The clutch is an original, 2005 with 134000km's. I've had the clutch buzz on my other S2k, and i think i can dismiss that one. Because the rattle sound only occur with 10% of 5% throttle and the car slowing down very slowly. Because i replaced the prop shaft and the diff this weekend with a fresh set, the slop is much less in the drivetrain and some bearing noise gone away from the rear, i now can dismiss the noise comming from the back. I hoped it was my diff. I read something about the last bearing in the gearbox can make this sound... maybe i need an new gearbox.

 

Nope.

The isn't a rear plate on a lot of diffs on cars since the 80's. Seems maybe more of a truck or live axle thing.

 

How inconvenient! I've been working on too many cars from the 1950s.

 

A small update. Still have much lash and play in the drivetrain. I replaced the gearbox for a new one, replaced the clutch with all it's components. Replaced the driveshaft and the diff with a fresh diff with 79000km's. Still the rattling sound (i thought it was a bearing in the gearbox for 100% sure, but not) when i loosen the throttle while driving to 5 or 10%. And when shifting there always is a big clunck. Placed half shaft spacers to eliminate the half shafts. I'm out of clue's. Someone? Also changed the engine mounts and diff mounts. I begin to hate the car...

 

Lets worry about the clunk first, since all can agree that's not normal, even without hearing it. Hopefully addressing that will address the other noise too.

Here is my first thoughts (you already addressed so many possibilities by replacing parts, so this list of course excludes these things).

Retorque all subframe bolts, both front and rear.

Thoroughly check all front and rear suspension pivots. Ball joints, bushings, tie rods, etc.

Check shocks. Upper and lower mounts, spring mounts.

Check swaybar mounts and end links.

Check exhaust mounts and heat shields. Check catalytic converter (sometimes a piece can break inside and bounce around and rattle.

Check for loose stuff. Once I had a transmission rebuild done on a Ford Explorer. Afterwards it would make this annoying clunk only when accelerating from a stop, and only sometimes. Turned out to be a wiring plug that wasn't tied down. It was right under firewall right at drivers feet. It would move and hit firewall and acted like a drum and would reverberate. Just a thick, plastic wiring connector. Was supposed to slide into a holder. They just forgot it.

You'd think it'd bounce around over bumps and make the noise, but it never did. The way the wire hung it only happened on acceleration.

The point is maybe its just something loose somewhere that is just right to make the noise in your driving conditions. Many of the things on my list above you'd expect to also happen on bumps, etc. But since its driving you crazy and you've already ruled out so many things, time to check less likely things.

One of my troubleshooting philosophies is when things are weird, you gotta get weird. When things don't make sense, check things that don't make sense.

Often these methods don't directly lead to root cause, but they uncover new questions and new clues that will lead you there.

 

Thx for all the advise. I'll be looking at it next week. Yesterday evening i did something i've had to be done before. I placed my S2000 and another with 60000km's up in the air. The lash on the gearbox, diff and prop shaft are all identical. The thing i noticed that my 2 rear axles had much more play. The 60000km S2000 had almost no play. When i blocked movement on the diff, i still could turn my axles and there seems movement through the hubs on the diff side and wheel side (rotational). So i think i need new ones. Already put in half shaft spacers bud did not cure. Since you can't get new ones from honda apart from 5000 dollar for a set. I saw H-Gear half shafts for 200 a piece. Or i'll search for used. There is no DIY to rebuild the shafts?

 

You can buy new axle cups from Honda, which is the only part that really wears out. That and perhaps the spider bearings that run inside the cups.

So you could buy new cups, then follow the axle cup regrease diy's, of which there are several methods you can follow (fully remove axles or axle rebuild in place).

The out cv virtually never wears.

DO NOT buy aftermarket oem replacement axles. They vibrate horribly from day one. Be wary of rebuilt axles as well. Who knows what inferior parts they use. Unless you can find a local place that seems to do quality work. There are places that rebuild rare axles for classic cars, etc.

 

It's just sad that we can't get good replacement aftermarket axles. The weird thing is I have zero vibrations. Just a big clunk when I let go the gas end vise versa. The axles just have a big amount of rotational play in then. I'm just delighted that I now ruled everything out and could compare them to a fresh s2000 with almost zero rotational play between the differential and the wheels. Is is just that the cups and inside bearings wear and that's where the play comes from. I don't hope it comes from the splines. Next week I'll be pulling my axles.

 

Yesterday i mounted 2 used rear axles, with about 100.000km's on it. I did not mounted back my half shaft spacers. There was a noticeable rotational play in both axles (the old ones). When i fixen the shafts I could turn the cups a few mm's. The replacement axles where tight. Noticed on about 150km + full throttle pulls some vibrating the old axles did not have. But the play is a bit less, but still there and to much. I mad a standing video. You can here me shift back and forward, and release the clutch a bit. The you here the play and the noise/clunk. So a new gearbox, new clutch, low mile prop shaft, low mile differential, low mile axles, new rear diff mounts, new engine mounts, new oem clutch did not fix the problem.

 

Here 2 more videos of the cluck/knock. You van hear it when i get my feet off the throttle and then put in on next. A big knock.