XIKeiyaZI

So I just very recently acquired a 2000 z28 with suspension work done. It was driven over 800 miles to me with no issues and the sound I am about to describe has been checked several times with documented paperwork. Now I am somewhat familiar with the rear end assembly but this sounds different than what I can find.

At 45mph there is a loud grinding noise from the rear of the car. There are no back seats so this is very audible. It sounds like metal on metal contact or air howling through a thin hollow tube. Shops which are familiar with these rear ends have checked the rear, entirely disassembled it, and came back with nothing aside from confirmation of the Richmond 3.73's. Wheel bearings have been replaced. Seals seem fine. It sounds like it's coming from both sides - almost like a bad brake grinding is as close as I can describe it. Applying the ebrake or brakes in general at any speed makes no difference. The sound doesn't change with speed over 45mph. It's not apparent below that speed.

The previous owner installed Vette 19's on the rear with hub adapters/spacers which I feel like are the culprits but I am unsure on how to test that. The brakes look fine with no loose hardware. Drive shaft looks free of rubbing anything. Fluid in rear looks good. It shifts and drives like an absolute champ - save for this damn noise.

Absolutely any insight would be appreciated. Mechanically per shops it checks out fine besides the noise but for me the noise is a problem.

Hooker Long Tubes
ORY Pipe
No cats
SLP LM1 Exhaust
Lid
Ported/Polished Throttle Body
Throttle Body Bypass
LS6 intake
BMR Lowering Springs
BMR Lower Control Arms
BMR Panhard Bar
UMI Torque Arm Relocation Crossmember
UMI Adjustable Torque Arm with Driveshaft Loop
UMI 2pt sfc
Rear Airshocks
Upper Shock Tower Bar
BMR Lower Control Arm Relocation Brackets
Hocthkis Front and Rear Sway Bars
Richmond 3.73 Gears
TA Rear Girdle

the_merv

iTrader: (88)

Maybe the Wheels or Drive Shaft is scraping on something.

XIKeiyaZI

Quick update. I lifted the rear off the ground and checked everything I could visually. There appears to be no contact against the driveshaft with anything. I put the vehicle in Drive and listened. At first both wheels turned at the same speed, and then slowly the passenger side would slow to a stop, and then attempt to turn like something was rubbing against it. I had my helper tap the gas and I then could hear that the noise I am hearing is coming from that side.

I removed that wheel and found this.



One of the mounting studs for the spacer/adapter is missing. I tightened the nuts that I could which was an additional half turn at most, checked the e-brake which seemed to be releasing fully, and sprayed some carb cleaner inside of the hub. I put the wheel back on and took it for a drive. Noise is still there but it doesn't seem quite as bad as it was.

http://www.youtube.com/watch?v=oZnw6...ature=youtu.be

Again, wheel bearings have been changed and dif has bee disassembled, inspected, and refilled. This seems to be coming from the passenger side but I can't pinpoint what the hell it is. Braking doesn't effect it, only speed. I can grab the wheel and try to move it side to side or up and down and feel absolutely no play. So... yeah? Might it be that the missing stud for the adapter being gone is causing unevenness with it against the hub and it's rubbing something?

the_merv

iTrader: (88)

That stud will have no effect..Conical Lug Nuts. I have them same Spacers on the back of my SS.

Check that Caliper Bracket and make sure it's not rubbing on the Rotor.

jimmyblue

iTrader: (11)

I can hear a light scraping sort of noise in the rear
on my car, it seems not to follow road speed. I can
hear it at the wheel when I turn it by hand, I think
it's just slightly dragging pads "ringing" the rotor. But
I did not go so far as to remove the wheel, or the
caliper from the hub, to say for sure. Just going by
ear and proximity.

The noise has been there for quite a while and there was
no rear end debris at recent oil change to indicate any
internal wear going on.

XIKeiyaZI

This seems to only be prominent with speeds above 40-45mph. I did some driving today and noticed that it is -more- prominent with throttle but not by much. It is just a constant droning grinding noise. I pulled the fill plug and decided to add a bit of gear oil to see how the level was - 1 and a half bottles later it was full.

So....Huh. That's not good.

the_merv

iTrader: (88)

Sounds like the Gears are setup wrong..was it refilled with fluid when the cover was taken off?

XIKeiyaZI

Well in my 97 which was running 4.11's I had a humming noise on decel. I could understand humming but this is like metal on metal racket. Can improperly adjusted gears cause this noise and if so, how would I go about correcting it? What's my price range for repair and who could I search for to do it properly?

This is kind of an awkward first problem for me. Haha

Now also just to add - with the rear off of the ground if I spin the passenger side wheel in either direction the driver wheel spins at the same speed in the opposite direction which I know is normal. However if I spin the driver wheel forward, the passenger doesn't move. If I spin the driver wheel backwards, the passenger wheel moves. Is this typical or signs of failing/improperly adjusted gearing?

the_merv

iTrader: (88)

I would take a look at the wear pattern on the Ring & Pinion.

I'm not famaliar with the shops where you are at, but I do my stuff on my own for a reason.

XIKeiyaZI

What's your price?

the_merv

iTrader: (88)

Shoot me a message on FB..

XIKeiyaZI

Welp, to humor myself this morning I took it to a few different shops and let them drive it - each one was set on it being a pinion bearing. x.x

XIKeiyaZI

Updating this thread.

Had a friend who works for Chevy drive over and check it out. Turned out to be the inner Pinion Bearing and I believe he said both Carrier Bearings (Which press on to either side of the Dif) But either way, after picking up a Timken Set, Checking the gears to find that the ring and pinion were perfect, and some fuss with the driver side C-Clip as the wheel bearing on that side had been replaced, we got it rebuilt.

With Absolutely everything in spec, the car is quiet from 0-40 and then from 50 onwards. At 40-50 there is what is considered the "Typical" whine from the Richmonds, but we're running Amsoil Severe Gear right now. I may switch it out for something different, perhaps Lucas, shortly down the road to see if that eliminates the 10-/+mph whine.

1 FMF

iTrader: (1)

i posted a thread,
https://ls1tech.com/forums/gears-axl...ear-whine.html
having a picture of sound frequency. I have an s60 with 3.73 spicer gears that has a very audible 550 hz hum at 50-70 mph under power. i've had it rebuilt once, and then had it checked out a second time and told it was normal noise and if the axle was in a truck i would never hear it, and that my car was quiet. my wear pattern checked out perfect and was told there was no guarantee another gear set or bearings would solve anything because nothing was evident. but at 60mph it is very loud and ridiculous, and i had gutted my interior to use sound deadener before the axle install which really pisses me off.

if you can, if you have an android phone there's an app called "frequensee". it shows a real time graph of sound and on mine under that 50-70 mph i get a nice hump at 550 hz. see if you can do something like that to better quantify your problem. or you can record the sound then process it on your computer to see what frequency your noise is.