Rear end vibration

[Supershafts]

I got the car back after exhaust work was completed and the vibration still is there. Just to prove out the exhaust we change all the hangers to a different with more flex and it made no difference, so it not the exhaust causing the vibration.
Again,
The vibe starts at 2200 rpm and settles out at 2600 rpm but never really goes away above 2600.
It never shakes the car violently but is more like an hard rumble that comes in very quickly at 2200 never gets worse and will almost go away after 2600 rpm.
Vibe is the same in all gears and does not vibe in neutral coasting or parked
Vibe is the worst under any acceleration and will almost disappear off the gas pedal.
You feel the vibration in the seat of your pants and in the floor, not in the wheel or pedals.
Trans mount is stock rubber and appears to be OK
Motor mounts are solid aftermarket
I ordered a new trans mount, see if it makes any change
Any thoughts? I am lost:confused5:

Are you saying the vibe is present between 2200 and 2600 in all gears at that same rpm ? if so the issue is at the motor or front half of the trans

 

[Big Sugar]

The first thing I did to try to resolve this was to put in complete new driveshaft, new tube, new u-joints, new yokes and balanced.
Vibrates from the front fenders back.
I spoke with a custom trans and T/C guy today and he stated that if there were something wrong with the T/C or the flex plate that it would vibrate in or out of gear, anytime the engine were at 2200-2600 rpm.
With the car up in the air the wheels and tires run pretty true.
Can brake drums be out of balance?[/QUOTE]


Thats definatly worth looking into.
But if the vibration is up front as well I'm still thinking tranny, ?

Ron

 

[snakeoil24]

Pinion angle should be 1.5 to 2 degrees down and on a parallel to the trans yoke and rear yoke. add 200 lbs to the trunk and a full tank of gas then measure the angle with a magnetic angle finder on the face of the rear yoke and put a slip yoke in the trans and check it.

 

[snakeoil24]

All brake drums are out of balance to some degree. Thanks to heat warp.

 

[Supershafts]

brake drums aren't the problem, he's saying it's only from 2200 to 2600 in all gears, remaining somewhat noticeable after 2600.

 

[68gtx]

this may be way out there, but check to make sure your yoke is going far enough into the trans, has a car once with this issue, the d shaft was too short, and when you got it up into third gear the driveshaft woould start to wobble at the trans end , i got a new shaft that made the yoke sit further into the trans and it was gone

 

[500stroker]

I have a 66 Satellite that I am trying to chase down a rear of the car vibration The car has a 8 3/4 posi and has been mini tubed and connected with Cal-Trac bars. 500 cid with a 727 auto
The vibration comes on at about 2000 rpm under acceleration, no vibration of the pedal or coasting in neutral.
I have run down the the following to date;
Balanced and checked for straightness rear tires and rims
Replace the entire drive shaft, trans yoke and u-joints
Replaced both rear springs with all new poly bushings
No change
Before I tear in the rearend does anyone have any suggestions.
Thanks in advance

I fixed it.
Just today I changed out the Tranny mount, which feel apart in 2 pieces when I took it out.
Vibe is now very slight which I attribute to 512 cid and solid motor mounts.
Job over, Thanks to everyone that replied