KenGPW

Sorry I have to make another wonderful "I have this noise......" thread, but I going to try my best to describe it. I have searched and came up with some very old threads that provided some help. I figured I would give this a shot.

To start off all my mods are in my sig. I have 45,xxx miles on my00 s/c. I do drive the car aggressively, I will not hide that. Yes the car has been launched many times. I just installed ACT pp & disk about 1500 miles ago (love it). My old clutch was slipping for the longest. So now that I have a good clutch it would not suprise me if all the shock is going to the diff or somewhere else. I also did the axle-cv swap about 4 months ago b/c of the rear vibrating when accelerating. I did not get new parts just switched them left to right. When I took the CV apart there were pits on the inside of course. When completed 90% of the vibration was gone.....

2 days ago I drove the car for about 20 minutes on the highway with no problem at all. I pulled into a parking lot and when I was making very sharp turns at about 3-4 MPH (wheel cut to left or right 3/4 of the way + - when I noticed a pretty loud grinding/groaning sound coming from the rear. The sound is not constant but when rolling very slow with no load on (i.e. in neutral or clutch in) it does it about 3-4 clicks per wheel rotation. I could not here any other noises when going straight.

So today I take my belt off of the super charger so I can here the noise better. I deff have a clicking grinding noise coming from the rear ONLY when turning VERY SLOW. I also noticed a slight wine coming from the rear when coasting down hill at about 25 MPH with car in neutral.

I jacked the rear of the car up from the diff housing and let the car idle in first gear with clutch out. Both rear wheels were spinning freely with no noise at all. So I figured I will slow one wheel down at a time to simulate one wheel spinning faster then the other like on a turn, but no noises. I then turn the car off and try to spin the back wheels with trans in neutral. There was deff a lot of resistance. I was using the spokes on my 19 inch rims for leverage and it was pretty hard to turn. when I would spin (one rim) the rim I would get a clunk noise that seemed like it was coming from the drive shaft (between trans and diff). But it could have been me not turning the wheel smooth b/c of the resistance i mentioned and getting play in the driveshaft. When I turn the drive shaft by hand it turns very smooth and of course there is play there just like any driveshaft when turning back and fourth. But the noise I heard in the driveshaft was very similar to the noise when turning just not as steady b/c i'm turning the wheels by hand.

I also get a pretty loud clunk noise every time I let the clutch out when upshifting through all gears. The clunk is from the rear. Also if I an holding steady speed and tap the gas the car the car jerks and there is the same clunking noise. It is like there is alot of play somewhere in something..... Im not sure if all S2000 do this or not. And it is not the same noise I get when turning. The turning noise is more of a clunking and grinding where this is just like a clunk and rattle noise.

I am going to drain the fluid to see if there is any large metal objects floating around in there and I will get back to let you know what I find. I am also going to take the axles out and turn the input flanges on the diff by hand. That will eliminate any of the resistance from the wheel bearings and rear brakes.

Should the rear wheels spin very freely when turned by hand?????? Is there anything else to figure out what it is??? Could it be my wheel bearings (I doubt it) or even my LSD on its way out?????? Any one know how to check the wheel bearings????? What else can I do????? What should I look for?????? Is there anything to inspect on the driveshaft(problem with the driveshaft does not make sence to me b/c it only happens when turning).



I know that these "NOISE" threads are the worst but I would appreacite and advice or tips to further diagnose my problem. I allready have a diff lined up for this week if that is my problem........

Thanks for taking the time to read and hope someone can help.
Cheers
Kenny

Wisconsin S2k

This is just my adivce, but..... You're on the right track to start by changing your diff fluid. See if there are any abnormal or larger metal chunks attached to the magnetic drain plug or in the fluid. look thoroughly to be sure. also, be certain the diff fluid isn't burnt. (it would smell 10x worse than diff fluid normally smells if it was)

When we had my car up on the jack, it was fairly easy to turn the wheels with one hand. if you're having to crank on it, that would seem abnormal to me, but that topic seems up for some discussion. FWIW i do not have a damaged diff in any way.

The last thing would be to pull the diff out and take it apart and check for missing teeth. i dont think i've seen an LSD failure yet, but i guess anything is possible. though from what i've heard, that torsen unit is pretty damn solid.

KenGPW

UPDATE: I just put the car back in the air and spun the driver side rear wheel foward. When I spin the wheel fast i get the clunking grinding noise comming from the rear of the diff. When the clunking is happening I can see my passanger side axle move a little bit, kind of a shake like something is hitting it causing it to turn 1/4 of an inch but the passanger side wheel is not turning at all just the 1/4 of an inch every clunk. If I spin the drivers side wheel foward very very very slow and steady it does not clunk and my passanger side wheel will spin in the same direction and same speed as the wheel im turning. As soon as i speed it up passanger wheel stops spnning and I get the clunking.....

Not sure if this means anything. Going back out to drain the fluid.

Thank you Wisconsin S2k for the quick response. I know u have been around here for a while and trust your word. BTW how do u like the 4.57's saw the vid now this happens to my diff.........hummmmm

Wisconsin S2k

obviously i love my 4.57's. hehe.

yeah when I did the same thing with my car, spinning tires independently, together, opposite directions, etc, I NEVER got any clunking.

so i'll assume that clunking noise isn't normal.

here's another question. how many times does it clunk per turn? 4 times per tire rotation or 1 time per tire rotation? 4 times would indicate a damaged pinion tooth, 1 time could be gear tooth. then again, could be the LSD but I dont know about what those sound like or what they do when they start to fail. I was under the impression the LSD either works or it blows up and doesn't work, but that could be wrong.

I still say you are gonna have to take that diff apart!

KenGPW

OK diff fluid is very black. There was not much sludge on the magnet and no large chunks of metal. I felt the gear inside of the drain hole and all seemed ok. I slowly rotated the wheel while feeling with my pinky. That only means that the outter edge of the teeth are ok.
The clicking is 4 -5 times per rotation but only does it when spun fast would a wheel bearing clunk???? It is like there is a flat spot somewhere. The only think I can think to do right now is take the drive shaft off then spin the wheel. If there is still a clunk I will have to take the axles out. Im just trying to make sure it is the diff and not something else like a wheel bearing, trans or even the driveshaft. Is it possible to inspect the diff if I take it out and just open up the case, or do i have to remove the ring and pinion????
Also what is the pinion gear???? It is the bigger of the two right??????

dookiewhat

i didn't read your whole thread, but i had something like that... i changed out the rear diff fluid with redline and the noise went away for me.

KenGPW

Im not sure if it is the diff or not...... when u spin one back wheel should the other one spin or not when the car is in neutral??????? When I spin the wheel and get the sound it seems that it is coming from the driveshaft or the trans. If you wiggle your driveshaft back and forth in a circular motion that is the same sound that I get when I turn.....Like it is hitting a flat spot or skipping. Is there a bearing at the end of the diff where the driveshaft goes in??????

DOES ANYONE KNOW IF OUR REARS HAVE SPIDER GEARS?????? My brother inlaw thinks it would be the spider gears b/c it only happens when turning or when turning one wheel at a time.........

tizbad2k

from what i know, which is not much btw.

With the car in nuetral and jacked up, when you turn one rear wheel in one direction, the other rear wheel should turn in the opposite direction smoothly. Any type of noise or grind/vibration should be considered abnormal.

But you should wait for a more knowledgable person to answer, i just wanted to give you something to go by while you wait for a better response.

KenGPW

that is only when in gear as stated in the helms book....... I am wondering what should it do in neutral?????

xviper

We have an inner and outer pinion bearing. The outer one has been known to fail when the car is driven hard consistently. By the description given - clunk only on turning to one side, clunk when power is put back to the wheels and your manual tire spin exercise, I'd guess your LSD is going or gone.
If you had missing teeth on either the pinion or ring gear, you'd hear an evenly spaced noise regardless of turning or not. Noise on turning or when putting power down is an indication of the LSD trying to slip or locking up depending on what you are doing with the car.