Truck Repair: 2000 gmc vibration, hanger bearing, wheel weights

Question
2000 gmc extencab 4.8  2wd 4speed auto truck shakes even in steering wheel at 65-75 km/hr before and after that speed is ok.i have replaced all the u joints and vibration is still there.

Answer
Hi Archie,
it still sounds like a driveline issue, verify that the drive shaft is in phase..meaning the yokes at either end must be in alingment with each other. It is possible that when you replaced the u-joints that you may have removed the slip yoke on the end of the driveshaft and reinstalled it out of phase. also, being an extended cab is there a hanger bearing on the drive shaft? If so check the bearing for excessive play, also check for loose yokes on the diff, trans, and steady bearing if it has one. sometimes if the steady(hanger)bearing yoke gets loose enough it will skip on the splines and then your drive line is out of phase. be sure to solve this issue before driving it...driveline vibrations like this will cause damage to the transmission!!. Other areas to inspect are missing wheel weights, or bent rims.

Good luck,

Matt