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 Post subject: Give me a Brake!
PostPosted: Sat May 13, 2017 6:51 am 
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Joined: Thu Sep 01, 2005 1:12 am
Posts: 2084
Location: Darien, CT
Last weekend I jumped into the Z and backed it out of the garage. As I approached my other cars in reverse I noticed something a little disconcerting. The brake pedal went all the way to the floor! I had to be going about 2mph so it was not a big deal so I straightened it out in first gear and checked the brake reservoir. The fluid level was way down so I topped it off where it was parked and pumped the brake pedal for a good 5 minutes. No firmness ever occurred. So I slowly pulled it back into the garage and attached a plastic hose to one of the bleeder screws to see if I could get air out of the system. After a few pumps the fluid started appearing in my deposit bottle so I stopped and tightened up the screw. When I did this to the other bleeder screw no fluid ever appeared in the tube despite fluid in the reservoir.

So my questions are:
1) Why are there two reservoirs for the brake system in the first place? (front & rear?)
2) I assume that the next logical step is to remove the brake master cylinder and attempt to clear whatever sediment or blockage is occurring in the reservoir that prevents it from being bled?
3) If #3 is correct, after I reinstall the cylinder, am I going to need to bleed the brakes at each wheel or just at the cylinder?

Thanks for any help you can provide!!

Ross

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1978 280Z Black Pearl Edition 36k Original Miles
2008 350Z Bob Sharp GT-33 Edition


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 Post subject: Re: Give me a Brake!
PostPosted: Sat May 13, 2017 8:03 am 
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Location: Long Island, N.Y.
Glad to hear that there were no casualties. :shock: I have always been told that the rule of thumb is that if any part of the (closed) brake system is "opened", that you must follow the proper bleeding sequence. RR, LR, RF and lastly, Left Front. :thumbs_up:
Good luck.

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 Post subject: Re: Give me a Brake!
PostPosted: Sat May 13, 2017 9:46 am 
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Location: CT
"....a little disconcerting." :shock: :lol: Well, YEAH. Nice work diverting disaster. :thumbs_up:

I agree with Howie. You need to bleed your brake system completely, which is usually a 2-man job. Your helper will spend nearly an hour sitting in luxurious comfort, pushing and holding the brake pedal, while you scramble around under each wheel on your knees, monitoring the progress.

You'll need at least a very large can of brake fluid (and probably two or three), the rubber hose, the glass jar, kneepads and the nipple wrench which fits the brake nipples. I've also learned the hard way to open a large sheet of cardboard under the car and have a small bag of kitty litter close to hand for when I dropped or broke the glass jar full of nasty brake fluid. :roll:

Since you have to purge the entire system anyway, it's best to completely replace the contaminated fluid all at once. It should look clear like water; if it looks like tea (or coffee) (or tar) it needs to go.

Most mechanics would raise the car chest-high on a lift and remove all 4 wheels at once. You won't have that luxury so the best you might hope for would be raising one axle at a time on jackstands, then repeating the procedure on the other end of the car. I've had to do it one wheel at a time and I remember it as a real day-long chore. No pedal-pumpers wanted to hang around btwn wheel changes; good help is SO hard to find.

The master cylinder and all four wheels must be bled. Real mechanics would remove and "bench bleed" the master cylinder. You will have to settle for bleeding one chamber at a time. As you guessed, the front and rear have separate chambers to prevent you from losing all brakes at once. As Howie says, you start with the wheel farthest from the cylinder (RR) and work your way progressively closer to the cylinder, finishing at the LF. His progression sequence is correct.

Your method was wrong, however. Attach a hose to one reservoir nipple and into a glass jar. Open the nipple and pump all the fluid out of that chamber. Close the nipple. Swap the hose to the other chamber and repeat. With your master cylinder and reservoir completely empty of old "juice", fill the reservoir with fresh fluid and begin the bleeding process.

Leaving some fluid in the glass jar, keep the hose end below the surface. Open the nipple and have your helper push the pedal to the floor ONCE and hold it there. Close the nipple. Raise the pedal. Open the nipple and push the pedal down ONCE and hold it there. Each time the pedal is pushed, you will see air bubbles in the glass jar. Keep up this boring routine until you see no more bubbles from that chamber. Never let the reservoir get empty or you'll have to start over. Don't re-use the contaminated fluid from the jar. Never let your helper raise the pedal until you've closed the nipple, or that will suck air back into the system and you'll have to start again.

Once you've bled one chamber (and made sure the nipple is left closed), move to the other chamber and repeat. Once the master cylinder is bled, continue to each wheel as Howie described (RR/LR/RF/LF). Use the exact same procedure on each wheel that you used on the master cylinder. The farthest wheel (RR) will take forever, because you are pushing air thru the entire brakeline the length of the car, one pedal stroke at a time. As you get closer to the master cylinder, it will take less time to bleed each wheel.

It is absolutely vital that you never allow the reservoir to get empty, and never let your pumper lift the pedal until you have closed the nipple where you are working. To do either means pulling air back into the system and having to start over. You will get as tired of calling "up" "down" "up" "down" to your pedalman as he gets of hearing you.

At each nipple watch the hose in the jar fluid until no more bubbles get pumped out. As I said, use a lot of fresh brake fluid rather than recycle the old stuff out of the jar and back into your reservoir. I buy a couple liter size cans and expect to need more than I think.

There are "new" pump devices which are supposed to let one man perform all these functions alone, but I've never been fortunate enough to try them. Paul or Big Al might give you some pointers on that.

HOWEVER: having said all that, I will bring up a nasty subject. Where did all your brake fluid go? If your system appears still closed (e.g. no puddles of fluid under the car), there is a scary possibility that your power brake booster has ruptured the diaphragm and is allowing engine vacuum to suck fluid out of the master cylinder and into the booster. That's a separate Tech Talk discussion, but I just wanted you to be aware of that possibility if you can't find another obvious explanation.

Also, while I had the rear wheels off, I took that opportunity to adjust my rear drum brakes and lube my handbrake cable.

Frank

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 Post subject: Re: Give me a Brake!
PostPosted: Sat May 13, 2017 1:02 pm 
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Joined: Fri Dec 25, 2015 7:39 pm
Posts: 316
Location: Long Island, N.Y.
As Frank has implied, that the power boosters diaphragm might have ruptured and therefore allowed the brake fluid to be sucked into the engine, I would ask you if you recall seeing any tailpipe smoke when you started the car after the winter lay up. :?: That might confirm Franks suspicions, if you answer affirmatively, since brake fluid doesn't evaporate.

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 Post subject: Re: Give me a Brake!
PostPosted: Sat May 13, 2017 5:05 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
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Location: CT
And the tailpipe smoke would be very white.

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 Post subject: Re: Give me a Brake!
PostPosted: Sat May 13, 2017 5:15 pm 
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Joined: Thu Sep 01, 2005 1:12 am
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Thanks guys for the responses, especially you Frank for the detailed procedure.

Doesn't the fact that the one reservoir doesn't bleed mean that there is a clog in it? If so, don't I need to bench bleed and resolve that first?

I saw no smoke from the tailpipe upon starting and in fact am not sure that I even added that much fluid to the reservoir in the first place - my memory is going!

Ross

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1978 280Z Black Pearl Edition 36k Original Miles
2008 350Z Bob Sharp GT-33 Edition


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 Post subject: Re: Give me a Brake!
PostPosted: Sat May 13, 2017 9:13 pm 
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If you have the opportunity and ability to bench-bleed the master cylinder, by all means do that. Many people try to avoid it because there are multiple fittings to be disconnected (which require a holding wrench and a turning wrench) and there's a danger of spilling brake fluid onto your paint (sudden death for the paint). The possibility of stripping a fitting or spilling fluid on the car usually convinces people just to drain and bleed the cylinder on the frame. Personally I consider a bench-bleed to be a professional mechanic's job. I've done it once (and that's what convinced me it was someone else's job).

You have to remove the whole cylinder from the car (study that plunger arrangement) and wrap it in a T shirt to keep from spilling any remaining fluid onto your car's finish. If you spill even a drop of brake fluid onto your car's paint, be a real Z-man and lick it off immediately.

If you feel you absolutely have a blockage somewhere (or a bad check valve), you could more easily just buy a new $40 280z master cylinder and install it dry, or bench-bleed it before you install it in the car.

I fear stripping or cross-threading any of the copper fittings. I've never had that happen, but I know how much of a major pain it is to cut and refit a mangled connection in cramped quarters and if you don't do it perfectly, you get leaks on your paint. I actually use plumber's tape around the brass fittings because I'm so afraid of having a fitting leak brake fluid on my car paint.

I suppose you could blow compressed canned air thru the open nipples to make sure they flow freely, but by all means wrap your entire cylinder with a shirt when you do that, to prevent any brake juice from flying all over your car. Certainly drain the cylinders as much as possible first, obviously. A cheap turkey baster is indispensable for sucking old fluid out of your reservoirs. Do NOT return it to your wife after use or you'll be sleeping in your Z all summer.

Hopefully while you're bleeding the brakes you'll find a wheel or two which shows signs of having flung brake fluid up under the wheel well. That would be your fluid leak instead of a ruptured booster diaphragm, and a brake cylinder is an easy rebuild. I park my Z on an old carpet or slide cardboard under it, to show me where anything might be leaking. It tells me where to look first. Also search for any individual brake(s) which are "deployed" and not returning to "ready". The missing fluid might be holding the brake "ON", accounting for the low level in the reservoir.

I'm not sure what the DEP or EPA tell us today, but back in the day I just opened the small bag of kitty litter and poured all the old brake fluid into it. Then I enclosed it in a plastic garbage bag and thew it in the trash. I'll probably go to prison for admitting that nowadays, but I don't know of any other way to dispose of old brake juice.

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 Post subject: Re: Give me a Brake!
PostPosted: Fri May 19, 2017 4:46 am 
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Location: rhode island
Howard learned that bleeding process from me :P :lol: So anyways, fluid went somewhere........How are the wheel cylinders in the back? Are the backs of the drums wet, brake fluid on the tires? Or is the fluid running down the inside of your fire wall under the dash. If you don't see a line or hose leaking. Last would be front caliper seals, but rare.


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 Post subject: Re: Give me a Brake!
PostPosted: Fri May 19, 2017 10:21 am 
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HI All,

I'm sorry to say that I have not been able to focus on this task yet. I've got children graduating from college and Middle School and another returning from college this weekend. So things have been way too hectic lately.

Thanks for all the advice!

Ross

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1978 280Z Black Pearl Edition 36k Original Miles
2008 350Z Bob Sharp GT-33 Edition


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 Post subject: Re: Give me a Brake!
PostPosted: Fri May 19, 2017 4:26 pm 
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Location: CT
Gee Ross, it sounds like you might need to reestablish your priorities.... college comes and goes, but Z cars are forever. 8) :lol:

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 Post subject: Re: Give me a Brake!
PostPosted: Mon May 29, 2017 3:53 pm 
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Location: Darien, CT
Well the rainy weekend gave me an excuse to tinker some with the Z. First, I did what I always do before undertaking any repair project - looked for some good videos on YouTube! The advice on this thread has been great but nothing takes the place of a video.

After refreshing myself on bleeding brakes I decided to start with the brake fluid reservoirs. I cut two short plastic tubes and connected them to the bleeder nipples with the other end looped and held in place inside the the reservoir with a large paper clip. I then loosened the bleeder nuts and had my trusty (?) assistant Graham pump the pedal as I watched the activity under the hood. A significant amount of air cleared the system before all I saw was a solid stream of fluid. I then tightened the bleeder screws and "Voila", experienced a nice firm brake pedal. I took it out for a spin and it performed nicely. So I'm hoping and thinking that there is not air in the lines to each wheel.

I also took the opportunity to remove the stock steering wheel, which I had installed for ZCON in NH a few years back, and re-install my grant wooden wheel. The stock steering wheel on a 280 is much like the stock bumpers - way too big!

So now I'm just waiting for a sunny weekend day to start getting some enjoyment out of it.

Thanks again for all the advice.

Ross


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Ross Williams
1978 280Z Black Pearl Edition 36k Original Miles
2008 350Z Bob Sharp GT-33 Edition
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 Post subject: Re: Give me a Brake!
PostPosted: Mon May 29, 2017 4:11 pm 
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Location: CT
:D Hoorayy! Well done. If you get any swerve or drift during hard braking with hands off the wheel, you might have some air in the side you drift toward.

And that wheel! Wow. It reminds me of the one on Bev Bianchi's 1971 car. Were they the same?

Frank

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 Post subject: Re: Give me a Brake!
PostPosted: Thu Jun 01, 2017 3:02 pm 
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Joined: Wed Jul 23, 2008 2:38 pm
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Location: rhode island
:thumbs_up:


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 Post subject: Re: Give me a Brake!
PostPosted: Thu Jun 01, 2017 3:23 pm 
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Joined: Thu Sep 01, 2005 1:12 am
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Location: Darien, CT
Frank T wrote:
: And that wheel! Wow. It reminds me of the one on Bev Bianchi's 1971 car. Were they the same?
Frank


Hi Frank, I'm getting old and my memory is going! I can't remember what steering wheel the Bianchi's have on their car. If it is a 240, which I think it is (?), it might be the original fake wooden wheel.

Hope all is well.

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1978 280Z Black Pearl Edition 36k Original Miles
2008 350Z Bob Sharp GT-33 Edition


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 Post subject: Re: Give me a Brake!
PostPosted: Thu Jun 01, 2017 4:05 pm 
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Location: CT
No, Bev had a beautiful fat wooden wheel very similar to yours on her first-owner '71 240Z. She sold that car to a dealer s few years ago and he has it now.

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