i_york

I have a clunk coming from the rear of the car (M6) when driving slowly (<10mph) in 1st gear. The noise is easily repeatable by getting on and off the throttle and SOUNDS like worn UJ's, or play in the diff. This is not the same as the diff clutch pack issue, which AFAIK is only evident when turning.

Not sure what the cause of the problem is yet (or even if there IS a problem), but the clunking noise I'm talking about is quite loud (easily audible from outside the car). I've read a few other posts from people experiencing the same issue, but with no concrete follow-up on what the cause is/was. Currently, I'm thinking it could be any of the following...

1) Torque tube bushes
2) Diff / gearbox mounts
3) Excessive lash in the diff gearset?
4) UJ's (not sure if the driveshaft inside the torque tube actually uses UJ's)
5) Inner CV joints on the rear axle half-shafts?

A search yielded the following interesting threads on the C5 forums...

http://forums.corvetteforum.com/show...light=clunking

http://forums.corvetteforum.com/show...+tube+bushings

My car (like others that have posted about the same issue) is completely stock and has low miles. It's a 2005.

Any input from anyone that has experienced this issue would be appreciated. Please read my description of when the clunk occurs very carefully... this is NOT the clunking that happens whilst turning.

Cheers,
Ian.

User 2623

Joining this thread to add another voice to this issue.
I too agree this rear end clunking sound is not related to the clunk/chatter TSB, which has been widely distributed and primarily used as the focal point for diagnosing
this condition.

1_ The hard shift occurs at light throttle and could be considered random
unless the car is warmed up. The clunking may be worse if the
accelerator is relased before the 1-2 shift occurs ( in my vert @ 11
mph). This is a characteristic of a troubled transmission shift
(IMHO)
2_ The hard shift [noticeable clunk] is consistent and always occurs in
stop & go traffic. As replicable when evaluated with a tech. But
intermitently occurs [ can occur] at higher speeds notably a 4-3
shift situation when braking and coming on and off throttle.
3_ I have explored these options to try to remedy the stituation to date:
...i Check'd for the presence of DTCs. Some DTCs cause maxiumum.
line pressure resulting in harsh shifting and rear clunk.
..ii 1-2 accumulator value (371) is sticiking in the bore due to chips ,
debris or bore finish (tech cleaned this out- still have the issue)
..iii 4-3 sequence value (383) sticiking in the bore due to chips ,
debris, or bore finish
..iv 1-2 accumulator pistion (56) cracked or damaged or seal (55) cut.

Additonal description of this condition can characterized as:
1_ Dif Backlash
2_ Lash in the drive line
3_ Halfshaft Issue
4_ Loose CV/U joint problem
5_Clutch disengagement noise

frankz06_cf

I have the same noise you describe, it happens most to me when I'm at a parking garage so I'm in first gear slowing down to below 10 mph, it goes away if I engage the clutch so I've always thought it was normal. I was hoping to find on here if it was normal or not, I'm going to have to take it in for service and see what they say. I'll report back here when I do but it might be a while before I can get some time to take it in.

arizonavert

I have the same thing going on with my car. I have a 2005 6 speed z51I just thiught it might be the rear calipers rattling on the pins that hold them on. They have to have SOME play because they "float" MAybe? just a guess

2000WS6Vert

I just took my car in the to the dealership today for the new differential fluid swap. I asked to them to repair any other outstanding TSBs that are out there.

The tech did the axle nut replacement and lockthread fix. He associated this with the clunking noise you hear at low speed accel and decel. Maybe this is your issue too?

journeyc6

07 MN6, I have the same noise but only on reverse, my dad has a friend who had the same problem, took car to the dealer and they change something, mechanic told him that alot of vettes had the same problem.Still I have to find out what part they changed or fixed, my dads friend is an old guy, not mechanical inclined so he just know that they fix it.

frankz06_cf

Thanks for the respones, I noticed today that the noise only comes out when the car is making a turn. I guess it happens in the parking garage because I'm making a tight right turn to go up. The problem is I can't get it to do the noise all the time which now makes me realize that it is not a normal noise, since it would always be the same under the same condtions.

i_york

This sounds like the very well-publicised diff clutch-pack issue rather than the issue I started this thread for. From what many others have reported, you should find the problem you have will disappear (or be vastly improved) with new fluid in the diff. FYI, I believe the change interval is every 10k miles.

Cheers,
Ian.

shockwaveharry

I've had a clunking noise at low speeds in my 2006 A6 for a while but lately it seems to have gotten much worse.

I do not believe it's clutch pack noise/chatter. I have 20+ years as a service tech under my belt and I've herad clutch pack noise before. I'm smart enough to know that I may very well be wrong so I'm going to have the TSB performed anyway if it applies, but I really dont believe it's the problem.

Here is what I'm experiencing:

Parking lot speeds on rough pavement are the worst. It's a very loud, hollow knock that sounds as if it's comming from the rear. The rougher the pavement, the more pronounced and rapid the knocks become.

No noise on smooth pavement but I can duplicate it by swinging the steering wheel back and forth. I've tried holding it in 1st and goosing the throttle a bit but no noise there. I can only duplicate it by inducing lateral motion.

I have tightened very loose axle nuts and checked/torqued everything I could see with no improvement. I've dropped and re-mounted the exhaust and made sure it's not hitting anything. The only thing I can do that somewhat duplicates the noise is grabbing the axle half shafts and yanking them back and forth. They both have that hollow knock in the joints but pretty much any axle shaft does that.

Any thoughts?

shockwaveharry

bump...

2000WS6Vert

#9 and #10, I'm pretty sure that having the axle nut TSB done will cure your problem. You're describing exactly the noises I was hearing.

Since I got the car back on Saturday...no more clunking or knocking sounds.

shockwaveharry

Thanks! The TSB reports that "GMSPO has released a newly designed rear wheel drive shaft assembly for service". Made me feel good to know my diagnostic skills have not been completely lost to time!!

Gunna make an appointment for my new axle shafts today...

Lil' Red Corvette

Why in the world would you drive your car like this???

Any, and all manual transmission cars are going to have clearance between the teeth on the gears, as well as the clearances in the gears of the ring & pinion. Yes there is even tiny clearances in the U-joint bearings. Add all of these together and it would be reasonable to assume you might hear a clunk!!!

I guarantee you will have U-joint problems or transmission problems if you keep doing this. Then you can tell me, "I told you something was wrong in there". This is well outside the realm of normal operation, and in my opinion constitutes abuse.

If I were the service manager, and you told me you were driving like that, I'd void your driveline warranty because of abuse. That kind of kid's play is worse on a U-joint than drag racing.

I had to vent. This is getting crazy with what you people are doing with these cars, and then complaining about hearing an odd noise when you do it. Like the Doctor said. "If it hurts when you do that, quit doing it".

I'm done now. If I hurt your feelings, tough.

Ed

i_york

Ed,

Thanks for the highly-opinionated reply, but if you're telling me this, in your experience, is 'normal' then I can only assume you've driven C6's all your life! I've owned about a dozen RWD cars in my time, several of which also employed LSDs, so the fundamental architecture is the same; propshaft with UJs at each end, diff (with clutch packs in the case of LSDs) and half-shafts to the wheels. In all of these cars, I NEVER heard a clunk from the diff area unless there was a specific issue (mounts, etc). This is NOT 'normal' and does NOT present itself in all other RWD applications. I'm looking for sensible input on diagnosis of this issue and for experiences of others.

As for driving at 10mph and coming on and off the throttle being abuse? Do you work in the warranty department of GM, because that's the kind of response I'd expect from a dealer trying to wriggle out of a warranty claim! Try driving in rush-hour traffic and NOT coming on and off the throttle in 1st gear at ~10mph. Or, are Vette owners expected to avoid such conditions?

Sorry if I hurt YOUR feelings. If so, tough. I'm done

Thanks,
Ian.

Lil' Red Corvette

That's what I gave you, and I was afraid it would hurt your feelings. I guess it's only human to want a diagnosis or experience that agrees with your own opinion.


Read my profile, (I read yours) and you will see that I am a tractor trailer driver. Our heavy duty design of American machinery causes things to go clunk, instead of clink.

Only experience can teach you that, deft use of the clutch is necessary in these situations, and will totally eliminate any clunking noise. Forty eight years of driving has made me skilled at removing all clunking noise while driving in heavy traffic with a thirteen speed Fuller transmission.

Would you vote for me as the king of sarcasm?

Shall we continue this dance?

Ed

i_york

Please, no.

Many others on here know only too well about the axle nut TSB, diff fluid TSB and numerous other issues that can cause driveline clunking. The C6 is not a truck!

Please don't talk to me about clutch control... I've used a clutch ever since the age of 18 (now 33); I know about clutch control, lol.

You haven't hurt my feelings; I just object to opinionated and rude replies on forums.

If the clunking is a design characteristic, fine. I'm just trying to establish that. Without HEARING my car first-hand, you cannot tell me I'm talking BS!

Cheers,
Ian.

Lil' Red Corvette

So do I, but you didn't list those in your assortment of possible flaws. Have you checked those items on your car before posting this claim of impending disaster.

My respective numbers are 16 years and 64 years. Approaching 3 million miles.

Oh yea, ---- I'm afraid I have, and for that I'm truly sorry, but you need to be less defensive to constructive criticism.

Neither can anyone else on the forum, and I never said you were talking BS, but I can tell you that getting on and off the throttle to induce a driveline stress, is abusive use of your equipment.

Do you abuse your equipment frequently??

I have to stop doing that right now. And I think I will.

Cheerio old chap,

Ed

i_york

Ed, you're a sad, sad man. Thank goodness you've finally finished with this thread.

Apologies to the others that have participated some useful experiences and info.

Mods: You may want to delete this thread, as it's degenerated into something far less useful than I originally intended. Note to self: don't take the bait in future!

Cheers,
Ian.

User 2623

Hear, Here! I couldn't have replied better to Lil' Red Corvette.
Sorry I missed this discussion.

The only thing I have found to reduce or aviod the clunk is putting the car in neutral and letting it coast in stop and go traffic.
Perhaps this is the constructive comment Lil' Red Corvette was trying to get across?

frankz06_cf

Hey Ian,

You were right, my C6 had the diff clutch pack issue, I took it to the dealer were a quick fluid change resolved the issue.

Did you find out what was wrong with your C6?