General Maintenance & Repairs - Major Vibration Issues

Mike @ New Era had to take the car off the dyno the car started vibrating so bad. I can't figure out what is wrong with my Z28, once 65mph hits the car is vibrating really bad. Since and I think before I started modding the car I had a little vib but now the car is out of control. I have replaced every thing the rearend (bearings, gears, wheel bearings) and balanced the tires. Every component has been checked to see if they are loose are tight. I'm at a total loss on what to do. They couldn't even finish tuning the car, mike had to take it on the street and tune it. I have no idea what is wrong. This absolutely fucking sucks..... :bang: :bang: :cry: :cry: :cry: :cry:

Mike @ New Era had to take the car off the dyno the car started vibrating so bad. I can't figure out what is wrong with my Z28, once 65mph hits the car is vibrating really bad. Since and I think before I started modding the car I had a little vib but now the car is out of control. I have replaced every thing the rearend (bearings, gears, wheel bearings) and balanced the tires. Every component has been checked to see if they are loose are tight. I'm at a total loss on what to do. They couldn't even finish tuning the car, mike had to take it on the street and tune it. I have no idea what is wrong. This absolutely fucking sucks..... :bang: :bang: :cry: :cry: :cry: :cry:
You might want to check the drive shaft. It could have thrown a weight and is out of balance.

It has a brand new NHRA approved aluminum driveshaft as well . He has replaced the axles , tires and wheels are good he has tried different wheel/tire combos and it didn't fix it , the pinion angle is at -2 degrees with a fixed edelbrock torque arm . The car has billstein shocks all the way around and I believe it is lowered 1.25 inches , it also has some umi suspension products in the back including lower control arm relocation brackets and nonadjustable panhard rod . Hoping for someone to chime in here , I drive cars every day with similar mods done and even no mods done , and have never seen a car vibrate like this and not know what the hell is doing it . I had to pull it off the dyno because it was vibrating so bad .
The only thing I can think of at this point is frame damage ???? As this car has now been doing this for nearly a year now . From what Mike tells me , it always vibrated a little bit at that speed but over the past year it has gotten much worse , I would really like for maybe some other guys that have had issues to maybe throw something out here that had an experience like this to help him fix this issue , even though I know he has posted this a few times before .

Im a tire tech soto say. This may sound stupid but if it has aftermarket wheels some times they dont have clearance around lugnut on backside(recessed area) for the rotor clips put on from factory. this can cause vibration.
Check lug for centering issues.
Have the tires/wheels ROADFORCE balanced
Just because wheel/tire 0's on Dynamic spin balance dosent meen the tire wont vibrate. due to low and high spots in the tire and or wheel.

You have factory brake rotors? If so they warp so easy, mine did and even when I wasnt braking the car would shake like crazy.

I have rotors and calipers along with braided brakelines on deck but I would hate to put them in and have them have a problem ruin the brakes, I guess I might try it.

It has a brand new NHRA approved aluminum driveshaft as well . He has replaced the axles , tires and wheels are good he has tried different wheel/tire combos and it didn't fix it , the pinion angle is at -2 degrees with a fixed edelbrock torque arm . The car has billstein shocks all the way around and I believe it is lowered 1.25 inches , it also has some umi suspension products in the back including lower control arm relocation brackets and nonadjustable panhard rod . Hoping for someone to chime in here , I drive cars every day with similar mods done and even no mods done , and have never seen a car vibrate like this and not know what the hell is doing it . I had to pull it off the dyno because it was vibrating so bad .
The only thing I can think of at this point is frame damage ???? As this car has now been doing this for nearly a year now . From what Mike tells me , it always vibrated a little bit at that speed but over the past year it has gotten much worse , I would really like for maybe some other guys that have had issues to maybe throw something out here that had an experience like this to help him fix this issue , even though I know he has posted this a few times before .
I remember reading a post from another member who tracked a nasty vibration to a bent output shaft of the trans. I'm not sure if there is an easy way to check for this, but I think it could cause the vibration he has.
Hope this helps.

My driveshaft doesn't show signs on the input shaft that it is moving around, but I definitely have to take a harder look at it. I'm at a totally loss to what to do about the bad vibes.

My driveshaft doesn't show signs on the input shaft that it is moving around, but I definitely have to take a harder look at it. I'm at a totally loss to what to do about the bad vibes.
It sounds like you've checked or replaced almost everything else!

Yeah thatz how I have been able to stun everybody that knows everything bout everything....its sucks.

Harmonic Balancer?

the engine mounts.. maybe

Im a tire tech soto say. This may sound stupid but if it has aftermarket wheels some times they dont have clearance around lugnut on backside(recessed area) for the rotor clips put on from factory. this can cause vibration.
Check lug for centering issues.
Have the tires/wheels ROADFORCE balanced
Just because wheel/tire 0's on Dynamic spin balance dosent meen the tire wont vibrate. due to low and high spots in the tire and or wheel.

And while your looking at the tires, it's also a possibilty that one of the rears have separated belts. The steel belts, kevlar or whatever they use anymore, are the superstructure of the tire. If that fails, then the tire can become misshapened. If you can imagine yourself without a spine and trying to hold a weight over your head, something like that. It's just a possible cause to your bad vibes.

Yeah I though about that too so I had mike @ New Era put new tires and rims on it and no difference.

It would be cheap if it is the engine mounts, maybe tranny too.

There has been 3 different wheel tire combos tried on the car to see if it went away , so it is not the wheels or tires , the rear rotors are not warped , when you hit the brakes the car smoothly comes to a stop . The only thing that hasn't been checked or replaced is the trans output shaft , or the motor mounts , not sure the motor mounts would cause the rear of the car to shake though . Keep me posted Mike .

have you guys seen this thread in the handling section?

http://www.ls1tech.com/forums/showthread.php?t=436736

i am considering motor mounts myself i have checked/replaced everything else!

jBOOSS I'm on that thread too, I'm going to check my mounts and then look at the rest of the car this weekend. By tuesday/wednesday I'll have an answer.

hey Mike any news?

John

check the tranny mount ?

Cantech in Cuse just balanced the wheels and did some other checking and think they have fixed the problem. They want to come in for a test ride and see if they want me to let them do more work. They think that I might have a motor balancing issue cause at 1700rpm they say the motor has some vibes. I'm going into the shop in the morning to see what the story is. I might have them check the motor mounts and tranny mounts while they have the car there on the lift. Maybe not if the the weather gets warming in NY.

so did you ever notice it vibrating when you had it in neutral and rev it up?

I was going to mention roadforce in the tires but it looks like you have pretty much everything covered

Yeah the neutral rev up was fine.... this really sucks.

Any up/down side/side play on the driveshaft? Tranny tailshaft bushing or pinion shaft(due to the crush collar) busted loose could cause vibrations at highway speeds...did for me. :) Push on it/wiggle it from both ends and in the middle.

Just got the tires redone for a fourth time and things have improved, either the brand new torque converter or the brand new underdrive pulley is messing things up. The car is having a vibe in neutral at about 1700rpm that didn't show up on the highway neutral rev up.

i also have a vib,,,

any gear, or neutral
always at 18-1900 to 2500 rpms
have replaced everything suspension wise but from what others are telling me its in the motor (ie pulley, misfire, etc)