2JAWZ

iTrader: (1)

Just bought a 97 Camaro built to 427 hp and when she hits around 80 mph there is a vibration that feels to be between engine and trans. But that's it, after 80 mph it s gone. Its first time Ive owned car with high hp and just don't know if its normal mechanics or what. Its not like a sloppy somethings loose vibration but I notice it. Any advice??

VoyagerCamaro

Automatic or manual transmission? Is it more of a thudding or shaking?

NewOrleansLT1

Welcome to the F Body world where some things are just unexplainable lol.. But I know exactly what your talking about.. It sounds like driveshaft flex.. It's seems to affect cars with big gears and only at hwy speeds..

ahritchie

iTrader: (1)

That's a known issue with many of the steel driveshafts in these cars; it gets worse with shorter gears in the rear end. Upgrading to the LS1 aluminum driveshaft helps; it's also lighter; reducing rotating mass is a good thing! Faster acceleration, and it's better at dampening vibrations in general more than steel. I highly recommend one!

96LT1Z

^^^^ Aluminum LS1 Driveshaft fixed my issue

myltwon

iTrader: (1)

Problem with the LS1 DS is they have under 1/8" wall thickness IIRC and are a liability if you plan on drag racing it.

Since the car is modified that opens up a can of worms.
-Is the suspension modified?
-Are the wheels properly balanced?
-Does it have an aftermarket driveshaft?
-Does it have an aftermarket rear end?
-Does it have aftermarket wheels?

and many more I can't think of right now.

2JAWZ

iTrader: (1)

It has a manual trans and yes it is more like the shaking and thudding. The car does have aftermarket wheels(properly balanced), suspension and rearend. Built by reputable shops. I was leaning toward the driveshaft in my own opinion and now this kinda gives me good direction to go in towards eliminating. Thanks for the input***

ahritchie

iTrader: (1)

Mine had the vibrating issue pretty badly once I put 4.10's in it, which the LS1 driveshaft improved 90% of. Keep in mind many of these cars were recalled from the factory for this issue, it's the whole reason GM upgraded the 98+ cars with them! I also have a LS1 car which is Cadillac smooth at 80+ mph compared to the ancient cast iron LT1 and its legendary vibrating cast iron driveshaft! So, was kinda a no brainer upgrade!

Make sure you put some brand new heavy duty U-joints in it while it's out. I made the mistake of trusting some old U-joints with no telling how many miles and started getting a bad vibration a couple thousand miles later after putting used LS1 driveshaft in mine when the U-joint behind the trans started wearing out, lesson learned!

myltwon

iTrader: (1)

Improperly setup suspension can cause vibration, one of the most common being improper pinion angle set on the torque arm.

If the car was 100% built correctly by reputable shops you wouldn't be having this issue to begin with IMO. Not trying to be a dick but just saying there are some things to check before you start throwing parts at it.

2JAWZ

iTrader: (1)

well the pinion angle was set right so now I just received my new steel Spohn extreme duty driveshaft. hope this clears up the vibration.