2006 CM870 vibration in floor 6th gear

[bossboy2]

(02-12-2018 )berrytrucking94 Wrote:  Currently having a vibration in the floor that continues to get worse. Only happens when throttle is engaged, under load up until 1600rpm then seems to even out. Mostly happens in the high side of 6th gear, some on the low side but not as bad (18 speed). As time goes on I’m noticing it very slightly in 7/8th around the same rpm.

Recently replaced the yoke and nut at the tranny because the big nut loosened up and was causing some vibration in the driveline.

2007 Pete with an 06 cm870. Truck has just over 423k on it. Valves adjusted a few months ago, driveshaft/u joints are all solid..

Any ideas what it could be? Vibration damper? Bearing in the tranny?

berrytrucking94, believe it or not I had this same problem in my Cascadia (2013) but my issue was in 8th gear. Yesterday I had all four drive shocks replaced and the problem is all but gone. There is a bit of vibration but that's pretty normal to me. I had the drive line checked out, torque arms replaced, new cab shocks, new front shocks installed and nothing. I was assuming it was just that good old freight "shaker" syndrome. I was shocked when I picked up my load today and the issue was gone. When is the last time yours were replaced?