Gear driven cams?

Discussion in 'General Harley Davidson Topic' started by HeavyFuel, Apr 10, 2010.

  1. HeavyFuel

    HeavyFuel Member

    5
    0
    0
    Any idea why Harley doesn't use these stock? Just curious as a friend of mine has a Yamaha Roadstar and it has gear drive. I believe the Roadliner does as well.

    I suppose there could be a few reasons Harley doesn't. Engine noise is probably certainly one of them as that Roadstar has a lot of mechanical noise. Seems to be as reliable as an anvil though. I figure it's also down to cost of production since tolerances have to be tighter for gear drive.

    Anyone know for sure?
     
  2. glider

    glider Veteran Member

    25,464
    108
    44
    I think you answered your own question about the tolerances. The gear drives are less forgiving with crank run-out and Harley has plenty of that in the later bikes with the pressed cranks.
     
  3. itellya

    itellya Member

    47
    6
    0
    I just had my cam changed to a gear driven one. The noise is there but i dont find it any more noisy than when i use to have solid lifters. The power is what i have noticed the most. I find i have more power in the mid range when you find yourself in traffic etc. My vote is yes on the gear driven cam.
     
  4. Hoople

    Hoople Account Removed

    7,198
    0
    34
    I am Happy your results were positive but more power as a result of gear drive vs chain drive.? You must of had lots of chain lash or cam timing issues to feel a benefit of gear drive vs chain assuming cam profiles on each set of cams were the same. (maybe?) I would think a correctly set up chain system vs gear would deliver equal H.P.
     
  5. BUBBIE

    BUBBIE Well-Known Member

    4,959
    83
    113
    Back at sturgis in 2000? i went to a dealer display, selling the gear drive over the chain style cams in the new harleys 1999 and on.

    the booth was set up simple with a hand crank turning a mock-up engine (see thru type) one engine set was the stock chain drive and the other was the gear type...

    Believe me Hoople the cranking difference was HUGE....
    I could effort less ly turn the gears drives over , mind you BOTH were set up the same doing the same valve and spring operation.....

    The chain drive was VERY hard to turn over and I mean hard.. I think they were using the term robbing "6/8 hp out of the engine".

    I cranked on both back and forth trying to find a gimmick but found none.
    I did go with the GEAR drives when i rode my bike back home... my crank never measured 0.001 out at the oil pump, (crank in block).. now that was good.

    crank run-out wasn't as much a problem then on the older bikes... that was my first GOOD experience with gear drives in my 2000 hot rod.. The gears were quiet like they should be and I was happy.

    but mind you, PLENTY more needs to be done to the older twin-cams than just the change out of the old shoe tensioners that have a problem.. ie; high volume oil pump is needed and better cam plate and or gear drive or chain drive with newer hydraulic conversion.

    Hoople,
    I hope you trust my opinion as I really did FEEL the needed power to crank the chain vs; the gear.......... LOTS
    signed....BUBBIE
     
  6. Hoople

    Hoople Account Removed

    7,198
    0
    34
    No kidding. Wow I would not have guessed it could make such a difference. No doubt that would make a big difference. I have no internal engine work experience and will be the first one to admit that so what you say is right for me Bubbie.
    I figured the only gear benefit would have been precision timing. Thanks for clearing that up for me.
     
  7. BUBBIE

    BUBBIE Well-Known Member

    4,959
    83
    113
    I would not have believed it either but the simple gear and chain experiment proved to me..... see if you can feel this?

    the crank on the chain vs; gear was like this;

    stop,hard,stop,hard,stop,hard,stop,hard, at each link that rounded the chain sprockets.. I could not make it a smooth operation and I was fatigued trying, and that was 10 yrs ago.

    Now mind you they may have improved the chain NOW but at that time in 2000 they were using the stock chain of then....

    signed....BUBBIE
     
  8. Jack Klarich

    Jack Klarich Expert Member

    18,544
    153
    399
    Seems to me gear to gear less moving parts should equall more power, when was the last time you saw a 6 cylinder chevy motor with timing gears go bad compared to a v 8 with timing chain, tho no reason with the right cut on the gears the noise could also be reducedJMO
     
  9. gizz46

    gizz46 Member

    9
    0
    0
    I have installed two gear drives, both I used the S&S 510 G cams in.
    Both picked up a lot of mid-range power.
    The gear drive will pick up 5 to 7 Hp. but you can not use stock cam with a gear drive, So with the 510 cams you will pick more HP, I don't know how much, but you can feel it and if you can feel it, I think it would be about 10 to 15 more.
    I know the S&S 510 is much better than the Andrews.490 lift cam.:small3d036:
     
  10. BUBBIE

    BUBBIE Well-Known Member

    4,959
    83
    113
    on my 2000 fxds/ more than enough power!

    I went with ported-flowed heads/valves=manley with springs and 570SS gear drives, 95cu in 10.25/1 scrm'n eagle teflon coated pistons and 42 mikuni large manifold, programable ignition, 6speed gears. over 106 hp/tq
    signed....BUBBIE