Slight knocking noise near the rear of my 2002 Z28

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So I figure I will give this a shot and someone can help me out. About a year ago I bought my 2002 Camaro Z28 6-speed. Only had 35k on it and was adult owned and never abused. I have never had a problem with this car. During the first couple of months of owning the car I got all my fluids changes (including my rear differential). Now this slight noise I am about to discribe might have been there before the fluid change and I could have simply not noticed it. The best way to describe it is a slight knocking or chattering noise. It is in rhythm when it goes off, so I thought maybe it was a wheel bearing but a mechanic said probably not. Anyway, the noise is quiet -- You would most likely not notice it unless I pointed it out and the radio would have to be off. Another thing is that it's only really noticeable when I am making left turns for the most part which I found to be strange. I am just really going nuts over this, even though it hasn't gotten any worse. My one friend is pretty confident it is normal noise from my limited slip differential. And this could make sense if it started after the rear fluid change. I just wish I knew someone with an LS1 F-body so I could see if their car does the same thing. Anyone ever hear of anything like this?
 

jigen

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I forget but it was the mobil 1 synthetic and the weight was what was recommended in the manual. 75 something I believe, lol. I also bought the GM additive to reduce noise from the rear. Who knows... the mechanic could have forgotten it.
 
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if it were mine, I would drain the rear diff and put the proper fluid back in for starters, just in case the right stuff isn't in there.
 
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jigen

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I bought the fluids and gave them to the guy, I am hoping he would have put the right ones in. The mechanic was my dad's friend who rented a garage he worked out of on the side.
 

jigen

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 Originally Posted By: Buffman
hmm 7.5" 10 bolt with a 6 speed LS1. That equals KABOOM :) Making turns could be posi.
lol! I've heard this one before! I treat the car well -- and never do launchs from a stop or anything. But you sure are right -- these rear ends are weak!
 
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Is the noise a kink-kink-kink ...or a (reaching here) spooling up type sound. My buddies newer S10 carries on with every back up/3 point turn. I'd be more concerned with a howling when going down the road. Find an empty parking lot (office complex on a weekend) where you can both power and coast through some figure eight maneuvers. When going straight, weave the car side to side. Then back up while turning in both directions and then going forward in the same and opposite direction. See what that produces.
 

jigen

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More of a kink-kink-kink noise for sure. But it is more dull sounding than metal on metal. S10's have the same rear as these cars so I wonder. No howling noise. I will do a figure 8 drive and see what sounds come out. Me and my friend have tested the noise out on open roads weaving back and forth (usually in neutral so I can hear the sound). The noise is noticeable on sharp turns, primarily left turns. I can hear the noise a bit when weaving right, but not as much. When going dead straight there is little to no noise. Usually only when I go over some uneven pavement or bumps. But this is only heard with windows up and when it is very quiet.
 

jigen

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Yup, pretty sure they have the same rear ends. I also checked out a few Camaro/LS1 forums and I am finding quite a few threads where this noise seems to be a common thing. Some users ended up having unrelated rear issues, but others said it's normal. The 2000+ f-bodys have a torsen limited slip differential that is supposed to be noisy when not under load. I would love to be sure and get it checked out, but I don't want to spend money when I don't have to. Thanks for the replies.
 
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The 2002 differential lubes are the same for the standard and the limited slip (LS). See below. After changing lube and adding the LS additive, it is advised to find a large empty parking lot and do a series of figure eights in both directions. Four or five in each direction will do. This is to ensure the additive is fully incorporated into all the moving parts. I have the Auburn LS and these procedures have worked for me. I don't know much about the Torsen LS. Standard Differential Use SAE 75W-90 Synthetic Gear Lubricant (GM Part No. 12378261) or equivalent meeting GM Specification 9986115. Limited-Slip Differential To add lubricant when the level is low, use SAE 75W-90 Synthetic Gear Lubricant (GM Part No. 12378261) or equivalent meeting GM Specification 9986115. To completely refill after draining, add 4 ounces (118 ml) of Limited-Slip Differential Lubricant Additive (GM Part No. 1052358) or equivalent. Then fill to the bottom of the filler plug hole with the Synthetic Gear Lubricant.
 

jigen

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Thanks so much for the info. I didn't know the figure eights were actually advised. But I have put about 6-7k on my car since the gear oil was changed. Would it still make a difference at this point?
 

jigen

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I did buy the gear oil and additive for my guy, but who knows maybe he filled the rear with the oil and then realized he forgot the additive. It's definitely possible. Maybe I can change it myself with a buddy soon for peace of mind.
 
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It would be a cheap try, anyway. Plus, if you learn anything it would be a good thing, and if nothing else you can check for chunks laying on the bottom of the case! I don't think there's a drain on your cover and your gasket may/may not be in like-new condition upon removal. Be sure to check. If you don't have any other car handy to get to the parts store it might be a good thing to go ahead and have a new gasket standing by before you start wrenching. Again, cheap insurance. That figure-eight stuff would be more important for my LS than yours since mine has organic friction materials that would need to be fully coated with the new lube. Since yours is just gears I wouldn't think it would matter.
 
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jigen

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The mechanic who changed my fluids (rear and trans) said the stuff in there looked brand new and it might have been changed in the past. He said the gasket on there looked new as well and used the same one to seal it up. I guess I can always see how truthful he was. ;\)
 
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When it goes on sale at Amazon.com ..buy the Spectre oil change kit. You may never use all the parts in it, but if you get it at the right price, they have a nice 12v extractor pump. Makes all fluid changes much easier in those situations where removing 8-10 bolts may be inconvenient. It's also great at filling anything.
 
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