2nd Gen Non-Engine/Transmission Low Speed Read-End Vibration on Deceleration

[CyberRanger]

Discovered a low speed vibration in the (apparent) rear of the Big Blue today. Vibration occurs primarily between 20-15mph whether or not the clutch is engaged & either brakin' hard or just coastin'. Can also be felt between 25-20mph & from 15-10mph, but not as pronounced. No vibration at all under acceleration. Hmmmmmm?



So tonite I jacked 'er up & spun both rear wheels (engine off, front wheels chocked, parking brake released & transmission in neutral). Nothing. That's good. No expensive parts are bad--so far. Wheel bearings feel smooth as sippin' whiskey. The ring & pinion also seem to be behavin'. So bein' the ole mechanic I am, I figured the best way to simulate the vibration was to spin the rear end the same speed it occured while driving. I carefully jacked the rear end up, putting the rear tires a safe distance from the floor & then set it down on my 6 ton jack stands & made sure it was in 2wd. Fired up the power plant & put 'er into 2nd & carefully (makin' sure it wasn't goin' anywhere) let out the clutch... .



VVVVvvviiiiiibbbbrrrrrrraaaaaattttiiiiioon.....



Who needs one of them 25 cent (OK, 50 cent. No? 75 cent?) Motel 6 beds when ya got this?



Whoah! Into 3rd, then 4th & then 5th to get the speed up to 20mph while the truck idled. I got out & walked around the truck, bein' careful of the spinning rear tires (they sure do spin fast for only 15mph!). No major shakin' there. OK... Must be under the truck b/c it sure is pronounced at the rear bumper. Can hardly read "Rockies" on the hitch cover (OK, not quite THAT bad). Onto the creeper (missing one roller, but I still got 5 more) w/ the Maglite (stayin' plenty far away from those spinnin' donuts!). Lo & behold! Driveshaft looks a bit funky! Sure enough, the rubber around the carrier bearing is vibratin' like an out-of-balance washin' machine.



Seems the rubber has takin' a permanent vacation w/o leavin' notice. Right now we have only 32. 8K miles on it. Pretty early for it to go out. Bet that driveshaft ain't balanced too well. Will call Kotby Motors in Laramie Monday to schedule the "warranty" repair.



More to come... .

 

[CyberRanger]

Had a 9am appt & was in the truck & headed home by 1pm. Turned out to be somethin' simple. The original u-joint was on its way out, but not bad enough to show the real problem until on the way to Laramie this morning. It was obvious by the time I got there. It was just tight the other day, but not enough to even get hot.



As usual, Kotby had me in & out in nothin' flat. No fuss. No hassle. They even offered me another vehicle to run errands in. They offered more than once, but I didn't have any to run in Laramie. I just sat around reading Tom Clancy & shot the breeze w/ the service folks.