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Thread: Which Clutch System

  1. #1
    Senior Member fastzrex's Avatar
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    Which Clutch System

    I am rapidly getting ready to attach the engine/trans (2007 WRX 5spd) together and need clutch system recommendations. Engine target is 300 ft/pounds at rear wheels. Primarily a street driven machine with my preference to lighter clutch feel with a full clutch face sprung center (no pad type clutches).

    I like what I see in Exedy Stage 1 and ACT street/race. Any preference from those with their use in their 818? The Exedy has a lower torque rating of ~300 ft/pds with ACT at > 400 ft/pds.

    I will also need a flywheel. I see some as light as 8 pounds which sounds like a little light for general street use and I think the 14 pound version would be better. Thoughts?

    I have been doing research for some time and as this is my first Subaru just need some educated guidance. I have used Exedy clutches in a variety of projects with good success. NASIOC is all over the map on their recommendations.
    ~ Mark

    818C S/N 429ES: Start Date 1 September 2016
    2001 NB Miata LS3 V8 440 rwhp
    2004 Miata MazdaSpeed Factory Turbo

  2. #2
    Moonlight Performance
    Hindsight's Avatar
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    Would not suggest a lightened flywheel. You can run into ECU issues with them. I would suggest a brand new OEM flywheel, not a machined OEM flywheel.

    I'm running the South Bend Stage 3 Daily clutch and PP. You could probably get away with a Stage 2 (I forget their rating). Once it gets really hot, it can tend to chatter when starting from a dead stop. You can learn technique that will minimize the chatter but when it decides it wants to do it, it can be difficult to avoid completely. Mostly that is after racing it hard on the track or sitting in hot hot traffic.

  3. #3
    Senior Member TouchStone's Avatar
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    I have a exedy stage 2 clutch that I'm currently trying to sell on ebay. It was barely used. I'll sell it to anyone on this forum for much less. I would have used it myself had I not bought the wrong version (I needed a pull type).

    MODEL #EXE 15952
    PM if your interested.
    818S Chassis #288 2.5L 323hp
    Ordered: 9/19/14 Received Kit: 11/2/14 First Start: 5/31/15 First Drive: 6/7/15 Registered: 3/10/2016 Completed: 2/10/2017
    Status: Complete Build Thread Sold 9/22/2017

  4. #4
    Senior Member fastzrex's Avatar
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    Quote Originally Posted by Hindsight View Post
    Would not suggest a lightened flywheel. You can run into ECU issues with them. I would suggest a brand new OEM flywheel, not a machined OEM flywheel.

    I'm running the South Bend Stage 3 Daily clutch and PP. You could probably get away with a Stage 2 (I forget their rating). Once it gets really hot, it can tend to chatter when starting from a dead stop. You can learn technique that will minimize the chatter but when it decides it wants to do it, it can be difficult to avoid completely. Mostly that is after racing it hard on the track or sitting in hot hot traffic.
    Thanks for your input and experience. So many choices, not enough direct info!
    ~ Mark

    818C S/N 429ES: Start Date 1 September 2016
    2001 NB Miata LS3 V8 440 rwhp
    2004 Miata MazdaSpeed Factory Turbo

  5. #5
    Senior Member fastzrex's Avatar
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    Quote Originally Posted by TouchStone View Post
    I have a exedy stage 2 clutch that I'm currently trying to sell on ebay. It was barely used. I'll sell it to anyone on this forum for much less. I would have used it myself had I not bought the wrong version (I needed a pull type).

    MODEL #EXE 15952
    PM if your interested.
    Thanks for the offer. I really want an organic disk.
    ~ Mark

    818C S/N 429ES: Start Date 1 September 2016
    2001 NB Miata LS3 V8 440 rwhp
    2004 Miata MazdaSpeed Factory Turbo

  6. #6
    Senior Member fastzrex's Avatar
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    NASIOC Clutch Review

    I have looked all over for a better list/review and here seems like the better of what I have previously found. Just had to read a little between the lines:

    https://forums.nasioc.com/forums/sho...eight+flywheel

    https://forums.nasioc.com/forums/sho....php?t=1498967
    Last edited by fastzrex; 06-23-2017 at 10:37 AM.
    ~ Mark

    818C S/N 429ES: Start Date 1 September 2016
    2001 NB Miata LS3 V8 440 rwhp
    2004 Miata MazdaSpeed Factory Turbo

  7. #7
    I guess I get to be the guy that pushes you back toward the light weight one!

    I have the ACT streetlite flywheel (14lbs) and a OEM replacement clutch from Luk. Couldn't be happier with the flywheel. Car revs and almost "barks" like something that looks like an 818 should rather than an old Chevy Cavalier. It's also a really easy way to take 10lbs off the already heavy rear axle. Went with the luk clutch simply because I wanted an OEM replacement and have heard too many bad reviews on the crappy bearings Exedy puts in their kits. Can't really comment on engagement as my master and slave cylinders aren't really the sizes they're supposed to be.

    Generally speaking, you only have the tuning issues (commonly referred to as the "phantom misfire" on other scooby boards) with a sub-ten pound "race" flywheel, and not even the manufacturers recommend them for street use. I believe ACT even admits such a thing can occur and will need some CEL trickery to eliminate.

    If you are doing a full custom tune (rather than an OTS tune from Cobb, etc.) I would certainly do that with the stock flywheel first, then switch.

    Every OEM replacement I've ever done has had an incredibly light clutch pedal afterward. Not sure how the Stage 1/2/n clutches compare.

  8. #8
    Senior Member fastzrex's Avatar
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    Quote Originally Posted by phil1734 View Post
    I guess I get to be the guy that pushes you back toward the light weight one!

    I have the ACT streetlite flywheel (14lbs) and a OEM replacement clutch from Luk. Couldn't be happier with the flywheel. Car revs and almost "barks" like something that looks like an 818 should rather than an old Chevy Cavalier. It's also a really easy way to take 10lbs off the already heavy rear axle. Went with the luk clutch simply because I wanted an OEM replacement and have heard too many bad reviews on the crappy bearings Exedy puts in their kits. Can't really comment on engagement as my master and slave cylinders aren't really the sizes they're supposed to be.

    Generally speaking, you only have the tuning issues (commonly referred to as the "phantom misfire" on other scooby boards) with a sub-ten pound "race" flywheel, and not even the manufacturers recommend them for street use. I believe ACT even admits such a thing can occur and will need some CEL trickery to eliminate.

    If you are doing a full custom tune (rather than an OTS tune from Cobb, etc.) I would certainly do that with the stock flywheel first, then switch.

    Every OEM replacement I've ever done has had an incredibly light clutch pedal afterward. Not sure how the Stage 1/2/n clutches compare.

    Thanks for your input. Did not consider the possible tuning effects of a misfire detection, but I see that can be handled. Any problem with slippage with your stock pressure plate / clutch setup? I am using the WilWood pedal set with stock slave cylinder.
    ~ Mark

    818C S/N 429ES: Start Date 1 September 2016
    2001 NB Miata LS3 V8 440 rwhp
    2004 Miata MazdaSpeed Factory Turbo

  9. #9
    The Exedy OEM replacement clutch is good. So is the Subaru OEM Legacy GT/WRX clutch. However you are making more power than OEM and they may not satisfy you when you track the car.

    I've had the Exedy Twin Disk Hyper clutch now on two race cars and love it. OEM like lightweight leg push but very strong for higher HP applications. The only issue I've found with the twin disk is they rattle a bit. It's a totally normal sound for the twin disks to make but you might not like it in a street car.
    Owner: Colonel Red Racing
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  10. #10
    No problems with slipping, but I only have a 2.5NA though so it's not holding much. (That's actually why the master/slave are mismatched, the 2.5RS master doesn't fit the 818 chassis.)

    I've done quite a few flywheel/clutches on these cars and while every manufacturer recommends you match their own flywheel and clutch kit, thus far I've never seen two that are incompatible - at least for OEM grade parts.

  11. #11
    Should also mention that there generally seems to be some correlation between the phantom misfires and also having a light weight crank pulley. If you've removed the stock pulley you know that there's quite a bit of mass there. I've really never heard of there being issues running just the streetlite flywheels.

  12. #12
    Senior Member fastzrex's Avatar
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    Quote Originally Posted by Sgt.Gator View Post
    The Exedy OEM replacement clutch is good. So is the Subaru OEM Legacy GT/WRX clutch. However you are making more power than OEM and they may not satisfy you when you track the car.

    I've had the Exedy Twin Disk Hyper clutch now on two race cars and love it. OEM like lightweight leg push but very strong for higher HP applications. The only issue I've found with the twin disk is they rattle a bit. It's a totally normal sound for the twin disks to make but you might not like it in a street car.
    I have driven twin disk clutches (in a Cobra); the noise it very nice.

    Twin disk clutch is a little out of my price range, but I do appreciate the input.
    ~ Mark

    818C S/N 429ES: Start Date 1 September 2016
    2001 NB Miata LS3 V8 440 rwhp
    2004 Miata MazdaSpeed Factory Turbo

  13. #13
    Senior Member fastzrex's Avatar
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    Quote Originally Posted by phil1734 View Post
    Should also mention that there generally seems to be some correlation between the phantom misfires and also having a light weight crank pulley. If you've removed the stock pulley you know that there's quite a bit of mass there. I've really never heard of there being issues running just the streetlite flywheels.
    Thanks for the clarification!
    ~ Mark

    818C S/N 429ES: Start Date 1 September 2016
    2001 NB Miata LS3 V8 440 rwhp
    2004 Miata MazdaSpeed Factory Turbo

  14. #14
    Senior Member fastzrex's Avatar
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    I finally made a decision and purchased/received a ACT clutch / flywheel assembly. This SB11-HDSS package requires the use of the included flywheel (lightened (13.5 pds)) as it is different from a normal WRX to allow the fitment of the included 10mm larger clutch. It is like putting in an STI flywheel/clutch without the hassle of clearancing the inside of the bellhousing to fit the STI assembly. One downside is you are tied to the clutch assembly from ACT unless you want to also change the flywheel again in the future.

    In reading on NASOIC that many people were successful in fitting STI flywheel/clutches after removing material from inside the bellhousing. I considered doing this, but there were enough concerns about possible weakening of the WRX bellhousing that it did not sound like the right direction. I do not know if there would be the problem as I have not seen what a STI assembly looks like with the WRX bellhousing.

    This assembly is rated at 420 ft/pd torque which is plenty for my engine. The price is higher than the Exedy stage 1 and their lightened flywheel, but the holding torque of the ACT combo is what seems safe for my setup. Hopefully, the clutch pedal pressure will be reasonable.
    ~ Mark

    818C S/N 429ES: Start Date 1 September 2016
    2001 NB Miata LS3 V8 440 rwhp
    2004 Miata MazdaSpeed Factory Turbo

  15. #15
    Hi: Anyone had a experience with the clutch pedal being way too difficult to engage. Movement is minute and almost impossible to get a smooth takeoff without stalling the 818 street kit. It was suggested that there may be air in the line; any other thoughts? Capt. Bill

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