Yeah. This.

I am pretty much looking at just getting an OS Giken Super Lock off the shelf unit and hoping that I can get this solid piece installed for the pinion.

https://www.scienceofspeed.com/s2000...0-2000-09.html

And looking at this from OS Giken

https://osgikenusa.com/products/os-s...1-nKn2IsyPfUKh

Not sure if I want to muck around and go with shorter gearing too.

 

given the failure point I hear the most on the OEM diff is the crush sleeve, swapping to an OSG wont solve that by itself. The other reinforcements are still a good idea (higher grade internal fasteners, solid sleeve). As far as I can tell that noise you are hearing on mine during decel is due to the pinion moving in and out. That trashes the ring and pinion once it starts to occur.

My plan if my old case is still usable is reinforcements, OSG setup by Lugod and shorter gearing. Still debating on which gearing. A lot of people go considerably faster on 4.77 but it is a ton of shifting too. I believe the TT4 record at heartland was set on 4.77 and the driver told me that while it is a lot more shifting, it is overall faster. I also have talked to plenty that run 4.44 and seem to be happy there.

 

I would also consider getting the reinforcement kit from these guys, it includes a solid pinion sleeve. They will sell the kit to you or you can send your diff to them. I'm not a diff expert but what they show make sense, at least watch from 2:00

This second video of a broken diff tear down is good too, the diff in question had reinforcement caps like the ones from Driving Ambition

Was this with an AP1 or AP2 transmission? Since the AP2 transmission has shorter gearing on gears 1 to 4 I wonder if that would be too much

 

I honestly cannot recall what his car started as. I thought it was an AP1 but it had a lot of mods so not sure what tranny he had in it to begin with.

 

I would get in touch with puddymod.. http://www.youtube.com/@puddymod

 

A 4.77 is the correct gearing for a F20 and AP1 transmission combination.

Makes the car feel slightly more willing than a stock AP2.

 

How are your wheel bearings? Any dried up grease on brake dust shield?

 

No brake dust shield. Wheel bearings are good. recently replaced 11 track days ago. Replaced hubs with Karcepts hubs. Running C42 BBK out back, temp tape on calipers says everything is cool, has never reached 250F/121C - the lowest dot on my temp tape.

Have gone through multiple wheel bearings - I know what it feels and sounds like. This definitely isn't it.

 

100 track days and the oil coming out like that it's pretty safe to say the diff needs some TLC beyond an oil change. Let us know what route you go in terms of how you end up deciding to rebuild it (DIY, puddymod, Team Kelly). I remember seeing those videos of "Team Kelly" on facepage and it's a nice explanation but never heard feedback from people that have used him. His machined caps and beefier studs that fit snugly as well as the solid sleeve look nice. I had puddymod rebuild me a diff a couple years ago now but my car's turned into a garage queen primarily.. :/

 

Team Kelly did my diff. Installed my JDM Spec S OSG, deactivated some clutch plates, put in 4.3s, and did the reinforcement kit. No complaints so far. I originally contacted Puddymod but I would have had to wait about 9 months before he could get to me