vibration or low rumble over 84 mph

[zx1421]

anybody experiance this? I almost want to say driveshaft or rear tires out of balance. I dont feel anything in the steering wheel. I was also thinking mayby the vented hood makes a noise?

I know its not the motor, because in 6th gear 84 is about 2400 rpm, so I turned 2400 rpm in 5th, at about 65, no noise.

You can barly feel it, but can hear it, very low frequency. zing it up to 100 mph and it stays about the same?

[bw26ss]

Originally Posted by zx1421

anybody experiance this? I almost want to say driveshaft or rear tires out of balance. I dont feel anything in the steering wheel. I was also thinking mayby the vented hood makes a noise?

I know its not the motor, because in 6th gear 84 is about 2400 rpm, so I turned 2400 rpm in 5th, at about 65, no noise.

You can barly feel it, but can hear it, very low frequency. zing it up to 100 mph and it stays about the same?

it could be a u joint, have had similiar problem on other cars, but more than likely it is a tire out of balance, or a tire that is cupping

[zx1421]

Originally Posted by 11fastss

it could be a u joint, have had similiar problem on other cars, but more than likely it is a tire out of balance, or a tire that is cupping

just at 1000 miles today

[1MtnGoat]

Originally Posted by zx1421

just at 1000 miles today

Are your tires "cold?"

[ZL1ster]

+1 w/ your tires.

Have you checked to see if lug nuts are torqued down?
22mm w/breaker bar will ensure you can apply torque to factory specs...

Personally, i'd make an appointment w/dealer and let them deal w/it. It's great to have a SC car w/bumper2bumper and powertrain warranty

[OldScoolCamaro]

Originally Posted by zx1421

anybody experiance this? I almost want to say driveshaft or rear tires out of balance. I dont feel anything in the steering wheel. I was also thinking mayby the vented hood makes a noise?

I know its not the motor, because in 6th gear 84 is about 2400 rpm, so I turned 2400 rpm in 5th, at about 65, no noise.

You can barly feel it, but can hear it, very low frequency. zing it up to 100 mph and it stays about the same?

Vibration<feel, tangible, through ones hands, body, or seat>, and rumble<associated with noise, I.E hearing, and frequency noise<associated with hearing as well>, are different parameters. Sometimes one can feel vibration, or hear noise, that are distinct and different. I would suggest you articulate your observations more clearly so that we can understand your issue. It seems there is a confluence of words and meaning, that I can't understand, if you could be more specific that would be a great help. Sometimes noise and feel have the same issue, sometimes not, but they can't be assumed to be the same...

[zx1421]

no, tires are warm, I just ran out to phoenix from san berdo (about 650 miles round trip) so was speeding up and down for hours, at 800 miles decided to go a bit past 80 a few times(this is the longest I have ever broke in a engine) and I have built quit a few in my day. I think it is a rear tire out of balance, hoping its not drivshaft or halfshafts. I can hear it more than feel it. I brought it up to 90 and shifted to nutral, and coasted, it stays around till about 82-83 then quite and smooth again. I hate to take it to the dealer, I'll probably pay a tire shop to check them.

[OldScoolCamaro]

...I will chime in again about noises on the ZL1, nothing to the OP, just my observations. Noises come and go, seemingly without reason, depending on who knows what, outside temps, frequency of use, operation temps, it's seemingly less than scientific trying to keep a log or keep up with it.....it's a noisy, HP car, that balks and groans when it feels like. The S/C marbles, creaking and groaning from the rear, tranny/throwout bearing/input shaft, you name it...if the noise is associated with the drivetrain, it's in there, baked into the cake. My suggestion has always been...if it's persistant, regular, and gets worse over time, then Houston you have a problem, and it needs to be fixed. Vibration felt throught ones body in the seat, or hands on the wheel, signifies a problem, and needs to be corrected. Noises distinguished by ones ear with drivetrain systems is another story.

[Mil]

Check or re-torque your rear wheel lug nuts.

[mcchevy69ss]

+1 on checking the lug nuts. I have 3k on mine and was having similar sounds, found some of the rear lugs finger tight The rest moved at least a 1/4 turn when torqued to 110ftlbs.

[zl1rj]

if its a metal noise around 3k rpms. check mufflers they had to replace my entire exhaust system. the gm bulletin said to update the computer and the fuel pump curve is adjsuted which would fix the issue. ofcourse it was bs and they had to change the exhaust... tap each muffler and or try and hear it with rear seats down. my issue was right rear muffler so it sounds close to area you are talking about.

[Z4MB]

I had two issues that caused a similar vibration:

The more likely one was tread delimitation. Not uncommon in the Goodyear's used on the ZL1. The front tire was so bad it would not balance. Goodyear replaced the tire.

The other unrelated incident was a rear wheel where all the lug nuts loosened during a track day at Willow Springs, it not only caused vibration it destroyed the lug openings in the wheel. The other 3 wheels were at torque spec. Dealer replaced the wheel as the car was at the dealer the day before changing fluids and installing Scrothe Rally 3 belts for the track day. The car only had 2000 miles on it.

All has been perfect since. I have 5 track days in so far. Fun for sure. Close to 500 miles out of 3500 spent on road courses. Amazing car.

[motorhead magazine]

i have noticed the same vibration also i hope gm issues a bulliten if rear tires are comming loose that could cause serious problems and danger to people on the road

[yellow69z28rs]

I noticed a vibration when on the dyno at decelaration only, in neutral coast. Went back to dyno with new damper-pully, headers, CAI, and new drag radials, vibration gone....
Noticed when intalling DRs left rear had two lugs about to fall off.