Resolved Extend master clutch rod or shim pivot ball

[AWD-Tony]

So I removed the extra shim and added this and it doesn’t drag. I’m going to pull the slave to measure the bore and if it’s the smaller of the two, I’ll order an oem master and slave.

In hindsight, could’ve used a longer piece of bolt and drilled deeper.

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[m_0ney_pit]

Once you set the rod and you’re not blocking the port, that’s all the adjustment you can make as there’s no more room. You can do 1/4 or 1/8 turns.

If yours is engaging off the floor, I think you need to shim the pivot ball. That CAN be done with the trans in the car. I did it yesterday.

Did you cut the shim into a C or take the pivot ball out ?

 

[AWD-Tony]

Did you cut the shim into a C or take the pivot ball out ?

Cut it to a C shape. I don’t think you can back it out enough to completely unbolt the pivot ball and you don’t want to do that since it’ll be almost impossible to thread it back in imo

 

[AWD-Tony]

So I pulled my trans again and checked the torque on the pressure plate. 2 bolts were loose, one more than the other. Will this cause the dreaded drag? Pedal engagement point is fine, just dealing with drag.

 

[AWD-Tony]

Here’s an update.

I brought the flywheel back to the machine shop and had him measure the step height. It measured .609 which is within spec. He used a depth gauge that looked like a cross. I borrowed my buddies snap on torque wrench to retorque the flywheel and pp. Originally used my harbor freight torque wrench. Installed everything and now there very little drag compared to before. I’m going to see if there’s a little more adjustment on the master rod which I’ll do later today and update.

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[AWD-Tony]

NO MORE DRAG!!!

Took apart my slave and it’s the “good” one

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Here’s what fixed my issue.
1. I shim the pivot ball with two washers 3.8mm which brought the fork over to the drivers side of the window.
2. There’s a torque spec for the pressure plate floating around here that states 14ftlbs which seemed very low to me. @twicks69 told me 18-22ftlbs so I torqued to 22ftlb using new bolts

Before this, I tried extending the slave rod with a bolt I ground down to fit between the rod and the slave. This did not help.

 

[Vegas Smith]

Probably just needed a driver-mod

 

[AWD-Tony]

Probably just needed a driver-mod

Oh I missed that part. For sure, driver mod #1! haha

 

[Morphius]

Jack from Jacks trans had it right 12 years ago when he posted a video of how to shim the pivot ball.

https://www.dsmtuners.com/threads/shim-pivot-ball-while-still-in-car.422935/page-2

Keep in mind, Jack didn't discover this or figure it out. He just reiterated what was already known here. He was the first to make a video explaining it.

 

[Morphius]

You're not actually increasing travel in a physical sense with an extended slave rod, extended clutch master rod (in stock form), or by adjusting the clutch master rod, to include adjusting it to the end of its travel. You can only change the point at which those those components begin working together (in this case specifically, passing hydraulic fluid between one another). By making the appropriate adjustments to optimize the way these components all work together, the end result is getting the most (or the appropriate amount) of travel at the clutch fork. So, perception may be you're getting more travel, which may be true. In reality, you're just adjusting the system to get it to work at full capacity (which is also when it will move the clutch fork greatest distance). That's why extended slave rods and master rods have always been considered "band aid" fixes. Loosely demonstrated in math terms, say your clutch hydraulic system moved the clutch fork 10 inches when it's moving 100% of the fluid its supposed to. If you're system is only moving 70% of that fluid, you're now getting 7 inches of travel. You can either fix the issue, or find ways to make up for the 30% loss in capacity. Either that, or physically change components that net you more travel, e.g. different sized clutch masters and slaves.

The clutch master is limited to how much fluid it can move only by its bore size, and piston travel in that bore. Piston travel translates to pedal travel in the car, which is why there is a mechanical adjustment that can physically be made to the pedal. The pedal adjustment equates to the total amount of bore stroke allowed at the clutch master, or put simply, how far the master cylinder piston is allowed to travel in the bore. The more stroke allowed, the more fluid is moved to the slave, which translates to physical movement of the clutch fork, which disengages the clutch. In summary, increasing the clutch master rod length increases piston stroke, which translates to the amount of fluid moved to the slave. Longer stroke = more fluid moved = more travel at the slave cylinder.

Regarding the extended slave rod, the same principals apply. However, since the slave only receives fluid from the clutch master, there's no way to increase travel by increasing input to the cylinder (meaning unlike the clutch master, there's no pedal travel variable allowing you to control fluid movement).

In theory, just increasing the slave rod length shouldn't increase overall clutch fork travel. However, in practice it does in most cases. I believe the reason is because you change the resting position of the piston inside the clutch slave. For whatever reason, when you move the slave piston farther into the slave bore, you get more travel. If I had to guess, it's probably something screwy with how the relief ports are configured for the slave. That's also the reason you need to compress the slave completely when bleeding, to ensure air doesn't get trapped between the piston and relief. Again, on paper, an extended slave rod shouldn't increase travel, but it simply does.

You can test all this by installing everything, then leave the slave rod boot and clutch fork boot off. Have a buddy push in the pedal, and put a mark on the trans case where the clutch fork stops in the window. Repeat that process with various length clutch slave rods, and while adjusting the pedal stroke on the clutch master. You'll find changing each variable will yield different amounts of travel. At that point, you just need to figure out how much travel you need, and what combination of parts and adjustments will get you there.

Of note, the hydraulics have to be completely blead to do any meaningful work on the system. That process is outlined nicely here: https://www.dsmtuners.com/threads/how-to-properly-bleed-your-hydraulic-clutch.213503/

Lastly, if using an extended slave rod, you need to ensure the internal fluid return port isn't blocked by the piston being too deep in the bore. An easy test for that is to take your fingers, and compress the slave all the way in by hand. If the slave returns on it's own, you're good. If it doesn't, the master piston is blocking the fluid return port, and bad things are coming your way if you run the car like that.

Extended master rod. I mostly agree. It's somewhat about taking out compliance.
1G: It's been a while, but I think the larger arc, more travel applies to 1g.The 1g, correct me if I'm wrong, doesn't have a stop. There is also alot of flex in the pedal box on a 1g to deal with.
2G: The limiter is still the stop at the top of the pedal travel and the cut-off on the master piston. The cut-off point can be reached with the stock rod with the pedal hitting the stop (upper limit of travel). So, there isn't anything to gain. (I'm assuming/and read enough post that you can always hit cut-off with the stock rod. Anyone NOT see that?)

Extended slave rod. Disagree. It can't add any output. The longer rod, if long enough, simply will bottom out the piston and push the release lever to the left, preloading the TOB and PP fingers.

 

[AWD-Tony]

The 1g, correct me if I'm wrong, doesn't have a stop. There is also alot of flex in the pedal box on a 1g to deal with.

What do you mean by "stop"? You can block the relief port on the master when adjusting the master rod on a 1g.

[/QUOTE]Extended slave rod. Disagree. It can't add any output. The longer rod, if long enough, simply will bottom out the piston and push the release lever to the left, preloading the TOB and PP fingers.[/QUOTE]

I agree that there is no benefit in an extended slave rod. The clutch fork will rest where it rests. When you extend the rod, it will simply push the piston back into the slave.

 

[Morphius]

What do you mean by "stop"? You can block the relief port on the master when adjusting the master rod on a 1g.

It's been 10 years since I've needed to screw with a 1g pedal and my cars are in storage right now, not being daily driven. I don't recall, does the 1g have a dead stop, like the 2g which limits how high the pedal can swing up?

 

[AWD-Tony]

It's been 10 years since I've needed to screw with a 1g pedal and my cars are in storage right now, not being daily driven. I don't recall, does the 1g have a dead stop, like the 2g which limits how high the pedal can swing up?

Yes. The cruise switch acts as a dead stop but if removed, I think the bracket will serve as a stop as well.

 

[m_0ney_pit]

Keep in mind, Jack didn't discover this or figure it out. He just reiterated what was already known here. He was the first to make a video explaining it.

And it’s good he did with so many conflicting answers in some posts on the forum on this subject it’s hard to separate out good info

 

[bastarddsm]

Did any of you check the clutch before you installed it? that's #1, make sure it's physically possible to release the clutch. The extended slave rod is mostly a placebo. It won't help the clutch engaging off the floor, it won't help with jacks test method. Where it "might" help is at a high rpm shift.

 

[AWD-Tony]

Did any of you check the clutch before you installed it? that's #1, make sure it's physically possible to release the clutch. The extended slave rod is mostly a placebo. It won't help the clutch engaging off the floor, it won't help with jacks test method. Where it "might" help is at a high rpm shift.

My clutch and pp were new. Flywheel was used and had it resurfaced and stepped .609.

 

[bastarddsm]

I don't care about any of that. Did you check that it will actually work?

 

[AWD-Tony]

How do you check a new pp, clutch and flywheel to see if it works? Good news is that they all work now.

 

[m_0ney_pit]

Yea would also like to know please , you mean like the pressure plate finger angle?

 

[bastarddsm]

Yes, you need to make sure the the fingers are in a good position. You should also figure out a way to make sure the clutch actually releases, how much finger travel it takes to release, and that it can release before the fingers hit the disc. I define release as having 0.050" of airgap between the disc and the flywheel. Something like a modern act pressure plate and a act sprung street disc is on the verge of not working.

Lastly, every clutch manufacturer has a different thickness disc, a different thickness donut, a different thickness diaphragm, and a different fulcrum height. Usually clutch to clutch from the same manufacturer they can be different. How can they all use the same step height. They can't. The step height needs to be set to optimize everything.

 

[ErikTande]

Here’s my update:
So I cut a 1mm washer and was able to add this shim with a magnet and a long screwdriver. It fell once but no big deal fishing it out with the magnet.

What was your method for this? Grind down a wrench? Did you have to pop the fork off the ball to shim it?

Thanks!

 

[AWD-Tony]

What was your method for this? Grind down a wrench? Did you have to pop the fork off the ball to shim it?

Thanks!

I had a cheap thin 9/16 open wrench (5.2mm to be exact) that I wrapped with tape so it fit snug and left the fork as is. Didn’t want to cut my good wrench. Also notched it a little where it hits the housing.

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[ErikTande]

I had to trim my wrench down WAY more than that , i cut a washer into a "C" shape and used a magnet to get it in place. I cut the notch in the washer intentionally just a little too small to go over the bolt. Then I got it lined up with a magnet and tapped it in place with a hammer and screwdriver. That stuck it on while I was able to tighten it up again.

I'll post results in a couple days!

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[AWD-Tony]

I had to trim my wrench down WAY more than that , i cut a washer into a "C" shape and used a magnet to get it in place. I cut the notch in the washer intentionally just a little too small to go over the bolt. Then I got it lined up with a magnet and tapped it in place with a hammer and screwdriver. That stuck it on while I was able to tighten it up again.

I'll post results in a couple days!

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Glad you got it in there. Grinding it that much saved you some time turning the nut. It took me a while . When you get a chance, post a pic of where the fork now sits.

 

[ErikTande]

Alright so we have success. The extended master helped the most, and after shimming the pivot ball I have no clutch drag at 7000 RPM. at 7500 the car rocks forward a little bit but not enough to move. So I'm calling it good. After the extended master rod the engagement feels awesome, it's not right off the floor anymore, the pedal comes up a couple inches before the clutch engages.

Now time for break in. : D