Suspension / Transmission / Wheel problem

[JensM]

Help needed
I got a 2012 MSport 30D with 70.000 km.
Wheels is 255/50/19 & 285/45/19 org 223 wheels
App 1000 km ago I had to have the car through german TÜV inspection. It passed but there were a stabilization bar in the front suspension (left) there needed to be changed. It's a small bar app 25-30 cm long and with bearings in both end. Went to BMW Flensburg (Germany) and they changed.

At the same time I got two new rear tires as they were worn down in the middle (I have not been good enough to check air pressure).
The Service guy asked into the front tires - if too low tread he recommended to change due to the x-drive. I said they were about 5-6 mm and he replied this were okay then.
After coming come, I checked the front tires and they were only 4mm and the new rear is 8mm. I actually decided I better change the front tires as well, but due to busy on work etc, this will not happen before coming Friday - and then the car have done 2000km.
In th mean time I start to have the following issues with the car, and I'm not sure if it is related to the difference (too much) in rolling diameter.
1) Both front and rear wheels are actually out of balance with speed between 80 and 120km/h.
When reducing speed to stop, I actually feel the vibrations all the way down. I can feel it in the steering wheel and through the front seat.
2) When breaking, I suddenly have a feeling that the brakes are vibrating - discs out of balance? - or can it be the wheels out of balance?
3) Most concerning. When reducing speed to full stop, the last 2-3 meters I think I can feel vibrations through the transmission (to the four wheel drive) - not really sure

Questions:
I'm going to BMW the coming Friday but would like to hear experience in this forum first.
A) Can above all be related to wheels (front and rear) being out of balance?
B) Can the breaks discs suddenly be out of balance (no heavy breaking)?
C) The difference in tread in front & rear tires (4/8mm) - are we out of recommended maximum? And if yes, what will the symptoms be?

Sorry for the long text, but I hope someone can advise here prior to the BMW visit

Thanks a lot and thanks for being part of this great forum

Jens

[heatmizr]

Hi Jens
First off I would not think the different tires have anything to do with these symptoms.
Out of balance wheels would likely not be very obvious at the lower speeds, especially almost at a stop.

Brake rotors don't usually get out of balance - more likely they may develop a slight warp with the symptoms you describe gradually as they get near the end of their lifespan. (Or with track use, can develop "hot spots" where the brake pad may stick more in one spot, but you didn't mention hard or track use).
The "pulsing" you describe could indicate the rotors are near due for replacement.

However the short "stabilization bar in the front suspension" you mentioned is also interesting... I am not sure what bar you are referring to. However if it was installed and they left some "play" or looseness in the steering, you may be getting an issue where the front tires are not being held firmly in place and pointed correctly while driving and especially braking.

Since you say the symptoms have come on suddenly after this stabilization bar was replaced, that is the first place I would look.
Hope this helps - and pls post your outcome here so we all can learn from it. Also I want to know if I was right ;-)
- Todd

[Weebl]

See if they tightened your lug nuts. If the whole car is shuddering something is up but how do you know both F/R are out of balance? Especially the rear since they are new.
The brakes shouldn't start up right away like that, you would have felt it before

[JensM]

Originally Posted by heatmizr

Hi Jens
First off I would not think the different tires have anything to do with these symptoms.
Out of balance wheels would likely not be very obvious at the lower speeds, especially almost at a stop.

Brake rotors don't usually get out of balance - more likely they may develop a slight warp with the symptoms you describe gradually as they get near the end of their lifespan. (Or with track use, can develop "hot spots" where the brake pad may stick more in one spot, but you didn't mention hard or track use).
The "pulsing" you describe could indicate the rotors are near due for replacement.

However the short "stabilization bar in the front suspension" you mentioned is also interesting... I am not sure what bar you are referring to. However if it was installed and they left some "play" or looseness in the steering, you may be getting an issue where the front tires are not being held firmly in place and pointed correctly while driving and especially braking.

Since you say the symptoms have come on suddenly after this stabilization bar was replaced, that is the first place I would look.
Hope this helps - and pls post your outcome here so we all can learn from it. Also I want to know if I was right ;-)
- Todd

Hi Heatmizr
Unfortunately the visit to the garage has been postponed due to longer lead time on the front tires.

Brake rotors: Never done any tracks and no heavy breaking. The service indicator say changes in 60.000 km, so should not be near end of life time.

I have read somewhere some years ago, that if front tires is out of balance you can feel in the steering wheel. Rear tires you can feel through the seat. Hope it disappears after they change the from tires and re-do the balance of rear tires.

I'm actually also thinking off the stabilization bar (this is what they named it). It actually feels like they are not pointing 100% in same direction.
Will ask them to double check

Thanks a lot for the advise
Jens

[JensM]

Originally Posted by Weebl

See if they tightened your lug nuts. If the whole car is shuddering something is up but how do you know both F/R are out of balance? Especially the rear since they are new.
The brakes shouldn't start up right away like that, you would have felt it before

Hi Weebl,
They actually left a large sticker asking be to check this after 75 km - I did this and all were tight.
Well, there are two things
1) Rear wheels are defiantly out of balance - can feel it through the seat at certain speed.
2) The car feels like it is shuddering when breaking down to stop (slow break down). When I leave in gear and just let it run down the speed, there is actually nothing. Since service indicator say 60.000 km before replacing breaks, I hope this is down to the balance of the wheels, alternative a rotor suddenly off balance - if gearbox issue I assume it will be there when letting the car reduce speed without using the brakes. Going there Wednesday and will update

Thanks a lot
Jens

[JensM]

Update.
Went to BMW and the tire shop (owned by BMW).
Two new front tires - 255/50x19
And rear wheels re-balanced once again - he had to move weights compared to the first time he did when they changed to new tires two weeks ago (285/45x19).
New tires are Conti SportContact 5 SUV SSR (run flat). Wheels seems now in balance, and the vibrations when breaking down is gone.

But, we discussed air pressure - they only added what is specified by BMW (label in door pillow). I have however read several places than when running wide low profile tires (50 and below), you need to increase pressure to +2,8/3,0 bar in these sizes. They said they have newer heard about this! I challenged them on too low pressure as the rear tire tread is not touching the ground in full width! Actually it is app 3,5 cm from both outer side and inner side of tire, so around 7cm of the width is not in contact. Please see pic. After adding more air, this is however not changing. What is causing this??? Thanks in advance