replaced u-joints, bad vibration at 45mph

I replaced both of my u-joints myself today, took a couple of hours. I reinstalled the driveshaft but I'm feeling a pretty prominent vibration at 45mph, should I consider getting the driveshaft balanced or did is it possible I just didn't get it in there right?

 

Are you familure with uj replacing? Did you note the condition of the damper on the yoke? How about rechecking the strap nuts at the pinion.(diff)

 

First time I've ever done it, everything looked to be in fine shape. The strap nuts appeared to be in place just fine, I'm going to remove and reinstall the shaft tomorrow.

 

And no, I don't know what the damper is.

 

The part that stabs into the trans connects to the shaft, it has a ring around it with rubber made into it, this is the damper. I have seen where this comes apart and some guys tend to leave it like that and ballance the assymblies wiyhout it. I still have mine, if I were racing it I might considor getting a new one or not having one at all.

 

How do I check that? When I pulled the shaft out, it came out bare.

 

This part or ring is about 5" in diamator and quite visible. When you take the front piece off the shaft, it is part of this front piece. Towards the base of the splined tube that goes into the trans right by the front uj.

 

Not all driveshafts have the dampner. Its been my experience that very few do. Only thing I can suggest is make sure the drive shaft is sitting in the yoke properly. There is a resessed section with raised blocks on the ends. The u-joint bearings will sit flat into the yoke and between the blocks. If yours is mounted correctly, I'd pull the drive shaft and take it to a place that can check & balance it.

 

Dennis; I think the Comets had them, not the Mavs. Wonder why?

 

What does your tranny mount look like? Over the years these turn to mush and will cause alot of vibration, there easy to change and cost about $10.

 

I would double check the mounting pads like Mavaholic suggested. I had a vibration after changing the u-joints on my 71 F100 and it was a bur on the mounting pads making the u-joint be slightly off-centered
clint

 

Also, if you didn't mark the front part of the driveshaft & yoke before disassembly. That could cause a vibration, out of balance. Needs to go back together the same way it came apart. I found that out, the hard way years ago....

 

I did not mark the yoke and shaft, can it be re-balanced the way it is?

 

Mine tends to shake a little when I hit 90mph. Should I worry about that? I don't get there often, especially with 3.80 gears.

 

Too many other things shaking on my car when I hit 90 on my car for me to even think of my drive shaft being the only cause, .