brake bleeding

[JetDoc]

Hello

Well i finally got back to work on the Z after a 2 week school in Kanasas, right before i left i replaced the brake master cylinder, installed rebuilt front calipers and both rear wheel cylinders but ran out of time! yesterday i tried to bleed the system, i bled the master cylinder then the wheels RR,LR,RF,LF the problem is i have no pedal feel, it goes to the floor with little resistance, i had the rear jacked and the brakes will stop the wheels, i have clean fluid to all four corners and no leaks, someone told me i needed to bleed with the engine running (power brakes) i've never heard of this and was wondering if anyone else has? The brake booster seems to be working just fine! Any help or idea's would be greatly appreciated!

Al

[frank13]

Your MC rod is out of adjustment. Use the search function in the right forum: Wheels, tires, and brakes. :devious:

[SledZ]

One thing that is not in our forum is much on the booster. If it is leaking your brakes will be spongy when the car is running and feel ok when you disconnect the vacuum or don't run it. Also if your front or rear brakes gradually start locking up it is the adjustable rod in your booster, it is out to far and putting to much pressure on your MC.

Sounds like your booster rod might not be out far enough unless your booster is going bad.

I ended up replacing MC and Booster after hours of diddling....

[JetDoc]

Hey all

I appreciate the replys, i pulled the master cylinder and checked the rod length and it was dead on @10mm like the book calls out for a 1978, what i have done to get everyone on the same page is: installed new master cylinder, installed rebuilt front calipers l/h and r/h new rear wheel cylinders l/h and r/h and attempted to bleed! just a few minutes ago while i was attempting to bleed the clutch (another problem) i had the r/h front jacked, for the heck of it i had my son pump up the brakes and hold them but the front wheel still spun so i believe i still have alot of bleeding to do to fill the calipers! I hope anyway!! I will get back to u with more details!

Thanks again!

[2ManyZs]

Sounds like you still have air in the master cylinder if you aren't getting any pressure on the front caliper at all.

Bleed it again, and this time run about 2 full reservoirs of fluid through it before you go to the wheel cylinders and calipers. If that doesn't get all the air out, something isn't right....

[Daniel]

rods, air etc. are all good ideas. I cannot stress enough ,like SledZ pointed out, the booster. Damn thing drove me crazy, Makes you think you're on the trail only to dissappoint. "They " say the booster fail only makes the pedal harder. That is false!

[NapaBill]

Jett, sounds like there is an airlock. You have two methods to try:

1. Use a power bleeder.

2. Bench bleed the master cylinder. In other words, remove the m/c, clamp it in a vise and carefully (so as not to scratch the bore) bleed the cylinder by pushing on the piston with a screwdriver or drift. When all the air is out of the cylinder, reinstall it and you should be able to bleed the lines. Yes, you can do this procedure with the cylinder in the car by disconecting the brake pipes, but you will get brake fluid all over the place.

[landmizzle]

Hi all,

Not to be a turd or anything but, shouldn't this post be elsewhere as this really isn't a thread contianing a technical article?

I won't say anything if you guys won't; just thought I'd point out the obvious.............

Best Regards,

Landmizzle '72 240Z

[2ManyZs]

Oops, I knew there was another thread that needed to be moved.... I just forgot which one it was...:stupid: