Okay, What am I Missing???

[Dadandson]

Here is all the details:
Installed new Clutch master and slave cylinders on my 1974 Midget. No problem. Filled with brake fluid. Using the access hole and a 7/16 wrench I open the bleeder, my son pushes the pedal, I close the bleeder and then he lets the pedal up. We repeat this numerous times. Fluid is getting to the slave but there is no pressure push at the slave. We stopped after a half an hour or so. What am I missing here? I have done this on brakes and clutches on numerous other cars. Do I have bad parts?

 

[Morris]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Do I have bad parts?[/QUOTE]

You have "bad design."

If you do a search on the forum you will find that you are far from alone. You will also find tons of advice. Some of it is good, too.

 

[zblu]

Bleeders at 12 o'clock or 6 o'clock?

 

[Dadandson]

The bleeder is on top of the slave.

 

[jlaird]

Top is correct.

 

[Trevor Jessie]

Air sometimes is trapped at the slave cylinder. Pry it back with the bleeder open, then close the bleeder. Then have your son pump the pedal to build pressure, and bleed as before.

 

[zblu]

you pushing fluid downhill, ie from master to slave?

 

[lesingepsycho]

Here's what I do:

I unbolt the slave from the tranny so that it will dangle from the hose. First thing, notice the position of the bleeder to respect with the rest of the cavity. The hose is to one side, then the bleeder, then the rest of the cavity on the other side. Brake fluid, like other materials, following the laws of physics, will take the path of least resistance. If there is air in the cavity, then the fluid is going to come down the hose and bounce off that air bubble and go out the bleeder without filling the cavity. SO, what I do is, while the slave is dangling, I open the bleeder, depress the slave cylinder piston as far as possible (without forcing) into the slave cylinder, close the nipple, allow the piston to come back out thus drawing fluid into the cavity, repeat this process until you have filled the cavity and drawn out any air that may be in the lines and you should have a pressurized system with no air. At this point you should be able to reattach with the two bolts, connect the fork and good to go. I never bleed with the slave attached to the tranny because it is way to impossible to reach, even for a small guy like myself!

Good luck!

JACK

 

[Dadandson]

That makes sense. Correct me if I am wrong but I should have pretty strong pushing power at the slave when the pedal is pushed right? Currently I can push the piston back on the slave while the pedal is down!

 

[Trevor Jessie]

Right, because air is easily compressed.

 

[zblu]

I put a block in in lieu of the disk, think blood transfusion , lift the caliper up high, as fluid travels down the hose its probably passing air going the other way
Not while you bleeding
If you can, is still got air in there

 

[Dadandson]

I can see using a block for the brake caliper, but how would I setup a block for the clutch cylinder?

 

[bugimike]

Chock the throw-out lever maybe?

 

[jcatnite]

I have never been sucessful bleeding the 1500 clutch without a vacuum rig. I also use a long hose on the bleeder and put a big loop in it high above the slave cylinder. After vacuuming out the slave till I get no air bubbles in the clutch pipe(hose). I work the clutch pedal several times with the bleeder shut. You will get a large number of small bubbles in the line. Quickly vacuum the slave again. After a couple of cycles you won't have any bubbles in the clutch pipe. Even one of the $19 harbor freight vacuum rigs will work great for this application.
Hope this helps,
JC

 

[TexasSprite]

Has anyone tried using a system that pressurizes the MC? I saw a design on the Internet that uses a garden pump up sprayer which has its hose connected to an barbed fitting on a spare MC cap. Looks like you could build it for less that $15.

 

[tony barnhill]

Ezi-Bleed...I've one.

 

[jlaird]

And that sounds like a great idea. Think I will try that.

 

[Morris]

Jack, didn't you try the deal where you put a bicycle tube over the MC and apply air pressure from a compressor? Or was that someone else?

 

[lesingepsycho]

I've tried the pressurized system method but with no success. I actually took a apared MC cap and drilled and tapped an air hose fitting into the top and hooked it up to my compressor. At the end of a large ordeal, I still felt like the pressurized side was coming in and taking the path of least resistance out the nipple and not really displacing the air in the cylinder. I never did try a vacuum but maybe I'll try that next time. Hopefully that won't be for a long time though because my clutch is working fine right now.

JACK

 

[aeronca65t]

First, "prime " the slave cylinder by putting some brake fluid in it. You may have to remove the slave cylinder piston to do this. Much fluid will run out as you later attach to the trans, but get what fluid you can in it.

Then, with the bleeder closed, pump the clutch pedal fast about 20 times and hold down. While it is down, loosen bleeder.
Then tighten bleeder.
Then release clutch pedal.
Repeat this "20 fast pumps, hold down and bleed" several times.

Then pump clutch pedal 20 times and hold.
This time, loosen the line going into the clutch master cylinder (this can be messy).
Then re-tighten this line.
Then release clutch pedal.
(this bleeds the upper end of the system)
Repeat this several times.

This has generally has worked for me.
Be sure there is no "pinhole" in the hydraulic clutch line. I had this once (from battery acid, I think) and it drove me crazy until I found it.

G'luck!