Danwolski

So last week I replaced my differential mounts with Hasport mounts. Since then the car has been making a noticeably loud clunk from the rear when letting off the clutch to start moving and in between gear shifts. I assume when I got rid of the play in the differential it showed play or movement in a component that had it dampened out with the worn mounts.
I got it up on the lift today and found I have a good amount of play in the differential input shaft, where the driveshaft bolts up to. I'm pretty positive this is whats making the sound. So now the question is what exactly is worn out in my diff? Is it the actual LSD/differential assembly? (Part no 3: https://www.hondaautomotiveparts.com...R+DIFFERENTIAL)
How bad is it to drive on with the play, is it likely to fail? I have a track day coming up and I need to either fix it or run it as is.

speakeasy2009

I had my original diff replaced with a used one at 104K after it suddenly failed. My used EBAY diff has the same symptoms yours does but after almost 40K miles, it has held solid. It even whines a bit but I use Amsoil 75/90 severe gear and when I do my drains all looks good.

Diffs can make noise and feel as if they have some play. However it is important to note that my original diff failed about a month after an autocross where I spun out like 5 times and was really pushing the car. Not sure if the former owners son who drove the car a lot possibly wrecked the diff and it just took a while to show up.

I do not feel, based on my diff disaster, that yours will just fail however pushing it at the track is a different story so you might want to fix the issue before hitting the track. Also if the fluid is due for change soon, do it up now with Amsoil before hitting the track. That is just what I would do...

SmokeyGatto

No noise prior, install part, now you have a noise. tighten all the bolts down HARD. report back

Car Analogy

One thing that can happen, a noise is present but we don't notice it. Radio, just not paying attention, etc. Then we do some service and afterwards we are paying extra attention to things to make sure something didn't go wrong. Then we hear a noise, and assume its new. But it was really there all along.

Its kinda like how your butt dyno can lie to you after making a mod.

So OP, are you certain noise is really new?