DIY - Swap clutch slave cylinder and hydraulic line for improved feel and control

[ck-GT86]

First and foremost, I do not take any credit for the “Swap Clutch Slave Cylinder” mod, every bit of credit goes to the folks in this thread created by @Ultramaroon

Moving on, I haven’t found any tutorials on how to swap out the clutch line, figured this would be a great opportunity to perform both mods. Below are my trials and tribulations since there has yet to be a DIY about this very topic. @Chase Bays didn’t provide any instructions, and the product I received is very different from what they have posted online. I’ll explain more below

Tools I Used:
DOT 4 brake fluid
Aftermarket Clutch Line – (ChaseBays)
Subaru 30620AA111 Slave Cylinder
12mm socket – (removal of factory bracket holding in clutch line)
14mm socket – (removal of 2 bolts holding in slave cylinder)
15mm socket – (CB Clutch Line)
3/8 extension bars
15mm racheting wrench – (CB Clutch line)
8mm Open ended wrench – (bleeding of clutch fluids)
10mm Open ended wrench – (removal of OEM clutch line)
Rags/shop towels
Cup – (bleeding of fluids)
Roomate or an assistant – (you’ll need someone to press on the clutch when bleeding)

Note: If you purchase the clutch line from @Chase Bays, do not expect to receive this:

I received a cable that had two ends looking like this:

I panicked and e-mailed CB immediately thinking they eff’d up. Their website too shows Picture 1 with the bend mimicking the OEM line. I’m guessing they realized the Twins share the same master cylinder as the WRX some time after they released what appears to be a version 1 of the clutch line, hence the compatibility notes. It took some scouring of their pictures online to piece together that the parts are indeed compatible with one another. See the two pictures below, the Cosworth has the same line with a different reservoir cap, and the other has the exact same cylinder.

What you’ll notice in the package is that the two provided banjo bolts are different sizes, a quick glimpse and you’ll think they’re exactly the same. Continue reading…

Removal

1. Placed shop towels underneath the output line of the master cylinder, keep the cap on the cylinder to keep air from entering


2. Placed a cup near the 8mm drain bolt of the factory slave cylinder


3. Loosened the 8mm drain bolt and allowed fluid to drain into cup. Reservoir should be empty





4. Loosened the banjo bolt holding in the clutch line to the slave cylinder


5. Like how @Ultramaroon detailed, hold the clutch line upwards immediately after removing the banjo bolt to keep the fluids from going everywhere. I dumped the clutch line into the cup to let it drain.


6. Now, work on the banjo that attaches the clutch line to the master cylinder. Use the open ended 10mm wrench and loosen counter-clockwise. I stripped every bit of this nut by the way. The metal used on this is pliable, very easy to strip. 



7. The OEM clutch line is held in place with a bracket that also attaches to the master cylinder. Loosen and carefully remove the (2) 12mm nuts that hold the bracket in.





7.1 I used a retractable magnet tool to catch the nut closest to the passenger side, we all know how much of a pain it is to retrieve a nut or bolt once it drops into the engine bay. 






7.2 Grasp onto the master cylinder as the nuts come off – it’d be good to have your assistant keep their foot on the backside of the pedal and pull into their bodies to keep the pedal from collapsing into the floor. I did this part by myself and the entire master cylinder shifted downwards as I removed the nuts. Luckily I had a good grip on the bolts and fed the nuts back on to keep it all together. Assistant can take a break once the nuts are on.


8. IF the pedal did retract to the floor, crawl under the dash and pull the clutch pedal upwards so it locks. Make sure the master cylinder is straight, then reattach the 12mm nuts. 



9. Wiggle out the OEM bracket and line, catch a breather – slave cylinder is next.

Slave Cylinder

1. @Ultramaroon did a good job detailing how to swap the parts, it’s really easy compared to the clutch line and bleeding.


2. Remove the (2) 14mm bolts holding in OEM slave cylinder. You’ll notice that the cylinder will push away from the rear of the transmission as the bolts get loose. This is by design, the cylinder collapsed as the clutch is engaged. Use some force to keep the cylinder from pushing back, you can strip your bolts if you don’t.


3. Remove OEM slave cylinder, replace with new. The metal end of the cylinder needs to press against the concaved actuator. It should feel like a spring compressing as you press the cylinder into the dimple. 



4. Look carefully at the holes on the transmission housing when you put in the new cylinder. Get a feel for the bolt threading on while you’re compressing the cylinder. You should be able to thread the 14mm bolts by hand for more than 70% of the way in. Thread one side in, repeat with the other. THEN you use your ratcheting socket to tighten them down. 



5. Remove the white cap on the new slave cylinder. The new clutch line and banjo will fit into here.

Reattaching Clutch Line

1. Inspect the banjo bolts that came with your new clutch line if both ends are the same. Most other aftermarket clutch lines have a banjo fitting on one end, and the other end threaded male. Thread gently by hand if you can’t tell by eye to see which banjo goes where. It wasn’t noted anywhere that the two banjos provided by ChaseBays were different. Maybe they aren’t, but I had better luck threading what appeared to be a smaller banjo into the master cylinder. 



2. The “ChaseBays” logo’d end will attach to the master cylinder. I routed the cable down and under some rubber lines over to the slave cylinder. Less bends are key.


3. Place a washer onto the banjo, then the logo’d end, add another washer, and thread this into the master cylinder. Use the 15mm open wrench to tighten


4. The Slave Cylinder DIY says to replace the OEM washers. My new clutch line came with metal washers so use these in place. Same washer placement for the slave cylinder as the master: banjo, washer, end of cable, washer, into cylinder. Use 15mm socket to tighten.

Bleeding the Clutch Fluid

Note: You definitely need another body for this process

1. The 8mm drain plug on the new slave cylinder should be sealed, tighten if not.


2. Remove master cylinder cap and refill with brake fluid


3. Seal the cap


4. Loosen the 8mm drain plug on slave cylinder


5. Have assistant press clutch to the floor, DO NOT bring clutch pedal back up


6. Tighten drain plug, then have assistant manually bring pedal up


7. Loosen drain plug, repeat process until bubbles have escaped.

Inspect all lines, wipe any fluid residue off, start car and monitor for any leaks. Take your car out, engage all of the gears, return and inspect. Fluid level should remain the same.

[ck-GT86]

Originally Posted by Ultramaroon

Sure you don't want to start your own thread with it? I can plug your thread at the top of the OP and you can update yours at will. Either way's cool with me.

I think this mod with yours goes hand-in-hand, might as well do the line if you're going to replace the cylinder. And might as well flush the fluid if you're doing the other two.

I wouldn't have bothered to do either if it wasn't for your DIY. Proceed as you wish.

Thanks!

.ck

[Ultramaroon]

Originally Posted by ck-GT86

Thanks!

.ck

Thank you!

[SamS]

I replaced my slave cylinder with the AutoZone part last night, and it was immediately so much better! It's like a normal car now, and was very easy to do in a half hour.

[Ultramaroon]

Originally Posted by SamS

I replaced my slave cylinder with the AutoZone part last night, and it was immediately so much better! It's like a normal car now, and was very easy to do in a half hour.

Right? The spring and adjustment are nice but they don't quite nail it.

[Decay107]

Did the swap today. A+, do recommend.

...Free bump to the top

[stockysnail]

Originally Posted by Decay107

Did the swap today. A+, do recommend.

...Free bump to the top

I'd like to push your pedal next time we're at the same gathering. Hopefully that's not an innuendo.

[JB86'd]

I let someone at the Irvine meet drive my car with this slave installed, plus pedal height adjustment, return spring removed, Raceseng slammer knob, and mtec shift springs and he was quite impressed. I love shifting now

[Ultramaroon]

Originally Posted by JB86'd

I let someone at the Irvine meet drive my car with this slave installed, plus pedal height adjustment, return spring removed, Raceseng slammer knob, and mtec shift springs and he was quite impressed. I love shifting now

I pull back all the time with the spring removal crowd. Feels like I'm pissing in the wind and I wonder "What can I say to explain in words why, although it's good to ditch it, it's not THE answer."

I'm really thrilled that smaller cylinder is available and the results for those of us that have done the swap.

Just can't overemphasize the importance of a good crisp clutch.

[ck-GT86]

Originally Posted by Ultramaroon

I pull back all the time with the spring removal crowd. Feels like I'm pissing in the wind and I wonder "What can I say to explain in words why, although it's good to ditch it, it's not THE answer."

I'm really thrilled that smaller cylinder is available and the results for those of us that have done the swap.

Just can't overemphasize the importance of a good crisp clutch.

Mtec said their inner seals failed over time with the spring removed. So, i bought their spring to replace the oem one, awaiting shipment! I removed the spring a while back, but put it back in as the clutch started to feel funny.

. ck

[Ultramaroon]

Originally Posted by ck-GT86

Mtec said their inner seals failed over time with the spring removed. So, i bought their spring to replace the oem one, awaiting shipment! I removed the spring a while back, but put it back in as the clutch started to feel funny.

. ck

There is no relationship between the assist spring and longevity of any other component. Shame on Mtec for using scare tactics to drum up business.

Something else may be wrong but the assist spring is not part of the solution.

Do you have a link to their statement?

[JB86'd]

Originally Posted by ck-GT86

Mtec said their inner seals failed over time with the spring removed. So, i bought their spring to replace the oem one, awaiting shipment! I removed the spring a while back, but put it back in as the clutch started to feel funny.

. ck

What exactly did your clutch start feeling like?
Also, how are a pedal spring and inner seals connected if you don't kind me asking.

[ck-GT86]

Originally Posted by JB86'd

What exactly did your clutch start feeling like?
Also, how are a pedal spring and inner seals connected if you don't kind me asking.

It felt like the clutch dragged a bit, as if it wasnt catching 100% when driving aggressively. I also didnt like the few mm of freeplay in the pedal, my paranoid side said it was riding the clutch. Let me find what mtec said specifically... Might have interpreted it wrong.

[ck-GT86]

Originally Posted by Ultramaroon

There is no relationship between the assist spring and longevity of any other component. Shame on Mtec for using scare tactics to drum up business.

Something else may be wrong but the assist spring is not part of the solution.

Do you have a link to their statement?

http://www.ft86club.com/forums/showthread.php?p=2234804

Tada! How true that is, i wouldnt know. I dont see a reason to remove the spring after swapping the slave cylinder to be honest. Best mod ive done to improve the feel.