I have a 2002 c5 z06. My differential recently made a very loud noise and I replaced it with a Zip 4.10 differential after finding out it was shot.
I did the install myself and everything seemed fine for a few hundred miles while I broke it in.
Then a humming whining noise started happening in 3-6th gear. Not nearly as loud as when my original diff went out and the noise didn't come from the rear.
I did the shifter adjustment and it was still there. I might add that my shifter pin whouldn't drop when the gear lever was in the center of neutral. I had to almost put it in 3rd for the pin to drop all the way. No amount of wiggling would get around this so maybe that's a hint. 1st and 2nd also have a slight grinding sometimes. A search seemed to indicate that my synchros are worn.
I also lifted the car and had a friend put it through the gears while I listened next to the diff. No noise from the diff but plenty of noise right under the center tunnel. The shifter also vibrates quite a bit when the noise starts. I'm thinking something isn't aligned after I put everything back in. Does anyone have any ideas on this?

 

I recently had the not come loose on the front of the pinion shaft in my car. That makes a hell of a noise. No joking matter either. If it comes apart you're not going to like that.
Here's a link to a couple of my videos and the rest of the thread shows the entire disassembly. It's not the same thing as a C5 rear but it's the same principle. I mean it's a rear end. They all have a nut that can come loose.
https://www.corvetteforum.com/forums...post1599473147

 

PS, I can't imagine there is any alignment issue with installation. I have no idea what you could even miss a line. Either the bolts are in the holes or they're not. So no I'm not buying misalignment.

 

Thanks for the info and the reply. I listened to your videos and it sounds more like the whine I had from my original diff. It's also under deceleration. My new diff doesn't seem to have any noise coming from it. The noise is directly where the shifter is and only occurs under partial acceleration. If I use a little more throttle it goes away and no noise when I let off the gas pedal in gear. No noise out of gear. I'll record a video when I get off work and post it up here.

 

Sorry for the shakiness of the video but here is what it sounds like.

Whinning noise

 

Link fail.

 

Okay I put it on youtube this time.

 

I'm trying to reconcile what you said in the op and what I'm hearing in the vid.

Leaks? Do you have any?
Transmission. Did you take anything apart (separate halves) or otherwise loosen things?
TT. Did you have that out? If so, did you check the bearings and see if they felt ok? (I know that's a crap shoot).

It seems real pronounced in one particular gear, is that 4th when it REALLY starts making the noise? (that's straight through fyi. This appears to be on the second countershaft and I'm not positive if 4th engages that or not).

#1, I'd be making sure there's fluid in both the trans and diff. That's a must. The diff "Can" pump it out. At least mine can.

Goes without saying it seems like the trans, but I can't think of what to check. I'd make sure all bolts are tight, no gaps in mating surfaces between TT/Trans/Diff.

I can't think of an easily missed thing that would cause this, but I'd almost bet it's something simple.

 

If you installed the shifter wrong and it was really wrong (I have my doubts that's even possible), but if so, the shift forks do have a fiber pad on the ends that is the wear surface. Those could have gotten burned up by having constant pressure, and maybe that has now caused some other things to bind up. Still, I can't imagine that's possible.

Hate to say it but if it were my car, I'd pull it back apart if I didn't see something obvious while checking to make sure things are tight. I had mine apart before my oil analysis came back this spring. Just ain't worth replacing major components. My taking mine apart saved me anywhere from $5k to $10k, no joking matter. Total cost, <$200, including new fluids.

 

The only part I took off was the diff. I tilted the whole drivetrain so I could get the diff off though. Don't know if I messed something up at that point. I changed the transmission fluid at the same time I put new diff fluid in but haven't checked either the last 100 miles so I'll double check that. I used ATF for the tranny and I made sure to put the friction modifier in the diff. I can't think of any bolts I didn't tighten but I'll go over all of them again just to be sure. I was wondering if the shifter linkage not engaging a gear all the way would make the noise. Maybe I bent something there and that's why the shifter lock pin won't drop in neutral. I'm spit balling here because I don't know. If I have to I can deal with the noise but I don't want to damage anything by driving it.

 

I don't have a lift so yeah that's going to be a pain in the butt. I'll have to though if nothing else works. I doubt they'll be able to figure it out but I'm going to take to a dealer Friday and see what they say is wrong. Thanks for all the input.

 

1) Highly doubt it's possible to damage anything letting it hang there.
2) Highly doubt you could bend the shift linkage. Mine was also a bitch going back in fyi.
3) Not engaging all the way: Highly unlikely... The ring slides forward and aft to engage two sets of spines and it's pretty much either engaged or it's not. Yes, they can be hanging on the very edge of those 'gears', whatever you want to call the splines that engage... when that would happen, they will allow that ring to wobble because it's not straight and sitting on the full circumference of those 'splines'. That's easy enough to semi-test, just be a bit more aggressive as you put it in that gear and try to 'sling' that ring into place. Even if the forks are coming up short of pushing it all the way engaged, you can sorta fling it there if you slam the shifter some. Sorta like you're throwing it into place. That is indicative of forks not having the ends on them any more. Not sure there.
4) That's a very bad noise. I would not 'deal with the noise", I'd "Deal with the noise"
5) What ATF? Strikes me GM wants a manual trans fluid, but I could be mistaken.

6) The entire shifter moves fore and aft on the mounting bolts. That's used to adjust where the center position is. Meaning, you move the shifter body, and the shift handle moves forward / backward, opposite the direction you move the body. I'm not sure what you mean by 'lock pin dropping in". Mine has a roll-pin and it isn't connected without it. No choice but to have that in place.

 

I would ask around for a Corvette Shop to take it to. Under no circumstance would I take it to a dealership.

 

There is a pin that drops down when adjusting the shifter. Looks like an allen wrench. It only goes down when the lever is almost in 3rd. I'm going to take the whole thing apart and see what's going in it. I also thought it was odd to use ATF but everything on the forum recommended it. And yeah I don't know if I can handle the noise. Luckily it's not my daily. I'm going to top off the fluids tonight and check for leaks and loose bolts anywhere. I'm also going to change the clutch fluid using the Ranger method that I found and see if that does anything. Doubt it but worth a shot. My car was down for a month and half so this is driving me nuts that I can't just enjoy it.

 

Gotcha. Well there's 21st century performance and corvette world in my area. Don't know which one is better for troubleshooting.

 

Well, no... I don't know... It's been a while since I tore down my C5, and my C6 didn't have any such pin. I really don't recall them being that much different, I wonder why yours has some pin for adjusting and I'm not recalling that. When I removed mine, I seem to recall 2 large torx head screws, and a roll-pin that held on the linkage to the shifter output shaft. That was it.

If there's any oil/fluid in either of them, that's not what you're looking for. I'd be expecting to see one of em dry to make that much noise. Surely you'd see a awful mess under the car if there was a substantial leak.
Any shop that's truly familiar with Vettes should be able to read your posts and watch that vid and have a good idea. I've done a few, I'm not a vette shop. If I worked with these regularly, I can tell ya I'd have a pretty good idea what to look for. My C6 is the TR6060 and the beefier diff from the Z, so not exactly the same animal. But it's close enough. I just can't think of something else besides a part loose inside, and I know you don't want to hear that. I tore mine down as I said before. Watch your vid and mine, and they sure sound similar...

 

I actually got the shifter adjusted properly last night. Had to take the whole shifter off and clean out the hole where the pin drops into. The roll pin on yours is doing the same thing. Holds the shaft in place. It's all aligned now. I checked the fluid and it's fine so that's not it. I called Corvette World and they think it might be something with the torque tube. I'll be taking it in as soon as I get a chance. Been driving my GTI only and I'm missing the V8.

 

I think I recall now, the shifter has a clamp with a 10mm head bolt, 6mm 1.25? And that clamps the linkage tight? Much nicer than the rollpin for damn sure. That was a pain getting back together in mine.

I mentioned the TT above, but that seemed unlikely due to the severe nature of it. I mean, those bearings in there are just along for the ride. There's got to be some other side-load to create that much noise. Most of this stuff just doesn't go bad in 100 miles? It's very strange...

Upside if you don't need to drive it far, is gears are pretty resilient. Don't abuse things and they'll survive quite a bit. I hope you don't need to take it far in the present condition though. FYI, I bet I drove mine 200 total miles with the rear pinion shaft nut loose. Not real bad at first, but slowly getting worse. Didn't have a lot of miles left in it before it was catastrophic though. Do whatever you can to avoid making that noise when driving.