Hey s2ki

I've been trawling these forums since I purchased my '99 AP1 six months ago. And to be honest I haven't had anything to say until now - every problem I've come across so far has had a solution, and there have been many tips and tricks to keep me occupied!

My differential is making a high-pitched metal-on-metal grinding noise that I can hear quite clearly with the top and windows up - and it gets kind of skull-piercing after a while.

With the windows down, if I drive past a kerb, I can hear it even more loudly. This drives me insane!

I have had a local differential shop pull this thing apart twice now.

First time around, the owner reported that the backlash was so bad the pinion was loose - so a rebuild was required. I took advantage of the situation and ordered 4.77 gears This didn't fix the problem however - after a few hard drives it was back. More headache.

I thought that it might be that the Kaaz diff that the previous owner failed to install correctly just needed to be broken in. I did this, and took it back for an oil change, including a friction modifier - and this had no effect at all on the noise.

The owner offered to rebuild it again at his expense, as the diff obviously still wasn't fixed, and this time around I ordered a Quaife and had that installed to eliminate the Kaaz as the source of the issue. I got it back today, with no Kaaz and plenty of noise. I do prefer the way the Quaife handles however, and I had one of these installed on my previous car - and the fact that it is much lower maintenance than the Kaaz makes it worthwhile anyway.

Needless to say I'm pretty disappointed given that my problem is still unsolved, and I'm sure the owner of the diff shop will be too - he's a good guy. I will be booking it back in to get fixed, but do you guys have any ideas what might be causing this? Is there anything I can instruct the diff shop to look for? Signs of wear or bearings etc.?

I'm located in Australia, so as much as I'd like to enlist the services of PuddyDad, I'm not sure if it's going to be worth the money or the wait to ship it.

This is totally destroying the ownership experience of this car

 

You might very well have bearing issues based on the following driving conditions: High pitched noise on deceleration is a bad front pinion shaft bearing, if the noise is there on acceleration, its the rear pinion bearing, and if the noise is there during cornering, then it could be the side gear bearings. Hope this helps.

 

it could be a wheel bearing. once you been driving for about 15 mins go out the car and feel the rear wheel's center cap. if one side is noticeably hotter than the other, its likely your bearing is out for that wheel and causing the noise.

 

Im going to go with wheel bearing... Especially being that its a MY00. I had the same problem. Metal on metal grinding sound from rear end, very noticeable at low speeds. If you put the car in neutral at 20mph its extremely loud. At 40 mph + sounds like a loud roaring sound from the rear. Those were my symptoms at least.

Very common for wheel bearings to go especially in the early model years.

 

But the noise wouldn't go away after a diff change as the owner stated. Wheel bearings only get worse the longer you run them.

 

If it is indeed the diff making the noise, a used oil analysis would probably look pretty nasty.

I'm also inclined to believe your issue is a wheel bearing but if it's not I would start with a UOA.

 

Thanks for the advice chaps, even the possibility that it might not be the diff is great news!

The noise is there all the time - acceleration, deceleration, straight line, cornering, car in neutral - and gets worse the more power/speed I put through the wheels. After hitting vtec a few times it's really bad, but then quiets down after the car has been sitting for a while. It certainly sounds like it's coming from the left hand side, I'll check center caps tomorrow.

I'll take the car to a local Honda dealer to have the wheel bearings looked at, and failing that, will go back to the diff shop and get a UOA.

Thanks again

 

It's not the wheel bearing.

Had another drive and I can now more accurately describe the symptoms. I'll provide a quick summary of information.

I own a '99 AP1 with 101,000km on the dial.

- With the top UP and windows closed, the noise sounds like it is coming from the rear of the car
- When I drive past a square (not angled) kerb on the passenger side with the window down, it is very loud, and sounds like it is coming from the transmission area - but the sound is reflecting off the kerb and then coming through the window so this may not be a good indicator of the source of the noise
- When I drive past a kerb on the drivers side with the window down, the noise is still there but doesn't seem as bad
- The noise sounds like a metal-on-metal friction sound, but is very high pitched - if you took two discs of sheet metal and started spinning them against each other, but really fast, it would sound exactly the same
- I can only hear the noise under load - accel/decel, but loudest on accel
- There is a slight pause in the noise when transitioning between accel/decel (which I am assuming is due to backlash)
- The sound gets worse with increased load, RPM and/or speed
- The sound disappears when I push the clutch in, and braking with the clutch in does not appear to produce this noise (although perhaps it is too quiet to notice)
- Putting my foot down at 80kph in any gear it is very noticeable

The diff has been rebuilt twice. First, used 4.77s from a Kia Sportage wreck were installed, and then the Kaaz centre was replaced with a Quaife. The sound has been there the whole time, so I think it must be something that hasn't been replaced - perhaps it is a bearing as Mr Apex has suggested?

My gearbox does make a few noises - gear whine, clutch buzz, a bit of rattling at low RPMs - and this sound is definitely not coming from the same place. Looking at a photo of an S2000 transmission, even the output bearing looks like it would be too far forward to be the source - however the noise may be transferring and then coming into the cabin via the diff mounts.

Can you recommend a good viscous oil to use, to eliminate that as a cause? I'm not entirely sure what oil is currently being used, but I can find out. I have been working with a reputable diff shop which *should* eliminate the possibility of them using CRV oil...

 

well i put 75/110 but i have seen others use 75/140

 

Could it be related to this?

https://www.s2ki.com/s2000/topic/409...whining-noise/

Some people in this thread reported that it sounded like it was coming from the rear, but was in fact a bearing in the transmission.