Solved: Where to turn next? Chasing vibration/shudder.

As discussed in a previous post, I developed a pretty harsh vibration on acceleration under light load around 15-20 mph.

Vibration/shudder is present in 4HI. Although, when I removed the rear driveshaft I took it for a spin in 4HI using only front DS and could not replicate the issue. Therefore I reasonably assumed it was an issue with u joint, carrier bearing, etc.

I’ve since installed a Tom Woods 1 piece DS which did actually remedy those take-off vibrations that I’d given up trying to solve, so that’s a plus. But, I still had this new vibration/shudder.

Went ahead and did a tranny flush/fill at Toyota in case it’s possibly the infamous torque converter shudder. Vibration still present.

Also just left the tire shop to get rotated and balanced. Still no change.

I also have OVtune if that matters. I’m beginning to wonder if the truck could be missing at that low RPM range under load for some reason? I’m not throwing any codes. I did change spark plugs around 5k miles ago with Denso

Any other ideas?

edited to add additional background info

See replies for conclusion.

 

What kind of tires are you running? I found most of my shudders when away when I finally put new tires on again. Those large lugs can feel like a mechanical type grinding.

 

What's your suspension and tire setup, lift amount, alignment specs etc?

Might need ECGS bushing, rear axle shims, carrier bearing spacer, etc.

 

Toyo Open Country AT3 285/75/17

I should add, this new vibration just started out of the blue one day after having changed nothing on the truck. I’ve only been running these tires maybe 15k miles

 

3in spacer lift with 1” blocks + 1.5” AAL
Bilsteins in rear

ECGS bushing done two years ago. Axle shims were done years ago. I suspected u joints or carrier bearing originally which is why I installed the 1 piece driveshaft. This negates the need for the axle shims anyways and did successfully remove other mild driveline vibrations I was experiencing.

 

It's possible this is a wheel balancing issue then. Check for wheel weights that could have come off. Does it only do it at certain speeds?

 

I just left the tire shop getting rotated and balance. No change.

Yeah it’s around 15-20 mph and again around 35-40 mph. Low rpm, on the throttle, under light load.

 

Did they do a road-force balancing on all four wheels?

 

So when you remove the rear driveshaft the vibration goes away.

Have you looked to make sure everything is torqued and not moving in the rear? What about the rear u-joint angle, it is too extreme or to straight? Ideally it shoud match the transfercase angle but be opposite of it. What about your pinion bearings or carrier bearings in the rear diff. All these will create a vibration while under load and disappear while not loaded (driveshaft removed ) you already eliminated tires, wheels and drum balance.


Edited 'transfer case' for the incorrect autospelled 'taste'

 

Very easily could be the tires, I have the same tires and I get vibes when accelerating and when coming to a stop.

 

Does it happen at those speeds under heavier throttle? AAL + blocks puts some unique forces on the leafs. Have you checked rear end attachment fastener torques? All the stack up from added parts makes more room for things to move and clamp up to change.

 

Yessir

 

Yeah everything is torqued to spec. Driveline angles are money after the 1 piece driveshaft install. Although, rear diff is definitely still in the equation

 

No it doesn’t happen under heavy throttle. It has to be just the perfect amount of light resistance at relatively low rpm. Are you referring to U bolts?

 

Are the vibrations still there at whatever speeds they happen when you slip the gear shift in netural?

 

Haven’t exactly tried that but I’m going to assume I won’t be able to produce the vibrations in neutral because of the conditions that must be present to produce them. Light acceleration with light load is a must. Otherwise no vibration at those speeds. Also, the vibration goes away immediately after lifting off the gas

 

30 miles after the tranny fluid exchange, vibration is gone. Torque converter shudder must have been the culprit.