Driveshaft bend?

[DaFuzzyDude]

Hey turbobricks, I am having a few related (I think) issues with a 1986 volvo 245, manual. I got this car recently and within the last week it has started being extremely loud at highway speeds (louder than my leaky exhaust), and overall pretty shaky at those speeds to. Both via gear engaged and giving gas, and disengaged at around 3.5-4k rpms in 4th (m46). It has some clunking at lower speeds that sound a bit like worn bushings, but I didn't hear much of that until recently. Additionally, there is a bit of "wobble" when I accelerate at low speeds and rpms in 1st and 2nd (I also have a known gas delivery issue so that could be chalked up to fuel pressure too), and it is hard to get it into any gear from a standstill, but it will slide in if I let it roll a bit very easily.
We jacked it up and found that while engaged with the wheels spinning, the "wobble" was extremely significant, and it looks as if the driveshaft could be bent. I understand that u-joints and the center bearing are also common culprits, and I'm hoping it's not anything with the trans since it shifts very smooth. No play in the suspension other than shot front shocks, but there was a fair amount of wiggle where the two driveshaft sides mate.

Any suspicion of the culprit? My buddy thought it might be a bent driveshaft, but I'm unsure. It is on cut springs but I'm doubtful I hit anything near the driveshaft, since it seemed to randomly begin one morning. Any suggestions are helpful, thank you!

 

[JohnMc]

Hard to tell looking at that video, but it doesn't really necessarily look bent, since it wiggles more at the very rear (at least it appears to). If it was bent, it would probably wiggle most in the middle or wherever it was bent.

Wiggling like that at the rear makes me suspect the rear u-joint. If it's stiff it will resist flexing and instead move the diff around some, which in turn moves the driveshaft. I'd unbolt that rear flange and see how that u-joint feels.

 

[NLRegina]

It doesn't look bent in the video - I would pull it and inspect the u joints and center bearing, as well as the transmission output flange. See if anything has play where it shouldn't, or lacks play where it should (u joints). A bad center bearing can also cause a lot of noise. Its good to refresh all that stuff to stage zero new parts if you can, since it's typically neglected.

 

[2manyturbos]

Something is really off center where the drive shaft attaches to the rear axle input flange. That is where I suspect your problem lies.

 

[dl242gt]

A very important procedure on these is to make sure the driveshaft is assembled in alignment. If the two halves aren't properly put together then you get vibration which eventually makes at least the rear ujoint fail. The digram for driveshaft alignment is in a Bentley or Haynes manual.