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Clutch Master and Slave


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I just mounted my motor, and I unbolted the clutch slave while installing. I had trouble reinstalling the clutch slave cause I didn't know what I was doing and I may or may not have damaged the clutch slave or clutch master cylinder. I can't get the pedal to have a full stroke. Now its just on the floor after changing the slave master.

 

How do you diagnose the clutch slave and clutch master? The slave seems really simple, and when I changed the slave it made things worse.... not sure if its the part or what.

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Did the clutch master lose all of its fluid? If so, you'll need to bench bleed it. You also might bleed it again. When I use the speed bleeder stuff it generally takes me longer than just using two people.

 

Also, most people swap both clutch master cylinder and slave at the same time. The motto is that if one is failing, the other isn't far behind.

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Posted (edited)

how would i bench bleed it?

 

I think I am just doing something wrong. Cause everytime i did something it just got worse.

Edited by Tehnation
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The clutch master never lost all the fluid so I don't think I need to pull it out. I'm going to dial a friend at this point, seems like getting fancy is working against me.
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I seem to recall if you didn't raise the slave above the Clutch MC you should be ok.

 

Raising it above can introduce air into the line. I think that's in the service manual...?

305,000miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. CHECK your oil, these cars use it.

 

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Stupid question: but your slave is attached to the transmission and the tranny + motor + clutch fork are all installed and bolted together, etc.? The pedal won't return without the pressure plate actively pushing it back up.
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Posted (edited)
Stupid question: but your slave is attached to the transmission and the tranny + motor + clutch fork are all installed and bolted together, etc.? The pedal won't return without the pressure plate actively pushing it back up.

 

I understand what your saying but I don't think thats how it works. In a neutral position, ie pedal up, the fork doesn't have any tension really, its held in place by the clutch slave. The fork travel back and forth is all controlled by the slave the fork doesn't apply any force to the slave. The clutch system is basically a piston or ram, like your brake. You press the pedal it pumps the clutch master or moves fluid and that fluid then moves the clutch slave. It just a simple hydraulic ram, so when you depress the clutch that fluid moves back and the ram or piston moves back to its original position. The fork has no correlation to that ram.

 

hmm, but i guess your right in some aspect, when the piston hits the fork it needs a lot of force to move the tob, when that force stops the tob returns to its normal position. It isn't so much the clutch plate pushing back on the fork thus pushing the piston back in and more so that there isn't enough force to keep it engaged cause the piston moves back after letting go of the pedal . The piston on the slave moving back and forth isn't related to the fork would be the quicker and simpler answer lol.

Edited by Tehnation
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Did the clutch master lose all of its fluid? If so, you'll need to bench bleed it. You also might bleed it again. When I use the speed bleeder stuff it generally takes me longer than just using two people.

 

Also, most people swap both clutch master cylinder and slave at the same time. The motto is that if one is failing, the other isn't far behind.

 

I checked the fsm and bench bleeding is unnecessary, the standard bleeding method in the fsm(which states to grab a "coworker", so this is a 2 man job) is what they say to use when you replace the clutch master, and a new clutch master doesn't have any fluid in it.

 

Something isn't right, its either this cheap autozone slave is junk or the clutch master is shot. They are the only 2 parts in the system. I ordered a clutch master already, in the meantime i am going to have to phone a friend again and try the old slave to see if anything changes.

 

I get it to work after pumping the pedal a bunch of times, then after a while or after starting the car, it turns to crap. Seems like it can't hold pressure. During my fiasco, i put a clamp on the slave trying to compress the piston but I didn't realize the pedal was to the floor, so i'm thinking putting all the force on it to push it in might have busted some seal somewhere and air is slowly leaking in somewhere.

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I checked the fsm and bench bleeding is unnecessary, the standard bleeding method in the fsm(which states to grab a "coworker", so this is a 2 man job) is what they say to use when you replace the clutch master, and a new clutch master doesn't have any fluid in it.

 

Something isn't right, its either this cheap autozone slave is junk or the clutch master is shot. They are the only 2 parts in the system. I ordered a clutch master already, in the meantime i am going to have to phone a friend again and try the old slave to see if anything changes.

 

I get it to work after pumping the pedal a bunch of times, then after a while or after starting the car, it turns to crap. Seems like it can't hold pressure. During my fiasco, i put a clamp on the slave trying to compress the piston but I didn't realize the pedal was to the floor, so i'm thinking putting all the force on it to push it in might have busted some seal somewhere and air is slowly leaking in somewhere.

Bench nleeding is necessary for new MCs and when the MC has been run dry.
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Posted (edited)

I am just going by what the fsm says! And how exactly would you do that with this specific style of clutch master, I can use google but I haven't seen anyone bench bleeding a subaru clutch master. And if you bench bleed it how do you install it without fluid leaking out? There is line that goes out to the clutch slave, you would have to plug that..... I just don't see how you could do it without a whole bunch of madness.

 

[ATTACH]296611[/ATTACH]

 

[ATTACH]296612[/ATTACH]

Edited by Tehnation
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I would think you could install the pre-filled lines on the clutch MC before much of the fluid in the MC leaked out.

305,000miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. CHECK your oil, these cars use it.

 

Engine Build - Click Here

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I am just going by what the fsm says! And how exactly would you do that with this specific style of clutch master, I can use google but I haven't seen anyone bench bleeding a subaru clutch master. And if you bench bleed it how do you install it without fluid leaking out? There is line that goes out to the clutch slave, you would have to plug that..... I just don't see how you could do it without a whole bunch of madness.

 

[ATTACH]296611[/ATTACH]

 

[ATTACH]296612[/ATTACH]

No matter how you bench bleed it, it's messy when you swap lines over.

 

You're fine to follow the fsm, it just takes longer to bleed the air out. Don't forget to adjust the rod on the new MC to match the old one.

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  • 3 weeks later...

Actually I lied..... I keep getting this gap where when I push down on pedal about an inch or 2 and its just nothing, then it engages and its right on the engagement point for clutch. There is no resistance really in that 1st bit of travel on the pedal. It seems I just have shorter amount of clutch pedal to work with as well. Its fine when I 1st bleed it unstarted and undriven and then as soon as I start it up and drive, it turns back to crap. The 2 slave masters I tried are doing the same thing, so I ordered a clutch master. 

I'm wondering if switching to a single mass flywheel from dual mass has anything to do with it, cause of flywheel thickness which may affect the piston reach of slave. But I never heard there being an issue when going from a dual mass to single mass so I will assume it's just the clutch master not providing a full stroke and taking in air cause of a blown seal.

Something isn't right and I THINK I remember a time where the pedal had full travel on the single mass..... can't remember for sure at this point. 

It may be an issue with the Spec stage 3+ clutch.... I also ordered an 05/06 for dual mass and 07+ slave for lgts that switched to the single mass would use. Ive rarely driven the car over the past several years so its hard to say what the clutch was like prior....  

I got the master for like 25 bucks on rock auto, and the slave for like 15 and another 20 for the later model slave. I buy aftermarket everything at this point.... I'm not a member of the oem everything crowd. I'm not paying premium $$$ for 20-30 year old technology.... at this point someone knows how to do it better and cheaper or just rebuilds. Got clutch master, and 2 slaves from rockauto for under 100 bucks, 20 something for shipping. Normally an oem master is like 150 alone so yea, i'm not doing that lol.  Half my car is aftermarket at this point. 

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You don't move the throw out bearing when you depress the clutch pedal.  you're depressing the metal fingers on the clutch pressure plate to pull it away from the clutch disc.

 

I deal with OE and aftermarket parts all day.  the OE stuff is always better quality.  You do pay for that quality, but it will for sure last longer than the aftermarket item.

 

Edit: I mispoke, I was thinking the pilot bushing for some heckin reason. Long day in a hot shop

Edited by silverton
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I think that's the way it works for the wrx with the other style clutch. I'm pretty sure the clutch when depressed(pushed to the floor) pushes the clutch slave piston outward which pushes the fork, which then pushes the throwout bearing onto the pressure plate. I could be wrong but thats my understanding of it! 

My car has about 125k miles on it, and the master is out. For 150+ dollars oem I got 125k, for 25+ dollars if I get 25k miles at least and worst case scenario , I am still ahead.... If i get 50-75k ... its well worth it imo. Thats worst case imo as well. 

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"you're depressing the metal fingers on the clutch pressure plate to pull it away from the clutch disc."

That is correct.

 

 

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305,000miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. CHECK your oil, these cars use it.

 

Engine Build - Click Here

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Yea, he is right about that part, was a little confusing, but the throw out bearing does move, thats how it depresses the fingers, if it didn't move how would it apply force to the fingers? So could be my pressure plate? 

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I can see some kind of liquid around the clutch master from the cabin, not sure if its grease or brake fluid. Hopefully my part gets here soon and I can start replacing the master. 

Didn't occur to me that it could be leaking from the inside....

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My original pump seems fine, bit dirty inside the reservoir but otherwise seems to be fine. The other master did the same thing, so time to send that back get my 25 bucks back. I don't know what the hell is happening but air is getting in the system somewhere...

Going to pull the reservoir off my original pump and clean that seal and hopefully I can find an o ring that fits. The pumping action is on point, stuck my finger over the hole and pumped it, didn't notice any slack or play. 

And if that doesn't work i'm going to try the 2 new slaves, one for 05-06 and other for 07+, see what happens. 

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https://parts.subaru.com/p/Subaru_2005_Legacy-25L-TURBO-5MT-4WD-GT-Limited-Sedan/Clutch-Release-Arm-Spring/49239199/30534AA001.html

I don't remember seeing this part when installing my motor, does it sit inside the fork???...... what does this do??? 

I just put a camera in there and I dont see this spring..... did I remove it for some reason??? Was there some kind of upgrade? For some reason I remember I changed the fork to something else a long time ago..... who knows but ....shit

Jesus christ do I have to pull the motor again....anyone know the video for that dude that changes the clutch without fully pulling the motor? 

hmm, maybe I can get it on by unbolting the slave and doing some pliers gymnastics. Gonna go to dealership tomorrow to get/order one. 

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Apparently I did have it in there... it seems to have exploded, I pulled out half of it and saw some broken bits in there.... WTF!!

I really can't catch a break.... this is why I stopped spending top dollar on oem parts and the such... its like a high maintenance and expensive girlfriend who just teases and doesn't put out..... like 4+ years and less than 2k miles...

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That's the clip/spring that holds the fork to the pivot ball.  it's recommended to replace the spring and ball when you replace the clutch... some times the fork is pretty well worn too and also needs replaced.

Edited by silverton
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