Can't identify if U-joint or differential failure imminent (VIDEO INSIDE!)

[Brianl289]

So my car makes a loud shuttering sound under acceleration in 1st and 2nd gear. It usually goes away once I hit 3rd. Its a loud shuttering, like a banging almost, and I can feel it throughout the car.

I have replaced the rear shocks, rear shock mounts, sway end links, transmission mounts, differential bushing, and diff oil with no change. THe differential mounting bolts are tight.

The sound is intermittent, as in sometimes its there and sometimes its not. I think it may have something to do with the temp outside too. It is 32 today and I did not hear it.

Also when I am driving 35 mph in 3rd gear and I let off the gas, I get a loud clunking that sounds different than the shudder experienced under load, and I can hear it swaying back and forth. Like it it pushing back and forth on something while clunking loudly.

In the video's below you will see the car on the lift and in 1st gear. I turn the driveshaft by hand and get a little bit of play as well as sound. This sound doesn't seem to be coming from the ujoint, but the front of the differential. Also, I can feel a vibration when this sound happens throughout drive shaft and in the cv axles. I dont feel any obvious play in the cv axles, BUT if I rock them back and forth I can duplicate the same sound. Take a look and let me know what you think.


https://www.youtube.com/watch?v=0Vx1Umxrrh0

https://www.youtube.com/watch?v=5gPwNoxwv60

[Alpinweiss E30]

Center support bearing, guibo or rear subframe bushings are items I'd check.

Edit: Sorry - saw video again and it could be the CSB but the driveshaft itself might be bad.

[Brianl289]

I was told that a failing CSB would shake the transmission tunnel while driving. Which I do not notice. The CSB also looked to be ok, no cracks or looseness. The guibo is also in fairly good shape. I will be replacing them soon anyways, but this seems to be centered around the differential area as far as noise and movement is concerned.

[Alpinweiss E30]

Is there play in the flange or do the U-joints seem loose?

[Brianl289]

The ujoint itself does not seem to have any play. The play is coming from the differential output shaft. As in, the drive shaft is moving in and out of it slightly. But I also get some clicking when the driveshaft is rotated, or if the wheels are rotated back and forth quickly on the lift.

[Brianl289]

Any other opinions?

[tjmonsen5]

I dealt with this for years until i finally sold the car. I replaced the driveshaft and it got much better. But, it was never perfect. i think the differential is the culprit, or the transmission. The driveline would jerk back and forth while coming to a stop if you didnt clutch in early enough.

[Brianl289]

Hmm. Sounds just like my issue. I'm really thinking its the dif. Like there is play in the output shaft or something. But strangly enough I haven't heard it these last few days since its been 30-40 degrees.

[Brianl289]

Well I haven't been able to diagnose anything further since its finals week but we have only had weather in the 30-40's and I cannot get the sound to return. I drove around town for an hour, not even a hint of the sound or vibration. Do you think the cold may have caused the metal in the u-joint to tighten up or maybe the bushings? It's so weird that if its cold it doesn't do it but on an 80 degree day it sounds like the car is going to fall apart

[thejlevie]

I suspect two problems. The first being a drive shaft with binding u-joints and the second being wear in the differential and/or half shaft CV joints. The drive shaft has to come out to check for binding u-joints, but the differential and half shafts can be checked while installed.