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Discussion Starter #1 (Edited)
Yes. In half. Slave: In half. Master: In half. A Stock LS2 pressure plate: probably NOT cut in half, but maybe.

I have some fabrication to do still, but the plan here is to mock up the clutch system in an environment where I can get some pics and vids to show folks what is going on in an area we cannot see, because we dont have transparent bellhousings.

I strongly considered putting a motor to the flywheel. Part of this will be 'bugging' the system to show flaws. A spinning flywheel would show some of these better, but I think you will all get the point. Frankly, its a lot of mass to fling around with out a bellhousing to protect me. A static display will do just fine.

So lets start with the basics. The pedal. From the center of the pivot to the top of the pedal pad is 12". From the top of the pedal pad to the master pivot is 9.5". The pivot is 5.375" from the firewall, and My car with an LS7 and factory Hydraulic bits uses 1.25" of stroke.

Master (of Puppets?)

I submit, one stock master.

I submit one stock master, gutted. Note the lack of an internal return spring. That is a feature normally reserved for Brake Masters, though some OE clutch masters, and the Tilton units used in the GM after market both have them. Brake systems need them because there is no return spring in a disc system except for the Piston-to-bore seal in the caliper. The pedal wouldnt come back up with out it.

It is (basically) a .750" (3/4" for you fractional folks) bore.

The piston is 2.510" long. The bore is 3.9" long. Minus our 1.25" stroke, this leaves us a head space of ~.180", which is just enough to not block the outlet. this will be further documented when I cut the unit in half later.

There is a valve on the end.




There is a cap over the valve, which is just a little rubber diaphragm, and the back side has a copper cap for support. There is a hole in the piston. the purpose of this valve, and the hole it covers, is to re-fill the fluid in use. As the piston comes back, the valve opens, and fluid goes thru, but only if the back side pressure is higher. So even if your slave leaks, you can still draw new fluid from the reservoir. The lip seals on the side of the piston face forward for the same reason.

I put a nail in the hole into the bore from the reservoir connection. Do note that this hole faces the rear.

A 3/16 brake line, bubble flared, fits the outlet quite nicely.

Overall, I see no no faults in this part. If I can generate enough force, I plan to test it to failure pressure. The failure will occur at the Lip seals, unless I bend the pushrod.

Over the next week or so, I will post more, culminating in the Bi-Section of the slave and master. Because im a sick bastard like that.

The Piston does have markings: 'FTE' which could mean 'Ford Tickford Experience' and 'KG 19466 A'
 

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Discussion Starter #2 (Edited)
Lets Talk aboot the Clutch a little

These pics are of my stock LS2 clutch. I replaced it with an LS7 unit at about 1800 miles. You know, back when doing this was a new idea and all, before it was cool. the stock unit was not fond of the giggle juice, at all, and would slip at higher rpms.

before I get to the pics, I want to note some numbers. PP to FW clearance is .137". The remains of my disc measure .318" thick. Thats a solid .180" of 'preload' on the PP. Once we get some force numbers later in the experiment, we should be able to calculate holding force.

This assembly as a whole is pretty much junk:

How bout some hot spots? junk

PP isnt any better.

Disc is heavily glazed and just generally smurfed.


Invisible PP, visible Ape hand. This is how the disc sits against the FW


Invisible disc, worn very thin.


See the shiny? That is all the more contact area the bearing has with the PP fingers. not a whole smurfing lot.


PP half-ass mounted to FW, no disc. Needs more and better bolts.

The important things to note here:
The PP is strong. I stood on it, couldnt actuate.
The PP is the main "return spring" for this system.
The springs in the disc act as a shock absorber.

The PP is relaxed an unloaded at this point. I dont even have the disc centered at the point this was shot. Its on the pins, and the bolts are loose. Everything is even.
I torqued the PP down about half way on 3 bolts to make it look like that. That distortion WILL translate thru, but its hard to pick up on video apparently.
Clutch is now fully torqued down. Everything is even.



Next, we will discuss the slave. probably saturday. Ive got a show tomorrow night.
 

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Discussion Starter #3 (Edited)
A slave (in every sense of the word)

One can think of the Slave assy as a kid working a coal mine in 1899. It works in a hot dusty environment, and looks to be too small to possibly do the job it does.

The loads on this thing are pretty amazing. We ask "Why are our slaves such SHIT!", when the reality seems to be "How the smurf do these things last as long as they do!". But thats just a teaser for what is coming. Lets put it this way, Every test I run, I find another weak spot in my apparatus. I've had to add a few braces to a setup I thought was over built to begin with.


This is one BRAND NEW F-body slave, courtesy of Steve at SNL. I have adapted the plumbing to suit my needs. Its got a Throw out bearing as part of it, and spring that the TOB rides on. Pretty basic.


The Inner surface is 1.430" in diameter. The hole is for the Trans input shaft



The outer diameter of the thing is 2.250", and the wall thickness seems to be at least .115".

The Hydraulic piston is an annulus, like a doughnut. So to calculate its area, we subtract the little circle from the larger outer circle. Using that .115" figure for the wall thickness, and 3.1415 for Pi, we get a slave piston area of 1.598 sq inches.

I will confirm that when I cut it up. Which I know is all you guys really want to see.

EDIT: Ive cut the slave up, and the area is 1.205sqin.
 

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Discussion Starter #4 (Edited)
Lets talk about some Hydraulic theory.

on the surface, Hydraulic systems are very simple. Garbage in, garbage out. And that is exactly what we have here.

Most systems move a fixed volume, and use the nature of a sealed hydraulic system to alter the forces, and either give a reduction or multiplication of said force. But there is a trade off. Just as gears trade RPM for Torque, hydraulics trade travel for volume.

Pascal says that in a sealed system all pressures at all points are equal. And this is the basis we are working from.

We will pick a random pressure to work from, a nice round 100 PSI.

We know the slave piston has an area of 1.205 sqin, and the master piston an area of .441sqin.

So that 100psi of fluid pressure in the system puts:
44.1 lbs of force on the master
102.5lbs of force on the slave.

In other words, if you want to move 120.5lbs with the slave, you need to exert 44.1lbs at the master, an effective ratio of 2.73:1

A 205 lb load on the slave will generate 200 PSI of fluid pressure, and Master pressure of 88.2LB.

However, there is a trade off. Its a sealed system, so we can only move a fixed amount of fluid. If we move the Master 1", we move .441 cubic inches of fluid to the slave. The slave gets .441cuin, but only moves .275". the 3.62:1 relationship holds thru on BOTH sides.

This means that for our stock master stroke of 1.25", we move .551cu in of fluid to the slave, and the slave moves .3125".

Since the PP is a 'static' load, the slave always needs at least .3125" of movement to do its job. Pressure is also relatively static, but it can vary higher at higher rpms if the pressure plate has wedges that increase holding power when actuated by centrifugal forces. If youve ever seen a Centerforce brand clutch, youve seen these weights on the fingers of the PP.

Whats this all mean? You have to move the same amount of fluid. the base pressure is the same. If you go to a bigger bore master, you will have a harder pedal, with a shorter travel. If you want a softer pedal, you have to go to a smaller master bore, with a longer stroke.

Guess what? There are no aftermarket masters available with a longer stroke. So you cant have a softer pedal. Sorry.

I take that back. There is a way to a softer pedal, but you have to move the take off point on the pedal. The current pedal set up has an advantage of 3.8:1. A 10lb foot on the pedal gets you 38lb on the master. move the take off further away from the pedal, bigger ratio, more advantage, lighter pedal. but you cant move it much, or you lose the nice straight pushrod travel that keeps the side loads off the master piston.
 

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Discussion Starter #5 (Edited)
The Eagle has Landed.

First off, this shit generates crazy force. Bracing this and keeping it stable proved FAR harder than I expected.

Interesting Side note, an old 13/16" Craftsman sparkplug socket is the perfect size for the Disc splines to ride on. So thats what it is riding on to keep it centered.

Also, my assistant/camera man had a family emergency tonight, so I had to play JJ "Shaky Cam" Abrams. Sorry for that.


I had wanted to make the slave mount "slide" for quick and easy adjustment. but I could not get the damn thing to hold well. So I had to resort to a system of shims that are somewhat easily removed. Pain in my ass. But that is the basics of measuring for slave shim/no shim. We will get back to that tomorrow, when I set things 'wrong' to show how FUBAR things can get in a hurry.
1mm= .0393" But that is total clearance, so really we have 19 thousanths of an inch on either side of the disc. Thats not much. Sure, its the largest clearance in the entire powertrain, but its still not much. It is enough to allow for full release every time, at any speed, assuming everything is square and true.

SO lets talk about those assumptions a little.
Did you get pry bar crazy getting the bellhousing off the engine?
Did you then check to make sure you didnt gouge either surface?
Was the bellhousing a pain going back on?
Did you get tired of pissing with it and take the impact to it, using the bolts to pull it in?
Did you take the time to make sure everything was flat with a straightedge?
Did you use a power tool on any part of the clutch, or did you slowly take everything down evenly.

Think about some of that, and how we relate similar things to other common problems like wheel shake, and improperly torqued wheels. Same score isnt it?

Starting to build a picture of how its possible to tear up clutches easily, and have engagement problems on a regular basis, especially at higher speeds?

I hope so, because that is the point of all this.

Im going to start shooting bug videos tomorrow night. Dealing mainly with slave spacing, and things being even. Id love some suggestions, especially from the Sponsors on issues that have been seen, that I might be able to replicate with this setup. Then, I cut shit up.
 

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Discussion Starter #6 (Edited)

Fluid Pressure EXCEEDED my 300psi gauge for apply. 280psi just to hold. @1.205 sqin of slave piston, that means we need 331.37lbs to HOLD the clutch in. If the apply effort goes to 400 like I suspect, thats 482 lbs.

Folks thats nuts. I did not really expect that.

So lets look at some other numbers:
275psi @ master= 121.275lbs. Weve got that 3.8:1 advantage of the pedal, giving us a pedal effort of 32lbs.

Hydraulics and a lever let us turn 32 lbs into 439. This is why man rules this rock.

Ill let you do the math for the peak forces.


moved it 1/8 back, 1/16 out of spec, went from .039 clearance to .022" clearance (total clearances, divide by 2 to see room allowed on both sides of disc), and the clutch no longer spins freely. This is why you cant shift like a boss.

End of story. Thats why you cant shift.

I need to clean up some force numbers now that I have an accurate figure for the piston area, but here are 2 more videos showing the throw of the slave. Its the same in both set ups.


And here is one showing why I had to put threaded rod thru the middle:
 

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Discussion Starter #7 (Edited)
hey guys: what is the difference between me and a mallard with a cold?




I put a nail in the outlet to make sure it was visible. Note that the Inlet from the reservoir is never exposed to the front side of the forward seal. Note I also got better pics of the seals. Thanks Swmn for the photog tips! The head space is about what we expected, but a little to the high side.



Initially, I was ready to call the slave crap because of the plastic. And its crap, but the plastic was a decent choice, as it is a pretty good heat insulator. Going to metal would just make things hotter, and lead to earlier failures. That seal should have a steel core though. It would greatly limit its compression, which is a factor in all this. Its really pretty soft. and there should be more seals on that inner surface of the plastic to help sort the dust out.

 

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Hi, im here for the gangbang.
 

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Love it, question so it looks like a simple plunger to move fluid.

What makes the Triton a better unit? Seals, tolerance??

Slave will be interesting once you get there.
 

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Discussion Starter #12
If you need more spots in-a-row, let me know.
i think I'll be good, so long as I continue to host pics off site.

Love it, question so it looks like a simple plunger to move fluid.

What makes the Triton a better unit? Seals, tolerance??

Slave will be interesting once you get there.
http://www.tiltonracing.com/ins/98-1235.pdf

There are the Tilton guts. They are designed as Brake masters. The outlet is forward, the piston is metal, and it has a return spring. The 76-series I have my eye on accepts a -4AN input from the reservoir.

Sorting out what bore size I want to get the Harder, shorter pedal I want is a big part of this experiment. I also plan to play with the placement of the pushrod on the pedal.
 

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Konnie you are one sick mofo! You remind me of a guy I used to work with who had to know how shit worked...just because he could
 

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Discussion Starter #14 (Edited)
This is nothing, man. When the L92 heads first came out, I bought one just to cut up. brand new head, in 3 pieces. brand smurfing new. Took it out of the box, put it in the saw.

I already know how it works. Im a highly skilled technician. But I want to demonstrate a few things to help folks here out. This is the only way to do it.

Aside from playing with the pedal stuff without cutting up or downing my car, Im getting very little personal info out of this. Actual line pressures will be the big one.
 

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seckzy
 

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:hbang:
 

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You are a savant Konnie.... Maybe idiot savant but I can respect that... I love this kind of stuff..
 

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Konnie I applaud you for the effort you have invested into this, let alone the time. Will be interesting to get the results from your experimenting with this master. I'm not sure why, but I am shocked that the plunger is what looks to be polypropylene since it has a melting point of around 320F. If that is correct, I guess the weak point of this hydraulic system with nice Motul fluid would be the plunger (piston) itself. Is there an ID logo anywhere on the plunger? I would guess that after repeated hard launches at a track, this piece in itself would be fairly close to it's melting point, if not right at it.
 

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Discussion Starter #19
I did not see any markings.

Melting of the piston is pretty unlikely. The fluid in the master has a decent amount of heat sink for one. The piston has a reservoir of cool fluid bathing most of it. The Slave is going to see FAR more heat and has less cooling capacity since its trapped in the heat source. I think the slave will go first, and I think we've all seen that happen enough to agree.

But, your theory intrigues me. I think I have a junk toaster oven, I will melt the various meltable parts.

After I cut them in half. We must do that.
 

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I didn't think the piston would see much heat for long either, but under extreme use I think it is possible. The slave as mentioned is the weak link due to it's location. Wish GM would have used a better external design.

Anyway, If it melts at a much lower temp, it may very well be polyethylene. If so, that is pretty scary IMO. Would have thought it would be aluminum.
 
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