s2000Junky

Oh sorry must have been someone else recently with same symptoms, got you both confused. Yeah then, if you have already gone through all the cup/spacer configs up to the stated, then that only leaves this to config left to try. Hope it works out.

The only other thing that comes to mind at the moment then would be to check the easy stuff first if you haven’t already, such as the mounting bolts for the half shafts on both ends as well as the main drive shaft. You can check for excessive up and down and lateral play by hand at the trans output if the bearing is going out, and also check the diff yokes/flanges on half shaft ends and main input where the large shaft connects, if that makes sense. There shouldn’t be any movement if i recall at main shaft at trans end and only maybe 1/16th" on the yokes of the diff where half shafts connect.

Slowcrash_101

You should look for used axles and take the cups from them, it's cheaper than buying new ones from the dealer. Or use them if they're in better condition than your old shafts

stoiic

let me know if you diagnose or solve the problem. I do believe that we are having the same issue. We should keep each other updated lol @jyeung528

jyeung528

here's an update.

i swapped the cups back to the original config, this time with spacers. unfortunately, the vibration still exists at the same 70-80 mph range at light throttle. it is too coincidental to use the other side of the cv cup and have the symptoms at the exact same speed. this is telling me that it is not related to the cv cups because it is smooth at every other speed outside of the 70-80 mph range. i've had the cv cup vibration before in the original configuration and it vibrates at ANY speed.

so this led me back to thinking it may indeed be the differential. i went and bought le-1605 and did a diff fluid change. the fluid that came out was valvoline syn-blend 85w140. metal shavings were small, like before, smaller than the amsoil 75w110.

so i put in le-1605 and drove...the symptoms are still there, however at about 50% less.

my conclusion right now is that the diff is damaged and le-1605 is improving upon the symptoms.

me next check would be to try le-1606 (140w) and see if it continues to improve upon the symptom.

jyeung528

update: not the wheel bearings...diagnostics to be continued.

Slowcrash_101

Unbalanced propeller shaft maybe?

jyeung528

this is solved.

the nut in the middle of the differential flange was loose. tightened it, now it's smooth as butter.

starchland

Just curious how you found that?!

jyeung528

Removed the prop shaft to try rotating 180. When it was removed, was able to observe that the diff flange nut was loose. Diff has never been serviced, only removed once to install new mounts, so it seems like after 200K miles that nut wanted to get loose.

Slowcrash_101

That flange nut has to be torqued properly, so I hope you didn't just tighten it, it sets the preload for the pinion bearing along with the crush sleeve.