kidcamaro98

iTrader: (8)

ok this winter I installed a moser 12 bolt out of my buddys car. My 10 bolt, never did this.

I have a spohn adjustable torque arm that I cut to have it sit on the inside holes instead of the outside holes like on the 10 bolt. My pinion angle is set at -1 so I doubt this is the problem. My lca's are Heim joint adjustable lca's and so is my adjustable panhard bar. These are all tight. The other day I did notice my U joint nuts loosened up, so I tightened them back down.

the car is smooth as hell from 0-60mph. At 70mph +, in cruise control or accelerating slowly, it vibrates like crazy. It feels like its right under my ***. My rear view mirror vibrates so much that the cars behind me, are blurry. My steering wheel is solid as could be and I dont feel any vibration coming through it.

My torque arm is a chassis mount and the rubber in between the torque arm and chassis is very thin and kinda beat. Could this be what Im feeling? The vibration is driving me Nuts. I am afraid to take the car to 100mph + because the vibration is so bad.Could my U-joint be bad? How can I tell before I take it off the car? I have tried adjusting my pinion angle and it doesnt make it feel any different. A local friend and F-body owner thinks its my Heim rodded end Lca's that are making me feel this much vibration, true? I have stock length poly ones on the 10 bolt and it was smooth. I had the spohn adjustable torque arm on the 10 bolt as well, but set on the two outer holes, also smooth.

thanks for the help.

roy

I surmise your torque arm or the 12bolt is making contact with the body underneath the car at higher speeds. You will have to make room for it if it is.

89 formula350

iTrader: (8)

well what changes at higher speeds?

1 drive shaft speed
2 tire wheel speed
as you see you need to list what changes. (engine load at specific rpm can cause vibes too!)


I think I would look at what is really affected at these higher speeds. the solid joints and bushing will cause noise rather than vibrations..

kidcamaro98

iTrader: (8)

I cut the two outer holes off the torque arm so I could mount it by the two inner holes, because when I did have it mounted by the outer two it was touching my body. Now I have more then enough clearence all around.

how would my 12 bolt be making contact with the body?

kidcamaro98

iTrader: (8)

at 70mph where it does it pretty bad, in cruise control im at 2000rpms in 6th. As soon as I tap the gas, it goes away until I "cruise again". Or The car is so smooth from 0-120 when im WOT the whole way, until I let off. Then it vibrates like crazy.

I forgot to mention that I am lowered up front on the eibach pro kit with kyb agx shocks and on the rear I have the stock rear springs with the hose mod. I currently dont have relocation brackets on the 12 bolt. I am ordering them saturday.

roy

I installed a 9inch in my SS and it just barely touched the body in one which cause some hellacious vibration on light acceleration or or steady state cruise or on decel at speeds between 70-150 mph. Hard acceleration to 150 was not a problem.




Also from the added information you posted above:
Some possibilities are a u-joint angle problem or is going bad or the drive shaft is too short for this 12 bolt application. If the wear ring on the slip yolk is visible while the wheels are supported, then it is probably too short.

kidcamaro98

iTrader: (8)

ok thanks for the info. I will check this out today.

as far as the driveshaft being to short, I have the same setup I took out of my buddys car ( I bought his 12 bolt and swapped my 10 into his car) and he never had this problem. If the driveshaft was to short, wouldnt it have done it in his car too?

as far as "touching the body", you mean the actual rear end was touching? Wouldnt I hear banging or clunking?

Bob@BruteSpeed

iTrader: (16)

The Moser 12 bolt takes the same length driveshaft as the factory 10 bolt. I'd pull your driveshaft out and make sure the u joint bearings are all there and in good shape. If you overtighten the u joint u bolts it can ruin the bearings and cause a vibration. Bob

kidcamaro98

iTrader: (8)

great. Thanks for the info!

Bob@BruteSpeed

iTrader: (16)

You're welcome. Bob

89 formula350

iTrader: (8)

also check the tail shaft bushing for play.. mine was bad and made a similar problem. on the gas it was fine ... let off and you got a bad vibration.

kidcamaro98

iTrader: (8)

ok guys, I fixed it.

My one u joint bearing at the axle was completely blown out. The bearing race in the side had a dime sized hole in it. Scary ****.

Put a new U joint in, and the car is soooo smooth.

Bob@BruteSpeed

iTrader: (16)

Good deal, I'm glad you found the problem. Bob

01ssreda4

iTrader: (96)

Nice