I have done searches and read about diff failures and wanted to get a second opinion.

I have MY04, 21K miles, completely stock. Babied from day 1, never launched.

Ever since I had my diff fluid changed out at 15K, I hear a groaning/moaning noise coming from the rear when the steering is turned to either side and slowly accelerate between 0-10 miles. Seems to be more prominant as vehicle heats up. The fluid was changed out by Honda and from what I remember, it was diff fluid 80W-90 (black & yellow bottle - Havoline, I think).

After some research....some posts on here indicate that this is a normal sound for our vehicles, while others indicate a diff issue. So I had it checked out at Honda. Now Honda wants to change out the internal parts in my diff (excuse my lack of knowledge with the specific part names). All under warranty, no out of pocket cost.

Questions:

1. Could this be caused by a lack of LSD additive in the diff fluid that causes it to bind? (again knowledge of diff is nil, asking b/c I experienced this on a past vehicle).

2. Has anyone experienced this type of noise and have left it alone without issue? How many miles has it occurred for?

3. If it is the incorrect fluid, would changing it out now correct the issue, without replacing the internal parts in the diff? Or is the damage irreversible at this point.

Thank you for your time, opinions and advice. Wanted to get some thoughts before I commit my baby to surgery.

 

1. You are referring to friction modifiers that are added to rear diffs with clutch packs. The S2000 rear diff has no clutch packs, so an additives package is not required. If one was added, it does not harm and it does no good. It just sits there.

2. No way of telling what "this type" of noise is. This is the printed medium and it's nearly impossible to convey sound accurately in print. You may or may not have a normal sound. Turning the wheel severely to one side and slowly taking off will generally make the rear diff have a bit of a fit. It's supposed to slip, but the torque applied to get the car moving with the steering cranked makes it want to lock up. Who knows if yours is normal or not.

3. Was it GL-5 fluid? If it was the wrong fluid, damage can never be reversed with the change to the right fluid. It may mask the noise but the damage will always be there. Will it halt the continuing damage? Can't say. Changing the diff fluid is never a bad idea. It should have been changed within the first few thousand miles and then annually or 10K to 15K thereafter. 15K considering your description of your driving habits should not have been too severe for the first change. That should not have been an issue. Try something that is a known good fluid like Mobil 1 75W90 or LE-607 if you don't plan on using the car below freezing temps.

 

since it's under warranty, is there any reason why you wouldn't want a new diff? i guess unless you didn't trust them to screw anything else up? if it were me i'd probably just take a new one even if the one i had was functioning semi-decently.

 

Yes, ordinarily, if they offer a free new diff, take it. However, this is not an entire diff. They are going to take it apart and most likely put in a new LSD. It will still require experienced re-assembly and precise calibration. Not many Honda dealer techs will have any experience putting together a rear diff. They could just as easily screw it up and the "new" diff will have endless problems, too. Sure, they'll have to fix those as well, but then it becomes a matter of tying up the car for days on end. If that prospect doesn't bother you, then do it.

 

ohh, i see now. that part didn't register when i first read it...thanks for the clarification.

 

My thought of having a trained tech tear apart my diff compared to a specialized manufacturing plant in Togichi assembling it makes me hesitant in accepting a "new diff" from a local Honda dealership. Not only on the tech's knowledge but to have everything put together with exacting specs.

All in all, I guess I will go forward with having it replaced. If more issues come about it, I'll let you know. Otherwise, thanks for the advice.

 

Dealers do not tear into diff's as a general rule. Normally the entire unit is exchanged with a new one.

Just an aside, major components were not assembled in Togichi but made in an assembly plant elsewhere often under contract to HMC. Togichi assembled the car but the engine, transmission, diff, etc. where shipped in from elsewhere.

 

A local member is also a tech who works on S2000s at his dealership. He has indicated this very same fact. Honda dealers are not generally recommended to take an S2000 rear diff apart. They just exchange it for a new one. If that's the case, you should have no doubt or reservations about the whole deal.

 

Toucan (sorry your real name escapes me, we met once),

Have you taken the car to Cesar at Earnhardts? If he is saying replace than I would have to agree even if it wasn't free. If you're not taking your car to him then I will need a 500 word essay explaining why not