just replaced the rotoflex and noticing a vibration under acceleration, if I accelerate slowly (never touching 2K on the tach) I don't really notice it, but anything more than that I can see the vibration across the dash board. Where would you guys suggest next?

Don't know if this will help but I checked the rotoflex after hearing a noise on the road, it was badly cracked and torn up. I then decided that after 1 last drive around the corner to pick up my daughter from school that I would take the truck off the road until I replaced the rotoflex. That last drive around the corner was the first time I noticed this vibration.

 

have you checked all the other simple **** first; i.e. check alignment, uneven tire wear, tire PSI even all around, etc?

what type of vibration?
feeling it only through the steering wheel or entire vehicle?

just a thought to get us thinking in the right directions...

 

I feel the vibration through the whole vehicle, I can hear the whole back end vibrating (panels, sunroofs,etc.) and I can see it in the hood and the dash, actually pretty equal on everything else including the steering wheel (kind of like driving on a rumble strip I guess but not quite that violently). I have never had this kind of vibration before, I heard some noise coming from the back of the truck, so upon a visible inspection noticed my rotoflex was all cracked with 1 big chunk out of it, I have pics if anyone wants to see it. I then decided to order a new one and do minimum driving until I could replace it, about 20 minutes later I drove about a half a mile to pick up my daughter and that is the first time I noticed the vibration. Then decided to take the truck off the road and overnight the rotoflex. After replacing the rotoflex I can still hear that noise sometimes but not like I did before replacing it (almost sounds like it may be coming from the transfer gear box area). My first thought was maybe the rotoflex being bad may have did somethign to the rear differential, I was thinking about picking up a grease gun in the morning and greasing all the grease nipples underneath the truck.

I would like to think if it was any of the things mentioned above it would have started slowly and become worse but this happened all at once.

 

Check all you u-joints. If you haven't been greasing the joints they are probably ready to be replaced. Arizona dries things out very quickly as you know and grease in joints is no exception. Usually vibration is a sign something is about to fail.

 

grease em all

 

ok guys I have a question? I slid the driveshaft off the splines at the ujoint side so that I could work on it in a more comfortable position, when I put it back on it would only go on certain ways (like one or more of the splines were keyed) I am pretty sure I put it on differently then I took it off because I had to jack up the back end and turn the wheels to align the rotoflex. In doing this I am curious if I maybe caused my vibration to be alot more noticeable.

also if this is the case all I would have to do is jack up the rear axle, unbolt the rotoflex and turn the wheels to adjust the way the rotoflex adapts to the rear differential right? or will I have to remove the whole driveshaft again and realign it?

 

You say it is only under acceleration, so that means that if you are going a speed and let go of the gas the vibration stops? Spark plugs would produce that kind of "vibration".

 

actually if I get up to whatever speed I feel it but when I maintain the speed I dont feel it. I know it is there when the engine is below 1500 RPM but I dont really feel it until about 2000 RPM and up (it seems to get worse the faster I am accelerating)

 

Either your drive shaft is out of balance or you installed the new roto flex back wards, the arroe should be facing the direction the drive shaft turns.
Remove the rear drive shaft and drive in hi lock, see if you still have a vibration.

 

the only arrows I saw (more like triangles) were on the edge of the rotoflex at each hole, I was under the assumption this was the directional part as to which way which bolt should go in.