kenkaru

Mine felt sort of like a tire that was slightly out of balance and it was only noticable above 65mph. I can't really think of what would cause a tingly/buzz because I have polyurethane everything so my car tingles and buzzes all the time Maybe you need a louder exhaust or some subwoofers?

T/AFOSTERWS6

iTrader: (1)

I had the front a-arms replaced w/tubular, vibration gone, stock ride height,
I think the vibration has something to do with the caster/camber adjustment especially with the big *** wheel and tire combo from factory. IMO

scrmnws6

iTrader: (7)

Someone on here mentioned that the vibration was rpm related. If it was rpm related you could feel the vibration at 25 in first gear. This vibration (and I have it too) is related to a rotating mass revolving very quickly.

JD_AMG

hmm...
My friend had a Z28 that was smooth as glass on the highway though...

EDIT:
Does everyone with this vibration have aftermarket exhaust?

Gearhead1

Yeah, I do. Why, you know something we don't about aftermarket exhausts??? C'mon spill it!!
Mine was smooth until about 2 months ago. I had made a few changes, but I don't know if what I changed caused my vibration or not. I've been replaying in my mind what I did trying to pinpoint if it was something I changed or not. So far, no luck. I've been under my car 1/2 dozen times or so looking, checking, feeling, and all to no avail. It''s damned frustrating. Mine's definitly RPM related. It feels like when you have a Poly trans mount, you know kinda buzzy. I actually swapped my Poly mount back to the stock rubber one, and the vibration decreased by about 1/2, but was still there. I'm stumped.

kenkaru

vibrations are as bad a electrical problems. They're such a pain the *** to track down and if you took it to a "'mechanic" they'd replace everything on the car and still not fix it. Good luck

5.7LoFuN

iTrader: (1)

thanks for the uplifting comment in a thread for people trying to solve this problem...haha

There are only so many rotating bodies on your car....im probably just going to keep going down the list till i get this solved. The only thing is i have a blower wating to be installed, but i have to fix this damn problem first

kenkaru

Some have hinted at this but I'm going to go ahead and spell it out.
Those who are getting a vibration at speed and have custom exhaust might be feeling their exhaust vibrating/swaying. ...could try some stiffer exhaust mounts. My engine mounts fixed my vibes but I think it was because the exhaust was swaying but who knows.
Just one of a million possibilities

5.7LoFuN

iTrader: (1)

well i got back from the chevy garage (had my tranny fluid changed) and i mentioned what was going on with the car and of course they wanted $100+ just to look for the problem, and of course i said no thanks. But the guy who did the tranny flush drove it around afterwards and said he heard the noise as well. He used to work at a pontiac dealership and he said that he had firebirds and trans-ams come in all the time with the same thing and it almost always turned out to be the pinion bearing. So it looks like i at least found out PART of my problem....

StripedZebra

iTrader: (6)

Wonder how hard/how much to do the pinion bearing....?

Marc '99T/A

iTrader: (22)

Did mine not too long ago. Do some searches and you'll find a couple of good writeups. While you're doing that one, might as well change the axle and carrier bearings also. And there are two pinion bearings, a front and a rear. PM me about it if you want more info.

5.7LoFuN

iTrader: (1)

i think i might just go looking for a 10bolt someone has up for grabs cheap.... I was under the impression that if the bearings fail that the gear wear probably wasnt wearing properly...

JB00SS

I have the wom wom wom problem also. This problem was there BEFORE I had the rear gears swapped for 3.73's. i was hoping also that the pinion bearings would solved it. My buddy helped me with the gears. I have very little whine, lash is all good, new bearings through out. I am going to pull the drive shaft and have it balanced with new u-joints this week. I still have factory TQ arm and LCA's. I do have the tranny mount which yes does vibrate but i have gotten the used too. The wom wom wom sound started a few weeks after the tranny mount and did not go away after gears. The car has 29,6xx on the clock, garage queen, with factory cat-back dual/dual. I am watching this thread like a hawk hoping someone will figure it out! I am also going to have the wheels/tires balanced this week too. I still have factory front tires that I swap out with the factory rears since i have DR on them. I have played with air pressures but no help.

I am kinda leaning toward the DS, Tailshaft, TQ arm, and motor mounts as the problem.
edit: only happens between 55+, put in N and it really gets violent! I also dont feel it at WOT???

kenkaru

When my motor mounts were shot, the vibration was really bad sometimes (like bad at 50mph) and then other times it would be barely noticeable up to 75 mph.
...Just another random clue.

jyeager

That wom-wom-wom thing is very often cupped tires. If you have over 5K miles on your tires it could be that. It all depends on the tire compound and how often you rotate them as well as how much toe-in your running on your suspension.

cupped tires are the most common cause of this in my experience. I've never had any set of tires last past 25-30K miles before bouncing all over the road. I've tried having them rebalanced but it doesn't help once they are cupped.

Lowering a car is likely to cause a vibration because it changes the pinion angle. U-joints are not CV joints (constant velocity). When U-Joints are at an angle, they will accelerate and decelerate every revolution. This results in a vibration. Your pinion angle must be adjusted properly. If you lower your car, you need an adjustable TA to re-align.

Beyond these items, you get in to less likely causes such as flywheel/clutches, input/output shafts, bearings, and all the stuff that everyone's already talked about.

kenkaru

Hmm good post. I wonder if I took some junk out of my trunk right at the same time I did the motor mounts; raising my rear back up. I was driving around with a lot of stuff in my car around that time.

JB00SS

I HAVE A CUPPED FRONT TIRE! I rubbed my hand around the tire last night and the drivers side inside of the tire is cupped. I can feel it real good. Now do i mount the factory rears on the front wheels or go ahead and do skinnies? I am trying to maintain the stock sleeper look, but i do love the way f-bodies look with meats and skinnies.

Do you guys think i should try to do something with the tire in lieu of balancing the driveshaft and having new u-joints installed?

kenkaru

Congratulations man! Figuring out vibrations can drive you insane.

jyeager

Do you still have stock wheels such that you can rotate front to rear? If so, do a rotation per the owner's manual (I can't remember if fronts go straight back and rears around and up or vice versa).

Also, if you have a symmetrical tread pattern and enough treadlife left to be worthwhile, you can remount the tires in the other direction so that what is now the inside shoulder becomes the outside shoulder. That can help.

If this is the source of your vibration then rotating at least tells you so...this because the vibration would change in some way. The vibration moves from the steering wheel to the seat, or vice versa (depending on whether it's front or rear).

It could be time for new tires too.

JB00SS

i still think i will have the driveshaft looked at and u-joints replaced. the front tires are coming off the wheels and i guess new tires in their place. my BFG drag radials still have a little life left. im not totally convinced yet that it is tires. why does it only do it between 50-70 and why does it get really violent on the wom wom wom noise when i shift into N at these speeds? i am really thinking driveshaft, u-joints, tail shaft, or pinion nut or bearing...