Harmonic Vibrations

[0101fam]

So on my 2001 Land Cruiser it has a harmonic vibration that I have been trying to solve. Harmonic is most noticed 50-60mph, doesn’t matter if on throttle or not.

I believe it’s my front differential from everything else I’ve replaced. Started with what sounded like a pinion whine noise so decided to tackle the easy stuff. Wheel bearings, needle bearings, cv axles, both driveshafts, and all balljoints/tie rods. Each part replaced definitely helped a little.

Next step is to either try new differential bushings, but wondering if I should just go ahead and either rebuild or replace front differential.

 

[3_puppies]

try removing the front driveshaft, you will need to engage the center diff lock

 

[0101fam]

try removing the front driveshaft, you will need to engage the center diff lock

I’ve tried that, and removing the rear. Removing the front makes the pinion whine go away but harmonic still there. Need to pull flanges, shaft and test but haven’t had time yet.

 

[LJE]

Welcome to my hell.

Now, hopefully your problem isn't as bizarre, but, there's a ton of good troubleshooting in that thread!

 

[2001LC]

Spiders (AKA: U-joints) perhaps.

To eliminate engine & AT:
While coasting down hill at 65MPH (shift to N as you idle engine).

 

[0101fam]

Both driveshafts are new Toyota, so U-Joints good. Tried coasting in neutral, made no difference. Also replaced t-case output bearing when resealing just for maintenance

I’ve balanced tires twice, doesn’t seem to change any.

Only thing I notice that is abnormal is that it seems that the hotter the differential gets, the more I hear the harmonic. On a cool morning, it might not even make one sound. This is why I believe it’s pinion bearing or carrier bearing. I have had the cover off diff, gears looked normal, couldn’t feel any play in any direction. Backlash is definitely more than what it should be, but also has 228k on it.