Master cylinder, How you know when its time.................. Options

[eyecolor]

I have 4 beautiful rebuilt calipers thanks to Eric and PNB . I have already used 2 quarts of fluid and the pedal is still soft.

I have been very careful to bleed in the proper order with no air being introduced.

The back calipers close nicely during the pumping and the fronts move a little.

I did note someone mentioned bleeding the proportioning valve.

I have no leaks anywhere!!

Is it time to replace the master cylinder or am I giving up too soon.

I also have an an old pedal cluster that I may owe someone as a core replacement.
Let me know if it is you or I can send it to anyone with the best advice that can use such a mess.

thanks

George

Wilmington,DE

[dr914@autoatlanta.com]

yes I would say that it is time to replace!!!!

I have 4 beautiful rebuilt calipers thanks to Eric and PNB . I have already used 2 quarts of fluid and the pedal is still soft.

I have been very careful to bleed in the proper order with no air being introduced.

The back calipers close nicely during the pumping and the fronts move a little.

I did note someone mentioned bleeding the proportioning valve.

I have no leaks anywhere!!

Is it time to replace the master cylinder or am I giving up too soon.

I also have an an old pedal cluster that I may owe someone as a core replacement.
Let me know if it is you or I can send it to anyone with the best advice that can use such a mess.

thanks

George

Wilmington,DE

[JamesM]

Did you replace your rubber lines as well?

I have 4 beautiful rebuilt calipers thanks to Eric and PNB . I have already used 2 quarts of fluid and the pedal is still soft.

I have been very careful to bleed in the proper order with no air being introduced.

The back calipers close nicely during the pumping and the fronts move a little.

I did note someone mentioned bleeding the proportioning valve.

I have no leaks anywhere!!

Is it time to replace the master cylinder or am I giving up too soon.

I also have an an old pedal cluster that I may owe someone as a core replacement.
Let me know if it is you or I can send it to anyone with the best advice that can use such a mess.

thanks

George

Wilmington,DE

[PanelBilly]

I had all new lines and rubber. It seems to take forever to get all the air out. My master cylinder was new too. I thought Steve's (quadX) leg was going to cramp up. We just kept pushing more fluid till it worked.

[eyecolor]

I did replace all the flexible lines

[davesprinkle]

Typical symptom of a bad mc is that the pedal slowly travels to the floor. (This is with all bleeders closed.) If your pedal doesn't do this, then your MC is OK.

Try the "long tube" bleeding method. Get 15' of 1/8" ID clear vinyl tubing at your hardware store. Drop one end into the master-cylinder reservoir. (I tape the tube onto the fender to ensure that it doesn't fall out.) Put the other end on a bleeder. Open the bleeder. Sit in the car and pump the crap out of the pedal. Over and over. You'll see the bubbles chasing themselves through the loops of the tubing. Keep pumping until you don't see any more bubbles. No need for a helper and no need to waste fluid. Do this for all 8 bleeders.

BTW, you did adjust the rear venting clearance, right?

I have 4 beautiful rebuilt calipers thanks to Eric and PNB . I have already used 2 quarts of fluid and the pedal is still soft.

I have been very careful to bleed in the proper order with no air being introduced.

The back calipers close nicely during the pumping and the fronts move a little.

I did note someone mentioned bleeding the proportioning valve.

I have no leaks anywhere!!

Is it time to replace the master cylinder or am I giving up too soon.

I also have an an old pedal cluster that I may owe someone as a core replacement.
Let me know if it is you or I can send it to anyone with the best advice that can use such a mess.

thanks

George

Wilmington,DE

[VaccaRabite]

(IMG:style_emoticons/default/agree.gif)
try the long tube method before replaceing the master cylinder. That was how I got my initial bleed for the 914, and it has been great.

Set the tube on the caliper furthest from the master (pass rear) and just start pumping away. when that one is solid, move to the next furthest way. it won't take nearly as long, but there will be air in the system yet. Keep moving until you have done all 4 corners. it will take a little time. A LOT of air got into the system when you replaced the hard and soft lines. Now you have to get that air out. Since the fluid goes back into the brake fluid res. you also don't have to worry about the res going dry and introducing air into the master. Just make sure that the res does not go dry before fluid from that rear pass caliper gets there - you might need to do one fill up.

Zach

[eyecolor]

Thank you Dave and Zach and the all the rest

Great advice and I am certain that the lurkers (of which I used to be one) have learned something important.

I did find that I needed a 3/16 ID hose to fit .

I did not set the back clearance yet only because I seemed so close to rubbing now that I did not think it would make much of a difference before bleeding.

Let me know if I am off base and thanks again.

George