New calipers, master cylinder, brake lines, what to do first??

[yoshi_w]

Hi, I have a 1973 240z and I am about to try tackling the brakes on my own. I have new brake lines, new calipers, and a new master cylinder, but I don't know what to do first. Should I completely drain the system of the old brake fluid first, then do the brake lines? I will bench-bleed the master cylinder first and then hook it up but I didn't know if its a bad idea to completely drain all the lines first? and do I bleed the rear then the front or what order? Thanks!

[Hardway]

If you have everything listed above in hand I would drain all the fluid first, start at one end of the car and work your way to the other. It wont really matter which end you start with. If it were me I would start with the master cylinder. When you have all the lines off you might want to shoot some brake cleaner through the hard lines and then blow them out with compressed air. Then once the MC is installed do each caliper and associated flex lines at each corner. Once everything is done remember to bleed you MC first and then fill up the lines and bleed the system. If you run in to any issues just let us know.

[Zed Head]

No offense Hardway, but I wouldn't squirt any brake cleaner through the lines unless you know that you can get it all back out, which is unlikely with all of the twists and turns. It has a much lower boiling point than brake fluid and might screw things up if traces were left. Plus, the seals in the system aren't designed for brake cleaner. Seems like a good idea in concept, cleaning the lines out, but, kind of like engine crankcases should only have oil in them, brake systems should only have brake fluid.

Brake fluid is actually a really good solvent itself, as many have found out when they got some on their paint.

[72 OJ]

I will recommend to replace or rebuilt the brake booster as well :bulb:

Edited June 20, 2012 by 72 OJ

[Carl Beck]

Brake fluid is not very expensive {its not cheap either} - I would change the Master first, as you don't want junk from the old master pumped though the hard lines. Secondly you want a Master that can put the proper pressure on the lines to properly bleed them. Then I flush clean brake fluid through the system until all four corners are flowing clean fluid. I catch it in a clean clear plastic cup for inspection.

After that - I'd inspect and/or rebuild the rear wheel cylinders {unless they have been replaced within the last couple years}. Replace the rear rubber brake lines - Then do the front brakes.

I use this bleed order - Drivers Rear, Passenger Rear, Passenger Front, Drivers Front.

FWIW,

Carl B.

[madkaw]

I with Carl on this, change out the MC and then change the fluid BEFORE installing anything else. This will flush the contaminated fluid threw the old equipment. When you are doing individual brakes you can plug the brake line so you don't loose your fresh brake fluid. This will also make bleeding easier in the end with having some fluid already in the lines.

If you haven't done these drum brakes before, I would do one side at a time or take pictures so you aren't guessing later how things go together

[LeonV]

And I could always come by if you get stuck!

[yoshi_w]

Yea I haven't even touched the brakes since I have owned the car so I guess I'll look into rebuilding the rear wheel cylinders, how can I tell if they are in good working order though? And that order for bleeding the brakes is what I was thinking so that helps a lot thanks! And am I assuming correctly to bench bleed the master cylinder before putting it on and flushing out the old fluid? I have 3 quarts of brake fluid at the moment, should I get another bottle? And Leon, I have a feeling I may need to hit you up but I want to see if I can do this on my own first! I was gonna try doing the brakes tomorrow but the wheel cylinder suggestion may make me wait until next week, but I would rather be safe than sorry. Thank you all for the help so far!

[LeonV]

I would:

(1) Install master and gravity bleed all wheel cylinders

(2) Bleed master using ports on master and a hose looping from the port back into the reservoir

(3) Replace calipers and reinstall rebuilt rear cylinders

(4) Finish bleeding using your preferred method (pressure/vac, 2-person, gravity, etc.)

Rebuilding wheel cylinders is simple. There are kits at Rockauto.com and probably any other auto parts distributor.

Good luck and let me know if you get stuck!

[yoshi_w]

ok for sure it doesn't sound too daunting! should I rebuild the dry brakes too? or do you think I can re-use the old springs?

[yoshi_w]

drum brakes*

[LeonV]

I usually reuse the old springs unless they show visual signs of fatigue or damage (usually don't see this, esp. with Z drums). Rebuild the cylinders, install & adjust new shoes and you're good to go. Get new springs and hardware if it makes you more comfortable. I'd recommend adjusting the handbrake once everything else is set as well. The Z drums are great IMO, very easy and simple to work with.