In need of suggestions/opinions from those with experience with Evo drivetrain.

a couple months ago, I developed a drivetrain noise after a couple track days (road course). It seemed as though it was the beginning of the death whine. A fresh fluid change was made on the drivetrain before the track days, ensuring I checked the t-case multiple times after short drives to make sure it was filled properly. A slight vibration also also developed at this time beginning around 45 mph no matter the gear or in neutral. I changed the fluid in the t-case a second time, this time with a heavier red line fluid mentioned on the TRE site. The noise/vibration was lessened significantly. The ACD unit began acting unusual, so I changed the t-case fluid back to the OEM fluid. After this next fluid change, the noise seemed louder with slightly more noticeable vibration.

I was able to get a replacement transfer case, so I removed the current one and disassembled it to see if I could fine the source of the issue. I did find that two teeth on the ring gear had a chunk missing. Amazingly, the pinion looks fine. I also dissambled the front diff and did not find any signs of further damage. Honestly, I was surprised there was not more damage.



I was only able to find one of the teeth caught at the access plate on the bottom of the t-case. I also took the time to check the shafts on the trans for any signs of damage. The teeth on the inner/outer shafts look to be in good shape. I noticed that the shaft that has splines on the outside (the inner shaft) has some play (side-to-side and slight in/out). I assume this is normal as it is seated when the t-case is bolted to the trans. When rotating the inner shaft, it does spin, but does not super smooth and sounds like a slight gear moving noise inside the trans case. It did not appear that fluids mixed at all as the correct amount of fluid came out of the trans and t-case.

I guess I am looking for opinions about how the shafts rotate on the trans When the t-case is removed. I am assuming that from the fluid changes and difference in noise/vibration lead to the t-case. Wht are your educated thoughts?

 

The replacement transfer case is now in. I did, however, remove the tail section to make install easier without having to touch the front sub-frame. I have searched quite a bit, but am having trouble locating the torque spec for the rear tail section.

What is the torque spec for the 4 bolts that attach the rear tail section of the transfer case?

 

The FSM doesn't say.

 

That was the first place I looked. I can find the torque specs for the transfer case-to-transaxle, and where the seals go, and even the side cover bolt torque specs, but zero info about the assembly body itself.

 

Working on my car last spring I thought of pulling that tail piece. After a big tug and nothing moving I changed my mind. But, bolts always stick in aluminum. Still, I think they are pretty tight. I don't know why.