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...

Sorry. But that is the answer.

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

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?

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

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.

mine took a while.

Rear brake pressure regulator to be checked?

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.

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

Another excellent suggestion - thank you!

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

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

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.

...Chris just did the forum equivalent of a 'mic-drop'

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

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

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.

*****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
Click to view attachment

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

Will try the pressure trick!

The inner adjuster is not directly connected to the inner piston. The allen wrench inserts into a small gear which is next to the adjusting bolt. As a result of this, the direction of rotation is reversed compared to the outer adjuster.
If you are getting no action from the inner adjuster it may be because the gear isn't fully inserted in its bore. This is resolved simply by pushing the allen wrench inwards.

Its not possible to screw the adjuster far enough to lose engagement with the piston unless there are no pads in place to stop the piston from moving outwards.
When trying to retract a piston it is possible to pull the mechanism free of the piston. All that holds it together is a wire circlip between the piston and the hub. However this mostly only happens when the piston is frozen in the caliper.

Oops wrong thread.

Chris,

Thank you for the detailed reply, however, perhaps I did not make it clear in my post - I am referencing the outer adjuster and my references to inner/outer are the _outer_ locking nut and the _inner_ adjusting allen bolt. The allen bolt turns as if it is not connected to anything........The bolt that is in the picture I posted.

Thank you again Chris!

Both adjusting bolts operate in the same manner, except for the little gear that drives the inner one.
As I wrote earlier, it really isn't possible to fully unscrew the adjusting bolt from the piston as long as there are brake pads installed.
If the piston doesn't move when the adjuster is turned, then the piston and "hub" are no longer connected. The hub may be turning freely instead of screwing on and off the adjusting bolt.
You may be able to remove the outer brake pad and press the piston back into its bore to reconnect the two parts of the piston. Worst case would be completely removing the piston and hub from the caliper to reassemble them.

yup..brand new calipers. No workie on BOTH inside adjusters & yes it has adjustment gearz installed on both sides (now).

Sorry Rich, only 6 years late on a reply but, I was looking for this for another customer and just saw this.

If we look at the first picture in this thread:

IPB Image

...you can see the basic relationship of what's in the "inboard" 1/2 of the caliper. When you spin the adjuster and nothing happens, this means the adjuster shaft is spun up "tight" inside the mechanism in the piston. When it is too tight, it's like a frozen fastener. In turning it, you will be turning the entire mechanism inside the piston shell. This happens if they've sat for a while. If the mechanism inside the shell is spinning, no adjusting will occur.

To remedy this, you'll need to overcome the lock by spinning the adjuster gear in a "clockwise" direction at very high speeds with little or no ramp up. This means an air wrench. By turning the gear clockwise, you will turn the adjuster counter-clockwise and with a few short bursts, the velocity and inertia of the adjuster should overcome the mass of the piston and mechanism and release itself.

I know we're 6 years late but, hopefully that will help others. biggrin.gif

http://www.914world.com/bbs2/index.php?sho...rance&st=20

Like Chris said the new square o ring will hold the piston abit when new,,on the front...so take pads out insert some thing thinner than the pads, push pedal to make pistons move out...then push piston back just enough to slip in pads.....this will take the double pump out ,,unless you have air in lines ...

Ok, I hit it with the air wrench and it worked like a charm.

Didn't have an air wrench so I now have a compressor, fittings, hoses (why buy just one) and a few other air tools. Love the sound of an air compressor in the morning.....

I guess I could have used my electric impact?????? But then I would not have an air wrench. Now I have an air wrench.......ahhh.....

CTC911CTC