Winter driving X6M

[SCar24]

Hi,

This is my first winter with my X6M and I have a question regarding driving the X6M/X5M during snow and ice conditions.

The thing is that when braking at slow speeds on slippery surfaces, it feels like the car still wants to push me forward somewhat before it will stop.
I know there is a force distribution difference front and rear, but it seems to me that the front wheels will lock, while the rear wheels are still wanting to drive forwards.

The tires are not brand new, but fairly good, so I don't think this is the issue.

Anyone else noticed this? Is it normal, am I imagining it or could there be something off in my brakes?

Cheers

PS: This isn't my first winter, just the first with the X6M

[jab23]

What are the tires? All season? Summer only? In extremely cold weather, the latter can be a little wonky. I just put my dedicated winters on yesterday as the temps will be below freezing most nights for a few months.

[SCar24]

Originally Posted by jab23

What are the tires? All season? Summer only? In extremely cold weather, the latter can be a little wonky. I just put my dedicated winters on yesterday as the temps will be below freezing most nights for a few months.

I have dedicated winter tires for Nordic conditions, so the tires should be good. They are stud-less tires, but still should be good on snow and ice. Within reason of course.

A thing that can affect the tires is if the rubber has "gone" off, then they become very hard the colder it gets, but these are no so old that that should be an issue. It's about 14 degrees here at the moment.

It's just that it feels like there is something "pushing" when I depress the pedal to stop, so the vehicle has a tendency want to slide a bit further than I would expect.
My theory was that it might be that the rear brakes are not engaging enough, so they are actually still being spun by the engine, whereas the front wheels are held by the brakes and lock??

I have other vehicles without this issue.

[jcm3]

I have driven the last 6 years w various x5m ive owned. The one thing that has helped me is i run a narrow tire width typically a square 275mm width (running tire through the winter season and not the staggered setup.

[pachieh]

OEM brake pads? Could be a lack of bite due to them cooling off in the winter super fast. Could also be your tires not having as much grip as they age too…

Your brakes shouldn’t be locking at all. That is what ABS for.

The tires shouldn’t be getting rock hard when it’s cold as snow tire rubber is designed to be softer at colder temps. Kinda why summer performance tires are super hard around 30 degrees, the rubber compound isn’t designed to stay soft when cold.

[SCar24]

Originally Posted by pachieh

OEM brake pads? Could be a lack of bite due to them cooling off in the winter super fast. Could also be your tires not having as much grip as they age too…

Your brakes shouldn’t be locking at all. That is what ABS for.

The tires shouldn’t be getting rock hard when it’s cold as snow tire rubber is designed to be softer at colder temps. Kinda why summer performance tires are super hard around 30 degrees, the rubber compound isn’t designed to stay soft when cold.

Yes, OEM brake pads.

The speed I am talking about is just before I come to a stop, so the front wheels will at some point lock so the vehicle can stop and stand still.
During this transition it seems to me that something is still pushing the vehicle instead if it coming to a complete stop fairly quick, and during this it seems to skid slightly forward.

Yes I am aware of the logic behind winter tires, but as I theorized in an earlier post there are conditions where the rubber hardens and makes the tires fairly useless on ice. Age is one factor, how they have been stored is another, but I don't thing this has happened to mine though as they are ok when driving on snow an ice covered roads.

Just had an idea now.. If I flip the car into Neutral just before I press the brake pedal the car will essentially be coasting without any input from the transmission on the rear wheels, if it still doesn't stop as expected then it must be bad tires?

[SCar24]

Originally Posted by jcm3

I have driven the last 6 years w various x5m ive owned. The one thing that has helped me is i run a narrow tire width typically a square 275mm width (running tire through the winter season and not the staggered setup.

I actually have a squared setup already, albeit 295mm.

[pachieh]

Maybe on the neutral thing. What is the manufacturer and model of the tires?

[jcm3]

Originally Posted by SCar24

I actually have a squared setup already, albeit 295mm.

Little wide but still acceptible...you driving in what transmission setting?

[SCar24]

Originally Posted by pachieh

Maybe on the neutral thing. What is the manufacturer and model of the tires?

The tires I have are Nokian Hakkapeliitta, which are a Finnish high end tire.
Transmission settings D1 and everything in comfort.

Have done some more testing now, and I am pretty sure it is not the tires, but actually the rear wheels that are still pushing the vehicle.

At present my driveway is complete covered in wet ice as the temperature has risen a bit here. I tried to drive the vehicle slowly forward and then gently pushed the brakes, which resulted in the beforementioned behaviour, front wheels lock and vehicle slides a foot or two before stopping.

Repeated the same procedure, but this time I flipped it into neutral before I pushed the brakes, approximately same force as before, and the vehicle cam to a stop without sliding. Again, these are very low speeds I am talking about.

So my conclusion is that by pushing the brake pedal gently with the vehicle in D allows the rear wheels to keep applying power and wanting to go forward while the front wheels lock, and by that pushing the vehicle slightly before the rears engage enough to stop.

The is very annoying behaviour and if miscalculated can actually result in me hitting objects or other vehicles when this happens.

[pachieh]

I’m at a loss then. The majority of your braking power is in the fronts too…

When was the last time you did a rear diff fluid change and/or transfer case fluid change and t-case calibration? It’s about the only other random things in the driveline I can think of.

[SCar24]

Originally Posted by pachieh

I’m at a loss then. The majority of your braking power is in the fronts too…

When was the last time you did a rear diff fluid change and/or transfer case fluid change and t-case calibration? It’s about the only other random things in the driveline I can think of.

Haven't done it during my ownership, haven't had it very long, but it's on my todo list.

[///d]

Does it feel like your engine speed is high while stopped?

Do you know if any previous owners did any transmission work or tuning?

I've seen vehicles with improperly proportioned brakes do this. The rear isn't getting enough brake applied resulting in the torque from the engine wanting to push forward. It becomes more apparent if the rear tires are on ice and the fronts are on a dry surface, when holding the brake at a normal pressure the rear tires will still spin on the ice. This is usually on older vehicles tho. Could try a brake system flush, maybe your fluid is old or dirty and it's causing pressure loss at the rear. Or maybe your rear calipers need a cleaning.