mcalus

iTrader: (14)

I went and started my car today and as I was letting it run for awhile I was thinking about the things I need to do to it before I start driving it again.

I remember just before I put it away I was getting a vibration at 70+ mph. It wasn't there at 55 or 60 etc...

Well its hard to believe that its the wheels that need balancing because I haven't had this issue before. Its like it goes in and out its not a constant vibration, it will go in, vibrate for 3 or 4 seconds then go out for 2 seconds then come back. Any ideas?

Thanks!

71novaguy

iTrader: (2)

I had that issue before. Seems like u-joints fixed it, but now I have a constant vibration at certian speeds

mcalus

iTrader: (14)

lol thats convincing, get rid of one at 70 and get a constant one at certain speeds....

71novaguy

iTrader: (2)

sad, but true. I used to have a 3 hour cruise back home over the summer, and i noticed that in and out vibration you talk of. alignment and rotors didnt seem to fix it. Put in u-joints and it seemed like that variation left, but now I have constant vibration at different speeds. I'm golden from about 50-70 mph, but above that I have vibration. I also seems to depend on the load applied. As refered to in another thread, it may be due to my poly mount. I havent had time to shim it out. But when I do, I will post results.

wssix99

iTrader: (5)

All of the late model F-bodies do it. At that speed with a near-stock suspension, there is a natural resonance and the car vibrates. All cars have this issue, but some are more noticeable than others.

More info: https://ls1tech.com/forums/general-m...nly-65mph.html

98pontiac

No, it is definitley a tire balance issue. My car does not vibrate at all.

wssix99

iTrader: (5)

Does it stop at speeds above 70? If so, its definitely not a balance issue.

mcalus

iTrader: (14)

Bringing this back a bit... I just took it out of storage and as I was heading back home (stock rims and tires are on) it still vibrates 70 and on up.... I just got some poly engine mounts, and a poly torque arm mount for it. I guess if it still continues I will replace the u joints.


Any other suggestions?

wssix99

iTrader: (5)

If it vibrates at all speeds above 70, you must have something wrong behind the transmission or at the wheels. Maybe a driveshaft out of balance or something like that?

I'd suggest investing in a GM Factory Service Manual. There's a whole section on diagnosing vibrations and several pages of a procedure where you can walk through calculations that will tell you if the vibration is coming from your tires or propeller shaft.

wrd1972

iTrader: (12)

DS out of balance.

mcalus

iTrader: (14)

Randomly? The drive shaft has never been out.


I'm leaning towards the poly trans mount. Stock LT1 ones are easy to come by, that will work wont it?

THE SHOP

I would first of all at least rotate tires to see if it makes it feel different then it could be tire balance.

mcalus

iTrader: (14)

Doesn't. I first had the problem with my 19's on it then i put it in stoarage with stockers and it still does it. Plus, I had both of the wheels/tires checked the balance.

fleetmgr

Could be a dead shock, too.

Viper

iTrader: (6)

Mine does it when it's the drive in the morning to work. No where near stock suspension (koni and strano springs), 17" rims, T2R diff, nittos. Has done it for 8 years, nothing has ever broke and I autox the car.

mild2wild

iTrader: (2)

If you figure it out please post what the problem was... Mine just started doing the same thing, balance and rotating tires did nothing