Does anyone else have an OS Giken twin disk clutch? | FerrariChat

Does anyone else have an OS Giken twin disk clutch?

Discussion in '308/328' started by ATSAaron, Jan 9, 2020.

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  1. ATSAaron

    ATSAaron Formula 3
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    Jun 1, 2004
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    I have one. The engagement is OK, but the pedal effort is insanely hard. OS Giken is just blaming my car instead of their clutch, even though the clutch before theirs was fine.

    Aaron
     
  2. sltillim

    sltillim Formula 3
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    I would imagine, less a few racers in the UK, the crowd to field this question would be more appropriately addressed by the high horsepower import crowd.... Aaron, you are rare among us with your many hrsprs!
     
  3. ATSAaron

    ATSAaron Formula 3
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    Yes, I'm kind of an oddball. I've got a Clutchmaster's twin disk in my 1000 horsepower MR2, but they don't have an application for a 308.
     
  4. mk e

    mk e F1 World Champ

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    On mine I remember the forks had worn into the throwout surface a bit and and that caused it to require quire a bit of excess force to operate....I noticed the high force right after a clutch change, pulled it back apart to investigate and found the wear. It was back to normal after a quick cleanup or the surface.

    My other though is the tilton clutch I have requires WAY less throw than stock and with the correct ratio gives a freakishly light honda civic feeling pedal, but with stock linkage would be pretty stiff.....maybe confirm what travel the the new clutch is designed to work with?
     
  5. ATSAaron

    ATSAaron Formula 3
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    So I set this thing up in my press with a dial indicator to measure movement and a freight scale to measure how hard I’m pressing.

    At 350 pounds my stock clutch (which could actually be a Daytona pressure plate) deflected .356 inches.

    Under the same 350 pounds pressure the OS Giken deflected only .233 inches. It’s considerably stiffer than stock.
     
  6. Ferraridoc

    Ferraridoc F1 World Champ
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    PM sent
     
  7. mk e

    mk e F1 World Champ

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    I just looked at there catalog....is this a TR or STR? TR I'm guessing with the 800ft/lb spec? If so that is over double the stock clutches ability I think so even with the 2 discs it would need to have a stiffer spring. The description on the STR specifically talks about the pedal being lighter because races were complaining about the TR pedal but its only 575ft/lb....not sure where you are torque wise to live with an STR.

    The tilton I have is an 800ft/lb spec with the spring I have but is triple disc and carbon-carbon which has a much higher fiction coefficient. the down side is its not a bolt-on (it requires either a new flywheel or moding your existing), it is prone to a little light chatter .....and its about 5x the price of a Giken, but the pedal is REALLY light which is nice.
     
  8. ATSAaron

    ATSAaron Formula 3
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  9. mk e

    mk e F1 World Champ

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    I'm out of guess then other than maybe asking them to confirming designed throw at the clutch so you can compare to your linkage and see if the 2 match?

    I think Nick had a quartermaster dual-disc package he was offering, maybe give him a call and ask about it?

    Years ago I had an old 65 vette that I put a stronger clutch in.....the peddle force was ridiculous and after a few months the it sheared the linkage off and a few months after I fixed that the seat mounts cracked. Hopefully yours is not THAT bad......at the other end of the spectrum in my current clutch that I can push with a hand and had to remove the stock cable tensioning spring because it was causing the clutch to slip.
     
  10. smg2

    smg2 F1 World Champ
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    We switched up to Giken a couple yrs ago. We've been working with them and have gone thru many variations depending on build. Off the top of my head the full blown race version has a gold cover, it's a monster clutch. The green one is also but not as digital as the gold on/off. And the blue one is far more street friendly, we ran that one on a recent 328 SC build and it's very nice, took some breaking in, couple hundred miles. Hands down the smoothest is the twin grand touring.. easy pedal however in high TQ and high rpm engines it will 'float' at the top end of the rpm range, that's not a problem on the street builds with NA or even most FI builds for those not racing. But if you plan on racing or like to push the limit and shift at peak... it's a touch soft for that.

    The race version stays clamped well into 10k rpm range, hence the very high pedal effort.

    They recently reached out to us to test a new steel cover unit, supposed to be a touch easier in pedal effort then the aluminum versions. I know that back in Japan they have a 328 development mule.

    For the price its' a great clutch, esp since they provide everything from the flywheel to TO bearing and carrier. They want to control the stack height.

    All that said, I'm a terrible judge of pedal effort, I rely on Nicks feedback. I spend too much time in the gym busting out heavy squats and deads along with churning out 20+ miles a week MTB.

    On the install where is the pedal engagement? top or just off top, middle? When I initially setup the clutch I set them up with right at top to make it a quick 'flick' for shifting, drove Nick nuts, he hated it and complained of the effort. So I re-set it up to be more factory where there is something like 15mm of travel before engaging and fully open at bottom, it takes more pedal travel but it also really lightened up the effort. There's also the turn buckle ratios and linkage at the bell housing that needs to be set first before setting the final engagement point. It's a fiddly setup for sure. At least the early yrs in the 70's have a pin hole alignment for proper set-up. It's really a 2 person job, one guy on the rods and linkage and another working the pedal for feedback.
     
  11. ATSAaron

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    Thanks SMG2. I played with the engagement point to get the most "help" from the spring on the bell housing. At this point I intend to go back to my old single disk kevlar with the custom centerforce style weights. I have a Daytona pressure plate on the way so that I can test the spring tension too.
     
  12. hyenahf

    hyenahf F1 Rookie

    May 25, 2004
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    aaron

    what year is your gts? 78? the later 308 2v injected clutch pedal assembly has an altered geometry for an mechanical advantage lightening the clutch pedal efforts. another option would be perhaps to converted over to hydraulic? forumla-gt in germany has a kit...
     
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  13. ATSAaron

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    Thanks Hyenahf! I'll look for the later pedal. I vaguely recall a TSB about that.
     
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  14. hyenahf

    hyenahf F1 Rookie

    May 25, 2004
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    aaron

    i had a 2v injected car and early carb car... like the longer later shifters , its marginal.... it may not be enough to make a difference with your Herculean clutch?
     
  15. ginoBBi512

    ginoBBi512 F1 Rookie
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    I have a stock 328 , with a Kevlar clutch, 17 years and counting and about 40,000 miles, it still works perfectly , the throw and feel are perfect. Its way better than the stock clutch, it allows all of the power to get right to the wheels without hesitation, I can get my car sideways with the wheels burning through 2nd and then some. I thought about a gilken, only because its an exotic clutch, I dont think it would make a difference with factory 328 motor . They are very expensive, I would think it would work best on 300HP + motors , where money obviously makes no difference .

    Thank you
     

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