Savvas

[Could not find anything about my exact problem in the forums, if this has been solved before please let me know with a link to the thread.]
Okay, so here i am again, posting another problem once again with my car, hopefully not a big one.There is a humming noise, more like i have a second engine in the rear of my car (yes that loud) noticeable mostly in 4th, 5th and 6th gears (generally at speeds over 50mph).

• Noticed the sound today only, yesterday my brother drove it for very little miles and didn't notice anything (not high speeds though)
• It goes away when decelerating (foot off the throttle or barely on it)
• It goes away when the car is in neutral/pressed clutch (still decelerating in theory).
• Gets a bit louder when pressing on the gas pedal more in low rpms.
• Gets louder the faster i go (really loud at speeds over 70 mph, then it gets muffled out a bit by the engine but you can still hear it.
• Feels like its the rear diff because when you barely hit the gas the sound comes back (once i feel the rear diff gear engage).

I am afraid it might be the rear diff (recently changed diff oil, used to make a grinding noise but it got softer for a while)
So, yea thats it. I really would love your suggestions, all suggestions are welcome, Have an amazing day .

Chuck S

I was unaware the differential gear engaged/disengaged and though it was always engaged. If it was making a grinding noise it's probably the problem. What was on the magnetic drain plug when you changed the oil? What did you fill with?

-- Chuck

Savvas

There werent any noticable metal shavings during oil change. I used genuine honda diff oil recomended by a friend that works with s2k's often.
Sorry for the late reply i fell asleep by accident

S2KPUDDYDAD

Sounds like it's the differential, maybe your friend drove your car a bit careless and did not think it was a issue?

Jah2000

Perhaps this is the problem. If I'm not mistaken, and from what I've read countless times, time and time again...you're not supposed to use Honda Diff Fluid for our diffs.

Chuck S

Your buddy doesn't know the S2000. The differential is running without proper lubrication. Get that oil out of the diff and put the right lube in ASAP. There may be hope the damage isn't severe.

Honda differential oil is for front wheel drive cars. The spec you need is in your manual. If Honda wanted you to use Honda Diff Fluid you can bet they'd have specified it! They didn't.

Here's what I use in the gearbox and differential:



-- Chuck

Savvas

Welp... A few miles after this post and i get a howl with a whir under acceleration and heavy clicking every 2-3 feet for acceleration and deceleration so now i am looking at parts to replace, so far i think i have to replace:

• Rear pinion bearing
• Gear set or Pinion gear
• Carrier case-side gear bores
  

Savvas

Made a new thread for this topic, on what i should do now that my diff is dead (https://www.s2ki.com/forums/s2000-un.../#post24123296).
-Thank you to all that replied here all help is appreciated, have a wonderful day.