TSB about vibration around 55-70mph

[JusticePete]

Originally Posted by HPE650Ragtop

Not stock. Maggie, headers, high flow cats, cam, heads ported, Hennessey tune, kw variant 3 coil overs. All done at 30 miles. No issues for over 8k. At around 7,500 I added a janetty posi mod and Drive Shaft Shop 1400hp half shafts. Trouble started about a month later. It started slow with a very slight vibration and got steadily worse over 500 miles. Just changed the rear wheels, still no chage in the vibration. Stock half shafts are going back in tomorrow night.

Obviously the problem is in the KW coilovers

1. Start with bolts and torque values. Confirm all sensitive nuts are to spec and that all others are to German spec Gudentight.

2. Before you pull the shafts, try #1

That it has become 'steadily worse' would indicate some thing coming loose, wearing or tearing. adriveline joint, a slightly torn bush tearing more (diff bushes, sub-frame) or wear in the joints.

Please keep us updated.

[HPE650Ragtop]

Easy enough to check the bolts. Any suggestions on how to check the bushings without dismantling everything? The cars was drag raced two or three weeks before this started so a torn bush is possible but which ones could cause a power on vibration and be smooth when coasting? Also the car is laying down 522 to 579rwhp depending on the dyno.
.
I put it up and had someone do Rev - drives at idle. The differential seems to move alot but I do not have frame of reference. The bushings that I can see look OK. I will try to check the bolt torques tomorrow but I did not see anything loose.

Any idea where i can get a full set of rear bushings on Saturday in houston?

Put the stock axles back in. Seems better but may still be there. Some of the bolt torques were off but not by alot. I need to drive it around a bit more and run it down the highway. I am not sure yet if it is the axles or if the stiffer axles just transmitted it better. Could improperly timed bushings cause a vibration?

[55Designs]

Oh boy it seems to be escalating now that many more are having this issue.

When you check the rear suspension bolts use a torque wrench. We have found some cars with the bad vibration coming through the rear and floor to have made suspension bolts loose over time so double check that. usually one side will exhibit this.

Also check your trans and engine mounts and diff mounts. How low is your car right now? OEM Axles? OEM Diff not modified?

What do you mean properly timed bushings?


Now the best way to really see whats going on and this is a PITA but we did this on several cars is place two GOPro Cams under the car and make some videos of the driveshaft and pinion and both axles when the car vibrates, Honk the horn in the video to reference this. You will be pretty surprised what you might witness on video playback.

[JusticePete]

Originally Posted by HPE650Ragtop

Easy enough to check the bolts. Any suggestions on how to check the bushings without dismantling everything? The cars was drag raced two or three weeks before this started so a torn bush is possible but which ones could cause a power on vibration and be smooth when coasting? Also the car is laying down 522 to 579rwhp depending on the dyno.
.
I put it up and had someone do Rev - drives at idle. The differential seems to move alot but I do not have frame of reference. The bushings that I can see look OK. I will try to check the bolt torques tomorrow but I did not see anything loose.

Any idea where i can get a full set of rear bushings on Saturday in houston?

Put the stock axles back in. Seems better but may still be there. Some of the bolt torques were off but not by alot. I need to drive it around a bit more and run it down the highway. I am not sure yet if it is the axles or if the stiffer axles just transmitted it better. Could improperly timed bushings cause a vibration?

The differential bushes are deeply voided for noise vibration and harshness (NVH), but to be honest I have not seen a single torn rear bush in the 5th Gen. We see torn bushes in the LX differential and corrode aluminum sub-frame bushes on snow belt cars. We see torn inner control arm bushes on the GTO. It may be that the 5th Gen is too new, but I don't think we'll see torn bushes in any numbers.

Improper bush timing could theoretically contribute to a suspension instability. The uneven load from the rubber bushes might contribute to a driveline vibration. It would be unsusual, but it is possible as a common thread in some of the vibration issues on C5. Just thinking out loud, if the rear suspension blots were loosened for some reason and made tight with the wheels at full droop... maybe???

As for parts, we can certainly arrange for those, but I would prefer to get a resolution before we add any new variables to your puzzle.

[ROD1]

Had issues at 70+ when on the gas only. They did a vibration location test on it and found the drive axles were bad. Originally they suspected the joint between the driveshafts was bad.

[Cmurf_SS]

Guys,
My .02... I had vibration issues, and of course some pretty severe mechanical noise when i sheared the rear yoke bolts at the drive shaft. They have corrected the issue with the bolts but there is still a slight vibration. I would visually inspect all the bolts on the drive shaft and u-joints, I have sheard front u-joint bolts as well as now, the rear yoke.. I replaced all with hardened bolts, but this is just something that i have run into. Good luck with your issues.. I am going to replace the driveshaft next to see if i may have torqued it or slightly bent it and that is causing the "harmonic" style vibration at 60.. its extremely slight, but still there.

[RyanBoles]

I have the same problem on my 2010 2ss hope its still under warranty (it has less than 36k miles). Taking it to the dealer tomorrow any suggestions on what I should ask or tell them?

[v8]

I have the same problem but mine is at a much slower speed, mind you I havent driven it at 70+MPH. I noticed mine at 1500RPM in 3rd, its very slight and only lasts a maybe + or - 100 RPM. Also I can't be accelerating, I'm giving just enough throttle as to keep the car at a consistant speed.

[Chevrolet Customer Svc]

Originally Posted by RyanBoles

I have the same problem on my 2010 2ss hope its still under warranty (it has less than 36k miles). Taking it to the dealer tomorrow any suggestions on what I should ask or tell them?

Please let us know how your service went at the dealership. I am sorry to hear of the frustrations you may be experiencing.

I look forward to the update.

Brandon
Chevrolet Customer Service

[davidmk001]

Originally Posted by truckin-on

Any updates on this problem?

Vibration over 75mph - 2011 2ss convert
I have this exact problem on my new 2011 2SS 'vert. Doesn't really feel like wheels/tires to me - more like a drive-train vibration perhaps from the drive-shaft or half-shafts. Tire balance issues usually would show up at lower speeds also, but my car is smooth up through 70. The vibration at 78 is bad enough that the image in the rear view mirror is blurry. Annoying for sure for a $43k car! My 2000 Z28 'vert was smooth as silk the whole way up to the limit.

Anyone have any luck getting this addressed? Any updates from GM on it?

I've got the same issue on mine (2010 L99 SS). I went into GM a few times and they looked into their system for any bulletins or recalls and only came back with something pertaining to the Active Fuel Management System. Their claim was that this vibration or rattle can be caused by the engine switching to 4cyl mode. Well this didn't really make sense to me as I had read on here that owners of the manual had experienced the same thing. What they suggested was to used the car in Sport mode / tap shift so it keeps it in the V8 and doesn't allow for the cylinder deactivation to kick in. I tried this and I still have this issue. Also makes my rear view vibrate to a point where I cannot see too well out the back via the rear view.

So personally I don't believe the AFM system is the cause (as my dealer tried to tell me) ... Hopefully more info becomes available? This ruins the driving experience.

[Jbcamaro]

I'm having the same issues. Car vibrates at 70 mph, then it stops at 80.. Unbalanced tires? What do you think guys? Help is needed please. Going to take the car to the dealer next week

[Jbcamaro]

Anyone?

[shazam]

Anyone figure out what it is?

I just replaced my rr hub for the abs sensor and did the diff/tranny fluid with gms lube if that helps at all.

It feels as if your running on a flat.

I have a manual v6 so I have the same rear end as the v8s.

Thanks in advance

[FanDamNCSU]

I too just recently began to run into this issue. In my case I get the vibration through the steering wheel only. I bought new Motivos thinking it may be the stock Pirellis, however they didn't resolve the issue and would keep losing balance (balanced about 4 times). My mechanic thought the new tires may be bad so we replaced them. Balanced them and sure enough the issue is still present. Wheels look fine and I've had another mechanic road force and balance as well with no luck.

Did anybody ever get their issue resolved? If so what was the fix? I'm still getting steering wheel vibration at around 60 MPH with it clearing up after about 70. Interestingly, I've noticed you can easily reproduce the issue if I accelerate fast to 60.