Bottom Crank Pulley | The Z Club of Great Britain
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Bottom Crank Pulley

Discussion in 'S30 (240Z,260Z,280Z) Engine' started by jimyj, Feb 9, 2019.

  1. jimyj

    jimyj
    Z Club Member

    Hi anybody got a pulley. Suit 240 single groove with the rubber inner . Cheers Jim
     
  2. jimyj

    jimyj
    Z Club Member

    New one ordered from Z store
     
  3. jimyj

    jimyj
    Z Club Member

    Found out they are on back order from z store , so back to the search , never thought this would be such a difficult part to find ........ Some one must have one in the back of the shed . 20190210_110015.jpg
     
  4. franky

    franky
    Z Club Member

    For such a vital thing I’d get a new one.
     
    AliK likes this.
  5. IbanezDan51

    IbanezDan51 Well-Known Forum User

    Try your best to get a new one or one with very little use - the front pulley seals can harden over time and cause grooves in them - when you then fit them to your freshly built engine they can leak and you'll end up replacing it anyway.

    Dan
     
  6. AliK

    AliK
    Z Club Member
    Staff Member Moderator

    This was a thing that vexed me for sometime.

    IMHO if you enjoy revving the engine hard I would buy a decent damper as it's an insurance policy to protect your crank / engine.

    As I researched it, I got completely pulled away from the Z-store ones especially as I heard of others in the club (and outside) whose cheaper z-store harmonic dampers broke apart!

    For my money I would recommend the Kameari fluid damper with the large 136mm pulley - it's not cheap but not as pricey as a BHJ and a fine bit of kit used by many on the forum.

    https://www.rhdjapan.com/kameari-st...lancer-136mm-l28-l26-l24-l20-l18-l16-l14.html

    Oh and buy the bolt / washer too

    https://www.rhdjapan.com/kameari-l-type-reinforced-crankshaft-pulley-bolt.html

    Do not save on this part of your engine, it's an ubiquitous and yet pretty important bit of the engine that does a heck of lot more than turning your fan-belt.
     
    Last edited: Mar 7, 2019
    MaximG, Paul_S and jonbills like this.
  7. jimyj

    jimyj
    Z Club Member

    Well still unable to source a new or used standard pulley , this has turned up . Brand new twin pulley for use with ac or pas , its slightly wider as it is for the 12 mm belt and mine is the 10 mm , but i am sure it will work .
    Just gotta pop to the machine shop next door and cut the other pulley off . Will let you know how we get on .
     

    Attached Files:

  8. AliK

    AliK
    Z Club Member
    Staff Member Moderator

    Nice find. Good luck with the cutting especially as you don't want to create big heat on the process which may damage the rubber.

    Interested to see how you get on.

    Nice head!
     
  9. franky

    franky
    Z Club Member

    why cut it?
     
  10. jimyj

    jimyj
    Z Club Member

    Well i did think about just running it as is sure , but we have a machine shop we use and it looks an easy cut .
    Will see how it turns out . Oh and its in that awful blue Nissan used . w ill clash with my GREY block .
     

    Attached Files:

  11. johnymd

    johnymd
    Z Club Member

    does the front pulley just unbolt? I know my memory is bad but I seem to recall that some of these factory dampers had a bolt on front section. I have a front pulley section in my workshop that I removed.
     
  12. uk66fastback

    uk66fastback
    Z Club Member

    a) the grey block is lovely b) I like the Nissan blue but maybe a coat of black on that pulley would be nice c) I used to have those exact same shelves!
     
  13. jonbills

    jonbills
    ZClub Administrator
    Staff Member Moderator

    From memory, the 3 layer pulleys have the first layer bolt on (power steering) and the next two are connected in some permanent way I've forgotten, maybe press fit dowels?
    I have an unclear memory of trying to have the 2nd pulley cut off one for my engine a couple of years ago and the whole thing fell apart.
    I think the problem was down to the outer part includes the outer half of the v of the inner pulley.
    I hope that makes sense.

    In the end it allowed me to invest in the Kameari damper, which of course I secretly wanted to do anyway :)
     
    AliK and moggy240 like this.
  14. jimyj

    jimyj
    Z Club Member

    This is a twin pulley , the outer one looks cast as one bit , but my machine shop bloke does not see it as a problem , this is a guy who is making /rebuilding a pre war Lagonda in his front room ! i kid you not . Oh and he is single .
     
    AliK likes this.
  15. johnymd

    johnymd
    Z Club Member

    Just got back from the workshop and it’s the 3rd pulley that unbolts as Jon said. Looking at the 2 belt pulley I have, you cannot machine off the outer pulley section without removeing a large section of the rubber that bonds the inner and outer parts of the damper. You are asking for trouble and going to get a premature failure IMO. On my FI car I machined the front section of the 2 pulley damper to take a trigger wheel but did not remove enough to alter the dampers operation.
     

    Attached Files:

    jonbills likes this.
  16. jimyj

    jimyj
    Z Club Member

    Well all went to plan , cut was very simple so he says , and no damage to the rubber damper , just got to wait till its all assembled to see if we have any belt alignment problems .
    Trying hard to make Donnington .
     

    Attached Files:

    AliK likes this.
  17. AliK

    AliK
    Z Club Member
    Staff Member Moderator

    Nice work! That looks better than I imagined it would.

    Forgive me if I'm being a pest by asking this - how does the mass compare to a normal single row pulley? I can't help wonder if the damper needs the extra mass to operate effectively.

    My damper off a UK car with no aircon looked like this ...

    [​IMG]

    My ATI damper and the Kameari fluid damper that I have personally held in comparison are even heavier.

    [​IMG]

    [​IMG]

    Just a thought! Would hate to see you end up with a damaged crank.
     
  18. jonbills

    jonbills
    ZClub Administrator
    Staff Member Moderator

    Here's a pic of mine.
    Glad yours seems to have gone better.
    DSC_0221.jpeg
     
  19. toopy

    toopy
    Z Club Member

    This talk of pulleys and harmonic balancers is making me question wether i should look to replace mine as a matter of preventative maintenance, sooner rather than later.

    Are standard ones available anywhere? Rockauto don't have anything in stock.

    Should I be looking to fit one like Ali's one above, seeing as the engine is standard, and although driven in a spirited manner, it's hardly red lined every time i take a drive!
     
  20. AliK

    AliK
    Z Club Member
    Staff Member Moderator

    So Mr Toops, the harmonic damper is one of the most important yet ubiquitous parts of a straight 6 - often mistaken as just a drive pulley. The crank experiences large forces at either end and being long goes through torsional distortions. It also has a natural frequency that can resonate at certain RPMs.

    If you consider the firing sequence of 153624- cylinder 1 is pushing down hard while cyl 5 at the other end of the crank is compressing.

    [​IMG]

    Now factor in lots of revs and the "harmonics" that build up as a result of the other cyls firing and it becomes apparent what an important job the damper performs. A couple of great articles below:

    http://www.atiracing.com/products/dampers/101/index.htm

    http://www.atiracing.com/products/dampers/damper_dinan.htm

    Of course this becomes all the more significant as you raise compression / torque and revs, but harmonics are always there.

    I would always advise loosening the fan belt and checking the damper bolt torque as a first step. Mine appeared tight but was totally loose (1cm!!!) on the old smokie. Then if able, check the general condition. On tinter, I've not come across stock dampers that have failed on stock engines but maybe I haven't looked hard enough. At the end of the day it's an insurance policy on your engine and who knows how well 40 year old rubber is performing after all these years, miles, heat cycles etc.

    The stock dampers are NLA. But MSA do some interesting alternatives. The cheaper ones have been known / reported to have come apart and definitely avoid the Chinese knock offs of those on eBay! The consequences of a poorly performing or broken damper can be expensive.

    https://www.thezstore.com/page/TZS/CTGY/classic12d02c

    BHJ do a nice looking bit of kit but as one of the US guys recently posted they rust faster than a 70's Datsun on salty roads.

    This photo I believe was less than 1 year of use ...

    [​IMG]

    Kameari and ATI do great dampers (the latter only comes with a racing sized pulley). But both come in at around £400-500 delivered.

    They are both around 13kgs in weight.


    If you do go this route go Kameari street fluid damper. Zero maintenance and street sized pulley.

    I will let others more experienced than me chime in with their recommendations.
     
    Last edited: Mar 18, 2019
    Woody928 and toopy like this.

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