Clutch check (Coyote + T56 + Hydraulic Clutch)

[dbo_texas]

I spent a ton of time over the holidays getting all of my electrical/wiring sorted, and I'm quickly approaching 1st start. I wanted to ask to forum about my clutch setup - before I do 1st start I just want to check and make sure the clutch is set up properly. This is my first build so I'm not sure if there is anything special I need to do. My setup is a Gen2 Coyote + T56 transmission + Forte hydraulic clutch setup. Clutch line has been bled already.

I know this is a dumb question but I'm going to ask it anyway as I'm nervous about this --> is there a way to check that the clutch engagement is set up correctly? Currently the car is up on jack stands and starter motor is installed too (not sure if that impacts anything). What procedure/tests/inspections can I do to confirm if the setup is good? Any advice here would be appreciated!

[Blitzboy54]

If you have the external slave it’s just a matter of adjusting the piston against the fork. But for peace of mind put your car off the ground, put it in gear and have someone turn the rear wheel while you depress the clutch. It won’t be perfect but it will get you pretty close. Once the wheel gives that’s a little passed your engagement point. Obviously the engine will put more power to it than a person will.

[dbo_texas]

So when the rear wheels are able to spin (with the helper, and when I'm slowly depressing the clutch pedal) this will tell me when the clutch releases from the flywheel. But how does that help me? Does that just confirm that I'm engaged fully (with no pedal push), and at what point in the pedal travel the clutch is no longer engaged? Then anything beyond that point is wasted pedal effort? Sorry...I'm a little slow after about a week of crimping a thousand connector pins

[Blitzboy54]

So when the rear wheels are able to spin (with the helper, and when I'm slowly depressing the clutch pedal) this will tell me when the clutch releases from the flywheel. But how does that help me? Does that just confirm that I'm engaged fully (with no pedal push), and at what point in the pedal travel the clutch is no longer engaged? Then anything beyond that point is wasted pedal effort? Sorry...I'm a little slow after about a week of crimping a thousand connector pins

Yeah that’s mostly right. A person isn’t going to be able to generate enough power to rotate the wheel if say you’re over adjusted and partially engaged. If that were happening you either didn’t bolt the pressure plate down or the release bearing is partially pushing in the fingers. Unlikely you didn’t bolt the pressure plate. The initial setup you usually want the bearing right up to the fingers just making contact. After that I would assume you have full engagement. Just like brake pads. It will grab

When the clutch engages and the wheel spins then yes, the rest of the pedal throw is wasted effort. If you’re on the edge of being over adjusted (or partially engaged) you won’t know until you’re under power. If you apply power and the RPMs spike but the car doesn’t accelerate that’s probably what’s happening. Then just back off the fork.


Conversely if you have to push the pedal almost all the way to the floor to get it to release the opposite is true. Adjust the bearing closer to the fingers. You have some wiggle room there. There is a range that is simply preference. Anywhere half way through the pedal stroke is a good place to start.

But to go all the back to what I think your initial question was: No, other than being in neutral there is nothing you need to do special for first start.

[dbo_texas]

Yeah that’s mostly right. A person isn’t going to be able to generate enough power to rotate the wheel if say you’re over adjusted and partially engaged. If that were happening you either didn’t bolt the pressure plate down or the release bearing is partially pushing in the fingers. Unlikely you didn’t bolt the pressure plate. The initial setup you usually want the bearing right up to the fingers just making contact. After that I would assume you have fiull engagement. Just like brake pads. It will grab

When the clutch engages and the wheel spins then yes, the rest of the pedal throw is waisted effort. If you’re on the edge of being over adjusted (or partially engaged) you won’t know until you’re under power. If you apply power and the RPMs spike but the car doesn’t accelerate that’s probably what’s happening. Then just back off the fork.


Conversely if you have to push the pedal almost all the way to the floor to get it to release the opposite is true. Adjust the bearing closer to the fingers. You have some wiggle room there. There is a range that is simply preference. Anywhere half way through the pedal stroke is a good place to start.

But to go all the back to what I think your initial question was, no other than being in neutral there is nothing you need to do special for first start.

Thanks for the detailed feedback here. I'll take a closer look this weekend and see how it goes.

[Mike.Bray]

You can actually test engagement yourself if you have the driveshaft installed and transmission tunnel top removed. With the car in gear slowly start depressing the clutch while trying to rotate the driveshaft with your hand. You'll find the point of disengagement easily with this method.

[dbo_texas]

You can actually test engagement yourself if you have the driveshaft installed and transmission tunnel top removed. With the car in gear slowly start depressing the clutch while trying to rotate the driveshaft with your hand. You'll find the point of disengagement easily with this method.

I do have the driveshaft installed & trans tunnel top removed but the driveshaft is hooked up to the rear end. So it takes some force to turn the rear wheels....don't think I could turn the driveshaft by hand with all that friction from the rear end. I used to be able to sit in the driver seat, and I could reach over to the DS rear wheel and turn it. But after bleeding the brakes they now make very light contact and I can't get enough leverage from in the drivers seat to turn them so I may need a helper to do this.

[Mike.Bray]

I do have the driveshaft installed & trans tunnel top removed but the driveshaft is hooked up to the rear end. So it takes some force to turn the rear wheels....don't think I could turn the driveshaft by hand with all that friction from the rear end. I used to be able to sit in the driver seat, and I could reach over to the DS rear wheel and turn it. But after bleeding the brakes they now make very light contact and I can't get enough leverage from in the drivers seat to turn them so I may need a helper to do this.

That's strange, I can easily turn mine and it's driving the rear end. Might want to look into that.

[jgray]

Darryl - thanks for creating this thread. I am building a Type 65 with 302 + T56 + IRS and have the Forte slave cylinder. Like you, this is my first build, and I am nervous about many things! Yesterday, I bled the clutch hydraulics and trimmed the pushrod by about a quarter of an inch, and adjusted so that I have about 3/16 of play when the clutch is disengaged. I need to check that the clutch is fully disengaging when the pedal is in, but I need a helper.

[Its Bruce]

FWIW - I pushed my pedal in while someone put torque on the wheel then set my pedal stop 1/4'' to no more than 1/2'' beyond that point. No issues since.

[dbo_texas]

So I went an played with the clutch a little bit tonight. When the clutch pedal is all the way up (not depressed), there is a very small amount of play on the slave cylinder and the fork. I'd say less than 1/8". When the engine is off, and I'm in gear and slowly depress the clutch, I can't turn the rear wheels by hand until almost the end of travel on the clutch pedal, then they release. So the clutch releases very close to full pedal push (maybe 1/2 in prior to bottoming out the travel). It feels like a LOT of pedal travel and I imagine will be very uncomfortable to shift when driving.

What is the proper way to adjust this to reduce pedal travel? Maybe I just need to test drive it first to see if this is really an issue but just curious what the remedy would be.

[dbo_texas]

So I went an played with the clutch a little bit tonight. When the clutch pedal is all the way up (not depressed), there is a very small amount of play on the slave cylinder and the fork. I'd say less than 1/8". When the engine is off, and I'm in gear and slowly depress the clutch, I can't turn the rear wheels by hand until almost the end of travel on the clutch pedal, then they release. So the clutch releases very close to full pedal push (maybe 1/2 in prior to bottoming out the travel). It feels like a LOT of pedal travel and I imagine will be very uncomfortable to shift when driving.

What is the proper way to adjust this to reduce pedal travel? Maybe I just need to test drive it first to see if this is really an issue but just curious what the remedy would be.

Was just reading a bit more (and watching some YouTube videos on hydraulic clutch issues) - maybe I have some air in my hydraulic clutch line? I bled it several times and thought I had it all out, but maybe this is contributing to the excessive pedal travel?

[Blitzboy54]

You want to extend the piston so back off the set screw and increase the space between the fork and the slave cylinder. This puts the throwout bearing closer to the fingers and will engage the clutch sooner. You can also bring the pedal closer to your foot by lengthening the pushrod from the clevis at the MC. That won’t make it engage any quicker but will bring the pedal closer.

Obviously if you have any air in the system it will negatively affect performance and needs to be dealt with first.

You’re on the right path. Good luck.

[dbo_texas]

You want to extend the piston so back off the set screw and increase the space between the fork and the slave cylinder. This puts the throwout bearing closer to the fingers and will engage the clutch sooner. You can also bring the pedal closer to your foot by lengthening the pushrod from the clevis at the MC. That won’t make it engage any quicker but will bring the pedal closer.

Obviously if you have any air in the system it will negatively affect performance and needs to be dealt with first.

You’re on the right path. Good luck.

I spent some time messing with the setup this morning. I backed the threaded rod out of the heim joint rod end adapter about 1/4", but it didn't seem to help much. It definitely feels like the clutch isn't 100% released even at full travel - feels like it is dragging in comparison to when the transmission is in neutral. I completely removed the pushrod and measured it - looks to be around 1.940" in length. I think it needs to be quite a bit longer --> when I tried extending it further it unthreaded from the adapter so I ran out of length. I wasn't thinking and pushed the clutch pedal down when all of this was apart and blew the piston out the end of the bore. That was fun - brake fluid everywhere I put it all back together and re-bled the system - no leaks and have a firm pedal. But like I said, I think I need to make a new rod which is longer than the 1.94" currently in there. I believe I can do this with a 5/16-24 bolt and just cut the head off. Maybe I'll make it more like 2.5" length and see if that helps my situation. Anyone know how long your pushrod is (for reference)? I know all setups are a little different.




Here's a video pre-adjustment....it's not much better even after backing it off about 1/4" (that's as far as I could go without the pushrod coming unthreaded from the heim joint rod-end).

[dbo_texas]

I have 2 questions I was hoping the group could help with.
(1) Can anyone tell me what the typical stroke on the hydraulic slave is? I can't tell what the bore diameter is on the slave but it looks to be something around 3/4" (I'll measure it w/ calipers next time I disassemble). On the master cylinder I'm using the Wilwood 13/16 diameter as recommended by Forte (I originally had a 3/4 master that came w/ the kit, but switched this out early after talking to Mike).
(2) For the actual clutch, what is the amount of travel on the throw-out bearing you need to disengage the clutch (from the time you touch the spring fingers, to the time the clutch is fully disengaged)? I think this would be hard to measure with the engine installed but I want to get a general sense if I'm close (you can see it in my video above). In my setup it looks like the TOB is already touching the spring fingers....I don't think its preloading them but there isn't much clearance. And I'm getting somewhere around 1" or so on pushrod travel (I will measure an exact value). I bought a new 5/16-24 bolt (2.5" length) that I will cut the head off to try to get a longer pushrod, but if I'm seeing this correctly all this will do is start to pre-load the spring fingers which I understand is not a good idea.

[rich grsc]

You admit you have some brake drag, making it a bit hard to turn the wheel. What gear do you have the transmission in when testing the clutch release? Use 4th, not 1st, also a new clutch disc is going to have a bit more friction drag until it's been drive some.

[dbo_texas]

You admit you have some brake drag, making it a bit hard to turn the wheel. What gear do you have the transmission in when testing the clutch release? Use 4th, not 1st, also a new clutch disc is going to have a bit more friction drag until it's been drive some.

Thanks Rich - I have been testing it in 1st gear. I'll try 4th to see if there is a difference. While I do have a little bit of brake drag since I haven't worn in the pads at all, I can feel a definite difference between being in neutral vs 1st gear w/ clutch pedal pushed all the way in. That's why I think the clutch is still dragging a little bit. I'll compare in 4th gear and see what that's like.

[dbo_texas]

OK some updates. I took apart the slave pushrod and went to make a longer rod out of a 5/16-24 bolt (2.5"). However when I went to put it back into the slave assembly I quickly realized I didn't think it would go back together. So I ended up sticking with the original pushrod (1.940"). While I had it apart, I measured the slave cylinder piston diameter and it is 3/4". I also confirmed my Wilwood MC is 13/16 diameter (0.812").

I'm still a bit at a loss. What I can't understand is after disconnecting the pushrod, it looks very much like the throw-out bearing is still making contact with the pressure plate spring fingers or very close to it even with no forward pressure on the fork. This surprises me - I figured there would be some clearance between the fingers and TOB. I don't get the recommended 3/16 of free play at all (with no pressure on the fork). Based on my video below demonstrating this, Is this normal? Or do I possibly have something going on with the clutch fork assembly and pivot mounting? I didn't assemble any of this so I'm unfamiliar with how this goes together or comes apart, or is supposed to function as this is my first build.
https://youtube.com/shorts/yH1IA4M-0DU?feature=share

Anyhow, after realizing the longer pushrod just wasn't going to work because I couldn't figure how to assemble it without putting more pressure on the spring fingers, I just reassembled the original setup. I tried to back off the pushrod so it wasn't putting any pressure on the spring fingers. I did this by pushing the piston all the way in and measuring where the end of the threaded pushrod was relative to the threaded heim socket mounted to the fork. It has about 1/4" of thread engagement. I did slightly adjust the position of the mounting bracket so that the pushrod is perpendicular to the fork and co-axial with the slave cylinder. After re-bleeding the system, when I push the clutch pedal to full travel, this is what I get. You can see the piston inside the slave goes from all the way seated (bottom of bore) to just where the face starts to protrude from the bore (right before the o-ring is visible). So it looks like I'm getting about as much travel on the slave piston as is possible before the seal breaks. I also adjusted the MC pushrod to bring the clutch pedal forward about 1/4" more. After making these changes, when put it in gear and push the clutch pedal in, it does feel like a slight improvement - I don't feel the dragging that I felt previously and it feels the same as when in neutral so I'm pretty sure the clutch is fully disengaged.
https://youtube.com/shorts/D4lcNyILrmc?feature=share

At this point my only complaint is having to push the pedal pretty much all the way in to get the clutch released. This feels like it will really suck when driving. Just thinking through this, if I were to go to a larger MC size (say 1" instead of 13/16), this would decrease pedal force slightly and increase slave cylinder piston travel (more fluid volume for same pedal travel). However, I think I'm already getting full travel on the slave, so if I went this route I would need to install a pedal travel limiter right (assuming I hit max slave travel with less pedal travel)? Can anyone confirm if this is the way to fix the pedal travel issue?

[edwardb]

This is a video I did of the hydraulic clutch setup on my 20th Anniversary Roadster. This was a while ago so using a 7/8" CNC slave cylinder, which is no longer available, and a 1" MC. Plus the mounting is slightly different. But the overall setup is the same as yours. The amount of play shown here is more than enough and seems similar to yours. The throw out bearing will still be contacting the clutch fingers, which is normal and they're designed to work that way. Just without pressure. Assuming you have the air out of the lines and everything appears to be working normally, I'd wait until driving to see if you really need to change anything. There will be some clutch drag as Rich said. Especially on a new clutch. I'll bet you are OK.

[dbo_texas]

Thanks Paul - that's kind of what I was hoping to hear. I'll go through first start and go kart it a bit and see if I still feel like the pedal throw is too much before changing anything in the setup. I've referenced your video a lot while trying to figure this out.