Need brake bleeding help.

[redcoupe86]

I need some help on what to do about my brake feel since my caliper rebuild and brake bleeding.

Before working on brakes:

I could get "godlike" braking within the first 1/4" so of travel. Instant braking.

After bleeding:

Pedals travels 3/4" before any braking effort. Once that point is reached the car breaks well enough but not with the authority it did before.

How I bled the breaks:

I used a power bleeder and went 3 times around in proper order, tapping breaks with hammer each time and except for the first time around almost zero bulbs by the second time and zero bubbles the third time. Went into car and pressed brake pedal till it firmed up. Then went 2 more times around bleeding with zero bubbles.

Set the power bleeder to 3 lbs and let it sit the night - tapped the calipers all around before I went to bed.

Got up the next moring and tapped the calipers again, waited an hour and bled the brakes for the 6th time - zero bubbles.

My question is how do I get the "instant authority" of my breaks before the build. The system is holding pressure great, no leaks.

I've read that the breaks would be soft at first but after you drive it around they should firm up. How long, how many miles or did I do somthing wrong?

Oh - I forgot to add that I also changed over to SS brake lines on all four corners. In the process of doing this all the fluid drained from the resivoir. I don't know if this chages anything.

[peppy]

I only have good luck bleeding brakes by using my brothers legs to pump the pedal.
Would you like to borrow him.

[oregonmon]

I experienced the same thing after SS lines, Ate Blue fluid, new rotors and pads. Pedal was immediately firm then soft pedal for a couple hundred miles. Re-bled with not much difference and now probably 300 miles later they are firm. I chalk up to the pads and Ate slotted disks getting worn in. Not sure though.

[ljowdy]

OK, it BRAKES, not BREAKS

Try bleeding the brakes again by putting a small rubber hose on the bleeder screw. Put the hose end in a coffee can or other suitable container. Put about 1 inch of brake fluid in the container. Open the bleeder screw and pump the brakes making sure the reservoir stays full. The idea here is that you don't need to close the bleeder screw each time you pump the brakes as the fluid stays in the rubber hose and if it sucks anything, it will be fluid, not air.

Start at the right rear, left rear, right front and finally at the left front. Don't be cheap on brake fluid, by doing this, you'll also accomplish another task and that is flushing out all of the old fluid.

[redcoupe86]

Im in the middle of re-bleeding right now.

I've already gone through 4 32oz containers of BF, and I'm using a power bleeder that has 2 32oz cans in it right now with 10 lbs of pressure.

I didn't replace my pads and rotors, just did a caliper rebuild, so breaking in the brakes shouldn't be an issue.

Originally Posted by ljowdy

OK, it BRAKES, not BREAKS

Try bleeding the brakes again by putting a small rubber hose on the bleeder screw. Put the hose end in a coffee can or other suitable container. Put about 1 inch of brake fluid in the container. Open the bleeder screw and pump the brakes making sure the reservoir stays full. The idea here is that you don't need to close the bleeder screw each time you pump the brakes as the fluid stays in the rubber hose and if it sucks anything, it will be fluid, not air.

Start at the right rear, left rear, right front and finally at the left front. Don't be cheap on brake fluid, by doing this, you'll also accomplish another task and that is flushing out all of the old fluid.

[carsngolf]

I feel a bit of an authority on this as it cost me $150 to have mine bled after I replaced hoses and rebuilt calipers. My biggest mistake was putting the bleed valves in the wrong places on the rears. After numerous attempts and much fluid, I gave up and took it to the local wrench. They found the misplaced bleed fittings and fixed it right but it still didn't have much of a pedal. I took it back and they did the whole thing over again but it still doesn't have anywhere near the power it had originally. Apparently, when bleeding, the pedal goes all the way to the floor which takes the master cylinder way past where it used to operate. That "unexplored territory" is the problem. The only solution is a new master cylinder. I bought one and will install it eventually but meanwhile, the pedal has gained a bit in strength and it's safe to drive but still not where it used to be.

[Don Plumley]

Originally Posted by redcoupe86

Went into car and pressed brake pedal till it firmed up. Then went 2 more times around bleeding with zero bubbles.

1st clue: Did you push the pedal to the floor? What exactly did you do here?

Originally Posted by redcoupe86

Oh - I forgot to add that I also changed over to SS brake lines on all four corners. In the process of doing this all the fluid drained from the resivoir. I don't know if this chages anything.

Bigger Clue: Go read posts about new MC install and how hard it is to get air out of the MC.

My votes:

#1: Air in the MC
#2: Blew the seal in the MC pressing pedal

[peppy]

I did my brakes last summer ss lines and new rotors and pads. Filled master cylinder and opened bleeder screws, ate lunch, then pumped them the old fashioned way.
The pedal is just as firm as ever.

[redcoupe86]

After I bled the brakes 3 times with the power bleeder I openned the door and press the pedal by hand about 4 times. Not all the way to the floor but maybe 3/4's the way, until the pads hit the rotor and firmed up.

Understand that multiple pumps do not make the braking stronger. Once the pedal move about 3/4" down the brake pedal stops moving and I have decent braking.

Originally Posted by Don Plumley

1st clue: Did you push the pedal to the floor? What exactly did you do here?




Bigger Clue: Go read posts about new MC install and how hard it is to get air out of the MC.

My votes:

#1: Air in the MC
#2: Blew the seal in the MC pressing pedal

[boyt911sc]

Originally Posted by ljowdy

OK, Start at the right rear, left rear, right front and finally at the left front. Don't be cheap on brake fluid, by doing this, you'll also accomplish another task and that is flushing out all of the old fluid.

I've been following the above procedure of brake bleeding since working on cars more than 40 years ago. However, a professional mechanic (factory trained in German automotive) had told me that it is myth. That you cold bleed at random as long as you bleed enough brake fluid to remove the air bubbles in that particular circuit (brake line) using the power bleeding tool.

Explanation: The above procedure has been used by people using manual bleeding with the help of an assistant (helper) since the early days. With the introduction of new technology and equipment like power bleeder, such procedure is no longer mandatory.

My first reaction was to tell him "you got to be kidding!!!". It took me a long time to accept this procedure and now a new convert. Anyone has some thoughts, comments, remarks regarding this bleeding procedure? Thanks.

Tony

[redcoupe86]

I did a search on how to bleed the MC, but can't find anyting. Can someone illuminate the procedure for me or give me a link?
Also what are the symtoms of a bad MC.

also I ran accross this:

Being able to pump up pressure and maintain it but have the pedal go to the floor after releasing points to air in the system not a bad MC. A bad MC would let the pedal drop after you pumped it up and held it. No loss of fluid points away from a bad MC as well. Get a Motive Pressure bleeder if you don't already have one. Put a quart of your fluid of choice in it, follow the directions and flush the brakes out.

Another trick to do is preset the pistons. After you push the pistons back in the calipers in order to install new pads they can sometimes have too much pull back as they then move foward to meet with the new pad backing. This is more prevalent after a rebuild but can happen on pad replacements as well. What happens is the piston draws back too much between pressure strokes and the next time the pedal is pushed some of the MC stroke is spent making up the larger than normal pad to rotor gap. Remove each pad one by one and pump the pedal enough to move the piston in enough so the pad will not fit. Now move the piston BACK just enough that the pad can be wiggled back in. It is important the the piston be moved BACK to make the space and not pumped forward. Do this to all pads that have pistons one at a time. Many a wrench as flushed himself silly trying to get air out that was not there after a brake rebuild.

[JohnJL]

If its safe, drive it around a bit and see if they firm up.

Another trick I use, which may be a myth, is to have an assistant push the brake pedal down 1/2 way while the bleeder valve is open, then close it while the pedal is still depressed.

[JohnJL]

I also use speedbleeder valves. Brakes on the racecar are done this way and stopping is phenomenal.

[Don Plumley]

It is possible that your pistons are retracting more than they were before, which would increase initial pedal stroke. Here are some random thoughts:

1) Empty wine or champagne bottle for the bleed tube to catch fluid. Heavy bottom keeps from tipping, narrow neck holds tube.
2) A pressure bleeder means you really don't need speed bleeders. They are handy for a one-person pedal bleed though.
3) I have used a friend to give a little pedal pressure when I was not sure if the lines were fully bled. Very careful not to push too far. Routine is open valve, pump two or three times, hold pedal, close valve.
4) You don't have a hydraulic clutch (G50), but it should always be bled at the same time.
5) Letting the MC empty is a big no-no.
6) With the system closed, jam on the pedal a few times to make sure there are no leaks on the lines.
7) Using the pressure bleeder overnight is not a good idea. You are not moving bubbles down the fluid, and by putting the fluid under pressure all you are doing is forcing some moisture into the fluid.
8) I think you've flushed your system with all the fluid you gone through. I'll search on the MC bleed threads.
9) Getting air into an ABS system is a massive no no.

[Don Plumley]

Search results for "bleed+master"

Do you have the calipers on upside down? Bleed valve goes on top.
Did you match the 20 deg angle for the pistons?

Hope this helps - keep us posted.

[redcoupe86]

They are all up and as for the 20 degree thing I may be
+/- 3 degress. I thought that had to specifically to deal with break squeal though.

Originally Posted by Don Plumley

Search results for "bleed+master"

Do you have the calipers on upside down? Bleed valve goes on top.
Did you match the 20 deg angle for the pistons?

Hope this helps - keep us posted.

[redcoupe86]

ok, I tried presetting the pads by pulling the pads and pressing the brake pedal to get the piston to come out then pressed it back in. This didn't seem to do anything.

I dont think its the MC because my pedal firms up, it just firms up 3/4" - 1" further travel.

I think I'm going to risk manually bleeding the brakes with the foot pump method unless someone can give me a way of bleeding the MC while its still in the car.

[Rich Lambert]

I read a post somewhere on PP that said to use a prop to hold the brake pedal down overnight and bleed again the next day. After bleeding the brakes about 6 times with a pull type bleeder and still having a soft pedal I was ready to try anything. I used a cut off screw-in broom handle to hold the pedal down, bled the brakes the next day, and now have a firm pedal. I don't know what this could have possibly done, but it worked. This was after replacing the rotors, pads, adding SS lines, and rebuilding the calipers.

[911pcars]

Originally Posted by Rich Lambert

I read a post somewhere on PP that said to use a prop to hold the brake pedal down overnight and bleed again the next day. After bleeding the brakes about 6 times with a pull type bleeder and still having a soft pedal I was ready to try anything. I used a cut off screw-in broom handle to hold the pedal down, bled the brakes the next day, and now have a firm pedal. I don't know what this could have possibly done, but it worked. This was after replacing the rotors, pads, adding SS lines, and rebuilding the calipers.

Rich,
Sounds like your solution was due to the auto-retracting-caliper-piston syndrome so often described. Constant force on the broom-stick assisted pedal allows the seals to conform to the installed, ready position of the piston.

For less than 24 hour results, one might temporarily reinstall worn out pads, then depress the pedal to lock the brakes for about an hour, then see how that affects the pedal. If not, locate that cut off broom stick and retreat to the TV room.

Better yet, use an equivalent length of PVC pipe. A disabled broom prevents your significant other from being more useful around the house.

Sherwood