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Advice on net clutch??

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  • Advice on net clutch??

    After getting the car up and running seemingly reliable the past several weeks, after my first tuning session the clutch began to slip. Haven't even thrown timing at the thing and just got the A/F ratio to where it's fairly stable across the board and in the low 11s in boost. Below is the current setup:

    Spec Stage 2 with about 30K miles

    S15 turbo (around 15-18 psi depending on my demands)
    Front Mount
    Tomei mani/downpipe, etc
    The usual

    Current power level: 270/270 at the wheels at 15-16 psi before throwing timing at it

    Goal: HP range will be mid-high 300s to mid-low 400s (but since the clutch is more rated in terms of torque, I would like a solid 250-300 ft-lb at the wheels from 4K all the way to rev limit around 7700) after this season is over and the car is sorted.

    Car goal Will be mostly a street car with a rollbar/konis/rubber/etc. This will be my HPDE/PDX/AUTO-X car this year and on, so somewhat of a dual roll (would prefer a clutch that is not entirely too grabby. So maybe a sprung 6 puck setup or a fullface setup with proper friction plate. But please go ahead and school me!)

    Let me games begin


  • #2
    Your flywheel torque for mid 400 rwhp will probably be about 370-390 ft-lbs unless you're talking about a big turbo (GT3076R or larger), in which case reduce that maybe 20 ft-lbs.

    A Comp Stage 4 with springs is probably your best bet. You'd have headroom for future power.

    The limit for a streetable clutch would be something like a stock SR organic disk and an ACT HD pressure plate. That's as stiff of a plate as I'd really run (pedal pressure was reasonable, but not light by any means, the XT plate is way stiffer). Then pair it with a lightweight flywheel if you're still running the stock one (which is horribly heavy). It will be right on the limit of slipping above 400 rwhp. You might make it, you might not.
    '18 Chevrolet Volt - Electric fun hatch for DD duty!

    DefSport Koni Sleeve and Spring Perch Buy!!!


    • #3
      Turbo is still up the in the air since I have a stock mani/Cody ACE EWG/JGS 44/50mm wastegate setup sitting here in the basement. From what I am seeing with the latest and "greatest" from Garrett in the GTX3067R, it's tough to stay away.........We will see.

      Anyways, looking at the competition clutch website, the 6 puck spring stage 4 looks like a great bet! They did mention the issue of "clutch chatter" so for something that is dual purpose, I wonder if that will become an issue?? And I never like to come to grips with the the idea of clamping force vs torque capacity. I had a CM FX500 on my old FWD SR, and although the clutch pedal feeling was similar to stock (I guess it had to do with the fullcrum point and PP design), I rather enjoyed that clutch. A little grabby, so for my projected power level, and setup something less grabby would be nice.

      The second option you stated, yeah, pedal pressure is something I would prefer to keep on the reasonable side. If you have had the Spec Stage 2, a pedal pressure in that region is something that is very tolerable on a everyday/everything bases. Do you have any input on a slightly lighter pressure plate but coupled with a sintered iron friction surface?? Does that even exist in the RWD SR world??

      What setup do you have at this moment and which ones have you gone through DEF?? Pros/Cons of each??

      Either way, thank for the advice on the stage 4. I will surely bank that recommendation

      Also, next what would you recommend for a flywheel Def?? The stock NEEDS to go!

      Competition Clutch has it for circa $391. Not a bad price


      • #4
        The 6 puck sprung disks aren't too horrible to drive. I had an ACT 6 puck non-sprung in my car for about 7k miles. With a lightweight flywheel you have to pay attention, but it's something that you can definitely drive on the street. When it grabs it grabs, so you can't just absent-mindedly lightly engage the clutch like you're putting around in traffic. But as long as you're committed to making the car move and giving it some throttle it's not going to stall.

        I haven't driven the Comp Stage 4, but I imagine it's about the same pedal pressure as the ACT HD give or take. Probably a bit more than your Spec Stg 2 (which I felt in an E30 - was pretty light... like stock PP really). But it won't be horrible, figure 30-40% more effort. Just enough to let you know you're driving a big boy clutch.

        The stock SR clutches are big enough, and the thus the flywheels big enough that even at the extreme lightweight end they still have decent inertia. So I'd skip the really cheap stuff on eBay and get something like the Comp 10.2 lb flywheel.

        BTW - I can get you all this below MAP and some Redline MT90 to go with it.

        If you're staying ~300 rwhp or below, which is probably about 300-310 ft-lbs at the flywheel, I'd probably go with an organic disk, but much above that really starts screaming for a grabby ceramic disk to up the torque capacity.
        '18 Chevrolet Volt - Electric fun hatch for DD duty!

        DefSport Koni Sleeve and Spring Perch Buy!!!


        • #5
          I'm running ACT HD pop with a sprung 6 puck now and its not a problem at all. Yeah if you don't think about it, you'll look like your 16 all over again in traffic, but I haven't had a problem slipping it to get the car in/out of the trailer or through tech and grid..
          Its in a stockish KA so I can't say for ultimate torque capacity, but that doesn't matter when you're discussing driveability.
          Originally posted by SoSideways
          I don't care what color they are as long as they are LONG AND HARD.
          '04 G35 Sedan 6MT- The DD
          '96 240SX- The Track Toy


          • #6
            Def, PM me a price on both the on the stage 3 and stage 4 Def . I use a special blend of gearbox fluid, so no need for those.

            Matt, yeah, I am aware at some point drivability goes out the window the more capacity you require, but I wonder where than point it?? Hmmmmmm


            • #7
              The sintered iron disc you were talking about is another step up in engagement harshness.

              I'll shoot you a price on the Stg 2, Stg 4 and the flywheel. Looks like the Stg 3 was discontinued a long time ago. It seems like the same PP as the Stg 2 with a kevlar and iron/carbon disk. I imagine they had enough problems with those and decided to kill them. The hybrid disks sound good, but you end up wearing the one organic side even faster than if both are organic because it takes all the slipping. So it's almost the worst of organic and worst of a grabby material.
              '18 Chevrolet Volt - Electric fun hatch for DD duty!

              DefSport Koni Sleeve and Spring Perch Buy!!!


              • #8
                I got your PM Def, thanks! Those prices are very resonable.

                The reason why I asked about the sintered iron setup (as I am not too versed on it in the RWD world), is for the FWD setup, the sintered iron allowed some amount of slip while totting around and "cold", but once you got some heat in, the characteristics of the plate changed and the clutch was now able to hold upwards up 400 ftlbs at the wheels and became fairly "grabby". This jackle and hyde characteristics allowed good around town drivability, and once you get to the track or a decent to flog it on the street, it would hook up fairly well and take the abuse This is almost akin to how carbon brakes work (the whole idea of the more heat you issue it, the greater the mu became).

                However, I see your point about the mixed material disks however.


                • #9
                  Well, Comp discontinued the "iron man" disk, which is probably what you're seeing some places. I've seen hybrid 7.25" setups used where the organic disk takes all the wear and you reach the limit of the pressure plate really quickly.

                  Sintered iron disks don't like to be slipped at all in my experience. You might get a little slip for 1-2 engagements, then it's up to temp and it's going to GRAB. The ceramic pucked clutches are closer to a brake pad in that you can ease into things just a little bit. It's streetable if you pay attention as was mentioned.

                  If you want to go big boy style I can look into getting you a 7.25" dual disk setup.
                  '18 Chevrolet Volt - Electric fun hatch for DD duty!

                  DefSport Koni Sleeve and Spring Perch Buy!!!


                  • #10
                    Hahahhahah! My left leg is not big enough for a 7.25" setup............that and I would surely feel inadequate not fully utilizing such a brilliant piece and would much rather use this as a conversational piece for at an art gallery

                    I wish Rob's QM setup was compatible. The friction plates are cheap enough to source to rebuilt it.


                    • #11
                      Pedal effort for a newly purchased 7.25" setup will be less than most of these higher torque single stock sized clutches provide. The take-off NASCAR stuff is not all that cheap after outfitting it to use ceramic disks, and the pedal pressure will be a tad higher, but not horribly so (about 40 lbs with stock hydraulics, which isn't that much really).

                      It is more money than the setups you're talking about, but Fidanza does make a 7.25" flywheel that'll bolt up... just takes a while to get... and the clutches are not that bad and easily refreshable.

                      Rob's QM setup was a 5.5" sintered disk setup... not something you ever want to drive on the street. 7.25" ceramic setups can actually take quite a bit of street usage.
                      '18 Chevrolet Volt - Electric fun hatch for DD duty!

                      DefSport Koni Sleeve and Spring Perch Buy!!!


                      • #12
                        hey mate,
                        I have just replaced my clutch with one built by Jim Berry.
                        I don't know a lot about it but I'm extremely happy with the drivability etc for a clutch that is supposedly good for up to 900hp. Its a springless 5 puk ... it has just a tad of slip before bite and pedal is very light... it feels like Im driving a brand new little car. loving it..

                        don't know what prices are like over there... it was by no means cheap.. but like I said if you want something that still drives easy.. then this is a guy I can vouch for 100%
                        97 s14a 200sx
                        82 vh sle 5.0
                        2013 fg xr6t


                        • #13
                          Thanks for the recommendation, but for what I need, I don't think I will be looking across the pond since we have all we need over here and for much cheaper as well.

                          Def, thanks for clearing up my misconceptions


                          • #14
                            I figure I will update this since not many people order up the FX400 or FX500 from Clutchmasters.

                            I procured the FX400:
                            Its a Cermaic button 6 puck sprung clutch and thier HD Pressure Plate. From my reading, the torque capacity is between 450 - 550 ft lbs (I have read more, but being more conservative) at the flywheel. So suspect about 400+ wheel torque rating (I have seen numerous ocassions of 420 wheel torque without slipping and severe drag launches. As far as drifting, the dorifto boys have thier own bangwagon clutch folks to follow, so not much review from that end. This is placed in a HPDE/weekend vehicle).

                            Impressions so far:
                            Pedal feel: Clutch pedal feel is only but barely (and I do mean BARELY) heavier than stock. The Comp.Clutch Stage 2 with full face organic disk had a much heavier/harder pedal feel and not nearly the amount of torque capacity of the FX400. If my memory is correct, the KA "white bunny" setup have a little more capacity before slippage occurs (and if they use the same PP across the board (they have an in house designed full crumb point, hence how they can have the holding capacity without the pain of a heavy PP) or something similar, which I think they do, expect the same or very similar pedal feel). The feel however could be tweeked slightly to get a better feel of engagement point, but I still have the stock clutch damper FWIW.

                            Engagement: The engagement is fairly pronounced and you know it's there (but not to the point of being intrusive). Its a sprung hub, so some of the engagement harshness/vibrations won't transfer over to the trust bearings or the inputshaft > gears>bearings either. Perfectly fine and took me two clutch pedal "pumps" to figure out engagement point. I have only driven it some 5 miles, so still have some breaking in to do.

                            Breaking in: It's a Ceramic hub and from my understanding, the break in mileage is around 80-100 miles or so according to clutchmasters (as compared to 500+ for thier Kevlar setup!) and then the clutch is ready to rock! On my old (Clutchmasters) FX500 setup, I broke it in for 50 or so miles (don't recommend, but for a point of reference) and it held up to several track days rock solid at 340 WHP and 280 ft lbs at the wheels.

                            Sounds: There is a slight chatter, but after a few hundred miles so far, it seems to be slowly subsiding (only chatters during take-off and idling). Also, the clutch is fairly new, and once the flywheel and disk are bedded in together, it's very likely the sound will subside even more.

                            Overall: Have now driven a total of about 200+ Miles and the clutch seems to have settled in. Made up a new Tune over the weekend and settled on 17psi and around 290 or so WHP and 260+ ft lbs of torque at the wheels (GT28R, Type X blacktop, Sheetmetal Manifold with stock runner lenght, etc). It seems to be holding up just fine. Haven't launched it yet (and do not plan to) and this will be on the HPDE vehicle. I haven't added timing, but will do in the boost transition zones, so we will see how the clutch holds up to the extra "umpphh" in the low-mid rpm range

                            So far, LOVE it! Clutch feel is barely above stock, the engagement point is perfect and I can DD it in traffic all day (not that I do anyways, I have an Infiniti for those duties) and not feel a damn thing. Slight chatter noises, but for a non DD vehicle, it's very easily overlooked.

                            Would recommend!


                            • #15
                              I want a 7.25" twin disc for my Civic but it is very illegal in Honda Challenge sadly.