The victim is my '06 RCLB Silverado. I just installed 2" drop shackles and a set of 17" alloys. I have a vibration in any gear (it's a 5 speed) under 1500rpms or so. I think the vibration may have been there before I did the upgrades, but if not, how can I tell. I'm at a loss, the truck has a 1 piece DS, so I don't think that the shackles would've caused it, but I am not sure.

 

if it happened right after you installed the shackles and wheels then it has to be one of two things.

1. Your pinion angle is off and you need to shim the rear end, kinda doubtful with just shackles but its a possibility.

2. The wheels aren't balanced right. Out of balance wheels will usually be most pronounced at lower speeds.

It could also be as simple as incorrect air pressure in your tires.

 

I bet it's your wheels. Change them out and see if it still vibrates.

 

Did you get Factory GM 17" wheels or aftermarket? If aftermarket, take the wheels off to see if they removed the clips on the wheel studs, those will cause the wheels to improperly seat and cause a vibration. If not, check the wheels and you might need to have the tires balanced. with my first set of Yokohama AVS ST's on Denali wheels, they had to balance them about 4 or 5 times and eventually got it right when they put it on a roadforce machine.

 

L33Z71 has a good point here! I also am running the Yokohama Geolandar H/T 275/65 R 16's and I've had mine balanced 3 times and STILL have some vibration.

 

great points about the wheels. I neglected to mention that it's only when I am on the throttle. They are factory GM wheels but, I will however, check the wheel studs and the tire pressures, thanks a lot for the leads guys

 

i'm running geolander 305/40/r22 and ive had mine balanced 4 times and they seem to be pretty good now.