DIY Network

4-Wheel ATV: Rear-Brake Service and Bleeding Brakes From "Weekend Mechanic" episode WKM-313

Bruce Bonebrake prepares to service the ATV's mechanical rear brake. Unlike the hydraulic front brakes, the single rear brake is cable-operated.

In this segment of DIY's Weekend Mechanic host Bruce Bonebrake continues the brake-servicing on a Honda 4-wheel ATV. Next up: the rear brakes and brakes-bleeding.

Materials:

In addition to standard auto-mechanic's tools (wrenches, ratchets, extenders, screwdrivers, nut-drivers, etc.), some of the specialty tools that will be needed for these projects include hydraulic bleed pump, brake-cleaner spray, brake grease, waterproof bearing-grease, needle-nosed pliers, high-speed drill, hole saw, torque wrench and an air-compressor and set of pneumatic tools.

DIY Difficulty Rating for the Project: This routine maintenance shown in this episode should be no problem for the experienced weekend mechanic. The brake work, wiring and winch addition are a little more challenging. Some experience with motorcycle maintenance and repair would be a plus. Overall, we gave these projects a difficulty rating of 2 on a 5-point intermediate-level scale. It took us about 8 hours to finish this job. Allow yourself a full weekend to complete this project properly.

advertisement

This 4-wheeler has a distinctive brake system in that it has two front brakes but only one rear brake. While the front brakes are operated by hydraulics, the rear brake is mechanical and cable-operated. The single rear-brake is located on the right side of the vehicle, and the brake shoe for the rear is larger in diameter than the smaller shoes used on the front brakes (figure A).

The adjustments for the rear-brake cable are located just behind the rear hub (figure B).

Figure A

Figure B

Rear-Brake Servicing

• To replace the rear brake shoes, begin by removing the cotter pin from the castel nut (figure C).

• With the cotter pin removed, use a large socket-wrench to loosen the castel-nut from the axle. Once it's loosened, remove the castel nut by hand.

• Note: The bearing on this wheel hub should fit tightly and look clean.

• Inspect the nut for wear, and carefully remove the wheel-hub from the axle. The wheel hub has a bearing inside. Check it for wear as well (figure D).

  Figure C

  Figure D

  
  

• Mark the brake-drum cover for proper alignment (when it is reinstalled later), and carefully remove the four bolts that hold it onto the backing plate. Once the bolts have been removed, carefully slide off the brake-drum cover (figure E) and inspect the brake drum itself.

• Slide the tip of a standard screwdriver between the drum and backing plate on both sides and carefully remove the drum.

  Note: If the drum is stuck on the axle, you can also use a wheel-puller for this operation.

• Once the drum has been removed, inspect it carefully (figure F).

  Figure E

  Figure F

  
  

• To remove the old brake shoes, first use needle-nosed pliers remove the cotter pins on the outside of the retaining plate. With the cotter pins removed, you can gently pry off the retaining plate (figure G).

• Once the retaining plate is removed, slide the shoes off with the springs still attached (figure H).

  Figure G

  Figure H

  
  

• Clean the backing plate thoroughly with spray brake-cleaner.

• Apply brake grease to the shoe-posts and cantilever (figure I).

• Seat the new brake shoes in position. You may need to screw the shoe adjusters all the way in to get the new brake-shoes in position.

• Reinstall the retaining plate back on the posts (figure J) and secure it with a new cotter pin.

  Figure I

  Figure J

  
  

• After they have been cleaned thoroughly, reinstall the brake drum, and bolt the brake-drum cover back in position.

• Slide the wheel-hub back onto the axle and secure it with the axle castel-nut (figure K). Tighten the castel nut to the proper torque specs. (For our ATV, the castel-nut was torque-tightened to 50 foot-pounds, per the owner's manual.)

• Finally, adjust the brake linkage to fit using the two cable adjusters at the rear of the hub.

  Figure K

  
  

  Figure L

With all of the new brake shoes installed, we can now bleed the front-brakes system to flush out the old brake fluid and ensure that there is no air in the brake lines.

• To bleed the brakes, we used a brake-bleeding setup consisting of a vacuum pump hooked up to a clear hose and reservoir (figure L). (Hydraulic vacuum pumps like this are available at auto-parts stores and cost around $15 to $20.)
  

  Figure M

• Attach the vacuum line to the bleeder valve on the rear side of the wheel.

• Remove the cap on the brake-fluid reservoir.

• Open the bleeder valve so that the old brake-fluid can be pumped out (figure M).
  

  	Figure N
  	Figure O

• Have an assistant pour new brake fluid into the reservoir (figure N) as you operate the pump to draw the old brake-fluid off (figure O).

  Note: Most Japanese ATVs and motorcycles use DOT 4 brake fluid.

• Continue bleeding the brake lines until all air is out of the brake fluid. Once the new brake fluid has been added, and the old fluid drawn off, close the bleeder valve and cap it shut.

• Empty the reservoir, and repeat the process on the other side of the vehicle.

Safety Alert: Always dispose of automotive fluids (antifreeze, motor oil, transmission fluid, etc.) and other toxic substances responsibly. Most auto center offer recycling of automotive fluids.

Important: Included in this segment are the steps in this automotive procedure as shown in the episode. These steps are general guidelines that are applicable to most vehicles. With any particular vehicle, there may be procedures, specifications, settings, tolerances, components, etc. that are specific to that vehicle. There are also variations according to the type and brand of repair-kit you select. Always consult your vehicle's service manual when undertaking significant automotive repairs, and read and follow the manufacturer's directions and precautions that come with your kit or replacement parts.

Safety Alert: As a standard safety precaution, don't rely solely on a jack to support the weight of a vehicle. When using a jack to access or work beneath a vehicle, always use jack stands for support. Make sure that the jack and stands that you use are rated for the weight and type of your vehicle.

RESOURCES :

The Complete Idiot's Guide to Motorcycles
ISBN: 0028624165
Author: editors of Motorcyclist magazine

Warn Industries Inc.
Provided the winch installed on the ATV in WKM, episode 313.
Website: www.warn.com