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Ok I thought I would make a thread to hopefully address questions and issues out there regarding clutch master cylinder (CMC) and slave cylinder options for the 9th gen Civic. It has been well established by me on this website that I was not happy with the way this car shifted. I have tried every CMC marketed for the 9th gen and I have swapped my CMCs back and forth over 20 times to compare and contrast the differences.


(from left to right: EM1 CMC, k20z3allmotor CMC, stock CMC, K-Tuned CMC. K-tuned slave on bottom)

Lets talk bout why we swap CMCs in the first place. The stock FB6 CMC uses a damper built into the CMC to prevent harsh engagements of the clutch, which could lead to clutch failure and/or damage. This was done solely as a bandaid to improper shifting as a way to hopefully lower warranty and reliability issues. The real problem with this is from a performance standpoint. If you are drag racing or doing something with your car where you need quick, positive shifting, you will want to swap out your stock CMC. The internals of the stock CMC are plastic which have not shown to have any issues, but just know that the internal construction is plastic.

Here is a pic of the stock FB6 CMC, and circled in white is where the internal fluid damper is:


Lets talk about the different aftermarket options out there:


Hybrid Racing EM1 CMC.
This is a very popular mod for the 8th and 9th gen to fix various issues. This CMC comes from the EM1 Civic (in case you didn't know) which was produced from 1998-2000. It is all metal construction internally which is why it is a popular option. The issue with this CMC is that you have to swap the clevis and rod from your stock CMC. The heads on the rods and pistons are actually different from the EM1 to the FB6 so the mating surface is not flush. All 9th gen CMC kits that use the EM1 CMC require using some of your stock parts. Pedal vibration is also a common issue, and it is something I experienced. I think this is due to the different shaped head on the rod, this creates an uneven mating surface for the piston/rod. Companies like Hybrid Racing, Hardmotion etc sell "EM1 clutch kits" that replace the hard line with a SS line. Clutch feel is very nice with this CMC, pedal pressure is slightly increased but almost unnoticeable. Engagement changes to a slightly shorter engagement window which I really like. I have been running this CMC kit from Hybrid Racing for a while and overall I really like it but it took some more modifications to get it to not vibrate, which I will talk about later on. It is 174.99 on their website: Hybrid Racing 8thGen Clutch Master Cylinder Upgrade Hybrid Racing


K-tuned CMC.

This came out several months ago, and to my knowledge it is the only manufactured CMC marketed to our car, meaning that this is not an OEM Honda CMC, K-tuned has this made to their specifications by a 3rd party manufacturer. This kit is marketed to the RSX, 8th and 9th gen Civics. Pedal pressure I would say is increased a bit from stock as well, due to both the EM1, and the K-Tuned CMC getting rid of the stock damper, this will increase pedal pressure by virtue of having no variable pressure inside the CMC. Engagement was long, slightly longer than the FB6 which I didn't like particularly. This is also 174.99 on their website:
CMC Upgrade Kit

Emmanuel K20z3AllMotor modified stock FB6 CMC.

Emmanuel is very well known in the 8th gen world, and has been into both road and drag racing. He sells a modified brand new, OEM Honda FB6 CMC that has the internal damper removed. Emmanuel has produced 2 very well known and regarded videos on how to adjust the stock CMC for proper engagement, and he has illustrated the cons of using the EM1 CMC. I finally got a chance to install this CMC but I have had it for almost 2 months (bought a house and moved) so before I installed it I wanted to take pics of all the CMCs and do a write up after driving on this CMC. Pedal feel is harder than stock, but engagement might be just slightly shorter. This is the best option out there IMHO. It requires no modification obviously as it is the same CMC as what is on your car right now. Emmanuel charges 215 shipped for a brand CMC that he modifies. You can email him @ [email protected] to purchase one.

Lets talk about vibration in the pedal:

There are a few schools of thought here. One is that the SS clutch line being unsecured in the engine bay can show engine vibrations through the line, which you then feel in the pedal. The another is what I have already mentioned, the piston/rod mating surfaces within the CMC. The last is the gasket for the CMC. The stock CMC gasket is very thin and soft. It really shouldn't be used more than once. It is a very soft foam type of material. The K-Tuned CMC kit comes with a very nice hard paper/cardboard gasket that is thicker. When I was experiencing bad vibrations with the EM1 kit, I tried this gasket and it eliminated pedal vibrations. The problem is, I cannot find anywhere that sells a replacement CMC gasket that would match the K-Tuned gasket.

In the next pics you can see the compressed, used FB6 CMC gasket, an unused, new FB6 CMC gasket, and the K-Tuned CMC gasket:





Ok now for the slave cylinder.
The stock slave cylinder has a clutch delay valve (CDV) which doesn't dampen the fluid to prevent harsh engagement, it restricts the movement for a very brief time to compliment the damper in the CMC. There is a DIY on how to remove the CDV from the stock CMC, which shows a nice improvement over leaving it in. If you don't feel like modifying your stock slave cylinder, K-Tuned came out with a replacement slave cylinder a couple of months ago. It is manufactured by K-Tuned similar to the CMC, and it does not have a CDV inside the unit. I felt no difference going from a slave with no CDV, to the K-Tuned so this really offers no performance benefit over a stock slave with the CDV removed. However if you do not want to remove it, this is a great option for you. I currently have the K-Tuned slave removed because I suspect it might have an issue, and K-Tuned is taking care of it.



I will update this thread as needed, and I will be happy to answer any questions.
 

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Nice write up bro
 
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Thank you for this! I think my next mods will be including an emmanual CMC and a CDV delete.
 

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Thanks very helpful. Wish I had seen this earlier, would have saved me lots of trouble...

I purchased the EM1 CMC not realizing that it requires the rod/plunger from the OEM CMC.

But I could not use it, since I destroyed the rod/plunger on the original OEM CMC while trying to adjust it :-(

I can sell it if anyone wants it, would like to get $175, but will take any best offer.
 

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thanks for sharing this info,
I'm up to do cmc upgrade to improve shifting
 

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subscribed! Thanks for posting this!
 

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Great write up!! I do have a question, which is better, changing the CMC without the damper, change the slave without the CDV or do both at the same time? I know some of you might say its a no brainer, do both, but changing only one of them with the modification might be better.
 

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Great write up!! I do have a question, which is better, changing the CMC without the damper, change the slave without the CDV or do both at the same time? I know some of you might say its a no brainer, do both, but changing only one of them with the modification might be better.
if you do them separate then you will be able to see the benefits of them individually. But that means you will have to bleed the line twice
 

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if you do them separate then you will be able to see the benefits of them individually. But that means you will have to bleed the line twice
Thanks for the reply, I know you are right :D What I was wondering is if anybody noticed that changing one of them, is better than changing both of them. I have a 2014 K24 and I am noticing the shifting is like everyone describes it here in the forum...my car still on factory warranty, still has 12,000 on the 3/36 so either I will do the CMC that looks factory, obviously for warranty purposes and i do not know what to do with the slave because if I do it myself its gonna get scratched and if I go with K-tuned the dealer will notice it...
 

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Thanks for the reply, I know you are right :D What I was wondering is if anybody noticed that changing one of them, is better than changing both of them. I have a 2014 K24 and I am noticing the shifting is like everyone describes it here in the forum...my car still on factory warranty, still has 12,000 on the 3/36 so either I will do the CMC that looks factory, obviously for warranty purposes and i do not know what to do with the slave because if I do it myself its gonna get scratched and if I go with K-tuned the dealer will notice it...
K tuned slave is the exact same as the stock but without the orifice which you can remove and hold on to if you ever want to go back to stock.
 

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K tuned slave is the exact same as the stock but without the orifice which you can remove and hold on to if you ever want to go back to stock.
Thanks for the reply, I guess thats the only way to do it if I want to take care of my synchros and my clutch :D
 

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Discussion Starter #14
K tuned slave is the exact same as the stock but without the orifice which you can remove and hold on to if you ever want to go back to stock.
It is but it isn't.

Yes, it is essentially a stock replacement slave without the CDV, however the internals are different. Also there is a slight difference in pedal feel with this slave versus stock. But you won't notice any big changes in the way the pedal feels overall by going K-Tuned or just modifying the stock slave.
 

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Discussion Starter #16
I just want to know the ktuned slave issue
What about it?

I actually had to remove my 2nd K-Tuned slave. Same issue as before, when pushing the slave in by hand it would not return quickly enough. I originally thought the clutch was slipping, not so. I have not contacted K-Tuned on this issue again and I am not sure if I want to even bother because I probably wont run one again.
 

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I'm getting ready to order these mods for my car, just wanted to check, is the Eman modded CMC and the stock slave with CDV still the way to go? or has there been an improvement since?
 

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The CMC has a dampener diaphragm that softens the pedal feel a bit and absorbs tiny vibrations that may resonate through the hydraulic system then to the pedal. The Slave Cylinder has a delay valve.
 
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