Hydraulic Clutch Woes

[busterswt]

Hello all,

I converted to a hydraulic clutch setup when swapping to a 350, and I'm having some issues with pedal return. Whenever the pedal is up all the way, and you push down to change gears, the pedal doesn't return all the way (about 1/2" short). Subsequent pedal pushes come up 1/2" short each time until you're right at the floor and eventually unable to engage the pressure plate properly. You can pull the pedal up with your foot and repeat the process.

Is this a symptom of air in the line? I have bled it many times and don't appear to get any air out of the system since the initial bleed. I'm think I'm overlooking something, but am not really familiar with a hydraulic clutch setup to know what's right/wrong. It's not behaving line air in a brake line would.

Any suggestions would be much appreciated.

 

[Purple77CJ7]

I had some of the same issues you have when I changed to a hydraulic clutch. The only way I could get all the air out was to use a power bleeder from the slave cylinder up to the master cylinder. I also run a return spring on the clutch fork arm and under the dash on the pedal to the dash. The spring on the fork is a pretty stout spring. The spring under the dash is not as stout as the one on the fork, it just needs to help with return.

 

[Sam5038]

To get all the air out of a hydraulic clutch is very easy. Have someone hold the clutch pedal down. Then loosen and retighten the line at the master cylinder. This will get all the trapped air in the line and master cylinder. I used a rag to catch the fluid from getting all over the place.

 

[Shifter]

The spring inside the master cylinder is not strong enough to push the heavy pedal all the way back up... a spring on the pedal will help. Also make sure that when the pedal is all the way up, the master is all the way returned. ie.. the rod is not too long.

 

[73CJ]

Springs on both ends as mentioned.

I made a longer push rod. About 3/8" to take up most of the play.

If you pump your pedal repeatedly and the pedal comes up. It's air in the line. If it doesn't change, then you got the air out.

 

[busterswt]

Thanks for the suggestions everyone. I could never find a definitive answer as to whether or not I needed return springs, and as a result I didn't install any. I will get to it this weekend and let you know how it goes. Thanks again!

 

[JR74CJ5]

Doing this soon, Want to see how it turns out.

Take and post some pictures of return springs etc if you can


~ Jr

 

[busterswt]

So it turns out I have the return spring on the clutch pedal already. Pretty big sucker that's sorta hidden from view.

One thing I noticed is that when I push the pedal down softly and slowly with my hand it goes all the way to the floor with no effort. I can see the fluid in the reservoir move up and down as I pull the pedal back up and push down slowly. As soon as I put any effort into the pedal I feel resistance and it's consistent all the way down (as it should be). I can immediately push down softly and slowly and simulate the earlier behavior (no resistance).

Would this be indicative of air in the lines or a faulty master cylinder?

 

[jdarg]

You can bleed w/ the following procedure:

- uncap the master cylinder

- disconnect the slave from the motor, hold it so the rod is pointing down towards the ground

- slowly (slowly - so its barely moving) push in the slave rod (while continuing to hold it so the rod is pointing down) until its all the way in, then let it return out.

- you should see bubbles in the master as you push the rod. repeat the in-out strokes a few times until they dissipate.

- gently tap the master a few times from a couple different directions with a dead blow

- repeat the operation at the slave again, 2-3x, until you sure there aren't any bubbles, and then reconnect it to the motor, recap the master, and see where you are at w/ the pedal.

 

[CJim7]

Sounds like a bad master cylinder to me. Last year, I had the same symptoms you describe....took apart the master and found the plunger gasket worn enough to allow bleed-back.

 

[Sam5038]

Sound like you need to bench bleed the master cylinder. Can't get all the air out of the system without bench bleeding it.

 

[busterswt]

I bench bled a new master, followed jdarg's process, and everything seems ok for the moment. Thanks everyone for the help!