[dsramme2]

Hi,

Wondering if anyone else have been tracking xdrive car and are having/had problems with understeer?

my current setup is camber plates with about 2,1 degrees front and have set about 1,1 degrees in the back camber. Have 18x8 rims with et 35 all around, right now with standard tire sizes (F225 R245) using kumho v70a. rest is stock.

The problem is that I experience the car as more prone to understeer then it was with stock wheel setup. The camber plates gives a lot better turn in just when you flick the wheel, but then it’s like all the weight just pushes it forward instead of sideways. More throttle = more forward. If I turn the traction control completely of it actually feels more fwd?! which is strange for during the winter in the snow this is a very rwd biased car. Have tried different approaches, more/less entry speed, but as soon as I go on the throttle it just goes straight, cant get the rear to break out.

Know that the obvious first step is to go for square tyre setup. But should I maybe change the wheel alignment a bit, more/less camber in the back for instance? to get a bit more neutral/rwd feeling in the car

Any thoughts?

[2016F22xD]

What's your tire pressure? I am running all stock setup (225 and 245 MPSS), no camber plates, about 40 psi cold front and rear that does the trick for me.

[xantdieselx]

Xdrive will understeer more that RWD mostly because there is more weight up front. You can play around with camber and pressure to get a little better turn in but you may just have to adjust your driving style a little.

I find two things help. The first is late braking. Some people will stay on the brake as the turn in but that just moves the contact patch toward the sidewall. Brake hard only when the wheel is straight just before turning in.

Second, is making sure you are rolling into the gas as you are unwinding the wheel. Stomping on the gas mid corner with any amount of wheel in it does the same thing - it shifts the contact patch of the tire toward the sidewall.

If you get it right in our cars you get a lovely little neutral four wheel drift. Get it wrong and you will swing wide.

I am by no means a professional or hot shoe and you may already know these things I mentioned but it's worth repeating. I learned this at BMW Performance Driving center and from a couple of BMW driving instructors.

[pikcachu]

also the staggered setup won't help either....

[rich8566]

Originally Posted by dsramme2

Hi,

Wondering if anyone else have been tracking xdrive car and are having/had problems with understeer?

my current setup is camber plates with about 2,1 degrees front and have set about 1,1 degrees in the back camber. Have 18x8 rims with et 35 all around, right now with standard tire sizes (F225 R245) using kumho v70a. rest is stock.

The problem is that I experience the car as more prone to understeer then it was with stock wheel setup. The camber plates gives a lot better turn in just when you flick the wheel, but then it’s like all the weight just pushes it forward instead of sideways. More throttle = more forward. If I turn the traction control completely of it actually feels more fwd?! which is strange for during the winter in the snow this is a very rwd biased car. Have tried different approaches, more/less entry speed, but as soon as I go on the throttle it just goes straight, cant get the rear to break out.

Know that the obvious first step is to go for square tyre setup. But should I maybe change the wheel alignment a bit, more/less camber in the back for instance? to get a bit more neutral/rwd feeling in the car

Any thoughts?

Change the tire pressures and run 2-4 pounds more pressure in the front. This will take some understeer away. Also go to a square tire and wheel setup. That will also help reduce understeer.

[bryan_G01]

yes. live with it, nothing you can do.

For those tracking with mpss, get a real set of tires with a stiff sidewall and stay under 38 psi hot.

[Anthony235]

I thought xdrive was already square?

[dsramme2]

Thanks for input!

Try to stay around 2,2-2,6 bar hot which should be around 33-38 psi.

Yeah the weigh up front t is definitely noticeable, followed a M135 around the track a couple of weeks ago and when it came to turn in I could not follow his pace/trajectory. Okok, that little four-wheel drift is sort of what I’m missing now, with the run flats (for better and worse) it was a lot easier to do, thanks for the tips.

Staggered will be square as soon as the front are worn out
Will see if its accept or change car after that.

Xdrive’s don’t come with square setup in Europe, maybe it’s different in the US?

[bryan_G01]

Originally Posted by dsramme2

Thanks for input!

Try to stay around 2,2-2,6 bar hot which should be around 33-38 psi.

Yeah the weigh up front t is definitely noticeable, followed a M135 around the track a couple of weeks ago and when it came to turn in I could not follow his pace/trajectory. Okok, that little four-wheel drift is sort of what I’m missing now, with the run flats (for better and worse) it was a lot easier to do, thanks for the tips.

Staggered will be square as soon as the front are worn out
Will see if its accept or change car after that.

Xdrive’s don’t come with square setup in Europe, maybe it’s different in the US?

I took out a race prepped 1m, he couldn't catch me or get around me. He looked really nice in the rear view mirror tho!

was the car

[crabu2]

Originally Posted by Anthony235

I thought xdrive was already square?

I've got a 230 with xDrive and it's staggered w/mpss from the factory.. I do have the THP though.

[FlyinHawaiian]

My wife is the primary AXer of her M235ix, though I have run it a couple times. I dont so much notice the understeer you refer to, though I do note that it chews outside tire edges due to the lack of camber. She runs a staggered set-up on her street tire (MPSS), but the track wheel/tire set-up is square and that might make some difference. I dont mean to question your driving skills, but the wrong line can lead to plowing understeer in many cases, especially going into a turn too fast or getting on the gas too early on exit (when you have not yet unwound the wheel). Check those things before making a bunch of changes to the car.

[Maynard]

I would have said that what you are describing is typical for AWD, but I am fairly new to driving one. The way I understand it, with AWD the fronts have both lateral (cornering) and directional loads (braking/accel), just like the rears, so four wheel drift is the default, and very hard to break out the rear. With RWD you can overload the rears by accelerating, to get oversteer; with AWD accel is balanced out, and the main imbalance is when braking overloads the fronts, giving push. To me it is a noticeably different dynamic vs. FWD or RWD, but one that I am really liking a lot (for sporting road driving, have not tracked it yet). Some say a square setup will increase oversteer, but I'm skeptical unless you are really at the limits and overheating the rear tires.

[Anthony235]

Originally Posted by Maynard

I would have said that what you are describing is typical for AWD, but I am fairly new to driving one. The way I understand it, with AWD the fronts have both lateral (cornering) and directional loads (braking/accel), just like the rears, so four wheel drift is the default, and very hard to break out the rear. With RWD you can overload the rears by accelerating, to get oversteer; with AWD accel is balanced out, and the main imbalance is when braking overloads the fronts, giving push. To me it is a noticeably different dynamic vs. FWD or RWD, but one that I am really liking a lot (for sporting road driving, have not tracked it yet). Some say a square setup will increase oversteer, but I'm skeptical unless you are really at the limits and overheating the rear tires.

It's more accurate to say that a square setup gives more grip in up front. It does not "increase" oversteer. Oversteer is just what's left over. This setup gives more overall grip.

Now if you were to to decrease the rear width of the tire to match the narrow front tire I would say you are increasing oversteer. This setup would decrease overall grip.

Semantics but that's how I like to describe a square setup.