master and slave cylinder

[volcakid8787]

Recently I experienced clutch problems. The clutch pedal was depressed easily and, when the gears were shifted, the gears would grind. The diagnosis I gave was no pressure in the hydrolic system. I inspected the reservoir, and sure enough, there was no fluid. Seeing as how my car has almost 100,000 miles on it, I decided to replace the master and slave cylinder. After the new parts were in place I replaced the fluid and bled the system. Now for my main question: now that everything is in working order and back in place, the friction point where the clutch starts to grab is at the top of the clutch pedal height (i hope this makes sense)...is this normal? I was thinking that it could just be because it has full fluid in it now. Anyhow, it used to be lower in the clutch pedal's travel.

-volca

 

[Friend-O]

A stock setup should have about 1-2 inches of free play before the slave rod begins to move basically putting it closer to top. you can adjust the master push rod under your dash to lower the point if its too high, just be sure to have enough room for full disengagement, you'll know if you need to raise it if you grind and stick a lot when shifting.

 

[kenamond]

Sounds like you need to adjust the pushrod on the master cylinder. There's an internal release valve in the MC that opens when you release the pedal (if all is set correctly). This lets fluid in the clutch hydraulic system flow back to the reservoir. If the pushrod is adjusted too long, that release valve doesn't open, and your clutch disengage point can get too high, and the hydraulic system can't auto-adjust. There's a good video out there from Jack's Transmission or something that explains the whole adjustment procedure, including a 2g DSM clutch hydraulics setup on a workbench.

One quick check is to jack up the front of the car, go under the passenger side and find the slave cylinder. There's a rod coming out of it that normally pushes the end of the clutch fork (the end of the fork sticks out of the bottom of the tranny through a square rubber boot). You should be able to push that rod into the slave cylinder (away from the fork) with your finger. If you can, then that means that the release valve is currently open, and you're basically pushing fluid out of the lines and back into the reservoir. If you can't, the release valve is still closed even with the pedal all the way up, which means your MC rod is not correctly adjusted. I'll find two links and add them. One describes that release valve, and the other is the adjustment video.

Description of the release valve:
http://www.dsmtuners.com/forums/drivetrain-tech/366222-totally-understanding-our-clutch-system.html

Video for adjusting the MC pushrod length:
http://www.dsmtuners.com/forums/new...ch-goes-floor-wont-go-gear.html#post151955635

 

[volcakid8787]

Both links were very helpful thank you. I'm still a little confused however. When I re-installed my new master cylinder, I didn't adjust the master cylinder push rod very far. In other words, the push rod is not screwed in very far. Saying this and reading everything above mentioned, I would think with the push rod being further away (in somewhat correct position) would allow the friction point to be at its normal place within clutch pedal movement. However, the friction point is at the top. Anyhow, I will do the test and repost.

-volca

Left to my own stupidity, I completed the test. It was just like what was said above and described in the video. I just had things backwards in my mind.
In conclusion, the master cylinder push rod needs to be at a precise distance to allow the internal release valve to operate correctly. (i guess) Screwing the push rod is a little more sensitive than I first assumed. Thanks for y'alls help.

-volca