UGH! You do a lot of high RPM dumping of clutch. Or 4-wheel/rear wheel drifting --- where you may have suddenly hit good traction?

 

Pretty much forget what I said earlier, except "it's done, sorry"
How that diff still kinda worked and transmitted power is almost a miracle.

 

I don't do any of those.. All I can think of is that I recently switched to slicks which may have put more wear it due to more grip?

Rest in pieces.

 

I doubt slicks, alone, caused that kind of damage. It looks like sudden shear forces. At least, that is my experience blowing out differentials. I've redone a couple BMW rear ends, which were subject to power-slides. On-again/off-again high torque moments. All done while racing.

Good luck with your fix!

 

Slicks will increase shock load under launch conditions and so will a puck type clutch disc - too harsh in most cases.

OP: I reckon you should go with a Puddy built diff and run 75-140 as he recommends for those. If it's too pricey then your best bet is to get a good condition second hand OEM one. the AP2 '04 and up diffs have strengthened casings. Up to you which path you choose.

P.S. If the wrong fluid was run in the diff for an extended period of time before you bought it then chances are high that the RP 75-90 you used was not the culprit as the damage was done. In the end it's a sorry sight...

 

Looks like sludge on the drain plug.

 

He didn't say if he hot-rodded the engine. Looks like LS3 type launch damage.

 

I found an 04 with low mileage for a steal. I have talked with Puddy and he is such an asset to the S2000 community. As soon as I can afford to I am going to send a diff his way to be overbuilt and hopefully grenade proof. What does the sludge indicate? I was assuming that was just very fine metal shavings and gear oil that stuck to the magnet.

No LS (that's a sin), no launches. Stock motor with header, intake and exhaust. I'm not the easiest on the car on the track and it has proven to be extremely tough and reliable up to this point, which is part of the reason I and I'm sure so many of us love this platform. I'm going to blame the diff failing on a combination of improper maintenance but probably mostly on my own driving habits. Research has told me that lost of traction in the rear that result in slides can cause major wear on the already weak diff.

In the future I guess I will just try to go a little easier on the sliding through corners but overall a few hundred bucks and alot of learning has left me even more intrigued to see what this car is capable of.

 

Good. I'm sure his built diff will be nearly grenade proof. Next thing you should upgrade are your diff mounts. Do you have a magnetic drain plug? I didn't know that. In that case it could just be metal shavings mixed with oil that stuck to it. Sludge would be an indication of "baked" oil as a result of poor quality oil (usually of a mineral sort) and oil that stayed in there way too long. Never been an issue in anyone's S2K I'm sure thanks to the high quality lubricants we all use and those lubricants get changed out ahead of schedule anyway

I'm sure you'll find our cars are capable of quite a lot of goodness

 

LS3 = sacrilege