Omcentarfer

Welp, did both front wheel bearings just for the hell of it… no such luck. I just feel like it has to be transmission, transfer case or front diff related. Once the “shutter” starts braking doesn’t stop it, but letting off throttle and it immediately stops.

@CamGTP @richard wysong

Not u joint related. Swapped both u joints on main drive shaft and swapped front AWD driveshaft and U joint and the vibration/shimmy hasn’t changed. I will say my old ujoints were shot, doesn’t really feel like a waste.

2007 (NBS) Sierra Denali AWD 1500. 160k miles. In the 100k miles I’ve had the truck, I’ve done a sensor or two, ball joints, cv axles and wheel bearings. Truck has original (transmission, differentials, drivetrain, etc.) Around 3 weeks ago I was pulling a 12ft utility trailer, (maybe 1500lbs loaded) and I noticed a weird shake/shimmy starting around 40mph while the truck was under load and with throttle. Notice it most when truck shifts up, and maintains a lower rpm. Fast forward to now and it seems to have gotten worse, I am occasionally hearing a little noise that starts around 15, ends around 30, but still the shake @ 40 ish. The shake gets worse and worse as speed goes up.. BUT ONLY under acceleration. If I take my foot off the gas, it stops. I’ve read it could be ujoints, TC, transmission, front end issues (since it’s AWD), rear end issues, sort of all over the map. I will say this transmission has the clunkiest and clankiest transmission I’ve ever had, but it seems to be hanging on by a thread and it’s been that way the whole time I’ve owned the truck. This issue doesn’t seem to impact shifting at all, if anything the shake might stop if for only during a moment during the shift itself. Would appreciate any ideas you have, things to look for. Going to be hard to put a 4k transmission in a 7k truck, so just trying to see what I can do or should do.