Vibration - looks to be driveshaft

[MatRacer]

Hi all,

Bought a 1987 325es equipped with a S50 about five years ago...drove it a bit and dissembled everything to put it in a cleaner shell. Fast forward to last Thursday when I first drove my new 1989 325i with the S50. I didn't took long to notice that it was vibrating really bad. I was surprised because the same setup (engine - tranny - 1 87 325es driveshaft - diff) didn't vibrate five year ago in the 87...

After some investigation, found out that I had done a hack job on the driveshaft :loco:. I had assembled the driveshaft 90deg wrong and failed to preload the CSB. Note that I also put a string between the output flange of the tranny and the diff input to centre as much as possible the CSB. I had big hope that it would correct the problem, but it did not. Also note that the driveshaft is not 180deg wrong, since I had a picture showing the balance weight when I dissembled it 5 years ago...

It still vibrates quite a lot. It its worst at around 40-50mph when coasting. I also vibrate under acceleration, but not has much as when coasting (at least it is less noticeable, maybe due to all the other nice feelings that S50 accel produce ;)) When reaching 60-65, it seems to vibrate less, but it is still present.

After a close inspection, I found out a bit of free play in the centre joint. Bentley calls for 0.006'' tolerance... Probably out of spec... Also, the centre nut with the plastic insert is damaged and the drive shaft is not really sliding freely... could this cause a vibration, I doubt, not enough axial movement (not a lot of angle movement in the joints) Front centering bushing seems pretty tight...

I have E28 535 front engine mounts and e21 tranny mounts. I slotted a bit the engine supports (I think pretty equal left and right) and don't have any shim under the engine...

My plan is:

1- order new centering bushing and center nut with plastic insert
2- install new parts
3- road test (no real hope...)
4- debating on trying to align the whole drivetrain vs getting the driveshaft rebuilt....

Please comment!

Thanks! R3V help is always appreciated!

[jlevie]

If the u-joints in the drive shaft feel stiff or feel like they bind, I'd start there.

[MatRacer]

If the u-joints in the drive shaft feel stiff or feel like they bind, I'd start there.

They are not stiff nor bind. There is a bit of free play in the center U-joint. Probably over 6mils (Bentley tolerance) since I can feel it.

EDIT: In fact, there is no stiffness in the operation angular range, but if I rotate one of the center joint to its max, it become stiff at about 1/3'' of its angular range... But it is really not moving a lot when in operation, so it is not going into that "region".

[TobyB]

Any free play in a BMW u- joint or driveshaft is no good...
if it even 'clicks' I start looking for something else.

hth

t

[MatRacer]

Any free play in a BMW u- joint or driveshaft is no good...
if it even 'clicks' I start looking for something else.

hth

t

Would it produce a vibration...?

[efficient]

just found out my guibo is ripping and that my csb is just free roaming around. i was wondering why it vibed so bad that it made my pass rear side rattle.
would bad u joints cause my guibo to rip and csb? and would a reman driveshaft be my best best?
i raised the rear of the car up and put it in first and i can hear a click coming from my diff

[MatRacer]

just found out my guibo is ripping and that my csb is just free roaming around. i was wondering why it vibed so bad that it made my pass rear side rattle.
would bad u joints cause my guibo to rip and csb? and would a reman driveshaft be my best best?
i raised the rear of the car up and put it in first and i can hear a click coming from my diff

You will have remove de DS and separate it anyway. I would not drive with a bad Guibo and CSB. So pull the DS and inspect the u-joints while your at it. the acceptable free play, according to the Bentley, is 0,006''. Getting it balance would not be a bad idea...but was is vibrating before Guibo and CSB went out?

[MatRacer]

Drove it this morning, I have an alignment appointment after work...

It really start to vibrate at 38-40mph and reach max vibration at 50. at 60-65, it kind of goes aways. It is speed dependant and not RPM dependant. The load kind of change the vibration, but not that much. Still worst when coasting.

Does this point toward driveshaft? Could get it rebuilt locally for like 400bucks...

I feel that it is really not good to drive it like that...The winter is coming pretty fast. I would like to solve this quick to enjoy it a bit before garaging it for the winter...

[efficient]

No I started to notice since last week that when I smashed from a dig, in the upper rpms that it would make my pass rear shake violently. It would only do this in the upper rpms so I could never figure it out until yesterday when I jaccked up the rear and noticed my guibo is starting to rip and that the CSB is flopping around.

Before the violent shaking my driveshaft would click here and there. Going to inspect it later on

[TobyB]

Probably over 6mils

0.006" is a LOT less than 'six mil's' which I read as 6mm...

But much more than 'none' really WILL make it vibrate... 0.020" will certainly
do it, I can confirm from experience....

t

[efficient]

So I replaced my guibo and CSB and it still clicks. I checked my driveshaft for play and it didn't have a lot of play at the joints. Guess its time for a rebuild.

[MatRacer]

0.006" is a LOT less than 'six mil's' which I read as 6mm...

I was referring to mili... to 10^-3...

http://www.convertunits.com/from/MILS/to/INCHES

It can also be milimeter....

But much more than 'none' really WILL make it vibrate... 0.020" will certainly
do it, I can confirm from experience....

My driveshaft doesn't have 0.020'' of free play... But I can feel It... I think I will try to film it while on jack stand... Maybe I will se it vibrate...

[TobyB]

Oh. Thousandths. Yeah. Why didn't you say so? :p

Yep, I had one with 0.020" and it shook around under there like crazy.
The odd thing was, the car it had previously been on didn't have
any vibration problem. I have no idea why not...

And yeah, take a look at it running. It can be pretty scary...

t

[MatRacer]

Because English is not my first language...:p

indexed my DS 180deg and guess what? no more vibration :D. Well Still have a very light vibration, but really nothing compare to what was going on! No more a real problem...

Also got it aligned last Friday! Hell I like my E30!

[efficient]

lol i just aligned my ds today because it was off. in the bentley it says pull the center bearing forward, so does that mean that the rubber on csb is supposed to be stretched forward?