njmatt

Hello and thanks for looking at my post!

I recently picked up my second s2000. It's a 2004 GPW and it has 135k on it (131k when I bought it). It's been perfect so far and doesn't have any issues except this one small annoyance. For the last 4000 miles or so I've noticed a whirring noise coming from the rear. It hasn't gotten any worse since I purchased the car, so it hasn't greatly concerned me. It's very noticeable when the top is up, but less evident when the top is down because of wind noise. He are some characteristics of the noise.

-Starts at about 35mph (in any gear)

-gets louder between 35-70mph.

-can still be heard while in neutral although somewhat quieter

-can be heard during acceleration and deacceleration, but doesn't get any worse depending on how hard of accel deaccel.

-seems to mostly go away at neutral throttle (i.e. keeping a constant speed)

-overall it seems to be dependent of speed, not which gear I'm in..

Any input is appreciated!

s2klariat

Possibly the diff? Have you changed your gear oil in the trans and rearend?

njmatt

I believe the transmission and diff fluid were changed sometime before I purchased the car. I'm not sure what type it was replaced with, though. I also suspect the diff, but it still works perfectly and the sound hasn't gotten any worse even with many days of "spirited" driving. It seems like it would get worse over 4000 miles if I had damaged gears. The transmission works fine and shifts like butter. I think I might replace the rear diff fluid again and see what happens. Any recommendations for brand and/or weight other than stock Honda mtf? Also, is there anything else such as the drive shaft which or wheel bearings which could be causing it.

Edit: Also, I have noticed that I seem to have a "sticky" differential. Sometimes when taking very tight turns with the clutch pressed in (turning into a parking space) I notice small clunking noises from the rear. From what I've read this is usually caused from a sticky diff which locks and unlocks during tight cornering. I've been told it's common and doesn't have a negative effect. Not sure if this might also play into the whirring noise..?

Thanks again

speakeasy2009

I have the same exact issue with a used replacement diff i had installed. Freaked me out for a while but its been 5K miles and it hasnt gotten worse. Some say its because i use aftermarket mounts that are stiffer than stock. Im using the AMSOIL 75w90 and i love the stuff.

When i first heard the whirring noise i dropped the fluid and it was clean, but it was new fluid so that didnt mean much at the time. I then went for about a month or so and then drained again and the fluid was clean, and the drain bolt had no silver..so i can only assume at this point, 2 months after the last drain, that the whirring is either normal for this diff or the stiffer mounts...

njmatt

I think my next step will be changing the diff fluid again... Has anyone ever fixed this noise by changing to a different type of fluid? Also, is there anything else that could be causing this noise other than the diff?

Thanks

jkelley

I believe I am having a similar issue so I'm very interested in any advice on this topic

I've had my 05 for about 2 months and have driven it ~4k miles. The whirring noise is completely dependant on speed alone and gets louder (or just "faster" really, volume only changes a little bit and is not terrible at all, just annoying, only with the top up). I dropped my diff fluid only having driven the car 300 mi. since purchase; fluid had no flakes in it and there was nothing on the magnet. Filled her up with Mobil 1 75w90 and the noise did not change. ~3,500 miles later the noise is still exactly the same and I'm not as concerned anymore only because nothing has changed. I figured if it was a bad diff issue, something would have gone horribly wrong by now. I don't get any "sticking" or anything around turns as mentioned above, though.

I will be dropping the fluid again just to check and see what it looks like after the ~3,500 miles and will report back to y'all on this thread (in case it helps you guys out ). I'll be replacing the fluid with Mobil 1 75w140 to see if maybe the thicker fluid will "gobble up that durn sound" and will also report that back to you guys.


Let's git 'er done

Edit: I'm also going tojack the car up first, on 4 jack stands, and then put it in 1st I guess and see if the noise is the same, different, or non-existent while it's in the air. I'll also be checking for lube spot and/or subframe bolts that may be loose.

speakeasy2009

My original diff went out on me after switching from conventional to Mobil 1. After that nightmare i will never use Mobil 1 again. Amsoil Severe Gear 75w90 is the best stuff in my opinion and thats all i use now. Its good to know im not the only one with this issue.

My old Isuzu turbo had a whine in the transmission for 7 years and never went out on me, so maybe these noises are normal after a while. This noise IS VERY SIMILAR to the whirring noise my diff made BEFORE it failed but that noise got louder and louder to the point it could be heard with the top down on the highway and lasted about a week from start to diff failure. This current whirring noise has been the same, constant not getting any louder, for about 3 months now.

njmatt

I just did a routine check under my car last night and I noticed that my car has a set of differential collars. They are "Blox" diff collars. I cant tell if the bushings are stock, though. Does anyone know about these and if maybe this is the reason for the noise?

Thanks

Billman250

90% chance your noise is from the collars.

njmatt

I thought that might be the culprit. When I found those it was sort of a relief. I don't know much about them but it appears that they essentially convert the existing diff mounts to solid mounts. I can definitely see how they might transmit and amplify drive train noise throughout the chassis.

I believe these are also why my car shifts very harsh and is sensitive to rev matching. If you don't get the shift exactly right, the car tends to jerk (my 6 puck clutch might also have something to do with this). It does seem to have an improved throttle response compared to my old s2000, though.

Does anyone know how hard these are to remove? I daily drive my car and I don't really need the added benefit from these collars. I feel like they might also add additional stress to the drive train since the collars don't absorb energy like bushings do. Will I need to remove the differential completely or just unbolt the mounts and pop off the collars?

Really appreciate everyone's help!