LOL, I guess Im on the right track, its on jack stands in the garage as we speak with both the rear wheels off. Was going to stop and get a mechanics stethoscope on the way home, and put it in gear and see what I can hear. Although I have a terrible phobia of pulling a Ferris Bueler (or technically a Cameron I suppose )...

 

And after thinking on this for a considerable amount of time, and consulting with everyone that will listen, my "guess" is that I broke a bearning or retainer somewhere in the diff that has put some slop into the pinion to ring gear mesh clearance. After looking at the parts list for the rear diff, and seeing near 30 different spacers available to ensure the diff gear mesh is within 6/100th of a mm of spec!! (each spacer is 3/100th of a mm thicker than the preceeding part# spacer) I now see how close the tolerences are in this Diff, and why we blow them up so much ....

 

Despite what people say, you need 350+hp to make first gear unusable. I have 360 and I can still use my first gear (granted it only lasts about a second)

 

Well, after refilling the diff fluid I let the car idle in 6th on the jack stands and climbed under. From underneath the car I could pretty closely identify the location of the sound. Which makes for a much easier diagnosis when you can re-create the problem without the car having to be in motion . I was able to isolate the noise to the end of the driveshaft / front of the diff housing. It could have been coming from inside the diff housing, but I could hear the sound best by the front of the diff (could be sound just escapes out the diff through the front bearing easier than the metal plate on the back ). However after listening to this close, I

 

The outer race of the "small" pinon bearing is well supported in the housing.
Parts need to be able to move (flex) to break IMO.

My $$$$ is on damaged rollers.

That will introduce damaged inner & outer race too and some play.

Question about the "stainless" 4.57's
Are you saying there is another manufacturer that makes 4.57 final drive gears other then Richmond Gear?


By all means.. I hope for you they are not made of stainless steel no matter what kind of cryo or heat treatment they have been through.



Your junkyard diff needs to be a MY00-03 or your propshaft companion flange may not fit your MY03 car.
I say "may" beause there was a post not long ago about a MY03 diff (IIRC) that did fit on a MY04 car (IIRC) or vice versa.
Take a picture of your old diff's companion flange and take measurements before putting $$ on the counter at a junkyard
(and refesh the oil straight away... better safe then sorry)

 

Yeah I was aware of the companion flange change on 04+ diffs. I was planning to go with an 04+ diff at first, (20% stronger I read) then heard it has to come all the way apart in oder to swap the flange correctly.

As far as the 4.57s I really don't remeber what he said they were made out of, but It sounded impressive at the time I'll be sure to ask again. I havent spoke to him again since, but basically they were a one off he either had made for a previous customer, or he knows someone who is planning to mass produce them, and is still doing r&d or something like that. Maybe they are richmonds he got stuck with, maybe they fell from the sky, I don't know All I know is he said he "needed a car to test them in, and hasnt had an S in the shop since he received them" But I trust this guy 110% and what will I be out in the end even if they are crap and they break? $200 and a re-broken, broken diff? haha, I can handle that, so Ill let him do his thing, and see what happens. If I do get them installed as planned, I'll report back with more details.

Also, thanks for all the help through this ordeal Spitfire!

 

Hmmm.. so you say someone did swap a 04 diff to 03 car or vise versa without changing the companion flange? Im going to check the manufacture date on my car, I don't know if its early or late 2003. It wouldnt surprise me if some my04 parts made it into a few of the very last my03 cars. I've seen that happen numerous times before on other makes of cars, especially the partially "human assembled" cars, the factory usually just uses whatever parts they have on hand at the time .

 

I think I may have a similar problem.. at constant speed, mostly on the highway, I hear a constant whine/drone like a wheel bearing. Stays constant whether in gear or coasting. I jacked up the car, and the bearings seem to have no problems (holding top/bottom of wheel and pushing/pulling).

I dont think I have heard it before I just put new wheels on though. I guess I'll stay tuned to this thread.

 

mine whine (stockers) and have for as long as i can remember. took it to a a shop that specializes in Diffs and they gave me my keys back and said turnt he stereo up louder...some diffs make noise some dont

 

haha that