Spindle bearing failure - HELP!

Discussion in 'Lawn Mowing' started by Jason Pallas, May 14, 2001.

  1. Jason Pallas

    Jason Pallas LawnSite Bronze Member
    Messages: 1,335

    I've been having a rather troublesome problem with bearing failure on my 48" Buntons. Seems that I'm constantly rebuilding the damm things. Sometimes they fail after just two weeks of cutting. I've done everthing I can think of - blades are balanced, greased regularly, etc... I've recently decided to give synthetic grease a shot - but at $5 a tube it's almost twice as expensive as the other stuff.
    Does anyone have any advice? Any advice would be appreciated. These machines work a lot (we do about 475 lawns a week around here) but bearing failure after 2 weeks on a new rebuild is just too soon. I'm willing to try anything to keep from having to change another spindle on the road or after work. Much appreciated.

    AVRECON LawnSite Senior Member
    Messages: 290

    I'm not sure if they will fit, but I'd almost bet they would. Try Scagg or Bobcat spindles.
  3. lawnman_scott

    lawnman_scott LawnSite Fanatic
    Messages: 7,547

    Is it the bearing in one particular spindle that goes, or is it in all of them?
  4. awm

    awm LawnSite Gold Member
    Messages: 3,354

    I know how much of the 475 yds that buntun does,
    but i guess they could be just over heating and burning out.
    get your men to lube every 6 hrs ,unless you decide to get an exmark
  5. racerdave

    racerdave LawnSite Senior Member
    Messages: 260

    Buy a new spindle. The spindle shaft in the spindle you are rebuilding may be slightly bent, causing premature failure of the bearing. Also, check with the Dealer to see if there is a bearing preload requirement for this spindle. If you have too much preload, the bearing will heat up, If you don't have enough preload, the bearing will skid instead of turn.
  6. Jason Pallas

    Jason Pallas LawnSite Bronze Member
    Messages: 1,335

    Thanks guys - some good ideas. It's not confined to one particular spindle. I'm pretty sure the shafts are all straight and relatively new. They all seem to fail equally. We could grease them more (every day). We grease them weekly now (it's such a pain because the grease fitting is underneath the mower - not like the new top greaseable spindles). I'm not sure if the scagg or bobcat spindles will fit - I defintely like the tappered roller bearings much better - however, I do recall looking into it and something wasn't compatible (bolt pattern, pulley diameter,etc....).
    Racerdave - I'm not sure what you mean by preload. If you explain to me what preload is, maybe I could explore that avenue. Thanks.
    One last thing that I read in a thread was belt tension - i.e if the belt tension is incorrect (too tight) this might cause the spindles to wobble - anyone have any experience with that? Thanks again -
  7. EROSS17

    EROSS17 LawnSite Member
    Messages: 49

    475 lawns a week? How many crews do you have going? What part of the Detroit area? 475 is an incredible amount of lawns.
  8. racerdave

    racerdave LawnSite Senior Member
    Messages: 260

    Jason, bearing preload is a setting used when rebuilding spindles in general. I'm not sure if yours fits in this field but I'll still explain it. Bearing preload is a required function for all taper roller bearings or angualar contact bearings. The preload ensures that the bearing balls or rollers will "roll", if the preload is not enough, the bearing balls or rollers may actually skid around the races. Too much preload will cause them to overheat and fail. This load is measured where the bearing is captured, and should be around .001" to .002". You should check with your dealer or mower manufacturer for the right preloads and assembly sequence. Grease may also contribute to your problem, most bearing failures are a result of over lubrication. If there is too much grease in the bearing, the bearing will also tend to skid instead of roll. Hand pack a bearing then rotate the races in your hand, the grease thats pushed out of the bearing is excess lubrication. A little dab will do ya! so try using less grease. As far as belt tension goes, use the minimum amount of tension required to keep the belt fron slipping. check your owners manual for deflection requirements.

    J, also make sure you are getting the right bearings. Get the bearing# from your owners manual, don't rely on the bearing # you just pulled out. Some are enterchangable, but they don't work the same. i.e. speed rating/load rating
  9. lawnboykb

    lawnboykb LawnSite Member
    Messages: 51

    :confused: Do you balance your blades?
  10. John from OH

    John from OH LawnSite Member
    Messages: 144


    Do the new bearings have seals on both sides? If so, remove the seal on the side the goes in the spindle housing so that the bearing can get lubrication. The new bearings are often sealed on both sides and are supposed to need no furthur lubrication. Its a good theory, but they seldom hold up without additional lubrication.

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