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  • Input on clutch components

    Severe clutch fork vibration at idle leads me to believe that the throwout bearing guide shaft/snout on the end of the front cover of my transmission has broken off. Is there anything I can do to prevent this aside from regularly greasing the snout? Reinforcing the front cover somehow?

    I figure while the tranny's dropped I might as well throw on a Competition Clutch Ultra Lightweight steel flywheel and maybe swap out my RPS Max 6 puck friction disc for a full face disc to improve driveability when on the street. Thoughts on these parts?

    Also, the clutch pedal assembly is too flexy in operation in addition to separating at the spot welds previously. Has anyone plated/gusseted/added more attachment points to the chassis on theirs with success?

  • #2
    If you are under 375'# of torque(about 435hp) the ACT XTSS with their 13# flywheel will suit your streetable drivability better. The lighter flywheel will probably make you run two shifts crossing an intersection though

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    • #3
      Originally posted by scarredone View Post
      Severe clutch fork vibration at idle leads me to believe that the throwout bearing guide shaft/snout on the end of the front cover of my transmission has broken off. Is there anything I can do to prevent this aside from regularly greasing the snout? Reinforcing the front cover somehow?

      I figure while the tranny's dropped I might as well throw on a Competition Clutch Ultra Lightweight steel flywheel and maybe swap out my RPS Max 6 puck friction disc for a full face disc to improve driveability when on the street. Thoughts on these parts?

      Also, the clutch pedal assembly is too flexy in operation in addition to separating at the spot welds previously. Has anyone plated/gusseted/added more attachment points to the chassis on theirs with success?
      A full faced disc wii generally improve streetability, dependent upon material. Generally pucked clutches are very on/off while full faced allows more slippage, the downside is often power handling as the pucked units often use more aggressive ceramic/metallic facings.

      Light flywheels don't generally improve anything for street driving beyond a certain point, they're usually preferable in track cars where you tend to keep the revs higher and shift quicker. While they let the engine rev a bit quicker the also let the revs drop quicker. Trying to lug off from a stop sign on a hill becomes tougher due to the lower amount of rotating mass that helps keep everything spinning when you've asked a little too much of he engine.

      If the clutch pedal is flexing you may want to look into a clutch with a lighter pressure plate and more aggressive friction material. You don't need a clutch that wears out your left leg to hold 400hp any more. I had an RPS years ago and it was way oversprung for what it was spec'd to hold power wise. I'd get with the tech dept. at ACT or Comp Clutch to see if they can offer any help there based on your actual needs.

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      • #4
        The only really big benefit to daily drivers with very lightweight drivetrain components (knife edge crankshaft, light flywheels, light wheels, etc...) is fuel economy. It can make a big difference.

        my fathers car doing 65mph average with the A/C on put down 29mpg highway. 15.2:1 air fuel open loop, knife edged crank, steel exedy flywheel, 6puck sprung, and the rest of the drivetrain is stock including oem wheels. I used the oem wheels to get a more exact mileage. (s13 sr20det, eagle rods, cp pistons) 97 240sx FULL of luggage (at least +200 lbs + me(165)) + full tank of gas

        I know it does better than 30 with the A/C off...
        I have a video if you want I would never quote mileage numbers without actually having tested it myself with a camera rolling for proof.
        Last edited by Kingtal0n; 08-26-2013, 11:45 PM.
        Originally posted by Def

        The reason why you want signal lines as slow as possible, is that there is actually some mass flow through the signal line, enough that the cross sectional area and "long" run can cause significant minor head losses.

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        • #5
          I don't think you found a big difference there, my stockish SR setup typically got 29-31 without the a/c on, i'd figure your repetitive tuning to have gotten the small gain you got.

          Wheels aside, that stuff isn't going to make a notable difference.

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          • #6
            My car with super draggy aero got about 28 mpg going 80 mph to a track event with a 4.36 diff ratio. No AC of course.
            '18 Chevrolet Volt - Electric fun hatch for DD duty!


            DefSport Koni Sleeve and Spring Perch Buy!!!
            http://www.nissanroadracing.com/showthread.php?t=5902

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            • #7
              the problem here is we are all +/- only a few mpg. and thats exactly what you gain or lose when swapping around these lightweight parts. also consider weight, you lose 300lbs or so and you gain a mpg or more from that alone. I have no idea what my father's car weighs so the whole "I get this" "you get that" is completely moot.

              To really dial this convo in, we would need, constant speed on a highway, vehicle weight known, and compare from there.

              Ill try to get my dad's car weighted. Then Ill try a few things to see if I cant break 33mpg or so. I bet it can.
              Originally posted by Def

              The reason why you want signal lines as slow as possible, is that there is actually some mass flow through the signal line, enough that the cross sectional area and "long" run can cause significant minor head losses.

              Comment


              • #8
                What does it matter? This topic is about clutch components, not what MPG you get or I get... It's a 90's era sports car and most on this site get flogged on the track.
                VVL S14 on KW's...

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                • #9
                  Lightweight driveline components don't make much if any difference for MPG. I've gone to lightweight flywheels on my DD's a few times, and it never changed anything.
                  '18 Chevrolet Volt - Electric fun hatch for DD duty!


                  DefSport Koni Sleeve and Spring Perch Buy!!!
                  http://www.nissanroadracing.com/showthread.php?t=5902

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                  • #10
                    A lightweight flywheel by itself removes how much rotating mass?

                    Not much. But some. So there is a benefit to fuel economy 100% guaranteed if the tune is right. You didnt notice because it was such a small change that you didnt notice.

                    but a change took place, mass is mass.

                    The combined effects of lightened rotating assembly, lightweight flywheel, lightweight driveshaft, lightweight wheels, and weight reduction in the vehicle itself, would all culminate right? One piece at a time or all at once.

                    Anyways. I was just trying to bring some alternative viewpoints on clutch related parts. I consider wheels, for instance, as clutch related since changing a set of wheels/tires can make or break a clutch's performance. Every aspect of the drivetrain including vehicle weight needs to be considered when looking at which clutch to buy.
                    Originally posted by Def

                    The reason why you want signal lines as slow as possible, is that there is actually some mass flow through the signal line, enough that the cross sectional area and "long" run can cause significant minor head losses.

                    Comment


                    • #11
                      Sorry but 3-4 lbs on a flywheel isn't going to effect mpg a lot.

                      Doing something like unbolting a set of 25 lb each wheels, which isn't all that uncommon, and bolting on a set of rpf1's knocking 10lbs off each corner and you'll see a difference.

                      The small things together such as the flywheel and crank reduced weight didn't get you much, from the way you make it sound they gain you a notable difference, in reality they don't, 40lbs rotating weight in wheels yes, 4 lbs in flywheel, not so much, diminishing returns man.


                      Back on topic, yes when the input plate sleeve is broken you'll get clutch pedal vibration, mine was fun because if you had your foot just slightly on the clutch sometimes it wouldn't do a thing, then it'd get all upset and give my foot a massage.

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                      • #12
                        All this rotating weight is inertia. If you're accelerating up and coasting down, did you really change much? Not really.

                        Maybe if you're hauling ass up to every light, yea, some 0.000001% change might be perceptible, but even then I'd argue it's not really going to be a big change.

                        As for how much mass, on one flywheel it was about 5 lbs, and about 17-19 lbs on the other. Changed how the car drove in the lower gears, but didn't affect mpg much because you didn't have that stored kinetic energy to keep you moving on coasting.
                        '18 Chevrolet Volt - Electric fun hatch for DD duty!


                        DefSport Koni Sleeve and Spring Perch Buy!!!
                        http://www.nissanroadracing.com/showthread.php?t=5902

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                        • #13
                          I suppose if you've got enough space where coasting is going to make a difference, but around me stuff is flat, coast time is minimal, wheels have made a notable difference on multiple cars in my experience, its a lot of weight that must be kept turning.

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                          • #14
                            You guys need to experience a knife edged crankshaft in an SR20 before you judge! The engine is so light, that when I kick on the A/C compressor, the idle drops 500rpm.

                            how many lbs you think is missing? I dont know, but it completely changed the way the engine runs, and feels, and even the ignition timing profile required. Its a completely different animal.

                            I think it makes a difference where you remove weight. 40lbs of wheel weight vs 4lbs of crankshaft weight, yeah 10% of the weight removed at the crank, and its a completely different car.
                            Originally posted by Def

                            The reason why you want signal lines as slow as possible, is that there is actually some mass flow through the signal line, enough that the cross sectional area and "long" run can cause significant minor head losses.

                            Comment

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