Drivetrain Vibration

[ChevyIIMan]

I just swapped in a 200-4r for my th-400. Now I have a vribration around 40-60mph or so. the only thing I can think causing it is that the driveshaft is only engaging the transmission 1 3/8" which im thinking may not be enough and may be causing the vibration. is this possible?

[myclone]

Thats not much spline engagement IMO and if it is allowing the yoke to wobble then it could vibrate as well as worn splines on the output shaft or yoke (or both). Is the vibration present in all gears 1st-OD or just one gear and at a certain MPH/RPM?

[ChevyIIMan]

Seems like all gear but most noticable around 40-60mph or so and when crusiing, seems if your on the throttle a bit it clears up. Make me think that its just that the thing is too short ill get under there tommorow and see if there is any noticable play when its in park if there is im sure thats what it is. I am having the driveshaft legenthened on monday. I knoew that wasnt much engagement but it was enough to test drive the car. Ive only put 20 miles or so on it and wotn be putting any more on till the new driveshaft comes on monday.

[myclone]

If its present in all gears then Id say its just the lack of engagement in the splines allowing the yoke to wobble which would set up a vibration you feel and my guess is the "natural" harmonics of the driveline make it worse 40-60mph. Since youre getting a new drive shaft have em throw a new yoke on the trans end since theyre only a couple bucks.

[ChevyIIMan]

Yeah it seesm to get worse the faster yo go, I cant say ive ben over 60-65 yet so I think that may be all it is.