Complete Brake Re-build complete - Still pedal travel is wrong, Pedal travels 2 inches first push, is firm at the top 2nd push Options

[ctc911ctc]

All,

The brake build is over, new from the reservoir to the rotors.

Rotors
Pads
Calipers (PMB thanks!)
Lines
Master Cylinder (19MM)
Rebuilt pedal assembly

Found 2 leaky bleed valves, needed a little more torque to seat properly.

Went around the car 4 times in pursuit of bubbles, used almost a gallon of Brake Fluid. Did both the top and bottom bleed valves at each caliper (bottom first, then top - air rises, right?).

Brakes work (back is a little tight, need to adjust the calipers) however the pedal is not right. First press it travels 2-3 inches before there is the familiar FIRM feeling, second press the pedal travels less that an inch before contact.

OK, I am out of ideas,

WHAT WOULD YOU DO NEXT?????

Thank you in advance all 914worldies

CTC

[ConeDodger]

Keep bleeding...

Sorry. But that is the answer. (IMG:style_emoticons/default/sad.gif)

[dr914@autoatlanta.com]

have you set the rear venting clearance? Also make sure that the feed lines are forced in

against the two washers in the master cylinder

All,

The brake build is over, new from the reservoir to the rotors.

Rotors
Pads
Calipers (PMB thanks!)
Lines
Master Cylinder (19MM)
Rebuilt pedal assembly

Found 2 leaky bleed valves, needed a little more torque to seat properly.

Went around the car 4 times in pursuit of bubbles, used almost a gallon of Brake Fluid. Did both the top and bottom bleed valves at each caliper (bottom first, then top - air rises, right?).

Brakes work (back is a little tight, need to adjust the calipers) however the pedal is not right. First press it travels 2-3 inches before there is the familiar FIRM feeling, second press the pedal travels less that an inch before contact.

OK, I am out of ideas,

WHAT WOULD YOU DO NEXT?????

Thank you in advance all 914worldies

CTC

[Chi-town]

I'm gonna ask this question and by no means is it meant to insult.

Are front caliper bleed screws above the brake line connection?

[mepstein]

Rear adjusters aren’t included in the rebuild. Make sure you install them.

[iankarr]

I agree that incomplete bleeding is the likely culprit. Are you using a pressure bleeder?

Also...since you're replaced the pedal cluster and the MC, verify tht the gap between the pushrod and MC piston is correct. Factory manual says it should be 1mm. Slight deviations have big effects.

[porschetub]

Keep bleeding...

Sorry. But that is the answer. (IMG:style_emoticons/default/sad.gif)

(IMG:style_emoticons/default/agree.gif) mine took a while.

[Philippe]

Rear brake pressure regulator to be checked?

[davesprinkle]

All,

The brake build is over, new from the reservoir to the rotors.

Rotors
Pads
Calipers (PMB thanks!)
Lines
Master Cylinder (19MM)
Rebuilt pedal assembly

Found 2 leaky bleed valves, needed a little more torque to seat properly.

Went around the car 4 times in pursuit of bubbles, used almost a gallon of Brake Fluid. Did both the top and bottom bleed valves at each caliper (bottom first, then top - air rises, right?).

Brakes work (back is a little tight, need to adjust the calipers) however the pedal is not right. First press it travels 2-3 inches before there is the familiar FIRM feeling, second press the pedal travels less that an inch before contact.

OK, I am out of ideas,

WHAT WOULD YOU DO NEXT?????

Thank you in advance all 914worldies

CTC

Keep bleeding. I like to use the Long Tube Method. Get 20' of clear tubing. Secure one end inside the MC reservoir (tape, zip-tie, whatever, just make sure it doesn't fall out). The other end goes on a cracked-open bleed nipple. Sit in the car and pump on the brake pedal. You'll see bubbles running the length of the tubing. Keep pumping until the bubbles stop. Do all four corners. Then do them again.

Advantage to this approach is that because you won't be opening and closing the bleed nipple you don't need a 2nd person. Also, because you're recycling the fluid back to the reservoir, you won't use much fluid.

[ctc911ctc]

I'm gonna ask this question and by no means is it meant to insult.

Are front caliper bleed screws above the brake line connection?

Whoa.......I know EXACTLY where you are going with that question..........I will go check right now.........EXCELLENT thought!

[ctc911ctc]

I agree that incomplete bleeding is the likely culprit. Are you using a pressure bleeder?

Also...since you're replaced the pedal cluster and the MC, verify tht the gap between the pushrod and MC piston is correct. Factory manual says it should be 1mm. Slight deviations have big effects.

Another excellent suggestion - thank you!

[ctc911ctc]

All,

The brake build is over, new from the reservoir to the rotors.

Rotors
Pads
Calipers (PMB thanks!)
Lines
Master Cylinder (19MM)
Rebuilt pedal assembly

Found 2 leaky bleed valves, needed a little more torque to seat properly.

Went around the car 4 times in pursuit of bubbles, used almost a gallon of Brake Fluid. Did both the top and bottom bleed valves at each caliper (bottom first, then top - air rises, right?).

Brakes work (back is a little tight, need to adjust the calipers) however the pedal is not right. First press it travels 2-3 inches before there is the familiar FIRM feeling, second press the pedal travels less that an inch before contact.

OK, I am out of ideas,

WHAT WOULD YOU DO NEXT?????

Thank you in advance all 914worldies

CTC

Keep bleeding. I like to use the Long Tube Method. Get 20' of clear tubing. Secure one end inside the MC reservoir (tape, zip-tie, whatever, just make sure it doesn't fall out). The other end goes on a cracked-open bleed nipple. Sit in the car and pump on the brake pedal. You'll see bubbles running the length of the tubing. Keep pumping until the bubbles stop. Do all four corners. Then do them again.

Advantage to this approach is that because you won't be opening and closing the bleed nipple you don't need a 2nd person. Also, because you're recycling the fluid back to the reservoir, you won't use much fluid.

Love this approach, was going to look into the pressure method, but I like this a bit better. THANK YOU!

[DickSteinkamp]

have you set the rear venting clearance?

X2. It's pretty fussy and pretty important. Can easily cause the symptom you are experiencing (one long stroke before normal pedal action)

[ChrisFoley]

Long pedal is actually a common occurrence with new seals in rebuilt calipers. It is normal and not necessarily a result of poor bleeding or other flawed preparation. The square o-ring seals grip the pistons and pull them back into the bore. They will continue to do this until after a couple hundred mile break-in period with frequent brake use.
If the pedal is firm after the long stroke, and comes up after one pump every time, this is the likely cause of your frustration.

[iankarr]

...Chris just did the forum equivalent of a 'mic-drop' (IMG:style_emoticons/default/wink.gif)

[Mark Henry]

Air bubbles is usually at the proportion valve, I don't care if I get fluid on the floor, so I crack each brake line at the proportion valve as I'm bleeding. If manual bleeding you crack open/close the brake line just like the bleed valves.
Messy but it will cure the rear brake bubbles issue PDQ.


Venting has to be set before bleeding

[ctc911ctc]

Long pedal is actually a common occurrence with new seals in rebuilt calipers. It is normal and not necessarily a result of poor bleeding or other flawed preparation. The square o-ring seals grip the pistons and pull them back into the bore. They will continue to do this until after a couple hundred mile break-in period with frequent brake use.
If the pedal is firm after the long stroke, and comes up after one pump every time, this is the likely cause of your frustration.

THE BEST Solution is always the one where you are told.....wait......it will go away........

Like when I was in my 40's and had the L4-L5 sciatic nerve debacle, the surgeons with a gleam in their eye that screamed 'Boat Payment is Due' telling me they could 'cure' me and my 85 year old neighbor told me - wait a year, it goes away. I waited with excercise and patience it went away.

I will double pump for a few weeks - will report after a few hundred pumps....

THANK YOU 914World

[steuspeed]

I had this exact same problem. I tried bleeding and bleeding, over and over with the same results. Tried a pressure bleeder and that did it. If you do not bench prime the master before installing there will be air trapped in it and you can't get it out with old school pedal bleeding. Maybe at the proportioning valve Mark? Try Mark's trick first, then get a pressure bleeder.

Also, 19mm requires more pedal effort, so it's going to feel different even when it's right. I went with 17mm stock b/c I felt the pedal effort was already too high.

[ctc911ctc]

*****UPDATE*****

Started on the left side of the car performing the vent clearance procedure as specified within the PMG post.

1. Got the outer nut release
2. Did not go too far with it - just up to the retaining clip
3. Loosened the inner allen 4mm bolt until I could slide the feeler gauge in between
4. Oops, too loose, need to tighten a bit.
5. WHAT, the bolt just goes around and around and around

I must of loosened the bolt beyond the threads of the internal component. cannot get it back engaged.

ANY TRICKS OUT THERE??????

UGH

Thanks in advance!

CTC911CTC

All,

The brake build is over, new from the reservoir to the rotors.

Rotors
Pads
Calipers (PMB thanks!)
Lines
Master Cylinder (19MM)
Rebuilt pedal assembly

Found 2 leaky bleed valves, needed a little more torque to seat properly.

Went around the car 4 times in pursuit of bubbles, used almost a gallon of Brake Fluid. Did both the top and bottom bleed valves at each caliper (bottom first, then top - air rises, right?).

Brakes work (back is a little tight, need to adjust the calipers) however the pedal is not right. First press it travels 2-3 inches before there is the familiar FIRM feeling, second press the pedal travels less that an inch before contact.

OK, I am out of ideas,

WHAT WOULD YOU DO NEXT?????

Thank you in advance all 914worldies

CTC

[ctc911ctc]

We have the same wheels and color! 74 2.0????

Will try the pressure trick!

I had this exact same problem. I tried bleeding and bleeding, over and over with the same results. Tried a pressure bleeder and that did it. If you do not bench prime the master before installing there will be air trapped in it and you can't get it out with old school pedal bleeding. Maybe at the proportioning valve Mark? Try Mark's trick first, then get a pressure bleeder.

Also, 19mm requires more pedal effort, so it's going to feel different even when it's right. I went with 17mm stock b/c I felt the pedal effort was already too high.