REAR BRAKE INSPECTION AND ADJUSTMENT

From a post on the Durango Owners Club Forum by Barry Ho; Reproduced here with permission.

I put together some basic instructions on how to do an inspection and adjustment.  I also included more detailed steps in the event you have to replace the drums, shoes, or wheel cylinders.  Since your post stated that you have never worked on drum brakes before, here are some basic steps to follow in order to gain access to the rear brake drums.  Iíve also included some images of tools you will need, in my additional reply posts, as well as a web link with additional brake information.  Although I have tried my best to include comprehensive instructions, I hope that I havenít forgotten anything.  If so, I am sure the knowledgeable folks in this group will help out.

  1. Have all of your tools ready and on hand:
      1. Vehicle jack
      2. Vehicle safety jack stands (2 minimum)
      3. Lug wrench (extension bar if lug nuts very tight)
      4. Blocks of wood (in case the jack doesnít have enough height for the D and for blocking front wheels while rear wheels are off the ground)
      5. Steel hammer
      6. Brake fluid $2 (manufacturer spec -- see owners manual or call dealer)
      7. Portable propane torch $5
      8. Brake slave cylinder adjuster tool $3 (see following images)
      9. Brake spring tool $5 (see following images)
      10. Brake cleaner spray
      11. High temp brake lubricant $2 (small tube: ask your retailer)
      12. Catch basin/pail
      13. Cardboard (3í x 3í minimum)
      14. Shop rags, or heavy duty paper towel
      15. 12" to 18" sitting stool/box/cooler (trust me it will save your joints)
      16. Adjustable pliers, various sizes (for getting grip on springs if removing)
      17. *Socket wrench and various socket sizes (should have one on hand)
      18. *Brake line wrench $4
      19. *Electrician tape
      20. Hand Cleaner

      21. *These tools only if shoes or wheel cylinders need replacing
  1. Block front wheels of vehicle in front and in back of each tire to prevent rolling.
     
  2. Slightly loosen each lug nut on rear wheels.  Be sure to loosen nuts in the appropriate "star" pattern order, where you loosen the next nut farthest/across from the last.
     
  3. Place jack on the appropriate frame section near the rear wheel (usually just forward of the rear wheel) and jack up the vehicle until rear wheel is slightly off the ground, place safety stand near the rear wheel area, toward the front of the vehicle on the frame, and slowly lower the jack until the vehicle weight is supported by the safety stand.  At this point, you may jack up the other side of vehicle repeating the steps above, or simply work on the side at a time.
     
  4. Remove the lug nuts completely, and remove the wheel.
     
  5. At this point the brake drum may or may not be loose enough for you to simply pull off.  You can try it.  Sometimes turning the drum forward and back along with a little encouragement will do it.  It is important to note that there are two main reasons the drum may not come off: one, the brake shoes are tight on the drum and behind a lip on the drum (created during wear); two, the drum is seized onto the axle spindle around the lug nut seated area.  Consequently, You may need to "back off" the wheel cylinder brake adjuster, and/or free up the seized drum with a bit of heat and/or hammering.  As a general rule, if it is a seized drum, you will not get any side-to-side movement, whereas if it is a tight brake shoe, you will.  Side-to-side means that the drum will slightly move along the lug bolts as you pull.
     
  6. To free up a seized drum, you need to create vibration to loosen the two metal surfaces (drum and spindle).  This is done with a metal hammer.  DO NOT HAMMER ON THE OUTER DIAMETER SURFACE OF THE DRUM! Only hammer with the flat face of the hammer square on the front plate surface of the drum surrounding the lug bolts.  Be sure to thread the lug nuts back onto the lug bolts to protect the threads from hammering.  You may also bang the hammer on the ends of the lug nuts/bolts, with less force than the drum, as long as you are careful that the lug nuts are fully threaded and protected from damage from the hammer.  Moderate to light force hammer blows will help to vibrate the surfaces free.  You can also try heating up the drum with a propane torch prior to hammering.  Heat the drum primarily at the hub area, though you can do so along its outer diameter as well.  Heat can sometimes do the job alone, but most often hammering will also be required.
     
  7. To free up tight brake shoes, you will need to use a wheel cylinder adjusting tool (pictured in the following post) to turn the wheel adjuster either up or down (try either and see which makes it looser - several cranks or turns will be necessary before any change will be noticeable).  You can also use a flat head screwdriver instead, but the adjuster tool will work better.  The adjuster can be reached by way of an access hole located on the lower half of the rear wheel plate (behind the drum) and covered with a rubber stopper plug.  Simply remove the plug, and insert the tool.  You will need to explore somewhat with the tool for correct placement onto the "teeth" of the adjuster, as well as determine which end of the tool is the best angled for correct contact.
     
  8. Prior to removing the drum, place a collection pan beneath the brake area.  You may also place a large flattened cardboard under the pan to collect any over spray or debris.
     
  9. Spray the brake cleaner generously over the entire brake components -- follow the instructions on the can.  You should also spray the inside surface of the drum, holding it with its inside surface facing the floor (over the pan/cardboard), being sure to spray complete area in drum.  BE CAREFUL, BRAKE DUST CAN CONTAIN ASBESTOS, OR METALIC PARTICLES THAT ARE HARMFUL.  Take precautions not to breath dust.  The brake cleaner fumes probably are not too healthy either.  Be careful.  Let surfaces dry for about one minute (it dries fast).
     
  10. This step is only to be followed if parts need replacing.  Donít let it scare you.  I included it in the event that you need to do more than just make some adjustments.  At this point you will be able to determine if brake shoe/drum/cylinder replacement is necessary, or if all you have to do is some maintenance work.  If the brake shoe lining is less than 1/8th to 1/16th of an inch thick, they likely should be replaced.  If they are wet with brake fluid or oil, they will have to be replaced.  If oil is coming from the axle seal area, you will need to have the seal replaced (probably best for you to have this done at a shop).  If brake fluid is leaking from the wheel brake cylinder, it should be replaced (they arenít very expensive $20 or less each).  It can be a bit more difficult to determine if the drum needs replacing.  If the wear lip on the drum braking surface is substantial, it may be below safety tolerance and should be replaced.  As a general rule, if the shoes are replaced, then the drums should be measured and machined by a brake shop (usually about $10 each).  They will tell you if they can be machined or should be replaced.
     
If all components look fine go to Step 12.

Replacing the shoes is relatively simple.  Removing the spring retainer clips then the springs will free up the shoes for removal.  You can draw a diagram of how they should be positioned, or use the other wheel as a reference.  Before installing dap a small amount of high temp lubricant on the areas of the back plate that the shoe rest on (they are two to three slight jut-outs that support each shoe on the back plate).  Be sure not to get any lubricant or grease on the brake shoes linings at all.

With the shoes off, it is easy to remove the wheel cylinder.  Disconnect the brake line (using the brake line wrench) being careful not to strip it.  Tape the end of the brake line to minimize fluid leak and need for "bleeding" air out of the system later.  Remove the two bolts holding the cylinder to the back plate.  Installing is reverse steps of removal.  Make sure to fill the new cylinder with brake fluid; by removing the bleeder nipple and reinstalling bleeder nipple once filled being careful not to let any air into the cylinder.  Also, be sure to have the end pistons in the cylinder positioned so that their ends stick out of the cylinder even with the rubber boots (as minimal as possible).  If they stick out too far, it will be hard to fit the shoes together with the springs in place.  At this point the cap on the brake master cylinder reservoir should be removed (located in the engine bay) to allow for fluid expansion if you need to press in the pistons a bit to gain more room for the shoes to fit.

Next, see Step 14 (Tightening cylinder adjuster)

Finally, you should bleed the brakes once both wheels are completed.  This is done by having someone press the brake pedal down a couple times and hold, while another opens the wheel cylinder bleed nipple slightly to let air out, and retightens the nipple.  The pedal is released, and this process is repeated until no air bubbles emerge from the cylinders.

  1. If the shoes/drums/cylinders look fine, a simple application of the lubricant onto the back plate where the shoes rub should be all you need to do at this point.  You can grab a shoe with a pair of pliers (donít contact the linings with the pliers as this will damage them), and pull each away from the back plate enough to apply the lubricant (just a very small drop - less than the size of diameter of a pencil eraser end).
     
  2. Turn the adjuster to the point where the shoes will just fit when you refit the drum over them.  Replace the drum.
     
  3. Tighten the shoe adjuster from the back plate access hole until drum turns with a little drag.  Do not over tighten.  Replace the access hole rubber cover.
     
  4. Reinstall wheel.  Slightly tighten lug nuts in order described during removal.
     
  5. Remove catch basin and cardboard.
     
  6. Place jack in appropriate position, and raise it until supporting vehicle, remove safety stand.
     
  7. Lower vehicle to the ground.
     
  8. Tighten wheel lug nuts (in appropriate pattern, and to about 80 ft lbs: fairly tight, but not too tight that they cannot be removed later on).
     
Here is the link to additional drum brake information:
http://auto.howstuffworks.com/drum-brake.htm/printable

Good luck! Barry



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