shorten slave pushrod?

[NC325iC]

alright im sick of this,

my clutch pedal throw is about 75% before the friction point.

as far as i can tell the only way i can alter this would be to shorten the pushrod on a slave cylinder. i have access to machining... machines and could do it well. anyone done this? anyone have alternate ideas? concerns?

[allwheeldrive]

What kind of clutch do you have in it? OEM? Has it been replaced recently? I know of some American applications that use shims for the flywheel. I don't know if it could be applicable here. Just throwing out ideas.

[jlevie]

It sounds to me like you are saying that you have to push the pedal about 75% of the way down before the clutch disengages. That being the case, shortening the slave cylinder push rod would make the situation worse.

Assuming that you don't have worn clutch, which will move the engage/disengage point lower, or that you don't have a high performance clutch, many of which have a low engage/disengage point, the fix for large travel of the pedal would be a bigger master cylinder or a smaller diameter slave.

[NC325iC]

damn, forgot about this thread, no levie actually its the other way around, the clutch releases at the very top, that is the problem. if it were the other way around id be happy with it

Spec stage 3+ clutch
re machined (fresh step) flywheel
stock hydraulics

[jlevie]

Got it! I think an easier solution would be to insert a spacer between the slave cylinder and the bell housing. I don't think it will take much of a spacer and that has the advantage of using a stock slave cylinder.

[CarsSuck]

i know this is mad obvious, but have you screwed around with the eccentric bolt adjustment on the pedal?

Some cars also have heim style adjustment on the master where is attaches to the pedal. (according to bently)

[jlevie]

That would move the rest position of the pedal, but won't change the engage/disengage point. Meaning that you can position the pedal lower, but it will still actuate in the top 25% of pedal travel.

[Easily Distracted]

Adjustable clutch stop. Unscrew the plastic stop from the floor beneath the pedal and replace it with an elevator bolt and a lock nut. The best $1.75 you'll ever spend on your car. Did it a couple of years ago ago from a write up on here. Do a search for it.

[NC325iC]

Adjustable clutch stop. Unscrew the plastic stop from the floor beneath the pedal and replace it with an elevator bolt and a lock nut. The best $1.75 you'll ever spend on your car. Did it a couple of years ago ago from a write up on here. Do a search for it.

the problem is my clutch throw is also very short to begin with, if i just put a clutch stop behind it id only have like an inch of travel

and yes i messed with the eccentric bolt, but all that does really is change the pedal height.

i figure ill put some washers on the bellhousing to space it out some, then maybe take out the shaft and machine that thickness out of the shaft on the lathe at the shop

[jlevie]

I think the cause of this is the Stage 3 clutch. That level of clutch is designed to require very little motion to engage/disengage, so it happens at the top. I highly recommend just using spacers so that as the clutch wears you can remove spacers to compensate for wear.

[NC325iC]

thats a good point, ill give it a test run, maybe ill just machine some solid spacers so i dont have to be worrying about shitty washers etc.

edit: wait a sec, as the clutch wears, the engagement will move back up the pedal because with less material the springs will be out farther

[jlevie]

Wear on the clutch disc results in needing greater movement of the pressure plate to disengage the clutch. Which means a need to have more motion of the slave cylinder.

The two classic symptoms of a worn out clutch is slipping or not being able to select gears when the clutch is depressed

[NC325iC]

i dont think so, the PP is bolted to the flywheel soldily on the outer edge, the actual contact surface is on pivoting springs so when the TOB pushes toward the engine the contact surface is pushed out, which means that if the clutch disc were thinner ie worn the pivot springs would protrude out farther than if the disc were thick, and since the pivot point is fixed the TOB would require less movement to completely disengage the clutch disc.

i wish i could draw it for you

[jlevie]

I understand what you are saying, but what I'm not communicating very well is that a thin clutch disc means that the more motion is required of the PP fingers to get the pressure plate to lift off the clutch disk. Yes the fingers do extent a bit more, but that's because the pressure plate is seated deeper, so the fingers have to be pushed further towards the flywheel to get the pressure plate to release.

[NC325iC]

ok i was illustrating the workings of the clutch when i thought of something, assuming the TOB has the same starting point for both conditions, with a thinner disc the springs will be closer to the tob at rest.

In condition 1 the tob (this is just a theoretical not a real life) has to move to take up the slack btw it and the springs then it has to push on the springs moving them through some flex until the pp lifts from the disc.

assuming the tob starts at the same position, the spring flex distance and the distance the pp lifts from the disc are the same and require the same pedal travel ie. it take 1 inch of pedal travel to flex the springs and seperate the plate and disc.

In condition 2 the springs are closer so there is less slack to be taken up, everything else requires the same pedal travel, this may not be 100% accurate but it is very close, the altered angle of the springs will have a small effect on this but nothing big.