Cars


Evo 8 - Brake Bleeding


Precautions

1. Brake fluid will eat through paint. If you spill any on the bodywork, wipe it off immediately with a wet rag.

2. When you jack the car up, be careful.

3. Test the brakes before you put the wheels back on and drive off. The brake pedal should be firm. If it isn't, don't even bother driving it. There is a leak or air in the system. Go back and recheck everything. When you finally do go for a drive, take it easy until you are certain the brakes work. Keep one hand on Mr. Parking Brake, just to be sure...


Your brake system works via hydraulics. You press the brake pedal and that exerts force on brake fluid in the master cylinder. The master cyclinder's job is to multiply that force and send it out to all four brake calipers, where the brake pads are pushed against the rotors, creating friction, and slowing your car down. The brake fluid is nearly incompressible, so any movement of your foot on the brake should immediately be transmitted out to the brakes. However, if there is any air in the system you are going to have a soft, mushy feel when you press the brake pedal. Why? Because unlike fluid, air is easily compressed. Bleeding the brakes will replace old fluid with new, uncontaminated fluid and remove any air within the system.


There are two ways to bleed brakes and either will achieve the same thing. In either case, you need to put fresh brake fluid into the reservoir and then force it out to the bleeder nipples on the brake calipers. You can force fluid through the system by pumping the brakes. This is the most commonly-used method and will require two people working together. The second method is to buy a tool that does the pumping. You can do the work a little quicker and easier this way and you won't need anyone to assist you.


One-Man Bleeding: If you try the latter method and buy a one-man brake bleeder, I do not recommend the MightyVac for this. It is a lot of work to use as you have to pump the thing by hand constantly and you have to stop often to ensure the reservoir is topped with fresh brake fluid. Instead spend just a little more and get one from Motive Products or Snap-On. These system are small plastic drums that you fill with brake fluid, attach to your car's brake fluid reservoir (see pic below), and then pressurize. This will force new fluid through the system without you having to continue to pump and without having to top up the reservoir every few minutes.


Two-Man Bleeding: If you bleed the brakes manually, start by gathering the tools you'll need.

* 11mm wrench for brake bleeder nipples
* Paper towels
* Some DOT 3 or 4 brake fluid


Also you'll need somewhere for the old fluid to go. You can make a tool for this very easily. Buy two to three feet of 3/16" ID clear vinyl tubing. This is available at auto parts stores, hardware stores, and pet stores (used for aquariums). Get a plastic cola botttle with a plastic lid. Cut a hole in the lid just big enough that the tubing will fit through it snugly. Fill the bottle with about an inch of fresh brake fluid. Seal the bottle and push the tubing into the bottle until it reaches the bottom and it's opening is fully immersed in fluid. Also, cut a small vent hole in the cap. If your car is on a lift, you can wrap a wire coat hanger around the neck of the bottle and hang it from the suspension. If your car is on jackstands, you can just set the bottle on the ground while you're using it.
Bottle and tube.

Bottle and tube combined to form brake bleeding tool.

Two-Man Bleeding Procedure

One of you will be the brake pumper (the brawn) and one will be the bleeder (the brains). The pumper will sit in the driver's seat with the car turned off. The bleeder will go to the first nipple, place a 11mm wrench on it, then slide the clear tubing as far down onto the nipple as possible. The bleeder will say 'pump'. The pumper will reply back 'pumping' and begin pumping the brake pedal. He will continue to do so until the bleeder says 'hold', usually after 3 or 4 pumps. The pumper will reply back 'holding' and push the pedal down as far as he can and continue holding. The bleeder should loosen the nipple just enough to get fluid flowing out of the caliper and down the tube. After just a second or two, tighten the nipple again and say 'pump'.


Repeat this procedure until you don't see any more bubbles, usually about 3-5 times per nipple. When done with that nipple, say 'release'. The pumper can now let go of the brakes. Before you move to the next nipple, top off the reservoir. If you let it run dry, you'll suck air into the system and you'll have to start from scratch. You should quickly develop an idea of how often you'll need to top-up the reservoir based upon how much fluid is being pumped out at each caliper.

The Evo 8 brake fluid reservoir.

The brake and clutch fluid reservoir.


A safe way to top up the reservoir.

Now why all this formality? Because you are trying to coordinate the actions of two people who won't be able to see what the other is doing. Most of all, if the bleeder nipple is open when the brake pedal is released, it will suck old fluid and air back into the system, undoing all the progress you've made.


Now that you've got the procedure down, start bleeding the calipers in the following order, per the factory service manual. Note that the Evo does not follow the usual pattern. The order is unusual and there are two, yes two bleed nipples on every caliper.


Bleed order

1. Passenger's side rear outside nipple
2. Passenger's side rear inside nipple
3. Driver's side front outside nipple
4. Driver's side front inside nipple
5. Driver's side rear outside nipple
6. Driver's side rear inside nipple
7. Passenger's side front outside nipple
8. Passenger's side front inside nipple

Evo 8 brake bleeding order diagram.
So to summarize:
Evo 8 on jackstands with all 4 wheels removed.
Jack the car up - you'll need access to all 4 brake calipers
Top-up the brake reservoir.

Begin bleeding at the passenger side rear corner, outside bleeder nipple.
Placing the bleed tube onto the caliper nipple.
Place the closed end of an 11mm wrench over the bleeder nipple. Slide the clear tubing over the nipple. Begin bleeding the brake (see procedure above).
Tighten the bleeder down.

Move to the inside bleeder nipple and repeat.

Continue bleeding each nipple in order.

When done, start the car and test the brakes. They should feel firm and the pedal should immediately return to the top after you let off. If it doesn't feel right, re-bleed each caliper again in order.

When the brakes feel right, double-check that all the bleeder nipples are tight and not leaking. Top up the reservoir if necessary and replace the cap. Put the wheels back on, torque them down to 72ft-lbs and take the car for a slow, cautious test drive.

For best results, bleed your brakes once a year, or after seeing extremely hard use (trackdays, etc.).


Placing the bleed tube onto the caliper nipple.
Bleeder catch-can.

Bleeding the front caliper.
Front caliper - note the bleed nipple on both the inside and outside

Looking down on the front caliper.
Top-down view of the front caliper.

Looking down on the rear caliper.
Rear caliper.


Return to Evo 8