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Carbonetic Street Twin Clutch Review (and my clutch's claim to fame)

21K views 43 replies 12 participants last post by  mrfred 
#1 · (Edited)
According to FedEx my clutch is waiting for me at the leasing office when I get home. As there's not much user info out there on the Carbonetics Twin I'll keep this updated as I go through the lengthy break in as well as compare it to my Exedy Stage II. I'll also update with my personal reasons why I chose this clutch.

And as to it being famous: It's the model for the pics on Jacks Transmissions' page. (Currently listed as the evo 8 and 9 clutch, but that's my clutch!).

Pics from the site, will take some myself when I get the clutch:





Clutch will be installed in a couple weeks. Transmission is currently on it's way to Jacks for the rebuild w/ center diff fix.

Also want to say thank you to Jack's for taking the time to answer my obnoxiously many questions and for the great prices.


PICS (I know I need something better then cell phone camera)

Clutch and fluids:


Clutch:


And transmission back from Jacks Transmissions:



Updated 3/01:

Picked up the car last night. First impression of the clutch feel and how it drives: WOW. Engagement is soo smooth, clutch pedal is significantly lighter then my Exedy Stage II. It's been too long for me to remember what stock felt like, but I don't think it's any heavier then stock. It's very light.

It's also an amazing combination between being able to start smoothly, and having crisp nice shifts. It still grabs plenty hard, but allows for a smooth start up. It's quite amazing. As I've only driven ~20miles on it and have 980 more to go in the break in, I'll have to update later what it feels like during performance driving. I do not and never will drag race the car though, so sorry for those interested in that aspect.

Noise
I feel this deserves it's own section as it is what everyone says the drawback to the clutch is. You can clearly hear the "clutch chatter" noise when depressing the clutch pedal. I was aware of this noised before I bought it, and frankly so far it doesn't bother me in the least bit. You can hear it, but it's not that loud.

Now, that isn't the only noise. This is still an ongoing "investigation," but it appears that you get a few more noises with this clutch that I was not expecting. We had the car back up on the lift last night and checking everything because of these noises. I'm waiting on replies and doing some more research, but both noises appear to be from the clutch and possibly normal?

1) In neutral with the clutch engaged, a very rapid "click" noise (seperate from and a little louder then the normal engine ticking noise) can be heard from the transmission area. Up on the lift we were able to confirm this is definitely from the clutch/transmission area. After talking with Jacks, he confirmed it was the clutch. This noise only occurs with the car in neutral and clutch engaged. Put it into gear or press the clutch pedal and no more noise. It also doesn't always happen, just sometimes. The transmission was vibrating quite significantly when it was making the noise.
UPDATE: I was unable to make the noise repeat today. I also spoke with ATS & Across who informed me that the noise sounded normal and should go away. So scratch this one of the list? We'll see with more time.

2) A "clunk" or "thud" that I still am trying to diagnose. This noise scared me when i first heard it. When rapidly applying gas (while already moving and in gear) so as to "shock" the drivetrain, you can hear a very loud and audible "clunk." From in the car this does sound like it's coming from the clutch area. It's also clearly audible when driving over bumps; even the little "lip" into my garage causes the noise. It doesn't matter if the car is in gear or not, clutch engaged or not. I thought something was loose, but we checked every bolt and the motor mounts and suspension and everything was on tight and securely.

I don't know for certain yet if this is another noise from the clutch, but as the clutch is the only piece that was changed on the car, I have to assume it is. I emailed ATS and Across about these and am waiting for a reply.

Videos of Noise #2

I recorded it when pulling into and out of the garage. This isn't a suspension noise as the same noise happens when giving it sudden gas on just a smooth paved road. It's 100% new since the clutch install, and louder then the videos makes it seem.

Also, this is a maybe 1" high little bump, this isn't a big or even very noticeable bump riding in the car!

http://youtu.be/atbV2DjjgJs

http://youtu.be/ihIPqmEv72M


UPDATE 3/02:

Noise #2 Fixed! Turned out to be a loose nut on the rear motor mount.

Also want to mention that ATS & Across called me back yesterday a few hours after I had emailed them. They were very helpful and discussed what could be possible causes. So good customer support from them the one time I dealt with them.

Now that that noise is fixed the car feels tight and runs beautifully. Now I can 100% say I LOVE this clutch. I guess will have to wait through the lengthy break-in period. But for driving around town it's both smoother then stock while being more aggressive and having more bite when you want. The control is phenomenal and the pedal feel is perfect. I couldn't be happier.

UPDATE 4/17:

I finally finished the 1k mile break in. (although, I have to admit there were a few times during break-in that I drove the car more aggressivelly then I was supposed to. Oh well, no ill effects soo far).

Why I chose this Clutch
I want to first go back and explain how I ended up choosing this clutch.

A little background:
-I bought the car brand new in march '08.
-Flashed AP stage 1 at 15k miles
-Replaced the clutch with an Exedy Stage 2 and ACD Streetlite Flywheel at ~25k miles.
-Installed TBE and flashed AP stage 2 at ~27k miles.
-CMC failed and replaced with Magnus + Evo IX cmc at ~31kmiles.

I bought the Exedy based off a couple days of research on the forums and a lot of guys at the time were upgrading and using the Exedy. I heard lots of positive feedback on it as a clutch, and seemed like something a bit more fun, a bit more bite, and would handle my end goals of ~350whp/wtq.

When I first had it installed I LOVED the Exedy as a clutch. Compared to stock the engagement and bite, it felt great. Made the car feel more like a race car. For the first year and ~5k miles this is how I felt about that clutch. However the car was not a daily driver, whenever I took it out I went out and enjoyed the ride.

Continued...
 
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5
#2 · (Edited)
... continued from last post:
At ~29k miles on the car and ~5k miles on the Exedy Stage 2, the car became a daily driver again. I quickly grew more and more annoyed and frustrated with the Exedy. Trying to drive smoothly to work in the morning was almost impossible. Either rev the engine to over 2k rpms, or have the engagement be very rough and jerky. Trying to baby it and start up at a normal pace was impossible.

So when I started having clutch drag issues after 4 more thousand miles of daily driving on the Exedy, I was frustrated but also relieved. I hadn't planned on needing to replace the clutch for several more years, and had been saving to buy wheels/tires and coilovers. But I knew that I had a chance to go back and do it over again and do more research and find a better clutch. I was excited to acutally enjoy driving the car again. So I spent litterally 3 weeks researching and searching for the right clutch.

My Criteria for the new clutch
- Smoother engagement and better pedal feel for daily driving.
- Able to withstand my power goals (now ~380who/wtq)
- Able to withstand the abuse of racing. Auto-x and track days (I don't and have no interest in drag racing)
- Reliable. I did not want to worry about having to replace the clutch again after only 9k miles. I wanted it to last a while.

I was immediately drawn towards Twin Disc Clutches. I was under the impression from reading posts on this forum that a twin disc clutch would satisfy all my criteria. It would offer the holding capacity for the additional power, would be a smoother pedal engagement, and would last longer as there as more friction material and surfaces. But I was not going to make the same mistake I did last time and jump into a clutch purchase without digging deaper and doing more research.

First I contacted several venders on here, including MAP, Sean at DSG, and Jack's transmissions. All three were very helpfull and offered good knowledge and great suggestions.

The first thing I learned was that Twin Disc Clutches are NOT a simple solution to my clutch search as I had thought. Some have a very heavy pedal feel, they don't last any longer then single disc clutches, and that due to the aditional rotational mass of multiple clutch plates they can really wear on and harm your synchro's. However, I was told that the Carbonetics, due to it's lightweight carbon discs, would not be an issue with regards to additional wear on the synchros, and that it also doesn't have a heavy pedal feel.

So, needless to say I was very interested in the Carbonetics Twin. It was the only clutch so far that everyone had said would satisfy my needs. BUT it was also quite expensive, ~$2k.

So I sarted looking again at single disc clutches. At many different manufacturers and all the different clutch materials and designs. However, as much as I searched I couldn't find a single disc that I felt would satisfy my needs as well as the Carbonetics. As labor install on a clutch is already quite a hefty figure, I didn't want to "settle" for something and in another measly 9k miles find myself pissed I made the wrong choice that took away from the fun of the car.

The Evo is an expensive purchase and is my hobby, so I figured why go cheap on a clutch which plays such a vital role in the drivers experience. So I bit the bullet and kissed goodbye to a large portion of my new wheel/tires/coilovers budget (bye-bye coilovers) and bought the carbonetics.

The only criteria that the Carbonetics didn't satisfy, but that no clutch is garunteed to offer, is a garuntee that it will last longer. However, I hope I can, with time, share with the community how well the clutch holds up and how long it lasts.

Impressions after breakin and first auto-x event
I've now had a couple weeks to beat on the clutch and test it some, as well as the first time at the auto-x track this past weekend.

All I can say is I LOVE it still. Going back to my criteria:
- Smoother engagement and better pedal feel for daily driving. Yes.
The pedal is as light as with the stock clutch, and the engagement is beautiful. Yes you can get a tiny bit of jerk/chatter during engagement, but only a very tiny bit, nothing even on the same scale as the Exedy Stage 2. It's actually enough to put a smile on your face when it happens knowing that you have a beast of a clutch under the hood. It's also easy to avoid if you focus just a bit during start up.
- Able to withstand my power goals (now ~380who/wtq). Yes, it's rated for over 700 torque, so I'll be fine!
- Able to withstand the abuse of racing. Auto-x and track days (I don't and have no interest in drag racing) Yes, and very well.
- Reliable. I did not want to worry about having to replace the clutch again after only 9k miles. I wanted it to last a while. We will find out, but form the few other people using the clutch, the reports seem to indicate it has a respectable lifespan. Not to mention it is supposed to be easy/realtivelly cheap to rebuild as the carbon discs actually ware very litte.

Ok, so performance aspects of this clutch:
First, shifting gears is absoultely beautiful now. I do not know how much to attribute to the transmission rebuild by Jack's or to the lightweight clutch. High RPM shifts are amazing though, better then on the stock clutch or the Exedy with the Streetlite flywheel.

Second, The auto-x event had you start straight behind the timing boxes, so I had to launch the car(highlighted to grab drag people's attention as this is probably the only usefull part of my post to them). I was hesitant because i didn't want to launch the car on this clutch, but decided I had bought the clutch to be able to race on so I was going to use it. Having had experience launching on both the stock and the Exedy Stage 2, this clutch puts both those to shame. I'm probably better at launching the car now after having practice and experience on those clutches, but I was stunned by how well the Carbonetics clutch engaged on launches. This clutch, which was soo smooth during daily driving, would bite so hard when launching. Due to the large range of pedal motion, controlling that engagement was very easy. Rev to 4500, quickly release clutch till it's biting hard, let off the rest of the way appropriately as to keep the rpms in the sweet spot. The Carbonetics Twin clutch just grabbed. I was very impressed. I was also very quick off the line.

The auto-x course also had a pinpoint turn needing to be heal-toe'd down into first, as well as a straight at the end needing to be shifted up into 3rd. I abused the clutch, and it performed beautifully.

The Fine Print
I feel I must include this as I am still investigating 1 remaining noise. When the car is fully warmed, and I sit idling at 750 rpms for a bit of time, something in the transmission/clutch area starts vibrating at a resonance frequency. Using my foot to pull RPMS up to 1k stops the vibration, and I never hear the vibration elsewhere.

As the shop that installed the clutch didn't fully tighten the motor mounts, I plan on jacking the car up this weekend and testing every bolt I can find in and around the transmission to make sure it's tight. However, having spoken to ATS & Across as well as Jack's Transmissions, this isn't something wrong with the clutch as the noise occurs independant of wheter clutch is engaged or not, and does not vary with RPM level.

However, while there isn't anything wrong with the clutch, the clutch could be contributing to the noise. THIS IS THE FINE PRINT: (I'm quoting a reply from Jack at Jack's transmission, which is what I believe is the noise/problem)
The sound could be noise from engine crank shaft torsional whip. If it makes the sound at idle only and not when you rev the engine, or have the RPMs higher, then it’s normal. If it makes the noise all of the time at any RPM, then something is wrong. In any transmission, there is slack in the assembly and if the engine has some torsional vibrations at idle, the parts will chatter and make a noise as you describe. The clutch you have increases the torsioinal whip, and harmonics, from the crank, and also transfers that noise into the trans. Things like lighter flywheels, stiffer disk hubs, and no dampening springs in the disks will cause this type of noise, and your clutch has all of the things which would do this. I would say it is a small annoyance, but one which is typical for a vehicle with such parts in it.
I will post a video of the noise later tonight. Once I check all the bolts are secure, if I don't find a fix to the noise, I will simply have my tune adjusted to idle at 1k rpms and that will solve this problem.

video of the transmission vibration noise


Thanks for reading!
 
#3 ·
Interested to hear what you think. If it doesn't take too much time to explain what happen to the Exedy Stage 2 you had?
 
#4 · (Edited)
Had the Exedy Stage 2 installed almost 2 years ago with ~26k miles on the car, along with a ACT Streetlite flywheel. Since then I have put 9k miles on the car, including a couple HPDEs and several auto-x events. No rev limiter launches, a couple from ~3500rpms.

After around 7k miles on the clutch the CMC failed, and so I replaced that with an Evo IX CMC using the Magnus adapter plate.

About 4 weeks ago I noticed that for no apparent reason it had all of a sudden gotten extremely notchy/grindy getting into gear. After speaking with Jacks Transmissions, daignosed that it was a Clutch Drag issue.

As such, the clutch had to be taken off the car to figure out the problem.

I don't know yet if it was installed improperly or a parts failure as clutch still hasn't been taken off. Exedy wasn't much help, just basically told me I was SOL as it has been more then 90 days; which is fair enough as that is their warranty on these clutches.

Anyway, as I was going to be paying to rip it out irregardless, I didn't want to put back in a used disk nor did I want to put back in the same clutch. The Exedy Stage II had a lot of bite and was great for racing, but for daily driving it was a PITA. It's possible my troubles with it as a DD clutch were because something was wrong or off about it; I'm still waiting to find that out.

That is why I began the hunt for a new clutch. Took me the better part of January doing research and talking to some truly helpful vendors on here to find the clutch that I was confident best fit my criteria.
 
#7 · (Edited)
Updated after first time driving on it. More info to come.


Do you have any experience with the "noises" I have described?
 
#9 ·
You do have me curious about what your issues/opinion of the clutch is. But I'll just keep updating this as I figure more stuff out and get more time behind the wheel.
 
#10 ·
I have a noise with the pedal depressed, I have been told by Carbonetic that it is normal. I can't describe it but it is rotational. I also have a Tilton CMC and I am not sure I am getting complete stroke out of it so I get lock out some times.
 
#11 ·
sounds like Clutch chatter or throw out bearing If I have to be general.

My stock evo had a shit ton of clutch chatter and dealer brushed me off. 27k miles later my PP completely failed. disc was fine.
 
#12 ·
#13 ·
It's not what I consider chatter. And the TB is fine. The TB does not live in the PP. t rides free on the input shaft. They actually use a modified Toyota bearing. I don't think my clutch is the issue I think it's hydraulic.
 
#15 ·
yup, that's normal. I have exact same noise. And it's what carbonetics calls "clutch chatter". Lord knows if I can explain exactly what causes it, but it's from the plates free spinning and colliding. As far as i can tell.
 
#20 ·
Added some videos of noise number 2.

From speaking with Jacks and ATS & Across it would seem that noise number 1 is normal and should go away. I was unable to get it to repeat tonight. So maybe that's taken care of
 
#21 · (Edited)
So both noises have been adressed and resolved. Clutch is awesome and I'm antsy to be able to take the car out!
 
#23 ·
What caused noise #2?
 
#24 ·
The rear motor mount wasn't tightened enough when the shop re-installed it.

Another $100 to get dealership to find and fix that, think I can get reimbursed from the shop that did the install? lol
 
#25 ·
So I volunteered to be DD last friday night with group of freinds. Excited to drive the car I head over to my buddies place to pick them up. Along the way I get a call and they tell me I'm going to be driving another buddies car because there were 6 of us.

Wtf? damn, the only reason I volunteered to DD was because I wanted to drive my car. Whatever, still wanna go out.

So I get there and turns out the car I was to drive was an H3. Ok, I guess I can be excited to get to drive a hummer. Never driven one before.

Anyway, that damn H3 was shit. Just reinforces my opinion that if you're going to drive a hummer, H1 or nothing at all. god they suck.
 
#26 ·
How's it holding up after break in?
 
#27 ·
Just finished break in.

I love this clutch. I'll update my review in a bit.

The only downside to it is the noise, but if you don't mind that I can't find a single thing that could be better about this clutch. Assuming it doesn't fail on me in some ridiculously short amount of time, I'm certain I will rebuild/replace it with another one of these.
 
#28 · (Edited)
Updated today and added a LOT of information.

UPDATE 4/17:

I finally finished the 1k mile break in. (although, I have to admit there were a few times during break-in that I drove the car more aggressivelly then I was supposed to. Oh well, no ill effects soo far).

Why I chose this Clutch
I want to first go back and explain how I ended up choosing this clutch.

A little background:
-I bought the car brand new in march '08.
-Flashed AP stage 1 at 15k miles
-Replaced the clutch with an Exedy Stage 2 and ACD Streetlite Flywheel at ~25k miles.
-Installed TBE and flashed AP stage 2 at ~27k miles.
-CMC failed and replaced with Magnus + Evo IX cmc at ~31kmiles.

I bought the Exedy based off a couple days of research on the forums and a lot of guys at the time were upgrading and using the Exedy. I heard lots of positive feedback on it as a clutch, and seemed like something a bit more fun, a bit more bite, and would handle my end goals of ~350whp/wtq.

When I first had it installed I LOVED the Exedy as a clutch. Compared to stock the engagement and bite, it felt great. Made the car feel more like a race car. For the first year and ~5k miles this is how I felt about that clutch. However the car was not a daily driver, whenever I took it out I went out and enjoyed the ride.

Continued...
 
#29 · (Edited)
It's almost been a month since your last update! Still loving it?

I'm looking into the twin plate clutches myself for the same reasons you had but have some concerns with noise and pedal modulation when on hills. I live in Los Angeles and a lot of our parking garages are underground with steep inclines to get out of them.

Do you happen to have any feedback on how this clutch does with steep inclines?

The Carbonetic Street Twin is looking like a good option. Especially with Jack's pricing :shades:

Also, did you take your clutch restrictor pill out when you did your Magnus?

Thanks.
 
#30 ·
Yea...my tranny is getting the rebuild at Jacks and the Carbonetic and CM850 are about the same price...I'm stuck on which one to get. I had clutch chatter on my VIII, but wasn't as bad as the vid you linked on EvoM. Gotta say if the chatter is that bad I think I might go with the CM850, but can you get rid of it on the Carbonetic?
 
#34 · (Edited)
Soo... Anyone have a good guide on how to bleed the clutch line?

About a month ago I let a buddy co-drive my car at an auto-x event as his evo was down getting boost leak issue fixed. Afterwards I immediately noticed the clutch pedal engagement was not as "crisp" for lack of better word. Not blaming my buddy, I'm sure 8 decently hard back to back launches instead of 4 was more likely the issue.

It still fully engages/dissengages and I've done a couple more events since then and it hasn't gotten worse. It still bites plenty hard on launches. I still love the clutch, but considering the sudden and noticeable change in pedal feel it's irritated me ever since.

Anyway, I'm thinking maybe I got a little air in the clutch line? So I was going to try and bleed the clutch line and hopefully that helps. Also I'll check to make sure the shop mounted the push-pull conversion kit properly.

Anyone have any other ideas on what could cause the pedal engagement to just feel less crisp?
 
#36 ·
Soo... Anyone have a good guide on how to bleed the clutch line?
It's pretty simple. Get a buddy to help you, an empty bottle with a hole drilled in the top of it for a vac line and a bottle of fluid. Pour some fluid in the empty bottle and make sure the vac line stays submerged in it.

Remove intake assembly to gain access to Slave cylinder on the trans. Yours will look slightly different from the others online because the ports have been swapped around due to the conversion. The nippled one will be the one you slip the other end of the vacuum hose onto.

Pop open your fill cap and tell your buddy to do the traditional "Pump and hold" method while you crack open the bleeder valve on the "holds". You'll want to shut the valve just before the fluid stops moving so you don't suck up any air into the system. Keep an eye on the reservoir level as to not suck in any air from that direction either.

Do this at least 5-10 times or until you no longer see air bubbles.

Also if your fluid looks to be in bad shape, do this until you see nice clean fluid coming out of it.

Happy bleeding!
 
#38 ·
Posted a video where you can hear the noise it makes at idle.

I have intake + UICP & LICP coming this week. So on Saturday I'ma rip the front bumper off and really check everything about the way the transmission is mounted.

That said, been living with that noise for a little while now and doesn't seem to be affecting anything negatively. Any idea's on how to get it to stop would be nice though.

 
#39 · (Edited)
I did check every bolt I could find on the transmission when installing the intake and intercooler piping.

I guess the cause of the noise is as Jack described in his email. But I haven't been able to find anyone else with a carbonetic's twin and experiencing the same noises though.

Is it possible that the modifications done to the center diff when i sent the transmission into jack's to be rebuilt could be causing this noise? Maybe if the "oil scoops" installed are out of balance, causing a vibration as it rotates?

EDIT
I realized it can't be the modifications done to the transmission because it only happens when in neutral or with the clutch dissengaged. As soon as the clutch is engaged and car in gear the vibrations don't ever occur. It's also definitely amplified when the AC is on, just some things I've noticed. Overall it hasn't been a problem though.
 
#40 ·
having some shifting issues now :(

So i checked to make sure the slave cylinder is fully blead, everything seems to be connected properly with the clutch.

After auto-xing this past weekend and doing several hard launches, which the clutch handled beautifully, now the car has been more difficult to shift into gear.

My initial scare went straight back to clutch drag again. But I don't believe that is it. I both adjusted the clutch pedal travel to increase the amount it dissengages, as well as tested it by revving it in first with the clutch pedal down.

I also noticed that it's hard to shift into gear even with the car turned off. This has never happened before. gonna rip stuff apart tonight and check the connections on all the shifter cables. If anyone has any advice or suggestions I'd appreciate it!
 
#41 ·
I know this thread is almost 6 months old but thought I'd add my insite into rattle #1 seeing as my EVO VIII has the exact same rattle with a carbonetics clutch. I am lead to believe it is gear rattle which is basically normal using a light weight clutch with unsprung centre. Essentially it is the gears in the box meshing and unmeshing due to the normal lash between the gears.

ACT have some information on the phenomenon here -http://advancedclutch.wordpress.com/2012/01/26/tips-from-act-gear-rattle/
and a workshop has done a write up here -
http://www.uucmotorwerks.com/flywheel/gear_rattle.htm

So, essentially harmless but annoying. I just noticed today that it is far more noticable with a warm transmission then at cold start which lead to me trying to find a reasoning for the noise. I had initially thought it was the auxilliary belt tensioner due to the same reason (engine pulsations). Exact same deal as yours, more noticeable with more load on the engine, only occurs at idle.
 
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