Clutch pedal sometimes hard

[soldave]

Got an intermittent problem which seems to be occuring a little more frequently in the past couple of weeks. Normally, my single-plate clutch (Centerforce) feels pretty much like stock with gear changes, and doesn't require much pressure at all. However, once or twice per journey the clutch pedal will become hard and require a fair bit of force to push it down. This will probably happen for a couple of gear changes and then it will go back to normal again. I have no problems finding a gear once the clutch is in, but obviously this is an issue I want sorting out.

My mechanical knowledge is very limited but my best guess would be one of the cylinders or clutch fluid that needs bleeding. However, I think the master cylinder was overhauled when I had my new clutch put in around 7000km ago. Thought I would check with much more knowledgable folk though before doing anything or taking my car to a garage.

Cheers for any help you can offer me in advance

 

[tbonitz301]

You are referring to what we know as "pump up". My car does it to. It can cause your clutch to slip if its bad enough. I dont know a whole lot about it. Its something to do with the master cylinder. Might try a search

 

[soldave]

Have done some reading about pedal pump and I understand some of it. Is the only way to get rid of it adjusting the master cylinder rod? Have just spent the past hour and a half upside down in my car trying to get an angle on the cylinder rod locking nut. I failed in loosening it and gave in after all the blood in my body had reached me head

 

[tbonitz301]

.Yea it can be a pain. Adjusting it is the only solution i know of. Try backing the master rod away from the firewall a little bit at a time. Be sure to drive it inbetween adjustments to find that sweet spot

 

[soldave]

Well I'll give it a go but am going to have to think of something out of the box to do it. My current (admittadly cheap-ass adjustable) wrench seems to be doing nothing but trying to round the locking nut and giving me a head rush from spending so long under there.

 

[spyderman1997]

when my car was doing this, my clutch master cylinder was bad. if you look under the dash where the clutch connects to the master cylinder you might see the fluid leaking. if so there is your problem. i chose to just get a rebuild kit which was just a piston with a seal and a spring. 14 bucks and back in business!

 

[soldave]

If you mean close to the master cylinder rod (near the pedal) then there doesn't seem to be any fluid leaking. I'm also not noticing any clutch fluid loss. The spring next to the clutch pedal does look well greased/oiled, but I don't think that's the clutch fluid.

And it was overhauled only 4 and a half months ago.

 

[spyderman1997]

well if your fluid seems to be topped off, maybe it wasnt bled right. i had this problem intermittantly. it would seem then there is air in the system.

 

[soldave]

Forgive me if I'm completely wrong here, but wouldn't air in the system cause the clutch to go really soft at times, rather than hard?

 

[soldave]

Well I shredded a couple of knuckles, but finally got that adjustment nut loose. Turned the rod about 1 and a half turns anti-clockwise (as you look from the drivers seat). Took it for a drive but it was shocking. The clutch felt really heavy and wasn't coming back all the way to its resting point. Went back and turned it clockwise about 1 turn. Went for another drive and it felt a little softer, but still stuck a little below the resting point. Turned it back almost to where I was and it is now returning all the way and biting at about 1/3 from the bottom. Not been on an extensive drive but am hoping it has done something and sorted it out.

 

[tbonitz301]

Well hopefully that helps. You might try bleeding the system again. Just to rule out one more thing. Be sure to bleed it the correct way

 

[soldave]

You mean making sure to bleed master & slave? Might do that this weekend.

 

[tbonitz301]

Yes. Be sure to slip a piece of hose over the bleeder screw, and run the hose into a container with two inches of brake fluid. This way air cannot get into the system.

 

[soldave]

Well, playing around a little with the master cylinder rod didn't help any. Was still stomping on the clutch a couple of times in traffic today. Will bleed the system this coming weekend and hope that for some strange reason, that sorts things out.

Quick question for you all. At the end of the slave cylinder rod there is a fork which goes into the clutch (see picture below). If I push the rod in using a couple of fingers (i.e. towards the rubber cover on the cylinder) and then let go, what should happen? Should it go back to its original position? If so then that could be my problem as it seemed to be stick where it was until I pulled it out.

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[tbonitz301]

Sounds like you may have air in the system still

 

[soldave]

But the same question again: would air in the system make it go hard?

This is going to be a case of eliminate everything until I find it though so I'll be doing that next.

 

[soldave]

I am assuming that the slave cylinder rod falling out of the slave cylinder when you're checking it against the clutch fork isn't a good thing?! That happened and, while I managed to put it back in and the clutch is engaging, it doesn't fill me with confidence. Think that could be my issue?

 

[soldave]

Well I rebuilt the clutch slave cylinder (which was all gunked up) and bled the clutch and... there was no difference

The clutch is going down and engaging ok, but then the final few inches just feel really stiff. My friend who tried pumping the clutch a few times says it feels like a grind at the end of the pedal push, which doesn't fill me with confidence. Have ordered a set of braided clutch lines in a vain hope that it might work, but am really starting to think it could be my 3-month old clutch now

 

[ryedog878]

This will suck, You may want to pull the tranny and make sure everything is still in tactfrom the clutch install. Was everything replaced when clutch was installed, trowout bearing, pivot ball, shift fork. When clutch was installed was there alignment tool used to set everything properly. Did u have a new flywheel installed or at least old one resurfaced.

 

[soldave]

Flywheel was brand new (Fidanza) with the clutch. Not sure what was replaced when the clutch was done as I left it to the guys at my tuning shop. It might be them that go have another look at it in a week or so.

Just read one person who had a similar issue, and SS lines seemed to help him out hugely. Hopefully they'll do the same for me.

 

[wimploki]

Here you go - RRE's Clutch And Flywheel Tech Info

Scroll down and read up on clutch adjustments. You might need to adjust your upper stop as well.

Have fun adjusting.

Got an intermittent problem which seems to be occuring a little more frequently in the past couple of weeks. Normally, my single-plate clutch (Centerforce) feels pretty much like stock with gear changes, and doesn't require much pressure at all. However, once or twice per journey the clutch pedal will become hard and require a fair bit of force to push it down. This will probably happen for a couple of gear changes and then it will go back to normal again. I have no problems finding a gear once the clutch is in, but obviously this is an issue I want sorting out.

My mechanical knowledge is very limited but my best guess would be one of the cylinders or clutch fluid that needs bleeding. However, I think the master cylinder was overhauled when I had my new clutch put in around 7000km ago. Thought I would check with much more knowledgable folk though before doing anything or taking my car to a garage.

Cheers for any help you can offer me in advance

 

[soldave]

Have tried adjusting the clutch and the upper stop but to no avail.

Strange. Went down to the car, jacked it up and pushed the slave cylinder rod and clutch fork to make sure they were moving ok. They were so I set the car down and got in. Put my foot on the clutch and it felt smooth as silk. God knows what's going on...

 

[soldave]

OK - got an update for you all which could be a big piece in the puzzle. Had been driving home and the clutch was feeling a little hard as per usual. Once I got home I jacked up the front of the car and just pushed the clutch fork and slave cylinder rod in to check it was moving freely. Fork went in and then came back out as normal again. Put the car back down and got in. Clutch pedal was smooth as silk. It did that a couple of days ago too but I didn't put 2 and 2 together then.

Now I don't know much about cars but that would suggest to me that it's not the clutch itself, and is something between the clutch pedal and the fork. Maybe this SS line will solve it after all. That is a big bit of info though, and maybe someone can deduce what it is from that.

EDIT: This problem may be solved, and I have a bit of a confession to make. It may have been this "pedal pump" situation afterall. I sat down in my garage, made a couple of movies with my phone and tried to think logically about what was causing the problem. When I pushed the slave cylinder rod in, the fork moved about 1cm towards it and then stopped. "Maybe it's only now that it's fully engaged" thinks I. So I adjusted the pedal by screwing the master cylinder rod about 1 1/2-2 turns anticlockwise (facing the front of the car) so as to give the system a bit of play. Left the upper stop at the topmost point and went for a spirited drive. 20 minutes later and only one crashing of gears into third (although that's just my poor driving ability) and the clutch wasn't feeling hard at all. Felt just as it was when I started.

My only issue now is that the top 1/2 inch or so of pedal play sometimes sticks a tiny bit. The clutch fully engages and disengages, but that last bit of freeplay can mean the pedal stays in a little. If I hit the gears hard, it will pop out fully, but if I slowly take my foot off the clutch, it can sometimes stay there until I flick it up with my toe. Will bleeding the clutch again get rid of that?

 

[tbonitz301]

I think you are getting air in the system somehow. Like you said hopefully the ss lines help. Im cashed on this one man. Ive been havin the same problem for months. Good luck

 

[soldave]

Installed clutch line and played around a tiny bit more with the adjustment screw. The clutch is getting better, but still the pedal varies from being very light to being medium-hard. Not as bad as it was before, but still gets harder as you drive longer.