Not Good Vibrations

[rollie]

After installing a new pro street stroker 383/496 in my 69 Roadrunner......I'm getting some not so sweet vibrations above 70 mph. At 120 the vibration is so bad, forget about looking out the rear view mirror.....and there's a lot more left in this motor. Looking for some ideas on where to start diagnosing the problem. I have an original A833 4-speed transmission, original driveshaft, 3:23 gears in a 486 posi rearend.

 

[Big John]

Driveshaft or u-joints most likely.

I had one that drove me nuts (short drive) and it turned out I had twisted the driveshaft enough that it caused a problem, but not enough to see when looking at it.

Could also be tires.

 

[mahoney0_00_3]

put it on a lift and run it /ck the tires not only are they round but if the belts are torn look at the tread---I bought a car like that and the tire looked round too-but the tread was crooked--ck and make sure your driveshaft yokes are lined up and good-look for play-the drive shafts twist a little and they shake-did they bal the crank with the same flywheel/bal-------------get the car up on a lift and run it------

 

[rollie]

Ok thanks for the tips. I will rebalance the tires....they are new....and will inspect the tread.................easy fix..........maybe. I suspect the driveshaft since I had some vibration with the original motor but not as bad as now.....but I wasn't pushing the shaft as hard as now.

 

[69hemibeep]

If your running radials make sure you don't have one separating