Lift Vibration Issues

[symplman]

2500 question. This will be long. I recently lifted my 02 2500 suburban. We put on a cognito 6 inch with fox shocks. Im getting a vibration at around 40 and it goes away around 75. I also get what feels like binding when i accelerate from a stop and turning (very random). I also get a condition like its in 4x4 on dry pavement. Tire binds and even chirps from time to time also while turning and accelerating. we've been all over this thing and cant figure it out. heres what we have done
Front Hubs
Axle shafts with spacers and without. GMT900 axle shafts
U joints then a custom drive shaft with 3 u joints
New transfer case
rear diff rebuilt
rear seals and bearings
Front seals and bearings
rear drive shaft balanced and u joints
new tires with road force balance
alignment x2
hub rings
Dif is lowered for geometry
rear is wedged for geometry
Im sure im missing something. Any pro tips would be great

 

[ORVietVet]

Welcome to your first post on the forum, from Oregon.

IMO, you started the whole "problem problem" when you lifted it. Bigger tires mean problems. Lifted means geometry changes. Lifted means more stress on the whole steering and suspension systems. Post a pic of the before and after alignment readings. Especially the after readings. Tire specs and pics. Tire air pressures. Bear in mind that the bigger the tire the more impossible it gets to balance and smooth out the tire feel and typically the tread causes lots of problems.

 

[stutaeng]

Yeah, that's gonna be difficult to find the problem with so many new/different variables and unknowns. Could be a combination of things too.

You can lift the truck on jackstands and "run it" and do a quick visual. Maybe will be able to see, hear or feel where the vibration is coming from? You can disconnect front/rear driveshafts to isolate front and rear drivetrains.

Welcome from Texas.

 

[99Sierra2500]

Agree with the rest, sounds like tires or alignment. Do they whine or make noise, are they smooth or gatoring? Driveline stuff usually vibrates low rpm and goes away in the higher ranges, tires are the opposite.

 

[symplman]

Tires were replaced twice and road force balanced. It seams to "bind" when pulling out and accelerating. It acts like its in 4x4 on dry pavement but not consistent.

 

[Tonimus]

First off, welcome to the forum. Sorry you're having issues. When I hear 4wd like binding, I think front axle shaft issues or front diff issues. If your front diff is locked and not unlocking, it will cause all sorts of issues. Depending on how the front diff is lowered, you might still have binding issues in the half shafts.

 

[99Sierra2500]

Sometimes shocks don't dampen the last inch or so, and that the wheels will dance on pavement.

 

[symplman]

First off, welcome to the forum. Sorry you're having issues. When I hear 4wd like binding, I think front axle shaft issues or front diff issues. If your front diff is locked and not unlocking, it will cause all sorts of issues. Depending on how the front diff is lowered, you might still have binding issues in the half shafts.

How do i tell if the front diff is locking and unlocking? it was my impression that with these push button 4x4, that the front diff is always turning and the shafts are engaged when the button is pushed and the actuator turns on

 

[Tonimus]

Jack up the front end and spin one tire while holding the other stationary while it is in 2wd.

 

[JorgeS]

No expert here, but some ideas to help narrow down possibilities, by eliminating potential causes...
Raise it on four jack-stands. In 2WD, you should be able to turn each front wheel without anything else rotating. Turn the rear driveshaft, and only the rear wheels should turn.
This should help tell you that the transfer case is properly disengaging, and that the front half-shafts are not locked together.
Good luck!