Knocking sound from rear end

**PatrizioD** · 03-25-2011, 03:39 PM

So I'm pulling into the gas station and all of a sudden I hear a loud clunking coming from the back end of the car. After a little experimenting it seems like it does it when the clutch engages while the car is in mid-turn. I'm pretty much broke, so I think I'm screwed. Any help or ideas would be greatly appreciated; its a 2006 GTO M6 with just under 59k on her, no mods, and I just had her aligned about 50 miles ago.

Thanks for reading! ~Pat

**98maro** · 03-25-2011, 03:44 PM

My car was doing something similar and it was the ring and pinion, that's the only thing I can think of.

**cammed goat** · 03-25-2011, 05:20 PM

Is the rear leaking? Sounds like your rearend is on it's way out. Speaking from experience. The noise happens when you put the car in gear, go through turns slowly and when driving around 5 mph, correct? Like a "clunk...clunk...clunk..."?

**PatrizioD** · 03-25-2011, 07:36 PM

Yeah thats the sound. I havent seen any leaking, havent driven the car much lately. Is this something that a simple fluid change could help? If not, what am I lookin at, new gears, new cover, and some other stuff? Im pretty handy and think I could tackle it myself, but any help is greatly appreciated. Well, off to look for new rear ends...

**98maro** · 03-25-2011, 07:44 PM

I dnt knw how the rear ends on GTOs are but on camaros. Sux.
If u want to keep the the stock. You need pinion, ring and bearings.
Usually that goes bout with labor around $800
Like cammedgoat said. My car did exactly the same. Plus vibrations.

**cammed goat** · 03-26-2011, 03:27 PM

Originally Posted by PatrizioD

Yeah thats the sound. I havent seen any leaking, havent driven the car much lately. Is this something that a simple fluid change could help? If not, what am I lookin at, new gears, new cover, and some other stuff? Im pretty handy and think I could tackle it myself, but any help is greatly appreciated. Well, off to look for new rear ends...

I doubt a fluid change would help. Sounds like a carrier bearing is on its way out. You can look on eBay for rears. The 05-06 will work but you need to change the pinion yoke for the rear to work with your driveshaft. From what I have read and been told, our rears are "non-serviceable" which means the parts inside cannot be rebuilt. You would have to get a differential and a rebuild kit. The factory rears are sent back to Eaton as a core and a new rear is shipped out from Eaton to the dealerships. You could get a good used rear off eBay and keep your old rear to rebuild with a TrueTrac and 3:91s.

**PatrizioD** · 03-26-2011, 04:30 PM

Wonderful, I love having things like this to do... You say the 05-06 will work but the pinion yoke needs to be changed to work with my driveshaft... I have an 06, is this still true? Basically what Im thinking now is that Im just going to take it to my local guy and have him tell me what it needs and what its gonna cost. Ive never done hard launches, never gone to the track, and I like to think I treat her fairly well, so this just isnt fair. I guess its the price we pay to drive beasts such as these. Thanks for the help, Ill post back with the quote from my guy and who knows, maybe it'll be cheaper for me to get a Moser M9 and throw it in myself.

**cammed goat** · 03-26-2011, 04:44 PM

Originally Posted by PatrizioD

Wonderful, I love having things like this to do... You say the 05-06 will work but the pinion yoke needs to be changed to work with my driveshaft... I have an 06, is this still true? Basically what Im thinking now is that Im just going to take it to my local guy and have him tell me what it needs and what its gonna cost. Ive never done hard launches, never gone to the track, and I like to think I treat her fairly well, so this just isnt fair. I guess its the price we pay to drive beasts such as these. Thanks for the help, Ill post back with the quote from my guy and who knows, maybe it'll be cheaper for me to get a Moser M9 and throw it in myself.

If you find an 06 rear, then go for it. It will bolt right in. Have your guy swap oil just for shits and giggles to see if the noise is still there.

**PatrizioD** · 03-27-2011, 07:34 AM

Ok I've been looking around online for info about doing the diff fluid change and I understand the whole procedure. My only concern is the type of fluid to use. I live in the Northeast, so we get huge temperature differences all the time; it was 70 degrees last week, and its 20 degrees now. (Thanks, Al Gore)
So I've seen some people using RP, some say Torco, some say 75W-140, and yet more say at least 85W should be used. I trust the guys here on LS1.com far more than on other forums, so I'd like to know what you guys are using, or even just what you suggest I use. Again, I am at the mercy of my fellow gear-heads.

**Sarge** · 03-27-2011, 08:05 AM

This may be of some help to you.............
http://www.ls1.com/forums/showthread.php?t=152383

**PatrizioD** · 03-30-2011, 10:03 AM

Thanks for the link Sarge, great info and easily understandable.

I took the car out for a spin last night and didnt hear any sounds coming from the rear end. Im going to pull the rear seats today for better hearing and drive it for a bit, then drain the rear and check for metal shavings or other signs of wear. I cant seem to find an Amsoil dealer near me, but was thinking about going for Mobil 1 Synthetic 75W-90 or 140 or maybe a Valvoline for high performance LSD. At the very least it will give me a chance to flush the old crap outta there and run some new stuff until I can scrape enough to order some good stuff off the web.

**wraith221304** · 03-30-2011, 02:11 PM

I bet its coming from the torque tube coupler. Look under the car if you see little road pieces hanging down thats it.

**nomolos1** · 04-02-2011, 06:39 AM

Before you do anything, Make sure your exhaust is strapped down correctly. I had that noise too, at low speeds, and making turns. It turns out that my slp straps loose or one missing. The pipe was bumping the crossmember. Cheap fix, for me. I thought the rear end was gonna need work at first.

**pmolina0436** · 04-09-2011, 07:51 PM

I here a knock, well more like a thump..on mine. it only happens when im coming to a stop..Never found out what it is.. Mine is an a4 though

**cammed goat** · 04-09-2011, 08:12 PM

Have you checked the rubber isolators where the driveshaft meets the trans tailshaft and rearend?

**PatrizioD** · 04-10-2011, 07:29 AM

I havent checked anything really in depth yet, waiting to get my jackstands back from a friend. All this advice on here is great, my first thought when the problem started was that it was going to be a thousand-dollar-fix at the least, but now that I see all the other things that can fail, Im relieved. Now that the weather is starting to break here in New England, Im looking forward to getting underneath the Goat and fixin' her up for some summer driving fun.
Again, thanks to all who've replied. What was gearhead life like before the internet?! I do not want to know.