Upgraded Clutch Squeak

[wheelhaus]

I used a few feet of fuel tubing from the local hobby shop, cut to desired length. Its stretchy silicone hose that fits snug on the bleed fittings. Plus you can get it in wacky colors lol

[Ultramaroon]

Originally Posted by Rybot

Alright. After not enough sleep, let's get back into this.



Ok. Glad I get to be a guinea pig for @Ultramaroon's knowledge base. I also find this very interesting from a mechanical standpoint.

That being said, how, or WHAT, is happening under there that's causing the engagement point to change through the pedal?

Mechanically speaking we've got the flywheel>clutch disk>pressure plate>TOB>fork all connected via input shaft. High rpms in gear, the entire assembly is spinning at that rpm. The only separate assembly is the fork and TOB. The only thing that would change the catch position is the displacement of the TOB to the pressure plate, so somewhere along the lines they are getting separated at higher rpm, possibly. I don't know...

Oh boy, not enough coffee yet.

Is high rpm vibration causing the retaining spring behind the fork to not push the TOB against the pressure plate tines?

As to your points:
1) With the engine off, I think the problem won't exist as at idle, the catch location is where it should be. I'll try it though.

Right, but if you have a friend squeeze back the fork a little, you can then press down the pedal to prove to yourself that it feels the same. I guess there's not much point to this. I'm already convinced as I believe you are, that it's what I'm calling kickback.

3) I'll definitely need to try revving it since your links say it should be reproduce-able given neutral revs.

I googled for something like "clutch pedal high rpm" and got a ton of relevant returns so, like @humfrz said, it's fairly common but no one seems to really get it. Crazy.

I don't believe it's pressure plate torque but it might be that some foreign object was lodged between the pressure plate and flywheel when you torqued it. It may also be some sort of manufacturing defect. It seems like you would feel that in the pedal. That's what makes no sense to me.

Unfortunately, it boils down to getting in there an carefully removing the pressure plate again.

Look for any signs of failure including, fasteners, contamination, pressure plate itself, installation misalignment...

Then when you don't find anything wrong, install a known good (not hopefully good) pressure plate and test.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Let us know if you get any air out of the system. I'm very skeptical about this.

[Rybot]

Originally Posted by Ultramaroon

Right, but if you have a friend squeeze back the fork a little, you can then press down the pedal to prove to yourself that it feels the same. I guess there's not much point to this. I'm already convinced as I believe you are, that it's what I'm calling kickback.


I googled for something like "clutch pedal high rpm" and got a ton of relevant returns so, like @humfrz said, it's fairly common but no one seems to really get it. Crazy.

I don't believe it's pressure plate torque but it might be that some foreign object was lodged between the pressure plate and flywheel when you torqued it. It may also be some sort of manufacturing defect. It seems like you would feel that in the pedal. That's what makes no sense to me.

Unfortunately, it boils down to getting in there an carefully removing the pressure plate again.

Look for any signs of failure including, fasteners, contamination, pressure plate itself, installation misalignment...

Then when you don't find anything wrong, install a known good (not hopefully good) pressure plate and test.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Let us know if you get any air out of the system. I'm very skeptical about this.

I'll admit I didn't inspect the PP fully when I had the transmission out, but I don't recall missing any fasteners. Looking at one of the pictures I took, there aren't any missing, though if one did back out, I doubt things would be going so smoothly right now anyway.

Why would any of this be RPM dependent though. If it were something stuck or contamination, the effect would be there at idle, but just compound itself higher in the rev range, I think.

It's not a bad clutch system, ACT SB7-XTSS, so I'd think it would be a known good system.

I won't get fluid until Wednesday, so bleeding will have to wait until then.

[wheelhaus]

Not to throw a wrench into it, but not all clutches are manufactured as precisely as we would hope. Several years ago a friend had a brand new Spec clutch that had a PP machined WAAAY too far, like, 1/4" was removed. On visual inspection it looked fine, but there was virtually zero pressure after break in and it slipped after a couple hundred miles. Just saying, sometimes BS gets past QA.

Anyways, I would also recommend checking the slave/fork at 5k in neutral, maybe wear earplugs because noisy engine is noisy. Just see what's happening there. If the fork is getting limp, then that likely means something in the clutch assembly is moving. If the slave cylinder gets limp, then the problem is hydraulic.

I can't wrap my head around the relationship to RPM unless the vibrations are causing a crack/seal to lose pressure. Also check the hudraulic fittings to make sure they're all nice and tight.

[humfrz]

Originally Posted by Rybot

What size tubing should I grab? 3/8ths? Also, so I can kill two birds with one stone, does that size also happen to work with the brake calipers?



Perfect. Thanks. Once I get some new fluid, I'll get to work on that. Nothing that 10 minutes can't solve, right?

I'd get two lengths ...... one of 1/4" and the other of 3/8".

Why two .....??

Because, I found out a long time ago that if I just get one ...... the correct size will be the other one ......

Maybe the nipple on the brakes will be the same ...... but don't bet on it .....


humfrz

[wheelhaus]

I know the clutch slave bleeder is smaller... 7 or 8mm IIRC...

[Ultramaroon]

Originally Posted by Rybot

It's not a bad clutch system, ACT SB7-XTSS, so I'd think it would be a known good system.

Nope nope nope... I am advising you against exactly that kind of thinking.

*virtual dope slap*

The only known good system is the one you knew was working before this swap. If you tossed it then you have 2 choices:

1. Hope you find an obvious cause upon inspecting your upgrade plate.
2. Roll the dice on a new OEM one or find a friend who didn't toss his.

This is why old wrenchers (pointing at myself) end up with a garage full of used shit. I need to throw out parts to cars I no longer own.

[Ultramaroon]

Originally Posted by wheelhaus

I can't wrap my head around the relationship to RPM unless the vibrations are causing a crack/seal to lose pressure. Also check the hudraulic fittings to make sure they're all nice and tight.

I intentionally haven't mentioned one thing on purpose. I have no firsthand experience so I'm completely spitballing here.


Crankwalk

[Rybot]

Originally Posted by Ultramaroon

Nope nope nope... I am advising you against exactly that kind of thinking.

*virtual dope slap*

The only known good system is the one you knew was working before this swap. If you tossed it then you have 2 choices:

1. Hope you find an obvious cause upon inspecting your upgrade plate.
2. Roll the dice on a new OEM one or find a friend who didn't toss his.

This is why old wrenchers (pointing at myself) end up with a garage full of used shit. I need to throw out parts to cars I no longer own.

I see what you mean now. I shall change my mindset, sensei.

Here's my list of shit to do:
1) Adjust pedal position to see if problem persists to the floor like it currently is. I want to know if the "limp" space is constant, or if it scales based on pedal catch location at idle. If it's constant and I move the catch position to half pedal throw at idle, then at 5K+ I basically won't be able to disengage the clutch at all. If it scales it back and always allows me to shift at the floor at redline, then idk what that means.

2) Bleed/flush the system. I'm just gonna fill it with DOT4 since I was going to do that anyway.

3) Wait on ACT's engineers who now know of the problem since I called them today (I hope they Google around and see the threads you linked or even this one now) to see if they can think up a solution that we haven't already dreamed up.

Originally Posted by Ultramaroon

I intentionally haven't mentioned one thing on purpose. I have no firsthand experience so I'm completely spitballing here.


Crankwalk

4) Pray to the car gods my car isn't walkin' the crank.

BTW, 1/4" fuel line is somewhat loose over the bleeder nipple. It fits, just not snug. 3/8" would have eaten the valve for dinner.

[humfrz]

Originally Posted by Ultramaroon

Nope nope nope... I am advising you against exactly that kind of thinking.

*virtual dope slap*

The only known good system is the one you knew was working before this swap. If you tossed it then you have 2 choices:

1. Hope you find an obvious cause upon inspecting your upgrade plate.
2. Roll the dice on a new OEM one or find a friend who didn't toss his.

This is why old wrenchers (pointing at myself) end up with a garage full of used shit. I need to throw out parts to cars I no longer own.

Brings to mind the time my F-250 stopped (like it was out of gas) about a 1/2 mile from a Ford dealership. I determined it was a failed fuel pump ..... because no gas was getting up to the carburetor.

It was a hot humid day in Missouri, but smelling of gas, carrying my old fuel pump, I walked to the dealership and purchased a genuine Ford remanufactured fuel pump. After lots of sweating and cussing, I replaced the fuel pump.

The damn truck still wouldn't run (no gas to the carb, but gas would run out of the fuel line from the tank (nope it wasn't vapor locked - I checked that).

Totally pissed I walked back to the dealership, tossed their bad fuel pump at them and told them I wanted one that worked ......

They "gave" me another one, which I put on, and the truck ran fine.

Oh, btw, I think I still have spare carburetor for a 1948 Chevrolet in my garage, if anyone needs one .....


humfrz

[Ultramaroon]

Originally Posted by Rybot

Pray to the car gods my car isn't walkin' the crank.

Haven't heard a peep about it since the engine went into production so, especially with all the big shot engine building going on, I seriously doubt it.

[Ultramaroon]

Originally Posted by humfrz

Right?

Just because it's wrapped in a nice clean box doesn't mean it's any good. Shit happens.

[Rybot]

I'll update you lot once I complete, or forget to complete, my list of shit to try.

[Ultramaroon]

Originally Posted by Rybot

I'll update you lot once I complete, or forget to complete, my list of shit to try.

Measure axial play to rule out the worst.

[ame="https://www.youtube.com/watch?v=_QACv117Sug"]Crankwalk - YouTube[/ame]