How did Deere raise the blade tip speed in 06

Discussion in 'Lawn Mowing' started by luckylawnboy, Nov 3, 2006.

  1. luckylawnboy

    luckylawnboy LawnSite Senior Member
    Posts: 431

    Im wanting to find out how deere raised the blade tip speed for there 06. We bought a 777 72" and I feel the extra speed really maxed out the power of the 27hp Kaw. I would like to convert mine back to the 05 where the speed was around 16000fps instead of 18000fps. Im hoping to get more torque to the blades. It bogs down so much now that the blades are turning slower anyways. Im think it may be the pully on the back of the deck that is the double stack pully where the pto belt and the deck drive belt come togather? Does any one have any exact information on this? or has any one had an 05 and and 06 72" deere to compare.
  2. pugs

    pugs LawnSite Gold Member
    Posts: 3,022

    If you look on there is a serial number break.

    The pulley that mounts to the deck that I think the PTO belt drives and then it drives the deck belt did change. It looks different even in the parts breakdowns like they made the upper pulley larger than the lower one.

    However there is also a serial number break for the electric clutch. Wether or not that changed diameter it would be hard to say.
  3. luckylawnboy

    luckylawnboy LawnSite Senior Member
    Posts: 431

    Ok I got and 05 pully today and the pullys are right about the same size. The pully on the 06 is larger on top, thus that is where the higher blade tip speed came from. My hopes are to get more torque to the blades. weather or not I will notice a difference, we will find out. the pully was about 71 dollars heavy duty with 4 bearings.. Hope it works. I will let you know. Ill take a picture of both pullys when I get them off
  4. green acres lawns

    green acres lawns LawnSite Senior Member
    Posts: 362

    My exmark blades turn 18000 plus from the factory. I raised the engine rpm's from 3600 to 3850 so the blades really spin now. I bet if you put the blades on upside down, it would fly. Ha!
  5. Richard Martin

    Richard Martin LawnSite Fanatic
    Posts: 14,700

    A larger drive pulley will increase speed while a larger driven pulley will slow it down. So if the top pulley of your new stacked pulley is driving something else like the blade pulleys your BTS will come increase and torque will decrease. If the top pulley is being driven by the engine pulley BTS will decrease and torque will go up.
  6. sjessen

    sjessen LawnSite Gold Member
    Male, from Knoxville, Tn
    Posts: 3,335

    I raised my engine speed as well. The dealer cautioned me that higher rpms can significantly shorten engine life. Have you heard that?
  7. slebeau20

    slebeau20 LawnSite Member
    from USA
    Posts: 103

    I was told by my dealer, they also changed out to a different clutch.
  8. luckylawnboy

    luckylawnboy LawnSite Senior Member
    Posts: 431

    yes When we received the 777 it was running 3650 no load so we raised it to 3900 no load and 3730 with the blades on. It helped alot but the blades seem to spin really fast. Faster than our Dixie by the sound and velocity of the the discharge. Im hoping to keep my rpms set at this setting and the new pully and be a better combo.
  9. DLCS

    DLCS LawnSite Platinum Member
    Posts: 4,378

    Right, they went with the adjustable clutch but I think they did that in '05.

    I was told they changed to a heavier duty spindle and changed the all the deck pullies too. I'm not sure you will achieve the desired results but its worth a try if you like the old 7 Iron decks better. Does anyone know how you find out actual blade tip speed, is there some formula?
  10. jdlen

    jdlen LawnSite Member
    Posts: 31

    I have an excel application to determine BTS if anyone is interested. A guy developed it on another message board and converts everything to FPS/BTS. You need to know input rpm and all the pulley diameters.

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