Is drive shaft balancing necessary?

[1969chargerrtse]

I have a vibration after about 60mph.  I pulled the drive shaft and was going to drop it off at a place tomorrow.  After reading some threads on the net most people say they are balanced from the factory and usually its a waste to have them re balanced.  They claim as U joints wear they come out of balance.  My shaft looks fine and I don't feel any play in the joints?  
Any thoughts?

I feel the vibration  under the car and maybe towards center rear.

[tan top]

yes i would !!    get it balanced  , or get a  new  drive shaft from a known good drive shaft builder /shop   , to me    one of the key parts to making a smooth ride , plus a well balanced drive shaft , puts less wear & tear on bearings in the gearbox  & bearings in axle - pinion bearings  ,  

[bobs66440]

Yes, it is necessary to have the shaft balanced, but it's true that they are supposed to be balanced from the factory and it's unlikely it would suddenly lose balance unless it threw a weight or got bent somehow. Are you sure it's not a wheel out of balance?

[1969chargerrtse]

This car had everything wrong with it when I got it. So who knows whats with the drive shaft? So I'll take the advice from here and Chris I PM'd and get it balanced and then take it from there. I'll return when it's done and road tested. If that's not it, maybe the yoke or U joints?
I have never had the tires balanced so that could be it also? But I don't feel it in the steering wheel. Seems to come from under the car.

[bobs66440]

I have never had the tires balanced so that could be it also? But I don't feel it in the steering wheel. Seems to come from under the car.

If it's a rear tire, you won't feel it in the wheel. It will feel like you are describing. It's very common. Keep us posted! 

[1969chargerrtse]

I have never had the tires balanced so that could be it also? But I don't feel it in the steering wheel. Seems to come from under the car.

If it's a rear tire, you won't feel it in the wheel. It will feel like you are describing. It's very common. Keep us posted!  

I think I switched the rear tires to the front one time to see if its was the rear and it stayed the same.

[Just 6T9 CHGR]

The one thing that "helped" my cyclic vibration from around 60-70mph was a new pinion bearing.....car is still not Lexus smooth but much better.
This was after a new drive shaft & joints, trans yoke, trans mount, Hub-centric wheel balancing etc...

[resq302]

I had mine balanced just to be sure and sure enough, the thing was out of balance.  The drive shaft place had me stand right there and showed me how wobbly it was on the lathe.  He said he has seen very few cars come out of the factory with a "true" balanced drive shaft that they all were sloppy and within a certain "tolerence" but never truely zero balanced.  If you are doing anything and have to take it out, I would have it checked just to be sure.  No need to cause any other problems down the line from an improperly balanced drive shaft.

[1969chargerrtse]

Again great advice. Gonna run it down after work. 2 years ago I found my motor to trani bolts loosened and tightening them back up helped alot but it's still not 100% right. Nothing worst than a Muscle car that can't go fast. I hate when little Honda's with 4 cyl's zip right past me.   This must end and end now. I have a image to up hold.  

[1969chargerrtse]

Dropped it off today.  The guy was real nice and showed me how he sets it up and checks for run out.  Anything over 30k could be felt in the car.  Then he showed me the machine he spins it on to balance.  Said check back Thursday.  If it needs U joints he'll put those on also.  Gonna rain all week, should be able to test drive by weekend.
My buddie told me this place is the best.  he gets his work done there.

http://www.camerota.com/

[68r/t]

I have built alot of tailshafts and the shaft should have under 10 thou runout if it is more then I straighten them.
Alot of shops will get it within 30-40 thou then balance the "runout" out of it.
If you find a shaft with a heap of weights there is a good chance that it has some runout.

[resq302]

I have built alot of taillshafts and the shaft should have under 10 thou runout if it is more then I straighten them.
Alot of shops will get it within 30-40 thou then balance the "runout" out of it.
If you find a shaft with a heap of weights there is a good chance that it has some runout.

My factory one prior to me having it balanced had a metal disc about the size of a half dollar on it.  The guy who rebalanced my drive shaft years ago laughed at it when he saw it and said it was typical factory crap.  Now I think I have a metal disc that is about the size of a dime!

[1969chargerrtse]

Just talked to drive shaft guy. He said the drive shaft is bent 20k. On the balance machine it's off 2 oz. The yoke for the tranny is no good as you can spin the u joint cap in it. Total job with straighting the shaft, new yoke and u joints and balance. 250.00ish. So I told him to do it and hopefully that is the issue. If not at least it is correct.

[bobs66440]

Sounds hopeful anyway...

[1969chargerrtse]

Sounds hopeful anyway...

Yeah, picking it up tomorrow, road test it with video on speedo Sat.  I wanna see 10 20 30 40 50 60 70 80!!!!  That's good enough for me.

[1969chargerrtse]

I have built alot of tailshafts and the shaft should have under 10 thou runout if it is more then I straighten them.
Alot of shops will get it within 30-40 thou then balance the "runout" out of it.
If you find a shaft with a heap of weights there is a good chance that it has some runout.

Yeah it had 2 weights which he said are now off.

[68r/t]

I have built alot of tailshafts and the shaft should have under 10 thou runout if it is more then I straighten them.
Alot of shops will get it within 30-40 thou then balance the "runout" out of it.
If you find a shaft with a heap of weights there is a good chance that it has some runout.

Yeah it had 2 weights which he said are now off.

That's great, under 10 thou runout usually means minimal weights for balancing.

[1969chargerrtse]

So here's the deal. It's definitely much better.  I would vibrate before around 60 and shake like mad at 75. This time at 75 there was vibration but not from under neath the car like before. I'm pretty positive whats going on now is wheel balance. So there is a big improvement, but more work to be done. I worked on this last year and found the motor to trani bolts loosend.  After I re tightened everything it was much better.  I'm gonna re check the bolts tomorrow.  If they are tight I know it's the wheels and rims because last year I jacked the car up and ran the rims and they were not true at all.

[resq302]

 

[doctor4766]

Only costs a few bucks to get the wheels balanced.
I'd be doing that regardless of everything else mate.

[tan top]

Only costs a few bucks to get the wheels balanced.
I'd be doing that regardless of everything else mate.

 

[1969chargerrtse]

Only costs a few bucks to get the wheels balanced.
I'd be doing that regardless of everything else mate.

Yeah I'll get them done.

Here's the new outlook. I took the car on the highway again and have to say it's much much better and that was the vibration problem. Last night was in rush hour traffic and I couldn't really get a good feeling about it. This morning I had open highway for miles. Where it used to start to vibrate at 60 was smooth. By 75 it was acceptable. I drive the car like a old man anyway. I'm very happy where it's at and this chapter is closed. Oh and the motor bolts were still tight.
Where I've been trying to get with this car is where I'm finally at. A classic that you could grab the keys, start it up and take off without having to explain any problem areas. Just go have fun. I feel the car is there.  

[bobs66440]

Glad to hear you are satisfied    It's a happy place to be!