Suburban shakes during acceleration

[SubSub]

Problem just started a few days ago. From a stop to about 45 mph, 99 Suburban V8 vibrates/shakes. Strength of vibration seems connected to how hard I'm giving it gas, worse on hills. Above 45 or 50, becomes much less noticeable. Any ideas? I've seen a few threads with similar problems, but I would expect a misfiring cylinder to be worse at high speed. Also no check engine light, or codes.

[777stickman]

Sorry to say it's most likely tranny or some kind of drive line problem. The "check engine light" is mostly for emission problems, like you said for missfires, etc.

[mr_mushroom]

funny thing about misfires.
at low speeds or on acceleration, they can be quite bad, but at higher speeds they have been known to iron themselves out a little.

if you have a misfire you should have a blinking check engine light.
if it's not blinking, then it's not major failure like that, it probably is in the driveline somewhere.

at any rate, i'd suggest not driving it until it's been diagnosed.

so pull the code and let us know.

edit:
sorry i forgot the 'no light/codes' part.
definitely driveline.
i wish you could see the other posts as you were replying, it'd make it easier.
or maybe i just wish i could remember things for more than 7 seconds.

[SubSub]

Additional info - Shaking/Vib was really bad with car fully loaded 4 adults, 2 kids, with 2 of the adults in the 3rd row seat. Since then, with only driver and passenger, the vib is much less severe. I've seen alot of posts regarding U-joints problems. Does this sound like one? Still no check engine light.

[cboyfan2020]

sounds like a classic drive shaft problem.....thrown weight most likely...look on driveshaft for a bare spot like something is missing.

[LastOne]

Any chance the distributor has been removed for intake gasket replacement or something else? I had a similar problem, after I rerouted spark plug wires misfire went away but shake was still there. I did my intake gasket a while back and never got the cam retard set. It was way off. If dist has not been removed, skip this bit of info and run some compression tests, examine plugs, lightly mist plug wires at night with water and look for arc's. Seafoam via brake booster vac hose and some Techron in the gas should nothing show up from tests and visual inspections.