Possible driveshaft issues

[StreetBu]

So I just installed my GN 8.5" rear, 3.42 with a Detroit Tru-Trac. Had my stock driveshaft shortened 1" and obviously rebalanced. I had several vibrations from the car BEFORE I put this rear end in....and was hoping it would take care of them. It made a big difference, but didnt fix them all. Basically my vibration comes thru the shifter handle (M-21) and is very annoying. After looking at www.dynotech.com I'm wondering if it's just my shaft and I need a larger one to stop the harmonics. BTW, I also installed double adjustable uppers so I could adjust my pinion but have not done so yet, waiting for my friends drive on lift to adjust it from ride height so for now they are set to stock length Any bright idea's?

 

[80montecarlo]

imo it may be an engine balance issue if it is coming threw the shifter, it may also be the tires.

But it just may not have been balanced properly

 

[Doober]

That's weird, I wouldn't think there would be any vibration if they're at stock length. Are the trans output shaft/rearend pinion parallel (aka angles to the driveshaft are the same/180º apart)?

 

[StreetBu]

imo it may be an engine balance issue if it is coming threw the shifter, it may also be the tires.

But it just may not have been balanced properly

Someone else said the same thing, It's making me wonder. I have a balancer from a 283 on it right now, but this engine didnt shake/vibrate when I still had a t-350 behind it so I kinda dismissed the engine as a possible cause.

 

[80montecarlo]

imo it may be an engine balance issue if it is coming threw the shifter, it may also be the tires.

But it just may not have been balanced properly

Someone else said the same thing, It's making me wonder. I have a balancer from a 283 on it right now, but this engine didnt shake/vibrate when I still had a t-350 behind it so I kinda dismissed the engine as a possible cause.

Get the shaft re balanced.(for free)

 

[Anonymous]

You say it didn't vibrate with the T350. To me that signals a possible issue with the manual or flywheel/clutch. I'd ask for a rebalance of the driveshaft for free, then look hard at the transmission/flywheel.

 

[StreetBu]

The other choice is toss a set of stock rear springs in it and see if it changes at all. Pretty quick and easy to do. Then I would know that it is/isnt driveline angle at least. :-k Now I just need to find a set of stock springs to borrow for a day

 

[swapmeetjunkbu]

What is the condition or what type of pilot bushing is in the end of the crankshaft?

 

[StreetBu]

Actually it's a roller pilot bearing. No I didnt index the bellhousing [-X But the trans shifts great and has for the past 7 years and about 5k miles so i dismissed that as the cause. Should I have?

 

[racecar77]

Possible bad input shaft bearing on the trans. Lee