We have both 8000 and 9000 series JD tractors. Winter service at the dealers this year the mechanic was on us to replace the harmonic balancers on about all of them. Did not do it. They are not up to the recommended hours yet but are getting 10 to 11 years old. He said JD recommended every 5 years or certain amount of hours (don't remember hours right off hand, think maybe 4500)

Anyone have these fail? Should I go ahead and have them replaced. I don't mind replacing if there is actually a need but sometimes I question mechanics need to replace parts all the time.

One example is underhauls. Dealers around here want to do them at 4500 hours. Yet I talk to guys in the south that put bookoo hours on tractors that say they never touch the inside till something goes wrong and they are getting 10,0000 to 13,000 hours out of engines. Things like this make me question if some of this stuff really needs done. 

I have heard if the balancers get bad they can cause crank failure and we did have an 8100 just a year old fail and slid up into the radiator but luckily didn't hurt anything cause we caught it right away. That is why I am asking if anyone has actually had failures - see if letting them go a while will cause me undue problems

John