Screw it! I'm getting Wilwood clutch MC.

[dongoesby]

Background story in case if you bother to read it:
http://zilvia.net/f/tech-talk/280761...ure-plate.html



Cliff notes:

• upgraded clutch with dual diaphragm pressure plate (harder pedal)
• slave cylinder pushrod not traveling far enough for clutch to disengage
• slap a 8mm socket on slave cylinder pushrod/piston = problem solve

After a month driving, the clutch pedal stiffness is unbearable. I basically drag myself to walk after an hour's driving. I got a new oem clutch master cylinder and an used nismo slave cylinder. After installation, no, the clutch won't disengage. The problem got worse than the old stock slave cylinder. I used the same old trick of a 8mm socket slap on that nismo slave cylinder, not much help, not disengaging.

Base on my trial and error, i know my old hydraulic system is fine, because they all worked for one month's driving without any leakage. The new clutch MC is working too because there is no freeplay on the clutch pedal. Also, I'm sure that the clutch pedal bracket is not bended. From here, i conclude that our nissan hydralic system is not strong enough to push heavy duty pressure plate.

Zilvia people who have heavy duty clutchs (stage 2 or stage 3, etc), please confirm with me on this. What master and slave are you guys using? Necessary for reinforced clutch pedal bracket?

I've researched that many Toyota people had to upgrade their slave pushrod because the stock one is not long enough to push the same length due to the extra pressure from heavy duty clutch. They have to buy this.

On that other hand, I also confrimed that a smaller MC (Stock) will shorten the slave cylinder travel when using with a bigger Salve (Nismo). This reason explains why I couldn't dissengage my clutch when using a nismo slave while I could when I was using a stock one.

To avoid the risk of exploding slave for using extended pushrod on the stock clutch MC, i'm going to try using a bigger MC (Wilwood). It is 3/4 vs 5/8 stock. I know it is not a huge different, but I want my car able to pop into gears without leg-breaking pedal stiffness. I know a bigger MC will require less leverage to push the slave piston more, but it will also make pedal harder to push. I need your opinion on this.

Am I really in a position that my clutch requires me to upgrade my hydraulic system? Is a bigger MC going to help me in my situation?

[slider2828]

I run RPSMax Street Face clutch which is pretty stiff I think. More than BMW M5 Clutch. Anyways, long story short, all the crappy clutch MC I have installed, PBM, Kragen, Samco, all suck.... I know a mechanic who got me a tokico, I have no idea from where and that so far is holding up. In general I dun have a problem...

What clutch are you using? Are you sure your clutch fork is not bent or installed right? How about your pivot ball joint, you check that for wear? I think you obviously would have removed the crappy slave box thing so you have a straigt SS line from the clutch master to the slave?

[slider2828]

ALSO!!! I don't like bleeding clutches the normal way, it never works. Reverse bleed it with a suction tube from the slave... Only way I would trust it.

[dongoesby]

Originally Posted by slider2828

What clutch are you using? Are you sure your clutch fork is not bent or installed right? How about your pivot ball joint, you check that for wear? I think you obviously would have removed the crappy slave box thing so you have a straigt SS line from the clutch master to the slave?

yes, i've done everything above. the whole problem is I managed to drive the car one month without any problem by using a gettho trick. Throughout the one month, if the clutch fork is bent, doesn't it would bent more? If there it is pivot ball, how come it doesn't make any noise and the shifting was normal throughout the time? yes, SS line from hardlines. and no leakage, the clutch MC was never lowered.

ALSO!!! I don't like bleeding clutches the normal way, it never works. Reverse bleed it with a suction tube from the slave... Only way I would trust it.

what do you mean by reverse bleed? I'm pretty sure that I got the air out since I don't see any freeplay on the pedal. When I was under the car, I ask my buddy to step on the clutch, and i see it doesn't travel out too far. The stock one with 12/16 would travel a bit further than the nismo 13/16 one but not noticebly.

The whole idea for me to ask in this thread is if getting a bigger clutch MC would help. IE a 3/4 Wilwood vs the 5/8 stock.

[godrifttoday]

before u go buy one get a new hard line could be clogged it happen to my friend he changes just about everything and it ended up being the hard line

[boske]

"Throughout the one month, if the clutch fork is bent, doesn't it would bent more?"

It could be bent, it wouldn't have to bend more than it is.

"If there it is pivot ball, how come it doesn't make any noise and the shifting was normal throughout the time?"

You wouldn't hear a worn pivot ball, it will just move the pivot point making it hard/impossible to disengage the clutch completely. You should read over your posts again before clicking the "Post" button.

[jspaeth]

I am running a ACT Heavy Duty PP on an S14 with an S13 blacktop SR.

Original master cylinder, damper loop delete, stainless steel from hardline to slave, NEW OEM slave.

Works fine, no problem.

As a matter of fact, there is NO preload on the MC (bc there is a TINY bit of play at the top).....and I only need to press the clutch pedal down about 1-2 inches for the clutch to disengage.

Working quite efficiently if you ask me.

[dongoesby]

Originally Posted by boske

"Throughout the one month, if the clutch fork is bent, doesn't it would bent more?"

It could be bent, it wouldn't have to bend more than it is.

"If there it is pivot ball, how come it doesn't make any noise and the shifting was normal throughout the time?"

You wouldn't hear a worn pivot ball, it will just move the pivot point making it hard/impossible to disengage the clutch completely. You should read over your posts again before clicking the "Post" button.

imagine a crack on a metal piece like a clutch fork, yes it would continuously bent as you put pressure onto it. the bigger the crack, the less it is able to hold pressure. If you ever to get push your fork with your bare hand, you know it is impossible because it requires 250+ lbs clampping force for the pp to hold the clutch.

most chance a pivot ball would just break its round head, and you will not get pivot movement at all. For there, my mistake, i should not hear any sound, but i should able to floor my clutch pedal with no pressure and it might not come back up at all.

[dongoesby]

Originally Posted by jspaeth

I am running a ACT Heavy Duty PP on an S14 with an S13 blacktop SR.

Original master cylinder, damper loop delete, stainless steel from hardline to slave, NEW OEM slave.

Works fine, no problem.

As a matter of fact, there is NO preload on the MC (bc there is a TINY bit of play at the top).....and I only need to press the clutch pedal down about 1-2 inches for the clutch to disengage.

Working quite efficiently if you ask me.

I can't say for sure here. I have similar setup. There are too many variables for them to go wrong. Prior this problem, the seller gave me a RB pressure plate. I can't say for sure that there are still wrong parts in my car although they were new.

For now, I just want to deal with what I can and what I have. I know I managed to make the system worked for one month with a little extra length on the hydraulic system. Hence, I'm trying to go with this route and at least get it running again.

before u go buy one get a new hard line could be clogged it happen to my friend he changes just about everything and it ended up being the hard line

The car is always kept in shape. The brake oil came out were really clear. But I will keep a note on that for myself. Thanks!

[jspaeth]

My friend is having a similar problem.

RB25 into and RB20 tranny....into a Datsun 260Z.

For months and months car was fine.

Then, all of a sudden, problems getting the car into gear....got worse and worse....to the point where he couldn't get it into gear at all.


We dropped the tranny, put in a new PP and clutch (ACT HD and 6-puck).

Still same problem.

I am not there with him, but he says the slave is moving a solid 1/2 to 1 inch, which should be enough I think.

We are completely dumbfounded....about to try the whole "slam it into gear" thing that has worked for a few other people in similar situations.

[dongoesby]

Originally Posted by jspaeth

My friend is having a similar problem.

RB25 into and RB20 tranny....into a Datsun 260Z.

For months and months car was fine.

Then, all of a sudden, problems getting the car into gear....got worse and worse....to the point where he couldn't get it into gear at all.


We dropped the tranny, put in a new PP and clutch (ACT HD and 6-puck).

Still same problem.

I am not there with him, but he says the slave is moving a solid 1/2 to 1 inch, which should be enough I think.

We are completely dumbfounded....about to try the whole "slam it into gear" thing that has worked for a few other people in similar situations.

I researched an article that it requires the slave to have a stroke of 15/16" minimum to disengage the clutch, so I don't think 1/2" would be enough.

From here, assuming the condition of the clutch system is good, I could narrow down couple possible remedies.
1. The hydraulic had leaks somewhere. Take this one out if the clutch MC remained full all the time.
2. The pedal bracket is bent somewhere.
3. The TOB is bad (making noise) or using a wrong TOB sleeve bearing. (I broke my TOB sleeve bearing before when I remove my TOB, and I recieved a different sleeve bearing from ray @ thenismoshop claiming should work the same. It looks a bit different, but there is a chance that the TOB is pushed too much into the sleeve bearing and shorten the overall length... possible?)

the distance between the clutch and pp when disenaged is only ~10mm, so I think even minor changes could be enough to cause problems in disenagement.

When you guys dropped the tranny, did you notice if the flywheel was wrapped with the clutch disc? Did you check the TOB, the sleeve bearing, the pivot ball and the fork?

[jspaeth]

The hydraulics appear fine....it looks like the slave is extending plenty far.

Could either need to be "slammed into gear" like some people have done.


Could need longer TOB sleeve (thing the fork pushes on).

It WAS working previously, so who knows....maybe it was BARELY working (barely disengaging) and clutch wear and air in the lines made it worse to the point where it wouldn't disengage.

I dunno, we'll figure it out.

[Def]

A SMALLER dia. master cylinder or a BIGGER dia. slave cylinder will give you a lighter pedal feel at the expense of slave travel.

[dongoesby]

Update: so I just came back from playing with it again. I swapped back the stock slave cylinder, and the situation got better, I managed to drive the car, but shifting is terrible. I can feel the clutch is barely lifted, and at 1st gear with clutch depressed, the rpm dropped and the car violently wants to go forward. scary!!

It is only a few mm difference!

I got everything figured out now. Simple physic, more pressure means more compression. A lot of you might have ACT heavy duty clutch, i'm not sure how heavy is your clutch, but I think it is not heavy enough to change the hydraulic compression rate too much. ACT designed the product to work with stock hydraulic system. Indeed, the stock hydraulic system was designed to push the stock pressure plate. When the pressure from pressure plate increases, it also increases the hydraultic compression, and when compression increases to a certain level, your hydraulic could no longer push far enough to push the pressure plate to disengage the clutch. In a way, it also putting a risk on blowing up your slave.

Base on this simple physic, I believe it is necessary for me to get a bigger master (more fluid for higher compression = more slave travel). Since my clutch was originally intended for AE86 local shop and now customized for silvias, i don't believe it was designed to work with our stock hydaulic system.

One question here, I know bigger slave requires less effort to step on the clutch, but what if a larger master? would it increases or decreases the effort to step on the clutch?

[Def]

You are GREATLY mistaken. Brake fluid is incompressible(like all fluids, for all intents and purposes).

You need more slave travel, which a bigger MC will give you at the expense of more pedal pressure.

It does sound like you just need to adjust your clutch pedal to MC rod. Look in the FSM.

[dongoesby]

Originally Posted by Def

You are GREATLY mistaken. Brake fluid is incompressible(like all fluids, for all intents and purposes).

You need more slave travel, which a bigger MC will give you at the expense of more pedal pressure.

It does sound like you just need to adjust your clutch pedal to MC rod. Look in the FSM.

thank you so much for pointing it out. A quick search on howstuffworks confirms me on that!

I came so far even on these wild thoughts is because I've tried almost everything. I've done many researches even on different cars and already adjusted that M/C push rod to almost out of thread. I've bleed the system many many times. Tried peek inside the tranny and everything look right.

Forgot to mention that my slave only got 3/4" travel. I believe it requires a minimum of 15/16" to full disengage the clutch. So i believe there is something wrong mechanically with my hydraulic system.... jezz

[clark]

just want to say i have an exedy stage 2 with an autozone slave and the original master cylinder from a silvia front clip. never had a problem with my hydraulic system. all hard line going straight to slave, no damper.

[ges311]

With my stock clutch, no damper box and new hydraulics, the clutch is disengaging in the first 1/4" of slave travel. Do you still have the damper box installed? Maybe the pivot is broken?

[slider2828]

There is something wrong.... we all know that... If you tried to get a new clutch and a new slave... and it doesn't work, I would try another set. Otherwise its a problem with the pressure plate. This isn't rocket science and since you said you already tried everything, time to drop the tranny.

I assume you know how the pressure plates work, so it s pressure plate problem. Done deal... Pretty much everyone runs a stock CMC and stock slave and it works.

[dongoesby]

I know bigger slave cylinder will make the pedal softer, but what about master? Would a bigger master like 12/16" make the pedal softer?

Just want to know.

[dongoesby]

A new nismo slave arrived today. Installed it immediately and measured the piston only travel ~10/16" out (that is like only 2.5/4"). This confirms that there is nothing wrong with past two slave I used, because I get almost 3/4" from a stock slave. (I double checked on that 3/4" today) I got this match the theory, bigger slave extend less than smaller slave. Hence, my 11 years old stock slave works!

I'm ordering a s13 11/16" slave tomorrow and see if it would extend a little more thn 3/4" because a few mm is all i need to disengage the clutch!!

[SoguRacing]

no. you'll just have less pedal travel to accomplish clutch disengagement.

[dongoesby]

Originally Posted by slider2828

There is something wrong.... we all know that... If you tried to get a new clutch and a new slave... and it doesn't work, I would try another set. Otherwise its a problem with the pressure plate. This isn't rocket science and since you said you already tried everything, time to drop the tranny.

I assume you know how the pressure plates work, so it s pressure plate problem. Done deal... Pretty much everyone runs a stock CMC and stock slave and it works.

I found that there is different opinion on the slave travel, which it actually travels as much as 1 1/2" inch.

YouTube - SR20DET Slave cylinder
http://zilvia.net/f/tech-talk/174878...edal-down.html

[jspaeth]

Originally Posted by dongoesby

A new nismo slave arrived today. Installed it immediately and measured the piston only travel ~10/16" out (that is like only 2.5/4"). This confirms that there is nothing wrong with past two slave I used, because I get almost 3/4" from a stock slave. (I double checked on that 3/4" today) I got this match the theory, bigger slave extend less than smaller slave. Hence, my 11 years old stock slave works!

I'm ordering a s13 11/16" slave tomorrow and see if it would extend a little more thn 3/4" because a few mm is all i need to disengage the clutch!!

You should really start listening to people in this thread, bc you have no clue what you are doing.

There is no reason to go buying 7 different slave cylinders.

If your slave is moving 3/4", that should be more than enough.

There is something wrong with how the motion of the slave is getting converted to the TOB physically pushing on the pressure plate.

Like said above, almost everyone uses stock CMC and stock slaves with no problems whatsoever.

[dongoesby]

Originally Posted by SoguRacing

no. you'll just have less pedal travel to accomplish clutch disengagement.

Base on what makes you say this? It has been proven that smaller slave yeild to longer stroke. I don't see what makes you so helpful and insightful to use the setence to answer my other thread which asking for complete different thing.

You should really start listening to people in this thread, bc you have no clue what you are doing.

There is no reason to go buying 7 different slave cylinders.

If your slave is moving 3/4", that should be more than enough.

Yes, i agree with most of you here.Hence, I'm not going for bigger M/C here. However, with the video i seen, other people's measurement and my own experience, I have a reason to believe 3/4" is not the right length for slave travel. Therefore, I'm going to try a smaller slave cylinder. If you read everything above, smaller slave would give more travel but stiffer pedal.

I will see what happens tonight. I know I just need a few more mm to disengage the clutch smoothly and completely. If this does not work, i will drop the tranny.

[dongoesby]

Swapped 89' s13 11/16" slave cylinder, gained ~5mm travel. the car shifts like butter now.

[jspaeth]

Originally Posted by dongoesby

Swapped 89' s13 11/16" slave cylinder, gained ~5mm travel. the car shifts like butter now.

excellent news, well done!

a lot of people have had working clutches with less slave travel, but if that's what it took, then congrats man.

[s13gebala]

i run a stage 4 on stock master and slave.

slave went out after dirt got into it somehow.

master leaked a little over time inside to my interior.

everything works. used for maybe 3k

[FaLKoN240]

I just read this whole thread, and I now have a headache.

[jspaeth]

hahahahahaha