Brake bleeding/fluid

[racephotoman]

Wilwood disc brakes in.....any secret regarding bleeding the brakes? Just put fluid in the reserve and have someone depress the pedal as I go around bleeding? How do you know when all the air is out? Is it best to use DOT 4. My friend was saying to use DOT 5, but see in many cases Wilwood doesn't recommend the "5." It will be a street car/4 piston calipers. Thank for any advice!!!

Walter

[edwardb]

DOT 3/4. Don't use DOT 5. Bench bleed the M/C's first. Then bleed (in order) PS rear, DS rear, PS front, DS front. Basically farthest to closest. Lots of on-line help for brake bleeding if you need the basic instructions.

[Jeff Kleiner]

It can be discussed ad nauseum but trust me on this---DO NOT USE DOT5. In a nutshell it is a silicone fluid and retains millions of tiny air bubbles making it compressable meaning you will never get a firm pedal. Additionally it is non-hygroscopic (does not mix with water) so any moisture will stay seperated and since it is heavier than the silicone will settle in the low points; i.e. calipers. Get the brakes hot, it turns to steam and you have no brakes! Stick with glycol based DOT3, 4 or 5.1 fluid.

Jeff

[CHOTIS BILL]

I tried DOT5 when it first came out in the 60’s in my LeGrand MK4. It was OK for 2 or 3 laps and then braking for turn 7 at Riverside, the car did a snap right turn and almost took out the fence. DO NOT USE DOT5.

Bill Lomenick

[Bob Cowan]

"Bench" bleeding is important. I never do it on the bench, though. If you do it on the bench, you'll be installing a MC and remove reservoir that is filled with fluid. I would just make a mess and have to start over. I bleed the M/C's after installation. With dual MC's, you should do them both at the same time.

For the calipers, start in the right rear, and work your way closer to the MC. With dual MC's, you should bleed front and rear at the same time. That will allow a full stroke of each MC. The Wilwood calipers have two bleed ports on each end. Only use the top two. I do the outside port first.

If you're going to track the car, you'll want to bleed the brakes pretty often. In that case, you should install some Russell Speed Bleeders. I can flush and bleed all 8 ports in about 15-20 minutes.

[racephotoman]

Now for the stupid question....do I fill the reservoir and just loosen the two lines I have coming out of the MC and get the air out there (bench bleeding in location), re-connect the lines and continue bleeding the brakes as per recommendation?

[CraigS]

The trick for bench bleeding or on the car bleeding of the MCs only is to make up two short brake lines to install on the MCs.Make them approx 6 inches long and bend them up and over so the fluid comes out of the lines into the MC reservoir. SOme like to use a piece of rubber hose to make the bend. I had good luck w/ just bending the steel line. Bleed til there are no more bubbles,remove them and connect the normal lines to the car. AT this point I like to let gravity help me. Just open all 4 bleeders and let them drip into a container. This will get maybe 90% of the air out w/ no effort. Then you can do a final bleeding w/ a helper. I used to bleed a lot by myself w/ a hose going into a bottle w/ a little fluid in the bottom. But I found that sometimes air leaks around the threads of the bleeder when I releqased the pedal. So I use a helper. I use this procedure.
-helper pumps the pedal til they get somewhat of a firm pedal (this is where the gravity thing helps) and yells 'holding'while keeping some pressure on the pedal
-you open the bleeder
-you let the fluid flow til it slows (do not wait for it to completely stop) and close the bleeder
-you yell 'pump it up'and wait to hear 'holding'.
repeat

[Dale Claytor]

I purchased a brake bleeding kit from autozone for I believe around $13. The kit has a hand held vacuum pump that attaches to a silicone hose that attaches to the bleed screw. A small reservoir on the pump collects the fluid being pulled through the brake lines and caliper. You just open the bleed screw and pump until you see no more air coming into the reservoir with the fluid then tighten the bleed screw. I like this method for a few of reasons. It doesn't make a mess, you can see what's coming into the pump reservoir, and it's a one man operation. After all the air is removed from the lines, just pump up the brakes with the brake pedal. Just follow the kit instructions. It worked great for me and no mushy brakes.

[Bob Cowan]

Now for the stupid question....do I fill the reservoir and just loosen the two lines I have coming out of the MC and get the air out there (bench bleeding in location), re-connect the lines and continue bleeding the brakes as per recommendation?

It's a little more than that. You need to make up a simple brake that has the proper MC connection on one end, and then loops back up into the reservoir. You are essentially making a closed loop. Then gently pump the brake pedal until no air bubbles show up. Quickly remove the loop and install the line. You'll loose a little bit of fluid, and that's OK.

[Avalanche325]

Definately "bench bleed", but on the car. Make short brake lines that dump back into the reservoirs.
Keep a constant watch on the fluid level in the reservoirs. If it empties, you have to start over.
For the rears (if you have ones that are mounted down low), you need to unmount the capilers and move them to the 3 and 9 o'clock positions for bleeding.

You can use a bleeder kit, ie vacuum pump, or a helper. If using a helper, don't let the pedal get all the way to the bottom. Keep going until you see no more bubbles AND have a firm pedal.

[racephotoman]

Thanks everyone----bought a few feet of hose and bench the MC successfully in the car---brakes are next.

Walter