Vernier Pulley how to Diy.

Discussion in 'Engines' started by Brian.G, Sep 22, 2009.

  1. Brian.G

    Brian.G Forum Member

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    After looking around at the price of vernier pulleys it got me thinking.........a pulley for an 8 or 16v is approx 150euro.
    What you get for that 150euro is usually a pulley made from anodised alloy, it looks very ''bling'' granted but I always wonder about the gripping power the little allen bolts have against fairly soft alloy slots.
    So, I got thinking and came up with a way to make one that costs approx 5euro and an hour or two elbow grease, obviously you will need the oem pulley too.

    So here it goes, I used a bit of 5mm stainless steel plate, mainly because I had some, and as well as that its pretty tough and wont rust.

    The plate in question>
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    Tape a bit of paper on there as tight as you can to make layout easier, you could use marking or layout fluid but I used paper as the camera picks it up better>
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    Now you need to measure the inside of the pulley as accurate as you can, make sure you come inside any chamfer or radius at the edge, you need the plate to sit flat. In this case it was 111mm(take note of where the calliper prongs are sitting)>
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    Divide that by 2 and set your compass to the radius length, draw your circle>
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    Draw a line through the centre point of circle>
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    Now, with a protractor on that line, divide it up into sectors, 60 degrees each>
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    Next, 2 more circles, diameter 94mm and 48mm>
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    Set your compass to 6mm and at the point where the 94mm circle intersects with the 60degree sector lines, swing a small arc both sides of the line, do this on all 6 sector lines>
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    Should look like this when done>
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    Join all the outer intersection points so a hexagon is created within the outer largest circle>
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    At all the red arrows below, mark with a dot punch and hammer, you should have 31 points in total, including the centre point location>
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    Like so>
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    Remove paper, pull off with care, you can now use this as a template to make another, plate should now be all dotted, and ready for drilling>
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    Join all the outermost points to form the hexagon again, these are your cutting lines, no harm to scribe them too so youll see them>
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  2. Brian.G

    Brian.G Forum Member

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    Next, you need a 3mm drill bit, drill the middle holes as shown>
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    And the outside ones on the sector lines, and the middle>
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    Next up you need to drill the centre hole, go 32mm, I used a holesaw, because I have a set, if you havent one, then maybe chain drill around, and finish up with a file, its slow as hell though so maybe your better off buying a holesaw. Spend no less than 20euro on a saw and arbor, anything cheaper wont last 5 seconds on stainless>
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    Done>
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    If you havent already scribed your outside Hex lines, do so now, then get cutting, stainless is tough stuff, and because I was born with an angle grinder in my hand I think its the only tool for the job. You could use a hacksaw if ya want, but prepare to get very tired......>
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    Done, finish up any rough edges with a linisher, file, or sand paper>
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    Because theres a pretty big radius around the centre of the pulley, your going to have to file the square edge off the centre hole in order for it to sit flat>
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    Sit the plate down into pulley, MAKE SURE you line it so that the holes are over the spokes of the sprocket, and all equal, or very near it, drill one 3mm hole, once you have one drilled, fit another 3mm bit in there to stop it all from moving once you go to drill all the others>
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    Bit inserted>
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    Drill all the rest with the 3mm bit, before you remove plate, mark some reference points on there so you'll know where everything goes when you come to putting it all together>
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    Remove plate and take the 3mm holes out to 5mm, 5mm is the pilot size you need for an m6 tap>
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  3. Brian.G

    Brian.G Forum Member

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    Tap holes with an m6 tap>
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    You now need to cut the inter piece of the pulley out, thread in a hacksaw blade and re-attach to saw, cut, cuts must be approx half way out along spokes, cut one slightly in a different place so you'll know the centre will only fit in one way> The right way!>
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    Tidy up the cuts with a file or grinder to remove the sharp edges>
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    Thats the pulley done now. Back to the plate again, Drill out all the holes as shown below with a 6mm drill bit>
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    And the 12 outers>
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    You now need to join up the 6mm holes to form slots, I used a metal blade in a coping saw, you could file it, or chain drill and file but the saw is pretty fast>
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    Last of the photos up in a while to finish it off, photobucket dragging its legs again,
     
  4. Tall Paul Forum Member

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    I'm by no means sure but if this is wazzing around at high rpm, should it be well balanced?
     
  5. Brian.G

    Brian.G Forum Member

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    Yes, its fine. Dont forget cam is spinning half the spped of crank, so the max itll ever see is 3700rpm approx. If you take your time marking it out as I have, It wont effect or have any impact on balance at all.
     
    Last edited: Sep 22, 2009
  6. Mikey C Forum Member

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    just grind out the woodruff key thing, adjust sprocket to wherever you want it, torque up the bolt properly.

    Job done, free and instant adjustable pulley
     
  7. drunkenalan Paid Member Paid Member

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    gring it out ??? just take it out!!
     
  8. Brian.G

    Brian.G Forum Member

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    Each to there own, lol!
     
  9. jamez Forum Member

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    I tryed this years ago but never got the pully to sit perfectly centered , so when it rotated there was allways a small variation off center causing the belt tension to vary. It worked ok but i didn't trust it. never ran the engine with it
     
    Last edited: Sep 22, 2009
  10. Brian.G

    Brian.G Forum Member

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    I guess its down to the marking out..I had this mounted on a motor i use for polishing valves and the dial indicator is showing it to be fine through all the adjustment range, I think the key thing to do is fit the 3mm bit after boring one hole so that they will all have to be in the right place then.
     
  11. Mikey C Forum Member

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    The last pulley i had off i'm sure had the woodruff key as part of the pulley, if you can just remove it then thats even easier. The key isn't there to hold the sprocket in position, purely to time the engine. A proper vernier pulley has a vernier scale on it, which allows fine adjustment. The pulley you have shown has no benefit over just removing the key, and in my opinion carries more risk - depending on the quality of manufacture.

    Mike
     
  12. bazoldskoolmk2 Forum Member

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    pattern

    makes sense, after all!, everything is made to a pattern of some sort!
     
  13. mark25 Forum Junkie

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    Wouldn't it be easier to measure the timming error on your car, then make an offset woodruf key to get things where you want them?

    Or make a new woodruf key slot in the pulley 180 degrees away from the standard slot , but +/- the timing adjustment you need.
     
  14. drunkenalan Paid Member Paid Member

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    personally ill stick with the kent pulley that i have, I would never run an engine without a woodruff key in and i jus dont have the patience to make a pulley as neat Brian has, its a good idea tho
     
  15. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    It is the bolt that keeps the pulley from slipping. Ford engines do not carry key ways on camshafts and cranks. The key way and gear key are just reference locators.
    On my turbo car I actually shaved off half of the key to allow for some cam adjustment.
     
  16. Nige

    Nige Paid Member Paid Member

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    Looking at this, even though you marked it out, you still cut the slots out by hand, with the best intentions, you can`t be 100% you got the same amount of material out of each `slot`.

    I`m all for diy-ing stuff, heck I do a LOT of it :lol: , but I`d be wary of something whizzing round at 3,700 that wasn`t balanced [:s]
     
  17. A.N. Other Banned after significant club disruption Dec 5th 2

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    This one from my build thread is DIY - created by an engine builder, but worked perfectly well for around 5.5 years:

    [​IMG]

    I suspect it was done in a mill, so has an even cut for the inner and outer sections.

    ^^ sheared bit, one mullered key, believed to have occurred from previous blow up fatigue. You can't ever run without these intact - VW engines without them are on a taper :thumbup:

    [​IMG]
     
  18. Mikey C Forum Member

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    That one is much better, the outer spigots on the OD of the disc rather than just bolts in slotted holes, so it is more likely to run true. But still unnecessary.

    Chris, what do you mean by that?
     
  19. A.N. Other Banned after significant club disruption Dec 5th 2

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    Sorry, I'd written "can" instead of "can't" - see edits in blue above.

    IIRC it's the diesels which have the cam sprocket with no keyway, and they're just held in place via the clamping force from the centre bolt.
     
  20. Brian.G

    Brian.G Forum Member

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    Im very used to cutting stuff by hand:thumbup:
    Hey though, dont let it worry you:lol: , Ive 100% faith in it, its not rocket science:thumbup:

    Edit, just got 20 adjuster plates laser cut today, yehhhhhhaaaaa!!
     

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