[Ron67]

Im pretty sure its the center from take off till about 60-70 it has a vibration then stops its a 411 posi its only a few years old with not many miles on it. So i put my non posi back in and no vibration! what could be wore out or broke?

Thanks Ron

 

[ahunt191]

How do the carrier bearings look/feel? Vibrations can be caused by worn out bearings.

 

[Spartikus]

Since it is so new, might want to check the drive shaft alignment as far as angling too.. Bearings shouldnt wear that fast. Is the ass end way up in the air Ron or do you have a modified drive train? (ie different trans or trans locaiton is higher or lower than stock?)

Poop happens but shouldn't kill the bearings in a couple years. I was going to suggest the u joint but if you replaced the center and it went away that kind of pin points it :/

 

[Ron67]

bearings should be ok its a few years old with less 2k on it. Think it could be the drive shaft with the extra load of the posi doing it? But I also thought if the drive shaft was off I would think it spin the rear seal out of the trans..oh all new u joints hell Im gunna has a beer and think it over some more

 

[cougarshaman]

Think it could be the drive shaft with the extra load of the posi doing it?

I've never experienced that symptom just because it had a lsd in it.

The chunk needs to be removed and the entire thing needs to be checked over before you develop a potentially serious issue with it.
I'm guessing that one of the new bearings is out of whack. All you have to do is drop a bearing once and it can be unsuitable for use after that.
Have it checked over. You'll probably find something wrong.

 

[Ron67]

My problems seem to grow!! Here is were Im at now the vibrating and another problem <I THOUGHT was the front end it has some type of wobble if ya will> Anyways I jacked the rear of the car up and took the rmp to about 3k and I fell the wobble something is out of balance. axle or axle bearing. I have had this car a part motor trans new floor pans, subframe connector roll cage and new strut rods bushings, control arm bushings, All new gaskets for the temp 289. So with the rear tires off the ground what would make it <wobble> i cant think of a better word...Drive shaft, axles bearings, I dont think its a rim/tire issue they just sat all winter. This is the other odd thing faster i go or more rpm the LESS it dose it almost like the more speed it will balance out some.

 

[Ron67]

update drive shaft is bent and ps axle on the hunt

 

[Ron67]

Ok still something is out off wack!!! When driving normal under aload I get some kind of shimmie/shake in the car but if I let off and coast or drop in 2nd gear and floor it the shaking stops. Its something in the driveline I was thinking converter flexplate not sure tho I had the car apart over the winter did a overhual on the 289 new gaskets,cam lifter,oil pump ect, floor pans subframe connectors roll cage. The other thing is i went with polyurethane motor mounts maybe this could be the problem?

 

[RoadRacer68]

So the driveshaft issue cleared the initial problem? The urethane mounts tend to transfer "resonance" through the floors. Did you happen to check pinion angle? Did you change the flexplate and converter?

 

[Ron67]

I pulled the trans replacing the flexplate and converter today...Before I pulled it got the car up in the air and ran its with a buddy looking looked to be making the rearend bind he said the shaft is to long. So after we got it out we compared it to the old one its about 2in longer then the old one but you can see where some cut some off the shaft on the yoke on the old one. The trans is a 78 year was the tail longer in 78? Here is my plan today new converter flexplate put the yoke from my old shaft on the new one instead cutting it and see what happens.

 

[RoadRacer68]

Oh ok, things are starting to make a little sense...a driveshaft that's too long and the yoke bottomed out against the output shaft of the trans could cause a vibration. There could be minor variations in the transmissions from year to year but where you're headed makes sense. On the flexplate I was thinking a weight may have broken off or the wrong flexplate (ie-a 50oz from a later model) could get the thing vibrating...interested to see what happens, good luck.

 

[Ron67]

So the driveshaft issue cleared the initial problem? The urethane mounts tend to transfer "resonance" through the floors. Did you happen to check pinion angle? Did you change the flexplate and converter?

Roadracer68, It was a few things the axle had a little bend to it the shaft turned out to be ok, but the polyurethane motor mounts was 90% of my shaking/vibrating but I did change the coverter and flexplate put in a 2800-3000 stall with the 4.11 gears sure woke it up lol.

 

[RoadRacer68]

Sweet! Glad to hear you got it worked out...