2009 X3 Driveline Vibration

[lroman3]

I have a 2009 X3 that has a vibration in the driveline I need help diagnosing. It is not a constant vibration.

It seems to occur in the following situations:
1) Accelerating when at speed
2) Accelerating from a stop, but not right away. Seem to happen once you get in to 3rd gear
3) At speed and hit a series of bumps in the rode

Once the vibration starts, I am able to make it stop by letting off the accelerator and then get back on the gas.

I have checked the following items:
1) Front Drive shaft - U-joints are tight
2) Front CV axles - Only the left had very slight motion but, didn't seem to be enough to cause the level of vibration I am feeling.
3) Rear drive shaft - U-joints were tight.
4) Rear CV axles were tight
5) Carrier Bearing - There wasn't any slop in it but, the rubber had a some squish to it. Not sure if this is appropriate or an indication of wear. Not sure how a could should be to compare.
6) I know tires could also be the culprit as well. I am in need of tires and do plan to get new tires in the next week or so. But, some what skeptical as the vibration is not constant and I would think tires would produce a constant vibration weather it be all the time or a specific speeds.

Any insights you can share would greatly appreciated. Maybe what I have described is a bad u-joint or CV Axle and I am not aware of it as this is my first ALL Wheel drive car.

[X3456]

Very difficult to tell the need for replacement visually other than the reddish/brownish colored substance dust like (reminds one of rust) at the -u- joints and the thin cracks at the rubber guibo/rubber doughnut...sometimes there's a type of clunk when shifting to drive after backing up, the unit gives it self away with a harsh vibrating ride...yours is most likely at the initial stages possibly. Depending on the cars use it's common to occur firstly around 95k to120k.

Sent from my SM-J727T using Tapatalk

[jclausen]

If the tires are in really poor condition it could be them also the alwhee drive system needs tires that are all at the same thread depth.

[lroman3]

If the tires are in really poor condition it could be them also the alwhee drive system needs tires that are all at the same thread depth.

Thanks for the reply. I am new to AWD and just learned what you have stated above. I am pretty my tires are my issue or at least contributing to it.

I apologize for the lengthy post. I have been trying to overcome the vibration issue and thanks to my brother-in-law and you kind folks it has been determined the cause is my tires. The current setup, from the previous owner, have a size difference of .5" or more from front to back causing a vibration/shuddering due to the transfer case trying to destroy itself when engaging power to the front. I just wanted to include all the information I used to see if you agree or not with my conclusion.

This is a decision that I have been noodling on for a couple days now. I have given this a lot of thought (probably way more thought than warranted for such a decision) but the last thing I want to do is spend the time, effort and money to replace the tires to solve my problem to only find I have perpetuated it.

Here is my thought process for coming to my decision. I am putting out here for evaluation as affirmation that my decision is sounds or for you to poke holes in my logic and put me on the right path before I make a mistake.

I have decided to go with the following tires:
Lexani
F-245/40/20 overall diameter 27.6"
R-275/35/20 overall diameter 27.7"

You may not like the brand but, they serve my purpose.

I pulled the overall tire diameter information from the company's spec sheet.

As you can see there is there is a diameter difference of .1" from front to back. As I understand it AWD cars can tolerate a size variance of 1% from front to back.

Based on the dimensions of the tires I have selected I have the following math to find if these would be within the range of tolerance.

1% of each tire diameter:
F-245/40/20 overall diameter 27.6" = .276"
R-275/35/20 overall diameter 27.7" = .277"

To keep the conversation simple, let's round the numbers to .3"

The difference in diameter between the tires is .1 (27.7-26.6=.1) which is well within the 1% tolerance or .3" calculated above. My logic says these tires will work.

In my research I did find two sets of tires by Pirelli that had a 0 difference in size front to back. On the surface that would be the easy choice but, the cheapest set of the two was over $600 more than the set I selected. I just don't see $600 for .1". If am wrong, please tell me. Is $600 less that A transmission or Transfer case. Absolutely, but if the selected set of tires will work and not cause any issues (as they are within the 1% variance) then I should be good to go. As I figure, even if the tires are the same size when installed. The front and rear could wear at different rates given driving habits. In theory, they too could at some point have a variance in size from front to back.

Again, I put this out there for your review to confirm my decision or correct me before I have committed myself.

I thank you in advance for your comments and advice.

[lroman3]

I am going to assume that no response to my post #38 above is an indication that I am correct in my thought process. And I have given this way too much thought and that I should pull the trigger. I have purchased the tires mentioned in post #38 and have an appointment to get them installed along with the new TPMS monitors (Mobiltron) this Saturday. I am going for two birds with one stone. I am very hopeful the tires will resolve the vibration issue. I will follow up with the results.

[lroman3]

Got the newt tires installed yesterday. PROBLEM SOLVED! The car drives wonderfully. No shudder, no vibration what so ever. I drove the car around for about an hour. put in every scenario that caused the vibration before the new tires and NOTHING! I am so relieved to have this issue behind me.

Now on to the other items: All fluid changes, plugs, DISA, etc. More threads to follow.

Thanks everyone for input and support on this one!