Suphachai Sangasri wrote on Wednesday, April 02, 2008 - 03:06 am:harmonic balancer is at the bottom of your engine ! it is wheel that drives all your belt relation like alternator , fan etc . direct drive from the crank shaft so its important to make sure it's balance it's a wheel so even our wheel tyre need balance. when get old it can tent to apart as two piece construction, hold together by a rubber layer. when rubber gets crack it will slowly shake it's way out! vibration from this makes the big end or main bearing stress as vibration takes away stableness !!you want the bearing to last as long as you can. trust me! if it comes off! your water pump will take the day off and the alternator will stay out of jail and not be charge! this leads to a tow truck. but if you're lucky your belt may be save . smoothness is the best at 7000rpm so lookout for harmonic balance is easy fixing from outside don't make it an inside job! for the ones that love your 1jz you might just do water pump and timing belt as you there at the party you re going not there everyday!or every year !!