BMW traction

[aliusa]

Why does BMWs have traction issues especially with higher HP/torque models like ///M?

Is that a design flaw? Weight distribution issue? P cars and Ferrari's are also rear wheel drive with lots of power but they launch pretty well with minimal wheel spin even without launch control. With M5 the wheel spin at lunch (without launch control) is embarrassing IMO...can't race any competitor unless it's a rolling drag - thoughts?

[Ickdeep]

I'm pretty sure physics has a part to do with it. Its just soo much mass that is trying to move from nothing that its causing it to slip. I gave up on doing digs with other cars and even with rolling I dont go below 40 mph.

[Noggie]

Weight is one thing. Tires is another.
If you have a non-high performance tire, or a lower grade performance tire, you will struggle.
I had severe grip issues on the half worn set of Michelin Supersports that was on my M5 Competition 575, when I bought it last year, lots of wheel spinn, losing traction at 50-60mph etc.
Put new Michelin PS4s on it (stock dimensions) and those grip like nothing I have ever seen.....

Ferraris and high end cars are probably running VERY high end Pirelli's such as the P Zero Corsa or Michelins Ps4s, possibly even semi-slicks like the Michelin Cup 2R tires or Pirelli Trofeo R. Meaning they have the grippiest rubber on the market.

So if you have saved some money on a cheaper tire, that is probably why you have grip issues. You can also mess it up with things like wheel geometry (camber) due to lowering giving less grip surface, wider tires is not the same as more grip, incorrect tire pressure or even a too stiff suspension setup will affect grip negatively.

I you have a car with a lowered, stiff suspension kit, 21" wheels and 305-315 tires of a "regular type" with incorrect pressure and rear wheel camber due to lowering or to fit said wheels and tires.
You will have significantly less traction than a stock M5.

[NYM5]

Torque?

[AlisterB]

I agree that traction at low speeds is a real problem in the F10 M5.

Most people recommend fitting Michelin PS4S tyres to address this (which I'm yet to do - still have plenty of life in my current tyres (P Zeros)).

IMO the engine/gearbox tune doesn't help this situation either. The way the car delivers its power relative to throttle position is a bit all or nothing (not linear/progressive) which can make it difficult to avoid inducing wheelspin in normal urban driving situations (eg pulling out of side streets).

I'd be interested to hear what if anything others have done to try to address this.

[aliusa]

Originally Posted by Noggie

Weight is one thing. Tires is another.
If you have a non-high performance tire, or a lower grade performance tire, you will struggle.
I had severe grip issues on the half worn set of Michelin Supersports that was on my M5 Competition 575, when I bought it last year, lots of wheel spinn, losing traction at 50-60mph etc.
Put new Michelin PS4s on it (stock dimensions) and those grip like nothing I have ever seen.....

Ferraris and high end cars are probably running VERY high end Pirelli's such as the P Zero Corsa or Michelins Ps4s, possibly even semi-slicks like the Michelin Cup 2R tires or Pirelli Trofeo R. Meaning they have the grippiest rubber on the market.

So if you have saved some money on a cheaper tire, that is probably why you have grip issues. You can also mess it up with things like wheel geometry (camber) due to lowering giving less grip surface, wider tires is not the same as more grip, incorrect tire pressure or even a too stiff suspension setup will affect grip negatively.

I you have a car with a lowered, stiff suspension kit, 21" wheels and 305-315 tires of a "regular type" with incorrect pressure and rear wheel camber due to lowering or to fit said wheels and tires.
You will have significantly less traction than a stock M5.

My car is all stock with the exception of BPM Stage 1 tune. And I have the Michelin Pilot Super Sports with plenty of tread remaining. Even before the tune traction was an issue.

But when I drive my friends Porsche or Ferrari and floor it I feel the power comes linear to avoid slippage yet it's still enough power to beat the M.

On a positive/fun side, did some pulls against my friend's F430 Scuderia from 60mph rolling and beat him each time. If the car wasn't tuned then I'm pretty sure he had it.

[schrickm5]

Pretty sure all the low end torque is the problem with traction, most fast cars nowadays have 4wd or a more linear build up to torque, not a lrge portion available under 2000rpm.
If I had a tune - I would definitely be Torque limiting in gears 1 - 3 to some extent.

[technician117]

This is where the manual transmission shines. Sure I have traction issues, but nothing like you guys complain about. The transmission gear ratios are only a little different but that probably factors in as well.
I run PS4S tires, and a heavy take off from a start will leave light black marks on the road, but you can barely tell it's spinning. We're not talking about blowing the tires off. It will generally break traction higher in the revs in 1st gear when going WOT, at which point a quick shift into 2nd and lay back into the boost for a neck snapping acceleration.

Chassis design, suspension design, tires, driver inputs, all play a big part in "traction". If it's a big concern, wait a couple mmore years for F90 prices to come down and then buy one of those AWD monsters!

[vafan13]

Why are we comparing an M5 to 2-door mid-rear/rear-rear sports cars weighing ~800lbs less?

A rwd 911 S has a peak of ~400 torque to put down through 305s to push a measly 3400 pound car. That 911 also has a *much* shorter wheelbase, so in addition to (I'm assuming) better starting weight distribution, it will also transfer a greater percentage of its weight to the rear wheels when launching.

And of course, as others have mentioned, the huge torque starting so low makes it trickier to launch. Personally, I wish they had toned down the gear ratio in 1st and just a smidge in 2nd.

[Noggie]

Originally Posted by aliusa

My car is all stock with the exception of BPM Stage 1 tune. And I have the Michelin Pilot Super Sports with plenty of tread remaining. Even before the tune traction was an issue.

But when I drive my friends Porsche or Ferrari and floor it I feel the power comes linear to avoid slippage yet it's still enough power to beat the M.

On a positive/fun side, did some pulls against my friend's F430 Scuderia from 60mph rolling and beat him each time. If the car wasn't tuned then I'm pretty sure he had it.

My car is currently Stock 575hp, but I plan to get a tune within a month, probably an ESS tune for 650-670hp, and I will probably go with low end torque reduction.
That might change things a bit, I just know my old tires and new tires are a world apart when it comes to grip.