Brake Bleeding Problem

phocussed · 05-21-2010, 10:03 AM

I'm knew deep restoring my '80 911sc and I just got done rebuilding my calipers and replacing my MC and all rubber lines.

I've pressure bled my brakes and the rears are fine, but I'm not getting much to the front circuit. I got flow with the pressure bleeder, but the calipers are just not budging with the pedal... and the pedal is still going to the floor.

I removed the pressure bleeder and tried manually with same result. I don't think there is a clog because I got vacuum backflow to the reservoir when I disconnected a line to check for flow.

I replaced the MC after the original was doing the same thing... I just assumed it was the MC.

Is there are check valve I'm missing? Something else I'm stumped.

Vintage914Racer · 05-21-2010, 10:37 AM

Are you getting fluid flow when you bleed the front?

Dixie · Dixie's Garage

Are the bleed screws at the top? If not, swap them side-to-side so they are. (Yes, I've read posts before where people have done this.)

phocussed · 05-21-2010, 10:44 AM

With the pressure bleeder yes, just a trickle with the pedal

tyro · 05-21-2010, 10:54 AM

Have you tried removing the bleed screw altogether or disconnecting the line to the caliper as a test for flow?

phocussed · 05-22-2010, 05:23 PM

I think Capt. Carrera is on to something... the front nipples are facing down, an I think are switched 180 degrees off... and I see how this might cause a problem with the bleeding.

1. I will try this fix in the am
2. It sounds so obvious... I feel stupid
3. If I hadn't spent so much money on power bleeders and brake fluid, I'd ship you a case of beer if this is it!

Thanks to all who responded... I'll let you know the result, possibly with head lowered in shame.

phocussed · 05-23-2010, 12:35 PM

Yep... calipers were switched. Pedal hard as a rock!

thanks all for your help.

trond · trond's Garage

I too had a problem after replacing master cyliner and overhauling all 4 calipers. It took a long time, 8 hours maybe over 4 days and many bottles of brake fluid, and I still couldn't get a good pedal. In the end I thought there was something so took the car for a drive and within a few miles I had good brakes.

The day after I bled brakes again, just in case there should be a bubble in one of the calipers and had a friend pump up some pressure and I cracked open the nipple. No air came out as the pedal went to the floor but once I touched the front brakes we were unable to get a good pedal again. Took the car out and had brakes within a mile.

Over the years I must have rebuilt 30 brake systems on cars and bikes and I consider myself good with brakes. I usually prefer either my pressure bleeder or my vacuum bleeder and i never had any issues similar to this. Reading posts from people struggling to bleed brakes have always made me smile and wonder. Now I see it different.

I have good brakes but don't know what was the problem or why I suddenly have brakes again

carslutt · carslutt's Garage

sounds like my SC when i got it the front calipers had been swapped side to side some how..... once i removed the 5 yes 5 coats of different colored paint from them i was able to unbolt them and put them on to the car in proper fission. i have no idea why someone painted every part so many times or how they didn't notice how crummy the breaks worked.