I need your thoughts on what this sound could be.

On sharp left/right turns, in gear, there is a clunking noise coming from under the car. Not quite sure whether its in the rear diff, carbon driveshaft, or transfer case (transfer case was just rebuilt by TRE). If I push the clutch pedal in, the noise goes away. I just changed both transfer case and rear diff fluids and there is no metal in them.

Link for the video is below. Thanks for your help - Marco

 

Did they change any gearing?

Also, try chassis ears to determine exact location of noise.

 

No gearing changed. I recently changed my fluid in the rear diff to Redline Heavy Shockproof Gear Oil and this is when I started hearing this clunking sound. I changed it again last night to Redline 75W90 Gear Oil and the noise went away....there's still very slight clunk but it was definitely the fluid change. I might try other gear oils maybe even go back to the good ole Diaqueen LSD or maybe a 80W140 Gear Oil from Redline.

Thanks!

 

It sounds like chatter in one of the limited slip differentials.

 

I think you should add this if using heavy shockproof:

http://www.redlineoil.com/product.aspx?pid=41&pcid=4

On the bottle instructions it says that the Heavy shockproof has some of the amount of lsd modifier. Maybe this is why it is noisy and you should add the above product. I don't know how much to add it.

 

Interesting! Thanks! I actually just bought some Diaqueen LSD oil from Mitsu. I might give that Friction Modifier a shot.

 

Yes, but add it only to heavy shockproof. Diaqueen or Redline 70w-90 doesnt need it!

 

Or don't add it because it means the diff is working better without. You're taking an LSD that works on friction, and then reducing friction by adding a friction modifier. Pointless....

 

Just checked the bottle and it says the heavy shockproof is good for racing diffs (where good friction is needed). And on road cars, the lsd modifier needs to be added. I am not an expert on this but looks like the problem was solved with normal lsd 70w-90 gear diff oil and the heavy shockproof is locking too much when turning. Better to ask Redline about this.

 

It's not a "problem", other then you don't want to hear a noise that a functioning clutch pack differential makes. You are simply reducing the effectiveness of the diff by adding friction modifier. By not adding it, you get the full effect, and some noise. This WILL NOT cause problems.

 

I apologize, "Problem" wasn't the right word. I hope Marco gets the idea that different oils can affect, how the lsd works.

Jacks Transmissions recommends oem lsd oil to the rear diff, not shockproof:

http://www.jackstransmissions.com/pages/oil

 

Thanks for all of your input. I now have first hand experience on these fluids. I also had a long conversation with Jon from TRE on these subjects. Thanks again for everything!

Marco

 

Sounds like a plated rear diff to me. If I am right, the only way you will get rid of the noise is to swap to a stock USDM Evo 8/9 rear diff and run Diaqueen. Plated diffs make noise, period. Even the stock USDM 8/9 rear diffs had plates installed upside down to reduce noise.

 

It is....from what the previous owner/builder told me, my rear diff has a carbonetics lsd which would make a lot of noise normally.

I am going to try Diaqueen this weekend and see if the noise completely goes away.

Thanks!

 

If your 6 has AYC (i.e., is not an RS), you should consider removing it and going to a USDM 8/9 diff. There are threads on it on lancerregister. The 6 AYC pump is a time bomb.