Vibration/rattle in the whole car. Like driving on the shoulder.

[alen]

Hey all,

I have an 85 318i with an M10 engine. It’s a pretty old and used car that I’ve had for a while now. Underbody has some rusting but it’s still solid, relatively.
I parked it for 5 months before firing it up couple of weeks ago. I do about 350miles a week in it right now, mainly highway.
Ever since I started driving it again, I’ve had some really strong and loud vibration/rattle coming out of maybe driveline?
It basically feels like I have no engine mounts.
However, it’s road speed sensitive. It happens at 30-40 mph, and then it comes back on at ~55-75 mph. At this speed, if I don’t touch the throttle it’s fine. As soon as I depress it more than just a touch it’s an onslaught of vibration that shakes up the whole car.
Weird enough, if I’m at this speed in 5th gear, let go off the pedal (vibration goes away), put it in neutral, it comes back again.

I tried to have a look at all the mounts, rubber bushings, and they all seem ok. My muffler is also a little messed up, where the exit pipe broke off a long time ago and the pipe inside the muffler has space to slightly move around. However, I did some testing and don’t think this is it.

To recap, it was perfectly fine before I parked it for a while. Now it makes this rattle.

I’m afraid that something might fall off as I drive the car. Does anybody have clue as to what it may be?

Thanks

[Wh33lhop]

Probably your CSB (driveshaft center support bearing). You have to remove some heat shields above your exhaust to see it. The rubber support bushing is probably torn up and no longer functioning, so your driveshaft is deflecting under torque and wobbling all over due to the lack of support and resulting u-joint angle.

Check your guibo too.



CSB is obviously #1.

[E30Nova]

That was the exact symptom I had when my driveshaft took a shit. It's either the CSB or one of the u-joints at the end of the driveshaft.

Matt

[alen]

Thanks guys I will check this out first thing. I assume if it's the CSB, that it would be the worthy and cost effective to replace the entire assembly (~$45) rather than just the bearing (~$22), right?

[Wh33lhop]

Thanks guys I will check this out first thing. I assume if it's the CSB, that it would be the worthy and cost effective to replace the entire assembly (~$45) rather than just the bearing (~$22), right?

The bearing is rarely the issue with the CSB, the bushing is. So yes.

In fact, when I replaced my CSB they gave me the wrong bearing (thanks pelicanparts, I forgive you), and of course I didn't check before I hammered/torched/viced the old one off, so I had to reuse the old tortured bearing with the new bushing/hardware for the time being. Still haven't pulled it off and replaced it yet.

Barring getting the old bearing off, it is not that tough a job, but make sure you mark the driveshaft when you pull it apart--you don't want to put it back together in a different orientation and screw up your balance.

[alen]

So I've done some research around the forums and noticed that the cause of bad csb might be due to bad u-joints, and that I may need to replace the driveshaft in order to fix the root cause of the problem.
I checked under the car, and the u-joints seem to be scored from twisting, bending. So, newer driveshaft is definitely on the list. Does anyone know what all driveshaft options I have. The car has an M10 5spd drivetrain.

[E30Nova]

I had mine rebuilt for $200. I'd rather rebuild it than try my luck with a used unit.

Matt

[u3b3rg33k]

On the bushing note, subframe / diff bushings can look ok visually while being cracked / trashed physically.