Rear end vibration (this one is different)
 

I've replaced a bunch of parts on the s2000 as of late, to try to tackle this issue. I'm running out of ideas. Initially, my vibration was DEFINITELY because of the worn axle buckets. It was only under load and more severe in hard corners, etc. I went ahead and first bought new aftermarket axels from O'Reillys. Import Direct. Vibration changed to going in a straight line between 40 and 60. Bought axle spacers. Didn't go away. Bought moderately new (2009 s2000 salvage with 18k miles) propeller/drive shaft. Didn't go away. Warranty exchanged the Import Direct axles for another new set. Didn't go away. Bought Re-manned OEM axles from MasterPro. Got less but hasn't quite gone away. Not sure what else to try. I've been reading around and noticed a few post about different types of shafts on axles. Something about solid vs hollow? Not sure.

Any suggestions would be appreciated. Right now the vibration comes when I apply at least more than 50% throttle between EXACTLY 40 to 50mph, going in a straight line or turning, doesn't matter. Before and after 40/50, the car is very smooth.

Stock motor, by the way. Lowered very slightly. My next recourse is to bite the bullet and buy new OEM axles... pricey.

Don't use aftermarket axles. Used oem should be fine, just make sure they aren't used aftermarket!

It could be that you have always had two problems, and replacing the axles only fixed one of them. Its difficult enough to troubleshoot two compounding issues. But in this case your troubleshooting may have been confused by the use of aftermarket axles.

Its well known that aftermarket axles don't work well on this car, and cause vibes. So my theory is the vibes changed a bit with one replacement or another, trading worn axles vibes for aftermarket axle vibes, or in some cases no more vibes, but the other, second issue, and its vibes, were always in the mix, making conclusions about any specific set of axles difficult.

So put the best axles back on (low mileage used ones I bet), then look for some other diff vibe issue.

Things that come to mind:

Pinion nut

Diff mounts

Wheel balance

Does your shifter shake or is it more in the seats?

I'll make a point to drive it, tonight. I feel it a lot in my seat, though. Seat, Steering wheel... even shaking the hardtop enough to hear it. Car Analogy, right now, the vibration is the lowest it's been on this quest. I'm wondering if I should go ahead and get the new OEM axles. I really REALLY don't want to. The price is ridiculous. Replacing the driveshaft, I saw the diff-mounts and they looked good. The wheels DID just get replaced but if it were the wheels or anything else, the vibration would probably be present regardless of load on the throttle. Lets see how much these things cost on Honda Automotive. I'm getting ready for my feelings to be hurt.

I buy my oem parts from majestic honda online.

I would rule out other diff vibe issues before dropping coin on oem axles.

Check the pinion nut. Ots beem known to come loose and cause vibes. Search for other drivetrain vibe issues (maybe second issue isn't actually diff, maybe its teans, etc).

Thanks,

Majestic Honda Online is HondaAutomotiveParts.com I believe. I buy parts from there from time to time as well. So, this Pinion nut.. would you be able to give a brief explanation on where/how I would get to it? Does it involve taking the diff, out and dismantling it? Thanks.

it's on the diff, you can access by removing the prop shaft.

there's a very specific procedure to tighten it to spec. but at this point you want to find out if it's loose. after that, you can tackle the tightening if applicable. in my scenario, it was tightened to where it still can spin freely with some drag, a very mickey mouse way of doing it.

i read a thread somewhere, where there is a solid replacement spacer, or something...let me know if you come across it, i've lost track.

you seem to have low miles for the pinion nut to have come loose already, but who knows.

What he said. Its the nut that holds the yoke to the diff. Yoke is the thing propshaft bolts to, at diff end of prop. So you remove the propshaft from diff, and look, there is a huge nut behind where propshaft was. Check if that bolt is loose.

If it is loose, then you gotta find the procedure to torque it down properly.

This is one of those things thats real easy to check and rule out.

i've had also rear end vibration on the right side wheel, and only in 2, 3rd gear at 60% throttle.
the problem was broken diff mount.