start’ button to begin the auto compensation process.

• The lathe will run for about 20 seconds and you may here a few clicking noises.

• Once compensation has completed the green indicator will illuminate.

• Push the ‘Start’ button to begin the auto compensation process.

• The lathe will run for about 20 seconds and you may here a few clicking noises.

• Once compensation has completed the green indicator will illuminate.

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Video LinkVideo Link

• Lateral Runout Adjustment• Lateral Runout Adjustment

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Make a test cut Make a test cut • Turn the outboard cutting tip knob until the

tip just makes contact with the rotor.• Note the reading on the scale.

• Turn the outboard cutting tip knob until the tip just makes contact with the rotor.

• Note the reading on the scale.

• Repeat on the inboard side of the rotor • Repeat on the inboard side of the rotor

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Reposition the cutting headReposition the cutting head

• Using the manual feed knob position the cutting tips at the very bottom of the rotor surface, in the rusted area where the pads do not touch the rotor.

• Using the manual feed knob position the cutting tips at the very bottom of the rotor surface, in the rusted area where the pads do not touch the rotor.

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Set the cutting depthSet the cutting depth

• The cutting depth must be more than .004” and should not exceed .020”

• The Pro-Cut Lathe is a ‘Single Pass’ machine which means that you do not need to do a final cut if there are no bare spots after the cut

• The “Sweet Spot” for the best surface finishes are between .006” and .012” per side

• The cutting depth must be more than .004” and should not exceed .020”

• The Pro-Cut Lathe is a ‘Single Pass’ machine which means that you do not need to do a final cut if there are no bare spots after the cut

• The “Sweet Spot” for the best surface finishes are between .006” and .012” per side

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Lock the cutting depth adjustmentLock the cutting depth adjustment

• Tighten the cutting depth lock to prevent vibration from the motor upsetting the adjustment.

• Install silencer block.

• Tighten the cutting depth lock to prevent vibration from the motor upsetting the adjustment.

• Install silencer block.

Silencer block

52

Engage the feedEngage the feed

• Push inward on the feed wheel handle to engage the automatic feed.

• Push inward on the feed wheel handle to engage the automatic feed.

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Automatic shutdownAutomatic shutdown

• The machine can be set for un-attended operation by adjusting the position of the feed stop trigger.

• Position the trigger block in the hole where it will contact the kill switch when the cutting tips are just past the outer edge of the rotor.

• The machine can be set for un-attended operation by adjusting the position of the feed stop trigger.

• Position the trigger block in the hole where it will contact the kill switch when the cutting tips are just past the outer edge of the rotor.

Trigger block Kill

switch

54Cutting processCutting process

• When the feed is engaged you should see small chips of iron flying off of the cutting tips as the rotor spins.

• When the feed is engaged you should see small chips of iron flying off of the cutting tips as the rotor spins.

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Check rotor surfacefor bare spotsCheck rotor surfacefor bare spots

• If the inboard and outboard surfaces of the rotor have no bare spots the rotor can be cleaned and the machine can be moved to the rotor on the opposite side

• If there are any bare spots a second pass will be needed

• Manually back the cutter tips away from the rotor to avoid damaging to the cutter tips when repositioning the cutting head

• Add an additional .004” + to the initial cutting depth

• If the inboard and outboard surfaces of the rotor have no bare spots the rotor can be cleaned and the machine can be moved to the rotor on the opposite side

• If there are any bare spots a second pass will be needed

• Manually back the cutter tips away from the rotor to avoid damaging to the cutter tips when repositioning the cutting head

• Add an additional .004” + to the initial cutting depth

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Video LinksVideo Links

• Making the cut

• Making the cut

57

Check rotor thicknessCheck rotor thickness

• Make sure that the rotor is above the ‘Machine To’ limit.

• Make sure that the rotor is above the ‘Machine To’ limit.

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Non-directional finishNon-directional finish

• Run a piece of medium grit sandpaper up and down the rotor surface while it is turning. This helps produce a non-directional finish.

• Run a piece of medium grit sandpaper up and down the rotor surface while it is turning. This helps produce a non-directional finish.

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Do not use BrakekleenDo not use Brakekleen• Do not use brake

clean, it is designed to remove grease and will actually bed the brake dust into the rotor

• Do not use brake clean, it is designed to remove grease and will actually bed the brake dust into the rotor

• Use water plus a little bit of dishwashing soap

• Dry with white paper towels

• Use water plus a little bit of dishwashing soap

• Dry with white paper towels

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Clean with soap and waterClean with soap and water

• Do not use brake clean, it is designed to remove grease and will actually bed the brake dust into the rotor

• Use a very diluted solution of dishwashing soap and water to clean metallic dust off of the rotor

• Wipe the residual soap and water off the rotor surface with white paper towels

• Do not use brake clean, it is designed to remove grease and will actually bed the brake dust into the rotor

• Use a very diluted solution of dishwashing soap and water to clean metallic dust off of the rotor

• Wipe the residual soap and water off the rotor surface with white paper towels

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Runout checkRunout check

• A post resurfacing check should show that the runout in now less than .001”

• A post resurfacing check should show that the runout in now less than .001”

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Resurfacing the opposite sideResurfacing the opposite side

• Loosen the center support lock and manually rotate the lathe to bring the cutting head to the position where the caliper anchor bracket was removed.

• Loosen the center support lock and manually rotate the lathe to bring the cutting head to the position where the caliper anchor bracket was removed.

• The entire lathe assembly is flipped 180 degree to cut the opposite side rotor.

• The entire lathe assembly is flipped 180 degree to cut the opposite side rotor.

Center support lock

lever

63

Lathe setup for opposite sideLathe setup for opposite side

• With the lathe inverted the adjustment of the cutting tips are much more difficult.

• If you made your initial adjustments with the lathe upright when the lathe is moved to the opposite side the setup adjustments have already been made and the only further adjustment will be the cutting tip depth.

• With the lathe inverted the adjustment of the cutting tips are much more difficult.

• If you made your initial adjustments with the lathe upright when the lathe is moved to the opposite side the setup adjustments have already been made and the only further adjustment will be the cutting tip depth.

64

Video LinkVideo Link

• Cutting the opposite side• Cutting the opposite side

65Cutting BitsCutting Bits

• Cutting tips can be rotated twice after installation.• After all three edges have worn out you swap the

inboard and outboard tips.• You can rotate the tips twice after swapping.

• Cutting tips can be rotated twice after installation.• After all three edges have worn out you swap the

inboard and outboard tips.• You can rotate the tips twice after swapping.

• The cutting bits are made of tungsten carbide.

• Each bit insert has 6 useable edges.

• If used properly you should get 7 or more cuts.

• Some badly warped rotors may require two or more cuts.

• The cutting bits are made of tungsten carbide.

• Each bit insert has 6 useable edges.

• If used properly you should get 7 or more cuts.

• Some badly warped rotors may require two or more cuts.

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1 4

6

3 5

2

Cutting edgesCutting edges

• There are six cutting edges on each bit.

• In order to use all six cutting edges you need to swap sides.

• Some cutting bits have dots to help the technician keep track of how the tips have been rotated.

• There are six cutting edges on each bit.

• In order to use all six cutting edges you need to swap sides.

• Some cutting bits have dots to help the technician keep track of how the tips have been rotated.

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Cutting tip rotationCutting tip rotation

• New cutting bits should be installed in the one dot position.

• If either bit is worn out both bits should be rotated to the two dot position.

• When you get to the three dot position if either bit is worn out the bits are swapped and set to the one dot position.

• New cutting bits should be installed in the one dot position.

• If either bit is worn out both bits should be rotated to the two dot position.

• When you get to the three dot position if either bit is worn out the bits are swapped and set to the one dot position.

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Worn bit edgesWorn bit edges

• The bits are worn out when they fail to make large granular chips.

• If whet looks like dust or power is all that is comes off the bits during a cut the bit edge is worn out and needs to be rotated.

• The bits are worn out when they fail to make large granular chips.

• If whet looks like dust or power is all that is comes off the bits during a cut the bit edge is worn out and needs to be rotated.

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Use a torque wrench to tighten the lug nutsUse a torque wrench to tighten the lug nuts

• Now that the rotors are true you don’t want to warp them by over-torquing the lug nuts.

• Now that the rotors are true you don’t want to warp them by over-torquing the lug nuts.

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Video LinkVideo Link

• Lathe Maintenance• Lathe Maintenance

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For additional Pro-Cut training materialFor additional Pro-Cut training material

http://www.procutusa.com/learning/Default.aspx

Pro-Cut Website