Drive line vibration

[lostagain]

The drive shaft broke at the U-joint last week on the hockey team 102D3.  I had the drive shaft apart at the spline slip joint and then put  it back together. We are on a road trip this week-end and there is an annoying vibration between 85 and 95 km/h in 6th gear, but not in 7th. (7 speed manual). Is a drive shaft balanced and should I have slipped it back just the way it came out? Is there a mark that I misssed for re-installing the same way it came out? What if I took it out again and put it on 90 or 180 degrees out? Or should I be looking at the tranny because it only happens in 6th gear? I did not have a vibration before the break down.

Any ideas? Thanks,

JC

[luvrbus]

JC, sounds like you missed the timing marks on the drive line,mine with a 740 would only do it in second and drove me nuts BK sent me an Email telling how to time it no problems in 2 years after I matched the arrows     Good luck

[lostagain]

Luvrbus, you're telling me there are arrows on the shaft to align it so it is balanced? I was hoping it would be a simple solution like this. I will look when I get home. Thank you. I did the repair on the side of the road and obviously missed it. Didn't think of it.

JC

[Busted Knuckle]

JC,
Actually there are not "arrows". But if you'll make sure that the U-joints and yokes are perfectly in-line with each other then your driveline should be "in time" and therefore should be vibration free. And yes the driveshafts are supposed to be balanced. When you say "the driveshaft broke at the u-joint"! Do you mean the driveshaft itself broke or the u-joint broke?    BK 

[luvrbus]

BK, mine did have 2 arrows when I timed it like you told me then I noticed the arrows on mine were in line, showed that in the Eagle manual too I read after the fact

[Busted Knuckle]

OH, okay see I learn something new each day! LOL! Seriously I didn't realize there were arrows, but hey that is cool as it makes it easier!   BK 

[HB of CJ]

Your are probably 180 out.  May be no index marks other than the ones made before removal.  Also a good possibility the driveline shop did NOT $balance$ the fix job. It happens. 

[lostagain]

Thanks, BK. I am on a road trip now with the hockey team. I will look at the drive line on Monday when I'm back home. I will align it as you prescribe. The U-joint proper broke. I replaced it on the side of the road and didn't think of aligning it when I slipped the male spline into the female part. It goes to show I'm only a half a mechanic...!!! This also goes to show how great this board is for info such as this.
I'll let you know if it smoothes out after I line it up.

JC

[dvrasor]

  a straight driveshaft does not need to be balanced.
if you put a driveshaft with balance weights welded on
in a lathe the high spot in its rotation is always 180
degrees from the weights to compensate for its out
of round construction.

     Dave Rasor 4104-2375

[Busted Knuckle]

  a straight driveshaft does not need to be balanced.
if you put a driveshaft with balance weights welded on
in a lathe the high spot in its rotation is always 180
degrees from the weights to compensate for its out
of round construction.

     Dave Rasor 4104-2375

Dave I won't argue one bit about this! But in all the yrs I have turned wrenches, I have seen more driveshafts with weights than without!
FWIW   BK 

[Blacksheep]

Uhh nobody I know of can weld up ends of a shaft that precise where it doesn't need balancing. I agree with BK! Most all if not all have weights and there are those occassions where a weight has come off and is not there but for the most part, any rotating mass should be balanced IMHO.

Ace

[dvrasor]

 

   It goes without saying that it is more cost effective
in mass production to build a shaft with weights added.
I have built 150-200 driveshafts over my 36 years of
welding for a living and if you take the time you can
get one to run within .010  BTDT.


    Dave Rasor 4104-2375

[boogiethecat]

Here's a nice writeup on driveline etiquette
http://www.4xshaft.com/driveline101.html

[lostagain]

Success!

I finally had time to crawl under the bus this morning to take the drive shaft out again to put it back together right. I found some arrows for alignment. Now the yokes are at the same orientation to each other, as well as the U-joints. Very interesting article that Boogiethecat recommended. I can picture now why everything must be lined up to spin smoothly. As well of course as the actual balance weightwise.

Took it out this evening on a dinner transfer and the vibration is gone. It is nice and smooth at all speeds.

Thanks all for the enlightenment.

I am sure the real mechanics on this board knew all about it and were rolling their eyes...

But for the half mechanics of the shade tree variety like myself, we learned a great lesson on the suttleties of drive shaft installation and troubleshooting.

Thanks again.

JC

[Dreamscape]

Hey JC,

Thanks for sharing your problem. I learned a lot and hope to never have to change one out!

Glad you got it ironed smoothed out!

Paul