Prop Shaft Vibration - N54Tech.com

mixhali · **Prop Shaft Vibration -** 09-14-2015, 07:52 AM

Hi all,

Hope this is a simpler issue than my mechanic is making it out to be. This week we installed the TFT kit and RB turbos however this is not the issue. After putting all back together and taking for a run i get a knocking vibration at around 20-40kph. After that it is fine. My mechanic tells me he only disconnected the prop shaft from the gear box and didn't touch any other points. It feels like it is coming from the diff area or mid section of the car. Ive done some research and i found some pointers regarding the flex disk which can cause this. I dropped them to him however he is adamant he put the flex disk back in correctly. He is waiting for a spanner to disconnect it at the diff however I'm not convinced it is something down that end if he never touched it. Any common mistakes for this?

Regards

jyamona · 09-14-2015, 08:00 AM

Can you post a video?

mixhali · 09-14-2015, 08:14 AM

not sure what you want a video of

blown07 · 09-14-2015, 09:30 AM

It is possible to install the center support bearing upside down (not sure if he disconnected this or not). When I took the shaft out of mine to do the diff I also marked the flex connection on the trans to make sure there was no vibration.

camberadam · 09-14-2015, 11:06 AM

Quote:

Originally Posted by blown07

It is possible to install the center support bearing upside down (not sure if he disconnected this or not). When I took the shaft out of mine to do the diff I also marked the flex connection on the trans to make sure there was no vibration.

I've done most of my driveline work on trucks so I'm not totally familiar w/ the e90/92 driveline because I haven't messed w/ it, but it sounds like it is out of phase. google "driveline phasing" & you'll see all the different types of drivelines & how they should be.

for example:

erichale · 09-14-2015, 04:42 PM

The guibo has arrows on it to point to the right direction. I accidentally installed mine the wrong way during my builds and it vibrated bad at slow speeds. Turned it around and no more vibration.

duracell8 · 09-15-2015, 05:10 AM

Most likely he did not tighten the nuts to the center support bearing mounting points. Easy to verify on a rack, you can see thru from the rear with the car in gear at that speed.