# Clunk in rear end



## pykes04goat (Apr 4, 2009)

Hey has anyone had the problem of clunking in the rear end when letting of the gas and then back on it again, you can really hear it in 1st gear if your coasting and then give it some gas. Dealership looked at it and said its the gap in between the gear and its suppose to be that way, i thought it was driveshaft yoke but it is still good, any ideas?


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## d50h (May 31, 2009)

change rear fluid with torco rgo and 2oz type f, this will fix it


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## 87GN06GTO07IRL (Aug 10, 2009)

Is it an M6? They do have a good amount of driveline slop.


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## pykes04goat (Apr 4, 2009)

it is a 6 speed but the plate under hood says m12. i asked dealership about replacing fluid and they said it was fine. i drives amazing just that noise is annoyong. when im in 6th gear and coasting and you put your foot back on it you can hear it as well just not as loud as in 1st 2nd


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## GTO JUDGE (May 14, 2005)

pykes04goat said:


> it is a 6 speed but the plate under hood says m12. i asked dealership about replacing fluid and they said it was fine. i drives amazing just that noise is annoyong. when im in 6th gear and coasting and you put your foot back on it you can hear it as well just not as loud as in 1st 2nd


Take it to another dealer. Did they tell you how they know the fluid is ok? There has been reported issues and documentation in TSB's regarding clunking. The viscosity was known to break down causing this. It did it to mine with less than 9K on it. Replacing the fluid with synthetic with FM solved it.

The MORON that told you clunking is normal is an idiot. Gap in the gear supposed to be that way and clunking is a normal by product of this?? 

Do not take this as normal. They either have NO clue on this car or are too lazy and or ill-informed to diagnose it. Their "normal" may cost you if you don't have that issue addressed.


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## Richtenb (Feb 1, 2010)

87GN06GTO07IRL said:


> Is it an M6? They do have a good amount of driveline slop.


+1 on this.. my driveline also clunks. It seems firm when you try to move the driveshaft although the power when you shift is probably a tiny bit stronger than our arms. the diff does pretty much sound all the time if it is broken not only when you shift or downshift


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## BobS (Jul 28, 2005)

+1. Clunking just as described.. no improvement with a rear end fluid change... although it was not Torco fluid.

Got worse after I had the Pedders Street2 bushing kit put in, obviously. I had the fluid changed at the same time (GM fluids), though.


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## jpalamar (Jul 22, 2008)

Hopefully they put it in writing the rear is OK as is. Def change the fluid. It will be the best $60 you ever spent. I would consider doing the trans fluid as well.


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## d50h (May 31, 2009)

gotta make sure to have 2oz of type F friction modifier


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## GTO JUDGE (May 14, 2005)

Clunking and growling may indicate the clutches in the gear are binding causing the noises. If changing the oil and FM doesn't remedy the issue get it looked at. Don't dismiss it as normal, what someone may determine is "normal" may cost you in the long run. How many techs are in a shop that are WELL versed in this rear end and know the history of it? DO NOT trust the word of a generic shop. 

The rear end whine issue: Rear ends were swapped out because of the whine. Dana built these rears and it wasn't determined if there would be an issue down the road associated with the whine issue, so they were replaced. The first course of action was to replace the oil and FM. If that didn't solve it then a full replacement was made, this decision was made by the shop manager, if the whine was so slight, it was a judgment call, some replaced rear ends were no better than the one removed and some have had multiple new rears installed before a "quiet" one was installed.. This is all documented.

So why didn't a dealer just tear open the rear and rebuild or replace gearing etc? The rear end is a Dana product and was one part number. By GM tearing open the rear end they would be working on a Dana rear. Dana was responsible for the rear ends. So, being the entire rear end, including drive shafts etc was one part number the whole part was replaced.

These were returned under warranty. There is good compensation to be made on back charging a vendor. More then just fixing and billing Dana. 

Many of you new owners have no clue on this issue. Many shops have no clue on this issue. Many are buying cars that may need a rear end servicing. Anyone purchasing this car should replace the rear end oil along with the engine oil etc.


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## pykes04goat (Apr 4, 2009)

Thank everyone who replied. I know quite a bit about cars and knew this is not right, i am going to request fluid change in rear end. I already changed trans fluid and put in the 6 fluid rather than 3


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## bignikk (Nov 14, 2010)

Is there anything else that I can use other then Torco and the Type F Additive? I am in Canada and have not seen this for sale anywhere. Royal Purple is readily available.
If not, no worries, I will order it online and wait the 2-3 weeks and triple the price to get it if need be.

Thank you in advance.
NK!!


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## jpalamar (Jul 22, 2008)

I used Royal Purple in my diff. It worked fine but didn't last as long as I hoped. I hear Torco is the way to go and FM is easy to get ahold of also.

When my diff started to cluck I just bought some junk oil with FM in it at a local parts stoor and my clunking went again. Not sure how long it will last but the next owner of my car I'm certain will be changing it shortly.


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## 04gto04 (May 21, 2016)

I had the same problem with my 04 gto but i drained the diff oil and went with royal purple with friction modifier and it worked like a charm thank u to every one that said to do it. Save yourself some money and do the same.


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## HP11 (Apr 11, 2009)

04gto04 said:


> I had the same problem with my 04 gto but i drained the diff oil and went with royal purple with friction modifier and it worked like a charm thank u to every one that said to do it. Save yourself some money and do the same.


I would hope he's solved this by now, it's been 5 years......


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## SANDU002 (Oct 13, 2004)

Probably does not even own the car by now.


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## HP11 (Apr 11, 2009)

Not really sure that the 'member' who revived the thread owns one either......


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