Sounds more like the u-joints aren't in phase instead of shaft balance since the vibration started after the shaft was disassembled. Being in phase means that the yoke of the front u-joint must be perfectly lined up with the yoke of the rear u-joint. If they are off by as little as one spline, the driveshaft can vibrate. There should be an arrow on the rear portion of the front shaft that needs to line up with the arrow on the front portion of the rear shaft.
I'm assuming you have a 105/115 series car?

 

Thanks for the quick post
I don't remember seeing any arrows. I'll have a closer look.
Car is a 10521 2000GT
Wolf

 

The arrows are only about 10mm long and not stamped very deep. Very hard to see. I have seen, though, some shafts without the arrows in which case I mark the shafts prior to disassembly. If the shaft has no arrows and wasn't marked, the u-joints will need to be phased by eye. I can post some pics over the weekend if you'd like.

 

Looking forward to the pics
Thanks again
Wolf

 

In the meantime, here's an article on vehicle vibrations that includes u-joint phasing.

 

Well this is embarrassing! Seems I've misplaced the rear driveshaft so no pics of it today. However, here's a pic of the front slip-joint/flange assembly. Note the yoke on the front flange is pointing straight up so this means that the yoke on the rear flange must also point straight up when the two driveshaft halves are assembled. The long arrow would point directly to the rear flange yoke.
This shaft did not have the pre-stamped arrows so I stamped some in as well as stamping alignment marks on the flanges. One of the front/rear shaft alignment marks can be seen at the tip of the long arrow. The short arrow points to one of the flange marks.

 

PapaJam,

Don't worry about it - it happens to the best of us. I currently have a set of 4 Koni Reds that are "misplaced" somewhere in the garage

 

LOL!! Thanks for the laugh, Joe!

 

I had driveline vibration issues with my '65 GTA. It took Driveline Services of Oregon a while to sort it, but they did a masterful job. Turns out the splines between the two driveshafts were worn. You can feel this for yourself, they should have very minimal play. We found a spider driveshaft in excellent shape and he sawed and welded the new spline end to my driveshaft, and away I went, smooth as silk.

I'd recommend their services to anyone, plus, an Alfista runs the place. Contact me for info.

Steve Schaeffer
Seattle, WA

 

In the end my problem was the result of an incompetent mechanic.

The two drive shafts were installed incorrectly at the rubber dooughnut. (Probably incorrectly torqued or not torqued at all!) This had somehow bent the front drive shat part that attaches to the rubber doughnut. This in turn ruined the bearing (a new one had been fitted) of the intermediate support.

Now everything is back to normal except that the gearbox is beginning to make noise. Damaged bearings?

Thanks
Wolf

 

Driveshaft Balancing

OK, I reread this thread and actually tried to understand it sometime ago. The last test drive in Lisa, the 69 Spider, showed a distinct clutch slipage. Hold tight, this is difficult to follow.

I changed the transmission and rearend oil to Spirax 80/90 HD a few weeks ago and took things apart elesewhere so I havn't driven it much. After the test drive I found that oil was pouring out of the front transmission seal. This was replaced years ago (15) and not more than 20K miles on the rebuild since.

So now I have to do a clutch probably because it is well oil soaked.

I have had a "lanch" vibration for some time which has gradually dimished as I replaced a variety of things. So after reading Papajam's notes on U joint aliagnment and the referenced article I look at the driveshaft and can't see much either. At any rate, this has been a helpful thread and I'm going to take things apart very carefully and use a magnifying glass to look for marks.

Thanks, Bill

 

Driveshaft Phase

Jim;

I found the arrow that you pictured; is the matching arrow on the fat portion of the rear D/S? I found a variety of white marks, punch marks, and a o marked on the rear flange. All seem to match after careful cleaning of all surfaces, but I still can't see the arrow on the forward end of the rear D/S. I'll take another look tomorrow with cleaned glasses.

I measured the runout on the shafts, never done this before with a brand new dial indicator. The average was about .013" for both shafts, that OK?

Thanks, Bill

 

Bill,
I believe the arrow (if there is one) on the 1750 rear shaft is on the tapered portion just aft of the splines. However, the 1600 service manual shows it on fat portion just to the rear of the taper weld. If you can't find it. you'll have to make one. Just hope that the shaft is in phase to begin with. If all else fails, eyeballing will have to do.
From the Giulia service manual (Diass Pub. #1222), the maximum runout in the center of the rear shaft is 0.4mm (0.016"). Max runout at the front of the rear shaft, just to the rear of the carrier bearing, is 0.1mm (0.004"). In addition, the max allowable play between the male and female splines is 0.2mm (0.0078").
I'm certainly no driveshaft vibration expert but I'd think that a launch vibration would NOT be caused by shaft runout. I'd suspect, and in no particular order,

center support
u-joint phasing
worn splines
donut
worn front shaft bushing/trans output shaft

 

Thanks Jim for the info.

More observations:

There is no desernable play in the M/F splines, but there is a considerable "thunk" when moving the D/S back and forth coming from the diff.

There are "o" stamped into the rear flange, and on the front "U" joint on the opposite side of the arrow (180 deg.) on the "U" joint boss. These lineup with the ones on rear flange.

The "U" joint bosses do not line up front to rear. After looking at the article you referenced It looks like the should. Perhaps this is some of my problem.

I have replaced over the last few years (again, not very many miles):
Center support
donut
rear "U" joint.

I'm going to take out the drive shaft tomorrow; I can then check several things. The transmission will have to come apart for seals and I'll look at the output shaft bush.

Do you think I should line up the "U" joints???

Bill

 

The "U" joint bosses do not line up front to rear. After looking at the article you referenced It looks like the should. Perhaps this is some of my problem.
Do you think I should line up the "U" joints???

Bill

Absolutely!!!

A certain amout of 'free play' is to be expected in the diff do to necessary clearance specs. This can sometimes result in a 'clunk' or 'thunk' when shifting gears or when getting on and off the gas.

 

Driveshaft Phase

After getting the d/s out and CAREFULLY cleaning and sanding the area I found the purported "arrows". They were very faint and not knowing exactly where to look took a little. But there they are along with another one pointing off to somewhere.

My shaft was 90 deg. out of phase so this was a worthwhile exercise. I don't remember if I had something to do with this or it was someone else. I've owned the 69 Spider for 17 years and this is the third time I've had it out. I'll report back if this fixes some of the thunk problems.

Bill

 

Driveshaft Phase

After getting the d/s out and CAREFULLY cleaning and sanding the area I found the purported "arrows". They were very faint and not knowing exactly where to look took a little. But there they are along with another one pointing off to somewhere.

My shaft was 90 deg. out of phase so this was a worthwhile exercise. I don't remember if I had something to do with this or it was someone else. I've owned the 69 Spider for 17 years and this is the third time I've had it out. I'll report back if this fixes some of the thunk problems.

Bill

 

driveshaft vibes

did that fix your problem Alberbat?

very interested to know. Mine seems to be in phase, but could be marked wrongly etc. Also - can you really have them 90degrees out of phase. I thought the drilling pattern was a rectangle, not a square, so that you can only be 180degrees out?? Maybe that is only at the rear.

Thanks,

-Richard

 

Yes, the hole pattern is rectangular but this affects only whether or not the flanges are 180 out, not the u-joint phasing. The u-joints are phased by engaging the correct splines on the driveshaft slip-joint.

 

Guys,

I have this problem of vibration as the car (1975 115 Junior) hits above 60MPH. The vibration goes away immediate when I slowed down to 60MPH. The transition is abrupt. This happens after I had changed to new springs and shocks.

Do you guys think a new U-joints or balancing of the driveshaft is a better solution?

 

Can I just check that I've understood Jim's description correctly: could someone confirm whether the two UJ assemblies should be symmetric translated onto one another, or reflected in a line half way between them?

Many thanks,

will.