So am I correct in assuming that vibration felt through the body (you can see the seats shaking) at highway speeds can pretty much only be the driveshaft if the wheels are fine (balancing / true etc)??? The U-joints seem fine.

There is definite vibration in the body even at 60mph but the balancing etc is fine.

 

is it making any noise ?? it could be a number of things ive had brake rotors get warped and do the exact same thing i thought it was tires or rims then driveshaft ended up being a warped rotor but your on the right track atleast if youve got a buddy that has a drive shaft you know is good just borrow it for a test run thats what we did and found out it wasnt the drive shaft for sure and it didnt cost a dime to do that way

 

hmmmm, no, not really noise I don't think. I can rule out the rotors though becasue there is no shuddering in the steering wheel when breaking. I have heard some people talk about fliping the driveshaft 180*. What is the purpose of that if it is out of balance? Will it actually do anything?

Also, I have heard so many horror stories about getting shafts balanced. Is it beneficial to try? Would getting one from a wreckers be a lost cause?

 

wooommm- wooommm- woommm.....Driveshaft noise!

 

Any ideas about the flipping 180* idea? What would that accomplish, if anything?

Also, like mentioned before with all the horror stories a bout balancing, is it worthwhile trying to get the current one balanced?

 

i've changed the length on well over 100, maybe 200 drive shafts and never balanced anything and never had a problem or a complaint. not to say balancing may not be a bad idea but i think it's not the first place to go looking for your problem.

 

So what would you suggest then? As mentioned, balancing, wheel, tires, brakes and u-joints are all fine......

Could engine mounts play a factor at all? Althought the engine seems to run very smooth at 2200-2300rpm when you rev it (and that is the rpm at cruising speed).

 

you have to look at everything, the most liekly first and work outward to least likely. i had a vibration in my iroc that started around 80 and got worse fast. tried everything, cheanged everything. finially decided to just buy new rear tires. when they broke donw the right rear if had about 2 cups of dirt in it. my guess is at one time someone had a flat or wrecked and broke the bead and got dirt in it. that was my vibration. if you're to the point you think it's a drive shaft issue i'd try to find someone to swap with me to test it. if not send you DS to a shop to be checked.