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Clutch Replacement Options

Discussion in 'S30 (240Z,260Z,280Z) Drivetrain' started by Woody928, Mar 28, 2018.

  1. Woody928

    Woody928
    Z Club Member

    Hi all,

    I'm just awaiting delivery of an S14 gearbox to do a conversion on my 240Z. While I do the conversion it makes sense that I swap out the clutch as I think its fairly knackered or the release bearing is at least on its way out.

    Having not embarked upon this route before can anyone point me in the right direction as to what my options are? I don't know if I need to be looking at an S14 clutch now or will it still be a 240Z one?

    The engine is a fairly stock L26 with nothing crazy done to it, ideally long term I'll have an L series engine pushing 240bhp ish built however the car is just used as a fun fast road weekend toy. Does anyone have any suggestions of what clutches to look at based upon my power levels and intended usage?

    Cheers
     
  2. toopy

    toopy
    Z Club Member

    Can't remember where i read it, but I believe the S14 clutch won't bolt to the S30 fly wheel, I think most retain the standard S30 clutch components, make sure you have the right height/thickness of release bearing, there are 3 different ones IIRC
     
  3. Rob Gaskin

    Rob Gaskin Treasurer in training Staff Member Committee Member

    Yes your conversion will use an S30 bellhousing, flywheel, clutch, release bearing, carrier and fork. I used a Centreforce 2 clutch - don't know if they are still available. 240bhp is not easily achieved so start saving.
     
    AliK likes this.
  4. datsfun

    datsfun
    Z Club Member

    USA engine builders are very generous with "their " BHP offerings :rolleyes:
     
  5. jonbills

    jonbills
    ZClub Administrator
    Staff Member Committee Member

    If you’re buying a clutch, I think the main thing to look out for is your flywheel friction surface diameter.
    Early cars (240,260) had 225mm diameter,
    later ones (2+2,ZX, perhaps more) have 240mm diameter.
    The release bearing carrier height goes with the flywheel.
    So if you get a clutch that matches your current flywheel, I think you’ll be ok.
     
  6. AliK

    AliK
    Z Club Committee
    Committee Member

    Or why not add a lightweight 240mm flywheel at the same time ;) !?
     
  7. Woody928

    Woody928
    Z Club Member

    Thank you all for the responses, some very helpful info. On the basis of my limited research now knowing I should have a 225mm clutch and flywheel it sounds like stock application clutches are up to the job for the threads I've been reading. Assuming so is there much in the way of UK availability? or is this a go to the US job?

    Got the bell housing from my 260Z 5 speed, flywheel will be stock (unless I'm convinced otherwise), clutch (need), release bearing (need), believe I can reuse the carrier and fork from the 260z 5 speed? Centreforce 2 are still available stateside by the looks of it. Whats the pedal feel like?

    That goal of building an L28 is a long way down the line. I've got far too many supporting mods to get sorted so that the car can even handle it first which will cost a mini fortune in the first place! Always good to have direction and motivation for the project though.

    Talk to me, what are the advantages? I presume it will take the bigger clutch plate will take more abuse? and with a lightened flywheel the engine will rev more freely?
     
  8. Woody928

    Woody928
    Z Club Member

  9. jonbills

    jonbills
    ZClub Administrator
    Staff Member Committee Member

    You could try Mike Feeney for a std Nissan clutch.
     
  10. AliK

    AliK
    Z Club Committee
    Committee Member

    Well Mr Woody, I really waxed and waned on this one and geeked out reading everything I could find. I also spoke to quite a few members with the lighter flywheels. Base on all this my humble opinion is:

    People I spoke with who have the lighter flywheels didn't suffer drivability issues and found their engines to be, in the words of one member "less like it's constantly towing a boat anchor", read much keener to rev. But also read revs will drop equally as quickly when changing gear so you have to modify your driving style a tiny bit to suit.

    One school of thought advises against lightening an existing flywheel for a number of reasons: 1. The energy in a flywheel is HUGE and if you introduce stress fractures during the lightening process it may choose to come apart at high revs - which will rip through your bell housing, legs etc like an extra hot Fal curry through your intestines. 2. If your flywheel also needs resurfacing due to 40years of abuse, or because you want a new clutch plate to go on a new flywheel surface then the costs aren't far off getting a new one. (Having said all that, I never came across a case where a lightened flywheel has come apart.)

    One member who runs an L28, runs this one and is WAY happy with it ...

    https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/222862718485

    I bought the Fidanza as it came highly recommended by people who build high end engines, had great reviews and has a replaceable surface should it ever need changing. It is a bit lighter than the one above - not been put it on the car yet, so time will tell when I get my engine back in.

    https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/122458092672

    Don't believe the hype about releasing horse power - a fly on it's own is not consuming or dissipating power, it is merely storing and returning it; and slowing down the rev-ability for smoothness.

    The sports stage 2 and 3 clutches have fewer "pucks" to increase pressure per point of contact (P= Force / Area) for high load applications but that also makes them less smooth and more "grabby".

    [​IMG]

    This is a truly annoying review of a 240z, but if you can ignore that bit, the owner is running a centre force and the reviewer is constantly speaking of how grabby or heavy it is:



    While most stage 2 are advertised as close to stock feel, they run pressure plates with more pressure and one member (I think it was Jonbills-could be wrong) said theirs was advertised so and it certainly is a lot heavier.

    240v225mm: again, I would beckon to the experts to jump in - it will help with longevity and smoothness on application of the clutch pedal; the additional friction surface is not necessarily going to give you greater Torque handling (remember P=F/A). That is very much a function of the pressure plate springs. If you plan to have an L28 one day, then 240mm would be a future proofing option IMHO.

    If you go stock Nissan clutch then Mr F is your man - in fact, like John Shaft, he is THE man, period!

    Disclaimer:
    All views expressed are that of a keyboard warrior/geek who has to do a lot of research and collect data before doing anything. It does not in any way represent the views of the club. No animals or members were harmed during the research.
     
    Last edited: Mar 29, 2018
    toopy likes this.
  11. AliK

    AliK
    Z Club Committee
    Committee Member

    Ps. Sorry for the long reply - but you did ask!! ;)
     
  12. strugrat

    strugrat
    Z Club Member

    I went with a ACT street/strip clutch from Summit Racing in the states. No idea what its like as I've not driven it yet but that's what was recommended to me by my engine builder.
     
  13. Rob Gaskin

    Rob Gaskin Treasurer in training Staff Member Committee Member

    My Centreforce 2 clutch was not grabby or heavy to use - it's not a 'puck' plate either. I have no memory of any problems driving 'on the road' including long trips abroad (Spa, Le Mans).

    I upgraded to a 240mm when I modified my engine. I installed a standard (Mr F supplied) clutch and it would not take the extra torque - it slipped. Hence buying the Centreforce clutch which was fine.

    A lightened (or light) flywheel will absorb less power when accelerating - what is going to be used to spin-up the extra weight of the heavy flywheel? If you tried to spin them with a handle you would notice the difference I'm sure.

    Driving technique - the engine 'spins-up' and 'dies-down' faster so it's great for upward gear changes and 'blipping' on downward changes. However I have not experienced a light flywheel on a standard engine so much of the extra responsiveness could be down to the engine characteristics too.

    225mm v 240mm - why did Nissan go to 240mm, it must have been to cope with the extra power of the bigger engine?

    Weight - I weighed two flywheels (225 and 240) and they were the same (21lbs I think). I had my 240mm flywheel lightened by 4 lbs but the bigger clutch was 4lbs heavier so no overall reduction from my 225 'set-up'. However is was lighter than the standard 240mm 'set-up'.
     
    Last edited: Mar 29, 2018
    AliK likes this.
  14. AliK

    AliK
    Z Club Committee
    Committee Member

    Now Rob is the voice of experience! :thumbs:

    The only thing I would ask Rob is: the weight distribution on rotating masses is where the difference most apparent: despite having the same weight, did it look like the the 240mm had more mass on the outside? Or is it a case of the overall size is the same and just the clutch mating surface is larger?

    Sorry for not being totally relevant to the original topic / question.
     
  15. jonbills

    jonbills
    ZClub Administrator
    Staff Member Committee Member

    The heavy flywheel doesn’t absorb a significant amount of power under acceleration. The engine is accelerating a 10kg flywheel plus a 1000kg car. Guess which absorbs all the power?
    Unloaded (no car attached) the flywheel is a significant % of the mass being accelerated so you do notice it with the clutch in.
     
  16. Rob Gaskin

    Rob Gaskin Treasurer in training Staff Member Committee Member

    Jon, yes I realise the total car is going to absorb the most power (but not all) but we are talking flywheels here not car body weight. I bet it takes a lot more power to spin-up the flywheel than the mechanical fan but I noticed that when I changed to an electric one.
     
  17. AliK

    AliK
    Z Club Committee
    Committee Member

    All good stuff fellas! I hadn't put it in the context of the car weight as I was only thinking rotating masses, so good perspective Jon. Also Rob, I'm amazed you could feel the difference with the fan changes - just shows you how much parasitic drag it adds.

    Coming back to the OP topic and summarising, is the consensus to go 240mm flywheel (light or heavy) and centre force / ACT clutch?

    Given what Rob is saying I'm now rethinking my clutch choice on the L28 :s :unsure:
     
  18. jonbills

    jonbills
    ZClub Administrator
    Staff Member Committee Member

    I’ve posted this before: http://www.w8ji.com/rotating_mass_acceleration.htm

    There’s a section about flywheel mass and drag racing (which is relevant to our discussion of acceleration)
    Basically, in all but final gears, you get the power stored in the flywheel back when you change up.
    In the final gear, a 24lb flywheel stores maybe 3 hp/second more than a 12lb flywheel that you don’t get back usefully before the end of the run.
    So a 2% difference in the final gear for a 150hp car.
    I think there are many better things to spend money on before a lightened flywheel.

    I find it really hard to believe the difference between a viscous fan and none is detectable under acceleration by the driver. I bet it doesn’t even pull 0.1 HP (a 50 watt electric fan is 0.06 HP)

    Anyway, for the OP, for now I’d just get a stock clutch to match the current flywheel, and worry about exotic flywheels and clutches later.
     
    datsfun likes this.
  19. Rob Gaskin

    Rob Gaskin Treasurer in training Staff Member Committee Member

    Yep, for drag racing it may be worth keeping the stock weight but drag racing is extreme - far more extreme that just fast driving.

     
    AliK likes this.
  20. Rob Gaskin

    Rob Gaskin Treasurer in training Staff Member Committee Member

    Jon out of interest look at this link (scroll down). It's an article by a very well respected engine tuner David Vizard.

    http://www.imps4ever.info/tech/875power.html

    I used 6-7k a lot on track and I reckon a Datsun fan is far more powerful than an Imp fan (I've had 2 Imps), their rads are tiny too.

    Also this - but it may be an exaggeration i.e. sales talk:

    https://www.ebay.co.uk/itm/DATSUN-Z-ELECTRIC-COOLING-FAN-KIT-240Z-260Z-280Z-280ZX-/112132492196
     

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