My brakes still don't work!

[4babycar]

Ok, I have mentioned before that with our new car the front calipers were frozen. So, today my Dad and I removed both front calipers and rebuilt them. The rebuild process was pretty straight forward, thanks to all of the advice and help from this forum. Anyway, after all that we started the process of bleeding and flushing the brakes and we got nothing but a dead pedal. No matter how much we pumped or depressed the pedal we still couldn't get any resistance or caliper movement. I removed one flexible line from the caliper to see if we had any fluid movement and there was none. I am assuming I need a new master cylinder, does this sound correct?

[kristoj]

A bad master cylinder generally makes your pedal go down to the floor. But you can usually get some pressure by pumping the pedal. Are you using new brake hoses? One way to ensure your brake lines are flowing freely is to use a vacuum pump at the bleeder valve to suck fluid through the system. If you are getting clean fluid coming through with vacuum pressure, then you probably do have a bad master cylinder.

[4babycar]

Yep, the pedal goes straight to the floor. I don't have a vacuum pump but we did loosen the connection on the master cylinder that goes to the rear brakes, with this fitting loosened a steady stream of fluid came out of the brake line at the front caliper so there was no major obstruction in the line. I haven't replaced the hoses yet but they were high end steel braided ones that had been installed shortly before it was parked by the PO, they are certainly on the list of things to be replaced but I really like the look of the braided lines so I would like to replace them with like ones.

[kristoj]

Yep. Sounds like a master cylinder. I bought mine from Vick's earlier this year. I believe it cost around $36. You might want to order some of the braided hose that goes between the reservoir and master cylinder and replace it as well.

[4babycar]

Thanks John! Your price is right on but I will probably buy from IAP since it is just an hour north of here so I can get it a few days faster without paying extra, unless I end up buying something else too then I will be a bit pickier about price. Is there anything special about the install? Thanks again.

[kristoj]

Nothing special other than the usual -- use a flarenut wrench or you will strip the nuts holding the brake lines to the master cylinder. I used a flarenut crowsfoot with my 3/8" drive and an extension for easier access. The hardest part of the job for me was threading one of the brake lines into the new master cylinder. I must have struggled with it for an hour. But other than that, it was a pretty straightforward job.

[4babycar]

SWEET! A job my wife wants done and new tools for me! Win-Win! I guess it will be a few more days before I can get her loaded on a truck to get the clutch fixed and the she will be road-worthy! Next will be babycar, my 81'.

[4babycar]

It just dawned on me, how do you go about bleeding the master cylinder?

[kristoj]

You don't bleed the master cylinder. You can only bleed the system at the individual calipers. So once you change the master cylinder, you must bleed the system at each of the four wheels, beginning with the wheel furthest from the master cylinder -- in our case, the rear passenger wheel.

[So Cal Mark]

you SHOULD bleed the mc, otherwise an air lock can prevent fluid to the wheels and it can take tons of bleeding to make it work. Bleeding the mc in a Spider is very easy; merely remove the steel lines in the top, fill the reservoir and attach the lines once you get a solid stream of fluid. Messy but necessary. The left front should then gravity bleed.
Question; was it difficult for you to remove the pistons from the calipers? If they were frozen, I'd expect the pistons to have been stuck in their bores

[kristoj]

Sorry. Mark is definitely the expert here. After I changed my MC, I used a pressurized powerbleeder and ran about a quart of fluid through my system during the bleeding process (brake fluid is cheap) and never had any issues.

[So Cal Mark]

a pressure bleeder changes the process, but I always still bleed the mc separately. That way I'm not pushing all of the old contaminated fluid through the whole system

[4babycar]

Thank you gentlemen. The caliper(s) were not significantly stuck. Once I took the calipers and boots off, and put air pressure on them each the pistons shot out pretty well against the piece of wood that I had placed. The passenger side piston moved rather slowing for the first 1/4 inch but after that basically shot out of the bore. Further inspection of both pistons showed no pitting or scarring but a little rubber-like residue on the passenger side. I am assuming the seal had seized onto the piston and that is what was causing the issue there. Otherwise, I think the M/C is the issue. Since I don't have a pressurizer it looks like I will be bleeding the old fashion way. Thanks again.

[So Cal Mark]

did you have any brake pedal before rebuilding the calipers? MCs do fail after sitting for long periods, so I'm asking just to make sure you don't have system that's full of air

[4babycar]

Yes, I did have pedal before I started the work.