91z28 98ta

iTrader: (1)

have 89 iroc and I have a vibration that feels like it is coming from back passenger side. Had worn out and dry rotted tires. So i wound up buying a set of chrome irocs with new tires balanced and shipped to my door. I still have a vibration at 55mph, and feels like its coming from back passenger side. ANY IDEAS? thanks


Driveshaft?
spring?
shock?

1MeanZ

iTrader: (9)

did it randomly show up or has it always done it?

JamesC

iTrader: (5)

And have you performed a visual for bent, broken, lose parts?

JamesC

///DAN///

iTrader: (1)

Have someone follow behind you to make sure you don't have a bent axle , that would usually do it all the time .a driveshaft would be a middle vibration not to one side or the other. Springs and or shocks usually wouldn't cause a vibration .

91z28 98ta

iTrader: (1)

Its kinda always done it, and yes i've done visual inspection and nothing is broken. Ill check for bent axel though. But it would seem if i had a bent axel it would vibrate all the time. Thats why i always thought it was a wheel or tire problem, like out of balance or broken band it tire or something.

1MeanZ

iTrader: (9)

If it only starts coming in at a higher speed, and the car has always done it and still does it after you swapped wheels and tires, then I'll lay money that it's the driveshaft. Thoroughly check the u-joints, and make sure there isn't too much slop between the slip yoke and the transmission. If the joints and yoke look good remove the DS and take it to a driveline shop to be ballanced. Most shops will ballance a driveshaft for $50-$75..

WHTrunner

How much slop in the slip yoke is acceptable? I've got maybe 1/64th of an inch of slop.

I've got the same problem as OP, only mine seems to be coming from the front. I already replaced everything on the front, so I started looking at the drivetrain. I found a ding in the driveshaft, and swapped it out tonight, only to have it do nothing for me. Already put new u-joints in. I was wondering if I had too much slop in the yoke, but I really don't know what is too much.

JamesC

iTrader: (5)

Any chance you're running a poly trans mount?

JamesC

WHTrunner

Me or him?

I'm not sure what it's made of.

JamesC

iTrader: (5)

You. Poly can introduce significant vibration in some applications.

JamesC

1MeanZ

iTrader: (9)

shouldn't be much more than 1/16" i'd say. That is just a speculation based on how much my TKO600 has...

squatingeagle

service manual says its a rough rear wheel bearing. ive got the same problem right now. ive replaced the drive shaft, u-joints, axle shafts, and tires. i dont have bent rims and ive got a gm trans mount. im going to run it today with axle shafts out and that will tell me if its the bearings. if it doesnt vibrate, its bearings

squatingeagle

its was rear wheel bearings. replaced them runs like a dream