A technician is using a brake lathe

Brake Lathe Maintenance Tips

Brake lathes, when adequately maintained, prevent vibration in brake rotors by reducing lateral turnout and thickness variation. When lathes aren’t maintained, they will do more harm than good. When they aren’t maintained, they can cause significant surface finish issues on rotors, including chatter marks or scoring.

Lathes that aren’t maintained will experience shorter service lives, contributing to higher replacement costs. They also cause longer cutting times and increased scrap rates. Failure to maintain your brake lathe can also increase injury risks for your technicians, as there is a higher potential for tools to break or come loose and a greater exposure to brake dust..

To prevent these risks, we recommend following the general maintenance tips listed below. Please note that there may be other maintenance suggestions based on the type of brake lathe you have. Always consult the manufacturer’s manual.

1. Clean the Machine

A technician uses a brush to clean off a dirty brake lathe.

Turning rotors (and drums, if that’s part of the service you provide) is a dirty business. If cast iron chips get under seals, on the arbor, or inside adapters, they’ll cause wear and inaccuracies that lead to problems.

While compressed air may seem like the best solution for cleaning, it actually poses an unnecessary risk. Compressed air is likely to force chips and debris under covers and into seals, which is exactly where they’re not needed. Additionally, it can be hazardous for anyone nearby who is not wearing safety glasses.

Your best method is to brush the lathe clean (along with the arbor and adapters), empty the chip tray, and wipe down all surfaces with a degreaser, such as WD-40. Cleaning should be done daily or at least as often as the lathe is used.

2. Lubricate Moving Components

Some brake lathes use grease in the bearings, and these will have visible grease fittings. Clean them off periodically and apply fresh grease as recommended by the lathe manufacturer. Be sure to look for an exit port for the grease and check if the new grease is pushing the old out.

Only use the type of grease recommended, as other types may be too thick or too thin or not have the right load-bearing and temperature characteristics.

We generally recommend lubricating your brake lathe monthly or quarterly, depending on the lathe’s workload.

3. Check Lubrication Levels

Many brake lathes have an oil lubrication system. If the oil level is allowed to drop too low or the oil becomes contaminated, parts will wear and may even overheat. You can avoid this by making a weekly oil level check part of your maintenance program. You should also replace oil as recommended by the manufacturer (and at least annually).

4. Perform Calibrations

Calibration is an important part of brake lathe maintenance. The two aspects to consider are runout and the gap between the opposed cutting bits.

Runout

On an off-car or bench lathe, it’s essential to minimize runout in the arbor. Impacts, or regular workshop wear and tear, can result in considerable runout, making it impossible to produce a satisfactory rotor. Runout is measured with a dial test indicator and should be less than 0.001″. Plan on checking runout at least quarterly, and preferably more often.

Gap

Sophisticated brake lathes, like the Hunter BL Series bench lathe, have technology for measuring the gap between the two cutting bits. This technology needs calibrating whenever the tool bits are replaced or if the machine has been powered down. Follow the procedure established by the lathe manufacturer.

5. Replace Worn Components

Several components will wear over time, including cutting bits, arbors and adapters, rubber boots, belts, seals, and bearings. It’s essential to replace these components as soon as you notice damage.

Cutting Bits

The condition of the cutting bits is critical for achieving the desired surface finish (which should be better than 60 micro-inch RA). Replace these as soon as the surface finish starts to go off, then calibrate the lathe if appropriate.

Arbors & Adapters

Likewise, if the arbor or adapters show any signs of damage, replace them promptly. Delaying this will only result in poor-quality brake rotors after turning.

Rubber Boots

Some brake lathes have rubber boots to protect sliding components and seals. If these are damaged, they should be replaced to prevent metal chips from entering and wearing out the moving parts.

Belts

Belts, as used to drive the arbor in the Hunter BL Series bench lathe, stretch over time. This can lead to slippage and, eventually, cracking and failure. Belts are not expensive, so replace them before this happens.

Seals & Bearings

Over time, seals (and eventually bearings) will need to be replaced. However, their wear can be delayed by staying on top of lubrication.

6. Inspect Components

Two technicians are inspecting a brake lathe before use.

Every technician should visually inspect the brake lathe’s condition before use. If only one technician ever works on it, they should conduct a visual inspection at the start of each shift.

This inspection should address:

  • Operation of any guards and dust extraction provided.
  • The condition of the cutting bits.
  • State of cleanliness.
  • Legibility/visibility/operation of all lights and indicators.
  • Note wear or other items of concern and address them promptly.

7. Always Use the Correct Speed

The surface finish achieved on a brake rotor is a function of rotational speed (rpm), feed rate, and cutting bit condition. Cutting too fast will generate excessive heat in the cutting bits, leading to cracking and accelerated wear. Comparatively, going too slowly can cause material to build up on the cutting edge. Both will result in a poor-quality surface, which will negatively impact braking performance.

8. Replace Safety Decals

An example of a safety decal that could be on a brake lathe. This decal states "hazardous pinch points. Keep hands and fingers clear."

A new brake lathe will feature multiple prominently displayed safety decals. The manufacturer didn’t apply these for decoration; they are intended to be read and followed!

Over time, especially when the lathe is cleaned regularly, decals can become scratched and worn. Eventually, they will become illegible. This poses a safety hazard that could potentially lead to an OSHA violation. To avoid problems like these, replace worn safety decals with new versions obtained from the manufacturer.

Get More Tips From Allied, Inc.

Allied, Inc. sells automotive equipment, including lifts, wheel balancers, tire changers, air compressors, and brake lathes, to automotive repair shops throughout the United States. We also provide lift installation, inspection, and repair services to customers in Michigan and northern Ohio.

Visit our blog for additional resources, or contact us today to discover how our team can help enhance your shop’s efficiency.