Why is rear end so squirrelly in straight line acceleration?

[MrSmartyPants]

Kinda surprised that nobody has mentioned a good alignment yet. Having all the wheels pointed in the right direction helps quite a bit.

Doesn't add grip or remove the need for driving skill, but the car tends to go straight more often under acceleration, IME.

[Eriksson8642]

Originally Posted by dezzracer

2018 M3 CS. Seems like with all the hi tech performance based electronics loaded into this car (especially the M e-diff) that one would be able to launch this car without the rear moving around side to side so much. With TC turned fully on it's ok because the tires are barely spinning but in MDM mode the rear ends gets so squirrelly side to side. Geez, I can launch my 500 hp 04 Mustang Cobra better and straighter and it has ZERO electronic aids. I don't get it :

It's simple... you need beefier boys in the back

[dezzracer]

Originally Posted by Eriksson8642

It's simple... you need beefier boys in the back

You might be onto something and you said it in one sentence. Admittedly, I was able to fit 315's with 10 inch rims on the rear of my Mustang. I love the stock CS wheels tho. I assume you have to change wheel width to go to a wider tire correct? My other option is to go to Michelin cups but I don't like the sound of small rocks that get stuck to them being kicked up against my car. I've also heard unless you get the cups up to temp they are no better hooking than the super sports. What about the 4S? Is that tire considered to be in the middle of the super sports and the cups twos's?

[Poochie]

Originally Posted by MrSmartyPants

Kinda surprised that nobody has mentioned a good alignment yet. Having all the wheels pointed in the right direction helps quite a bit.

Doesn't add grip or remove the need for driving skill, but the car tends to go straight more often under acceleration, IME.

It has nothing to do with the alignment; the M4 had problems putting down power from the day it rolled off the assembly line. It was a well known issue.

https://f80.bimmerpost.com/forums/sh....php?t=1056851

https://f80.bimmerpost.com/forums/sh....php?t=1003463

BMW's solution in later iterations was to tune it to be more back-loaded and add larger wheels in Competition Package but that all goes out the window once you add back some power or remap the boost.

It's what it is and certainly the reason the next generation M4 will be offered with an AWD option and sadly, eventually without a manual transmission, in an attempt to electronically harness the power output.

[chicagoshark]

Originally Posted by dezzracer

I thought about that. Are you guys with DCT saying your cars rear end does not get sideways when breaking the tires loose when accelerating hard while going straight ? Today I floored it at around 35 mph in MDM mode with all other settings in sport. The tires were lit up. The rear end moved from right to left to right before finally hooking up at around 55 mph or so then went straight.

I'm shocked at how Squirrley the rear end is even with moderate acceleration

[Mr. Hankey]

Put at least 295s on the rear. Until then modulate with your feet. Look at lap times of these cars before and after ZCP came out and there is clearly nothing squirrelly going on. On the '15 and '16s with original software yes, squirrelly, after that almost too tame down low with BMW's re-map...the CS is a well-balanced machine.

[swagon]

I don't know what y'all doing with your right foot. Or you've got greasy roads that you don't know about.

I just got back from a cold winter drive, did a WOT 1st-3rd gear pull in MDM mode and I had no squirrelly ass. Actually amazed at the level of grip. It was wet and zero degrees Celsius outside.

Stock non-ZCP 6MT on snow tires (640M & 255-section Goodyears).

I have seen DCT cars fishtail a bit because the 2nd and 3rd gear shifts are aggressive and if the road and tires are cold, there's gonna be some sideways action. Can be seen here at 1:50.

[Eriksson8642]

Correct, you need wider rims to accommodate wider tires, so you cannot use wider tires on stock rims, and I also love the stock rims on the M3 CS. And that's EXACTLY what I have been thinking, if I ever owned an M3, or any high horsepower car for that matter, I would probably buy some Sport 4S's, as Sport Cup 2's are a step too high IMO.

[onefastdoc]

I would agree with the OP. My M3 Comp seems pretty squirrelly when the rear loses traction in a straight line. It tends to snap sideways. I've driven a lot of high hp rwd cars and some will stay straight when the rear tires start to break traction, and some, like the M3, tend to snap sideways. I tend to think its the e-diff doing that as opposed to what a standard mechanical lsd would do. It's probably the only thing I don't like about the M3.

[Sedan_Clan]

Originally Posted by swagon

I don't know what y'all doing with your right foot. Or you've got greasy roads that you don't know about.

I just got back from a cold winter drive, did a WOT 1st-3rd gear pull in MDM mode and I had no squirrelly ass. Actually amazed at the level of grip. It was wet and zero degrees Celsius outside.

Stock non-ZCP 6MT on snow tires (640M & 255-section Goodyears).

I have seen DCT cars fishtail a bit because the 2nd and 3rd gear shifts are aggressive and if the road and tires are cold, there's gonna be some sideways action. Can be seen here at 1:50.

+1

[BoostinLI]

Originally Posted by dezzracer

2018 M3 CS. Seems like with all the hi tech performance based electronics loaded into this car (especially the M e-diff) that one would be able to launch this car without the rear moving around side to side so much. With TC turned fully on it's ok because the tires are barely spinning but in MDM mode the rear ends gets so squirrelly side to side. Geez, I can launch my 500 hp 04 Mustang Cobra better and straighter and it has ZERO electronic aids. I don't get it :

This car loves to get Squirrelly in the rear, period. Anyone that says otherwise is lying lol. The one thing with the guys that's denying it is, they've become accustomed to it as I've had. You honestly just have to get used to the power and the car's behavior, and obviously avoid smashing it, especially if the roads are a little damp and your tires are still cold. Also, a friend of mine was telling me about GTS coding for the rear diff, maybe something to try out. GL

[dezzracer]

Originally Posted by cesarlcase

This car loves to get Squirrelly in the rear, period. Anyone that says otherwise is lying lol. The one thing with the guys that's denying it is, they've become accustomed to it as I've had. You honestly just have to get used to the power and the car's behavior, and obviously avoid smashing it, especially if the roads are a little damp and your tires are still cold. Also, a friend of mine was telling me about GTS coding for the rear diff, maybe something to try out. GL

I agree. Lots of good advice to minimize and control the power but that's the bottom line. , I just had unrealistic expectations of the electronics stepping in to control. Thanks

[Ropes]

Coding the diff to the GTS and running PS4S goes quite a long way to settle the rear end down.

[dezzracer]

Originally Posted by Ropes

Coding the diff to the GTS and running PS4S goes quite a long way to settle the rear end down.

Thanks. I wonder how much different the GTS code is from the CS tho. Does anyone know if there is a difference. ?

[Sedan_Clan]

Originally Posted by cesarlcase

This car loves to get Squirrelly in the rear, period. Anyone that says otherwise is lying lol. The one thing with the guys that's denying it is, they've become accustomed to it as I've had. You honestly just have to get used to the power and the car's behavior, and obviously avoid smashing it, especially if the roads are a little damp and your tires are still cold. Also, a friend of mine was telling me about GTS coding for the rear diff, maybe something to try out. GL

Sure! We're all liars!

[AO08BAS]

Originally Posted by cesarlcase

This car loves to get Squirrelly in the rear, period. Anyone that says otherwise is lying lol. The one thing with the guys that's denying it is, they've become accustomed to it as I've had. You honestly just have to get used to the power and the car's behavior, and obviously avoid smashing it, especially if the roads are a little damp and your tires are still cold. Also, a friend of mine was telling me about GTS coding for the rear diff, maybe something to try out. GL

As true as the above maybe I think this whole thread shows the flip flop nature of the current sports car buyers market. We have here a 3 page thread about people complaining that an almost 500hp RWD car is a handful to drive.

These same people will be bashing on the G80 for being a 500hp AWD drive for not being a handful to drive....

[dezzracer]

Originally Posted by ZeCP

As true as the above maybe I think this whole thread shows the flip flop nature of the current sports car buyers market. We have here a 3 page thread about people complaining that an almost 500hp RWD car is a handful to drive.

These same people will be bashing on the G80 for being a 500hp AWD drive for not being a handful to drive....

It seems the point of my OP post was lost a bit. I am quite competent driving a high HP car. I realize now after all the reading replies, that my expectations of BMW electronics controlling fishtailing when accelerating hard we're unrealistic. I love the car and it's a blast to drive "dynamically" as BMW calls it. Lol. I'm just surprised I can launch my 500 HP 04 Mustang Cobra with zero electronic aids straighter and in more control that's all. I do appreciate all the advice and replies though. I think my main concern was that maybe me M active diff was perhaps not working as designed. I realize now that it's the nature of the beast. (Pun intended)

[Sedan_Clan]

Originally Posted by ZeCP

As true as the above maybe I think this whole thread shows the flip flop nature of the current sports car buyers market. We have here a 3 page thread about people complaining that an almost 500hp RWD car is a handful to drive.

These same people will be bashing on the G80 for being a 500hp AWD drive for not being a handful to drive....

This is true!

[Ropes]

Originally Posted by dezzracer

Thanks. I wonder how much different the GTS code is from the CS tho. Does anyone know if there is a difference. ?

I started with ZCP and it was typical M3/4 hooligan. The CS felt part hooligan and part serious about hooking up. The GTS feels very serious about hooking up and when the back end does step out; it does it in a much more relaxed manner. I feel the car should have come from the factory with this setting. The car now feels like a proper sports car and not a muscle car with more power than the chassis can handle. With a tune and I can now get to full depression of the gas pedal in second.

[Poochie]

Originally Posted by dezzracer

I'm just surprised I can launch my 500 HP 04 Mustang Cobra with zero electronic aids straighter and in more control that's all.

The Mustang can house 305 rear tires and the M4 only can accommodate 275 max.

This is one of those instances where size matters..

[CanAutM3]

Originally Posted by dezzracer

I agree. Lots of good advice to minimize and control the power but that's the bottom line. , I just had unrealistic expectations of the electronics stepping in to control. Thanks

Actualy you did not. With full DSC, the electronics do a fine job of keeping the rear end in check

[CanAutM3]

Originally Posted by Poochie

The Mustang can house 305 rear tires and the M4 only can accommodate 275 max.

This is one of those instances where size matters..

Say what ??

I comfortably fit 305 rear tires on my M4 with room to spare, as do many other owners. Some managed to fit even wider tires.