240Z Brake Questions

[Nigel1943]

Doh, misread. You're saying that my 12/71-built '72 should have the reservoir in the rear. Makes sense.

The F(front) and R (rear) marked on the M/C should be the giveaway;)

[alternativez]

I only mention this if everything mechanical and hydraulic are correct, no air is being drawn back into the system by a poorly seating bleeder or connection, and since you've tried all the usual bleeding methods. Bleeding is a job for method and patience as pumping quickly can cause agitation and aeration, which is easy to do, especially when refilling the entire system. Of course, make sure the fluid has not been shaken. I place a clear vinyl tube on each bleeder and into clean fluid in a clear jar. I bleed each, far to near, as usual until the tubes are full so they will not return air into the calipers/cylinders. Then I can let it sit, and any tiny bubbles will form into larger bubbles and then be expelled. As I keep the excess fluid clean, I can recyle it through several bleedings until every tiny air bubble is out. It does take a strong leg, and my wife may use both legs to apply sufficient pressure when bleeding. Give the fluid time to settle. There was air clinging to the inside of all the parts and must be slowly washed out. Also, an oddity, but hoses can separate and the air/fluid can be forced between layers of the hoses. Good luck!

[timhypo]

On a side note, has anyone made their own power-bleeder? I have a chunk of 1/4" plate that could be combined with some rubber, a c-clamp, and a few air fittings to make a universal-fit power bleeder when combined with my compressor/air drier. Why pump brakes if you can push the bubbles out with the compressor? If I decide to build one and it works well, I'll document it in a separate thread.

I'm postponed working on the brakes for a few days as the city is doing work on the only flat area I have to work on it - the street. My wife's Olds and my in-process chopper-build are eating up my garage space, so it's on my steeply sloped driveway, which is no good for brake bleeding.

[timhypo]

Ok, got back to this and discovered that the only wheel cylinder that I didn't replace is leaking. Also, since I put the new one in the passenger side last year, apparently the shoe has disintegrated - I guess that's where the weird pulsation in the brake pedal was coming from. When I get some more cash I'll replace the wheel cylinder and shoes and HOPEFULLY be rolling in my 240z with reliable brakes for the first time since I bought it 10 years ago.

In other news, I got the 240z tuneup video and a unisyn from Z-Therapy. This video is worth every penny. It's extremely rare messing with old cars to have that amount of real information available and it being on DVD and demonstrated makes it better than any manual...

[ZCCOR#109]

As I read this I find fault with some of the "explanation" of bleeding.

Why would anyone put "pressure" on the pedal while bleeding.

My wife and I have bleed the Z's brakes for over thirty eight years and only once did she put "pressure" on the system. That was my fault when I said "down" and didn't have the bleeder open. Result? The fluid shot out on the right front as I opened the bleeder, hit the inner fender/frame, went past my eye glasses from the side, and into my left eye. What's up with that?

Wife poured several glasses of water into the eye while I lay on the garage floor. Enough of that story. Bottom line you don't need Pressure while bleeding. Nice and easy does it. Move the fluid slow.

Bottom line. I open the bleeder and say "down". She slowly strokes the brake pedal down and when fully down says "down". I close the bleeder and say "up". She slowly raises the pedal and says "up". She is the best. There is NO pumping up the brake pedal! That only stirs things up and gets any available air into the mix. I have completely rebuilt the Z's system twice and changed to synthetic, so at least twice we were working with an empty system. Same process.

Sequence is:

Suck all old fluid out of the master with a turkey baster or similar. Wipe clean, and add new fluid. Bleed in order

1. Rt rear, Lf rear, right front, left front. far to near of the master.

You bleed each until fluid is clean and no bubbles are appearing.

My first learning experience with problematic brakes was the 1928 A of my brother that he had modified to hydraulics. 48 Ford wheel cylinders and 56 Master Cyl. Not compatable but I stopped that d#$% thing with all my legs could muster. But that's another story not told.

Edited July 20, 2010 by ZCCOR#109

[Marty Rogan]

After you replace the leaking wheel cylinder, re-bleed the master and then the rest of the corners as described above (farthest to closest).

If you still have a spongy pedal, try this trick that a racer taught me a long time ago. Bleed the rears properly first. Then on the right front caliper, remove the outside brake pad. Use some padded channel lock pliers and press the piston carefully into the caliper. It will travel farther than with the pad installed. BE very carelful when you push the pedal down, that you don't push the piston out past the seal. Do that a couple times till you get all the bubbles out. Replace the outer pad. Then remove the inner pad and repeat the process. Then move onto the drivers side and repeat.

Every time I would put new calipers on my race car, I could never get a firm pedal until I did this extra step. After doing it once, it was bleeding as usual.

Give it a try and let us know how it works out.

Good luck!

Marty

[mlc240z]

Sequence on a 240Z is driver's rear, pass rear, pass front, driver's front.

Unlike most other cars.

[doradox]

Could someone explain to me why the need to bleed rear brakes before fronts. Since the front and rear circuits are isolated from each other why would it matter?

Steve

[biddljj]

I think my logic explains the reason for right rear first...... I have a rule that says bleed the cylinder that is farthest away from the Master Cyclinder first, sesond farthest second....On 240Z's the rear brakes go into a junction block near the passenger side rear tire... Hence... Driver side rear is the longest.... Driver side front is the shortest run... Works for me.....

Jay

Not justa Z - Zdisease

[Inf]

Could someone explain to me why the need to bleed rear brakes before fronts. Since the front and rear circuits are isolated from each other why would it matter?

Steve

I have also wondered this, but saw no reason not to do the rears first in cases where I had to do all 4.

As I'm about to replace the front calipers, I'm wondering if I still need to bleed the rear brakes, or can I just get away with bleeding the fronts only?

[biddljj]

Stet....

Edited July 21, 2010 by biddljj
Posted to wrong thread

[doradox]

I have also wondered this, but saw no reason not to do the rears first in cases where I had to do all 4.

As I'm about to replace the front calipers, I'm wondering if I still need to bleed the rear brakes, or can I just get away with bleeding the fronts only?

No need to touch the rears. Separate circuits.

Steve