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Finally guys….. I have discovered the last thing that was causing a vibration on my S90 .
It was the front driver side axle bolt. It was loose somehow :angryfire::angryfire::angryfire:. Just another quality mess from Volvo. No tech or Technical Journal advised to check that. So happy that my mind told me to check it.
Background: In 2019, I discovered a play on the front passenger axle shaft. The bolt of the axle was loose also in that discovery. The inner boot was already damaged at 27K miles!! The dealer replaced the whole axle under warranty.
There are three assumption why these two bolts were loose:
1- The factory forgot to tighten the axle bolt
2- The bolt is very low in quality considering it’s 8.8 grade bolt not 10.9 grade. 8.8 grade bolt and the torque spec weren’t enough to hold that bolt tight for a long period (probably in the first 10k miles the bolt was loose already).
3- The axle shaft inner/outer boots are starting to wear out, thus, causing more play in the axle and loosen the bolt
My opinion: I would go with assumption 1 or 2 but not assumption 3 since these shafts should last more than 100k miles easily. Forgetting to tighten that bolt from the factory will not doubt damage the Axles after a period of time and this explains why I had my Drive axle replaced at 27K miles. BTW, I check the rear axle bolts and they were pretty tight compared with the front axle bolts.
For now: After replacing the axle bolt and tighten it, the car vibration is much less and I find it really acceptable. To be honest, the car is not yet buttery smooth at low speeds but, at the same time, it’s not bothering me as before replacing the axle bolt. I think uneven roads and AWD both are contributing to the left vibration at low speeds. I will need to drive the car more to evaluate things.
However, now, I find the car to be really smooth and buttery at high speeds compared with before. I didn’t imagine one bolt was the cause for such drivetrain/cabin vibration.
Anyway, I will continue raising that differential misalignment issue to Volvo to open an investigation.
Here is a summary for my journey with this vibration issue and I think all of these things helped a little (the car is less than 32k miles) – start with 1, 4, and 7 on your own.. if the vibration was still there check the other items with your dealer:
1- Fixed Bent Wheels
2- Volvo Warranty claim to replace front passenger drive axle because of excessive play
3- Volvo Recall for the propeller shaft CV joint
4- Replaced the tires 255/35/20 on my expense
4- Volvo Warranty claim to replace propller shaft due to worn bearing rubber
5- Volvo Warranty claim to replace top right engine mount (torque rod) due to crack
6- Volvo Warranty claim to replace top left engine mount (torque rod) due to weak rubber
7- Replaced loose front driver axle bolt with a higher quality bolt. I also checked the other three axle bolt for tightness. (This one made a big difference)
8- I’m happy and enjoying my S90 [emoji144]…
Here is a video for the discovery of the loose axle bolt and a DIY for replacing it. Enjoy it guys….
Ensure to use thread locker and tight the new bolt. You better use Volvo OEM bolt but It has to be new. Here is Volvo torque: spec for the front Axle bolt: 35 nm (26 ft/lbs)+ 90 degree….. Torque the bolt while the wheel is lifted off the ground.
Here is a video for my discovery of the defective front passenger axle back in 2019.