DIY - Swap clutch slave cylinder and hydraulic line for improved feel and control

[Guillaume]

Originally Posted by Ultramaroon

It will immediately be intuitive and you will say to yourself "Ah, I really CAN drive a stick properly!" Then you will quickly take it for granted until you drive someone else's 86.

A thousand times this.

[Joyride86]

@Ultramaroon wish you would just come over and do this for me. I'm too chicken to mess it up.

I've lowered the clutch pedal and pulled the spring, but still lacking the feel that I'm looking for. Feels like an on off switch which makes it tough to be consistently smooth.

[chaoskaze]

^ can't agree more, this looks really promising but I'm just a chicken... Haha I got use to only pushing like 30% of the total clutch travel... Don't know why they design it like this... I guess it's good that I don't really have to extend my leg like at all?? >_>


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[Ultramaroon]

Originally Posted by Joyride86

@Ultramaroon wish you would just come over and do this for me. I'm too chicken to mess it up.

I've lowered the clutch pedal and pulled the spring, but still lacking the feel that I'm looking for. Feels like an on off switch which makes it tough to be consistently smooth.

I wish I could too. Honestly though, if you can bleed your brakes you can do this. It's ridiculously easy in the grand scheme of things and, for an amateur, would be a great confidence building exercise.

The worst issue would be to run your reservoir dry but you would literally have to leave the hydraulic line hanging down while you go and take a coffee break. It oozes out that slowly.

Have you read the remove-your-spring thread lately? I was called out so I made one last speech and called it good. Don't want to alienate anybody.

[Joyride86]

Originally Posted by Ultramaroon

I wish I could too. Honestly though, if you can bleed your brakes you can do this. It's ridiculously easy in the grand scheme of ujijuujuuujuuujujujujuuuthings and, for an amateur, would be a great confidence building exercise.

The worst issue would be to run your reservoir dry but you would literally have to leave the hydraulic line hanging down while you go and take a coffee break. It oozes out that slowly.

Have you read the remove-your-spring thread lately? I was called out so I made one last speech and called it good. Don't want to alienate anybody.

Yeah, I just read it. I do think that there is a little bit more feel with the spring removed, but it doesn't solve the vagueness issue. You have stated that many times and I wholeheartedly agree. Sometimes people don't want to listen or don't agree. Don't worry about it man. Difference of opinion is what makes us human (this is good and bad).

I do mostly city driving with the FR-S so clutch feel is important to me. Just today I over revved because I thought I hit the engagement point. Guess not lol. Other times I don't have any issue. I just want to be smooth consistently and your solution makes sense. Others guys that have done this confirmed it also. I'll give it a shot when spring comes around.

[Ultramaroon]

Originally Posted by Joyride86

I do mostly city driving with the FR-S so clutch feel is important to me. Just today I over revved because I thought I hit the engagement point. Guess not lol.

That's precisely what drove me to this. I had zero confidence shifting this thing. Either I stalled or smoked the clutch. If you go back and look at all the "crappy throttle" or "I keep stalling" threads, people are searching because, for all the experience in the world, they just can't seem to get the swing of this one.

The root of the problem is that damn novocaine clutch.

[Tt3Sheppard]

Originally Posted by Ultramaroon

1. I don't like the idea of adjusting the clutch by comparing it to a non-related reference but in this case, it seems to work out ok.

2. That's a little disturbing. There might be a manufacturing defect in the new slave cyl. Now that you know how easy the swap actually is, I suggest going back to stock and compare. Remember, the whole purpose of this swap is to gain feedback from the clutch at the expense of pedal force.

On the subject of verifying clutch adjustment, here is yet another way to get comfortable with the tough/grab point.

Find a nice flat place where you can creep along at a casual walking pace, say 2 mph.

1. Get going in first and disengage the clutch.
2. Adjust your speed to coast at 2-3 mph.
3. Without giving any gas, slowly raise the clutch pedal.

You will feel the characteristic clunk of the driveline backlash when you reach the touch point.

What is happening here?

With the transmission in gear, the wheels are spinning the clutch disk.

The engine is idling a little faster than the clutch disk.

When the clutch begins to grab, it accelerates the clutch disk and all that transmission and differential backlash is taken up in the clunk.

You can tickle the clutch at that spot and get a feel for the exact touch point. Is it high enough that you know you can comfortably disengage the clutch for each shift? That's basically what you need to decide for yourself. Mine's maybe 1.5 inches off of the floor. I have long legs and I always mash it to the hardstop when I shift.

Any time you mess with the adjustment, always always always verify this.

I tried using the 1st gear method like you described and the car does the typical lurch forward when releasing clutch at that low speed. I think my only concern is disengagement when shifting fast since with the added force of the new slave I might not be pushing it as far/fast as I did with the original slave. I think I'm close to an inch 1/2 of travel before car starts to move.

Will keep testing, cold weather already making it hard to shift so hard to tell if due to clutch adjustment or just weather.

[Ultramaroon]

Originally Posted by Tt3Sheppard

I tried using the 1st gear method like you described and the car does the typical lurch forward when releasing clutch at that low speed. I think my only concern is disengagement when shifting fast since with the added force of the new slave I might not be pushing it as far/fast as I did with the original slave. I think I'm close to an inch 1/2 of travel before car starts to move.

Will keep testing, cold weather already making it hard to shift so hard to tell if due to clutch adjustment or just weather.

Doesn't hurt to raise the pedal a bit for confidence.

All bets are off when the trans is cold. Still, it's a good opportunity to work on rhythm. When upshifting, get through neutral as quickly as possible (no pause) and immediately apply gentle pressure to the target synchro. If you're quick enough, it will sink into gear like butter. If you miss the opportunity, double-clutch and try again. You'll soon realize force is never required.

[Tt3Sheppard]

Originally Posted by Ultramaroon

Any time you mess with the adjustment, always always always verify this.

Was checking this out today and noticed that at full rest it appears to be touching those clips which is a good sign. Curious, when you touch the pedal with your fingers does this move at all for you? Or is there some free play before this cylinder starts to move?

[Ultramaroon]

Sorry not clear on what "this" is but I'll do my best. We'll get there after some back and forth.

First thing we need to establish is whether or not you still have the assist spring installed. I only reviewed this page and I don't see it mentioned. If it is still installed and your cruise switch allows it, there will be some slop before push-rod begins to move. Is this the case? Let's discuss.

Also regarding the clunk and notchiness, I'm concerned that the throwout bearing might be hanging up on the snout. I've felt this on @Chen's car and made the connection after delving into this thread.

edit: aaand I just realized you've posted to the same thread.

[Tt3Sheppard]

Originally Posted by Ultramaroon

Sorry not clear on what "this" is but I'll do my best. We'll get there after some back and forth.

First thing we need to establish is whether or not you still have the assist spring installed. I only reviewed this page and I don't see it mentioned. If it is still installed and your cruise switch allows it, there will be some slop before push-rod begins to move. Is this the case? Let's discuss.

Also regarding the clunk and notchiness, I'm concerned that the throwout bearing might be hanging up on the snout. I've felt this on @Chen's car and made the connection after delving into this thread.

edit: aaand I just realized you've posted to the same thread.

Should have elaborated. The spring has been removed. The link you posted mentioned the push rod and cylinder being up against a clip. With the new slave, spring removed, and pedal adjusted when I slightly touch the pedal this rod will begin to move. (http://www.ft86club.com/forums/showp...&postcount=636)

This actually might answer my question. http://www.ft86club.com/forums/showp...&postcount=640

In regards to the TOB I believe mine is on it's last legs. When the car is off I push the clutch pedal in 100% and move it between 90-100% I can hear and feel a crunch/squeak. Weather has been in the 35-40F range so maybe related.

I've posted in a few other threads as well seems small group of people with similar issues.

[Ultramaroon]

In this context, the slop you feel is not actually slop. With the master plunger fully retracted, they hydraulic system is open to the reservoir. You can prove this to yourself by pulling the end of the clutch fork forward to depress the slave plunger. Where does the excess fluid go? Back into the reservoir. The master plunger closes that port/valve in the very first bit of travel as it is depressed.

This is the key to self-adjustment. As the clutch wears, the pressure plate gradually moves closer to the flywheel. The clutch fingers move in the opposite direction, lifting the TOB away from the flywheel, which results in a tiny bit of that motion you just verified by compressing the plunger.

If the master plunger is not allowed to fully retract, the system can't adjust itself because the hydraulic fluid has nowhere to go. Force on the TOB is never relieved and, in the worst case, the clutch itself eventually begins to slip.

[jcw99]

I was just reviewing that stuff in one of my textbooks about the role of the check valve in the clutch master cylinder and your explanation is better than the book's. I've been looking for my binder with my notes from manual transmission and driveline class for the last week and still haven't run across it.

[Tt3Sheppard]

Very informative. I did notice fluid going into the reservoir when I pulled the clutch fork forward.