Driveshaft balancing...'71 with carrier bearing.
 

Before I took this all a apart I marked all the yokes and shafts from the rear of the TH400 to dif. Two piece drive shaft.Replaced all the u joints and carrier bearing. Reassembled it all with aligning the marks but now have a vibration between 35 n 45 mph. Using a laser sight everything lines up straight, the one balance weight on the main shaft is there... Is there a way to check the shaft balance without tearing everything apart and sending it to a shop? I'm kind of leary about jacking it all up and running it up with a piece of chalk on a stick...
It is not a problem below or above those speeds.

Re: Driveshaft balancing...'71 with carrier bearing.
 

pics of the shaft

Re: Driveshaft balancing...'71 with carrier bearing.
 

Ill get some pics. Its in the garage with melting snow dripping all over at the moment.

Re: Driveshaft balancing...'71 with carrier bearing.
 

A start

Re: Driveshaft balancing...'71 with carrier bearing.
 

More

Re: Driveshaft balancing...'71 with carrier bearing.
 

is the yoke on the transmission indexed the same as the one on the rear diff?
take a pic of the yoke at the diff..

Re: Driveshaft balancing...'71 with carrier bearing.
 

Well, now that you mention that and looking at it I have to say nope. Close but no cigar.
The carrier bearing a two u joints were totally toast so I figured everything was because of that.
Before taking it apart I scribed index marks on every joint then used a white paint pen to highlight the scribes. Guess it doesn't really help if it isn't correct to begins with and I never even thought about it being off.
Pics of transmission end and at the diff.

Re: Driveshaft balancing...'71 with carrier bearing.
 

If I'm not mistaken looking at the clocking I'd say it's off a spline or 2. Welded piece to the tubing should lineup with the second half of the shaft. Even then it could be off 180

Re: Driveshaft balancing...'71 with carrier bearing.
 

I was thinking it looked off...may be only a spline or 2 like kw said ...looks like this to me..maybe more than 2

Re: Driveshaft balancing...'71 with carrier bearing.
 

I can't tell if they are out of phase, maybe if the u-joints were pointing straight up and down it would be easier to tell. I would think a driveshaft problem would be constant and not just at a certain speed. I was wondering how long the truck was out of commission and if the tires got flat spotted

Re: Driveshaft balancing...'71 with carrier bearing.
 

PO put new Wrangler tires on it just before I got it. Hasn't been sitting. He did some questionable things to this. Tackling one at a time...I'm going to slide under there and try getting the clocking taken care of. Like I said, with the bad bearing n joints I didn't even think to check if it was in there correctly to begin with. Be easier to fuss with n better pics if I had a lift instead of ramps and the backstroke on the floor. Thanks for sharing your knowledge with this guys. May not get to it today, wife's birthday...but I'll report back.

Re: Driveshaft balancing...'71 with carrier bearing.
 

If in doubt pull the shaft and have it balanced my 71 didn't have a vibration but kept eating carrier bearings before my ls swap had the shaft balanced for like 35 buxs never ate another bearing its cheap money

Re: Driveshaft balancing...'71 with carrier bearing.
 

Just be overly careful when working on those ramps....

Re: Driveshaft balancing...'71 with carrier bearing.
 

Yup Mongo...ramps, chocks, jack, jack stands.
Even though my scribes lined up perfect the front of the rear shaft was about 30 degrees off. Lined it all up like it should be and smooth as a baby's butt. Should have looked at it before putting it back. Moral of the story, don't believe it was correct if if you didn't do it yourself the last time and double check everything. Or, pay the guy that does it for a living.

Re: Driveshaft balancing...'71 with carrier bearing.
 

Glad it worked out, it's the little things

Re: Driveshaft balancing...'71 with carrier bearing.
 

X2