2002 Z06, lowered it on stock bolts leaving the 2-3 threads showing. Now after driving for a while I get a cyclic vibration. Cyclic = vibrates for a few seconds, then quits for a few and then comese back. Quits vibrating for about the same amount of time that it vibrates. Starts the vibration at about 75 mph and gets more pronounced the higher the speed. The cycle stays the same but vibrates more intensely.

Not sure if the lowing caused this. Could be a tire balance thing (coincedence) happening soon after lowered.

I did a seach for this and didn't get much of a difinitive answer. Planning on a alignment next week and wheel balance also. Could it be by lowering, it put a different stress on the axel U-joints??? I was thinking of raising the car and see if the vibration goes away.

Thanks for all input!

 

Dice,

I know EXACTLY what you are feeling. Say no more. This has been discussed on the forum & is not unique to your'e car. Mine did it as well (2003 A4 coupe) Mine was the worst on a particular stretch of road I take to the highway, it's blacktop & made the vibe more pronounced. I took the car in for this in '06 (car only has 6K on it now) and was encouraged to find a nail in the trear tire...thought hey, that would do it. Repaired the tire & same vibration. Road forced the wheels & replaced the Rear w/a DTE 3.90 & Vig stall & no more prblems. I guess what I'm saying is, the road force could have fixed it or I had a bad factory rear-end. These cars suspension are SO finiky, anything seems to upset the balance. Get a good tire balance & see whathappens.

 

"Road forced the wheels & replaced the Rear w/a DTE 3.90 & Vig stall & no more prblems"

You lost me..... road forced the wheels? DTE 3.9 & Vig stall

 

Sorry...

What I'm saying is I'm not sure which fixed the problem. I had the wheels balanced just prior to the mods I mentioned. The ride home from Illinois after the rear end and converter install was smooth...Coulda been the balance or coulda been a bad factory rear end.

Sorry for the confusion.

 

Road Force is a way of balancing the tires/wheels, actually the MOST effective way. I had the vibration, I took it in and got the tires road forced balanced and discovered one of the rear tires was grossly out of round, a local tire company on a standard balancer didn't pick it up...

RE: DTE 3.9 & Vig stall He's referring to a new and braced differential and a new stall converter.

Now a road force balance is that, balancing and a check of the tire and wheel's roundness. It does nothing to correct an out of round problem, it merely identifies one. It seems patrickboyle's problem was in the rear end more then likely.

 

I dont know what road force wheel replacement of the differential is but if this guy didn't have a vibration before lowering it then does have a vibration after, do you think changing the rear end is relivent? Not trying to be a complete *** but your story almost has nothing to do with this guys problem unless you can elaborate on what the problem was. Like say "when they changed my rear diff they saw that the torque tube bushings were shot and replaced those". But I doubt your torque tube bushings were shot if it only had 6k on it unless it were being neutral dropped or power braked at every stoplight for 6k miles.

Check your wheels and lug nuts, that's an easy job that costs nothing. I would even put the car up in the air and back off the lug nuts and then re tighten them in the star pattern and then torque them to 90 ft lbs. yes in steps.

Inspect everything. If you only lowered the car on the stock bolts it has to be something simple, both my friend and I have done it w/o a hitch. Do you have directional tires, did they get swapped from right side to left.

If that doesn't do it, try raising the car back to original height and see.

Lastly, thes suspensions are not finike. they are built like a truck. Have you seen the size of the cast aluminum upper and lower controll arm? Does the fact that it has a leaf spring attached to the k member going to both wheels add any support?

I have seen these things completely off the ground "jumping" the turtles at the track on a stock suspension and the thing didn't even get out of alignment (that was an 01 z06).

 

The correct torque specs for the wheels is 100#. When you're typing a response and you see a word underlined in red, it means it's misspelled.

 

I have no words with red underlines, if I did I would correct them.

I'm an engineer not a spelling bee champion nor is this a spelling forum.
I did put commas in between my listing of 3 items in a series.... Can I get partial credit?

How accurate is your torque wrench at 100 ft lbs? +/- 4% so there's a discrepancy of 16 ft lbs

the point is they are evenly torqued, I'm well aware the owners manual's spec is 100 ft/lbs.

check you lug specifications after the dealership is done driving them on with an impact wrench.

 

...never mind...

 

Easy guys..... lets take off the gloves. Hmmmm.....

Oh.... I don't get red words either.. ?

 

I think red words are a Vista thing, carry on...lol

 

sry, sensitive about the spelling, big ol hands don't always type so well either.

ment no harm

 

I apologize for pointing it out...

 

Its all good.......

 

Hunter GSP9700 (this will explain "road forced the wheels" ).

There's a link in the middle of the page that will help you locate a shop in your area that has a Hunter GSP9700 for balancing wheels/tires

Larry

 

Dude, with your avatar and sig, I think you have the right mentality for OT. You should check it out.

 

OT ????? Overtime???

 

the off topic forum section

 

Finally a member I can relate to...

 

Mine was doing the same thing, I had the tires roadforce balanced and the problem went away.