[scoale]

Originally Posted by dbworld4k

LSD and adjust your toe.

And lol @ "only" 410 rtq. These cars needed an LSD for traction at stock power levels, let alone almost 500 crank TQ...

This x1000.

Consider F80 M3 struggles to put power down despite LSD, wider tires, solid mounted rear subframe, etc.

[PrematureApex]

Originally Posted by feuer

I think that is what he meant, no? Brakes taking away the power, not engine reducing power. Like when we say extra weight will rub of power when the engine still makes what it makes. Just different wording.

Originally Posted by Fundguy1

Correct. Power to the wheels through brakes being applied is cut.

Open diff = 50/50 torque split, constantly. The amount of torque through the diff, however, is limited by the wheel with the least traction (aka the slipping wheel). With one wheel on ice and one on pavement, it takes very little torque to spin the wheel on ice. That same small amount of torque isn't enough to rotate the one on pavement. So one wheel spins, while the other one sits.

The "ediff" grabs the brake of the slipping wheel, INCREASING the torque that side of the diff is seeing, and because the split is always 50/50, the other wheel (with more traction) also sees a corresponding rise in torque.

Same reason why, before "ediffs" you'd drag your ebrake (or apply pedal pressure) if you had an open-diff'd car and you were stuck in the snow with one wheel free-spinning.

[PrematureApex]

But anyway, OP, they're right. One reason your car always goes right is due to the crown of the road. Slight angle, meaning it will always fall away toward that direction. And the "ediff" and TC simply don't react fast enough.

But maybe more to the point, in any RWD with 370+ whp, if you're ham-fisted on the loud pedal, the back end is going to get moving. A LSD will help, A TON. But you'll still be able to kick the tail out in lower gears.

I think your driving may need adjusting more than anything else.

[whosdady]

I still have not fixed my problem but I believe the thrust angle, stickier tires and the replacement of the trailing arms and bushings will make a big difference for my car.

For the record, my car pulls right under hard acceleration even when I tested it in the wrong lane. For me it has nothing to do with the crown of the road.

[PrematureApex]

Originally Posted by whosdady

I still have not fixed my problem but I believe the thrust angle, stickier tires and the replacement of the trailing arms and bushings will make a big difference for my car.

For the record, my car pulls right under hard acceleration even when I tested it in the wrong lane. For me it has nothing to do with the crown of the road.

I don't know what the guy was talking about regarding your rear thrust angle being off.

Unless I can't read (which is certainly possible) that alignment sheet shows 0 thrust angle after the alignment, with a proper, even amount of toe in on each side.

I will say, my 135 tends to fall right as well. I'm pretty sure that could be attributed to something like the direction of rotation of the drive shaft, and a bit of lash in the diff, leading to one end seeing power a hair sooner, perhaps. Or something subtle along those lines. That's not something I think you're ever going to be able to change, sans intentionally staggering the alignment, etc.

In any case, I'm also putting in whiteline toe link and trailing arm bushings this weekend, albeit for a different reason. I'll post my thoughts after I get through it.

[whosdady]

Originally Posted by PrematureApex

I don't know what the guy was talking about regarding your rear thrust angle being off.

Unless I can't read (which is certainly possible) that alignment sheet shows 0 thrust angle after the alignment, with a proper, even amount of toe in on each side.

I will say, my 135 tends to fall right as well. I'm pretty sure that could be attributed to something like the direction of rotation of the drive shaft, and a bit of lash in the diff, leading to one end seeing power a hair sooner, perhaps. Or something subtle along those lines. That's not something I think you're ever going to be able to change, sans intentionally staggering the alignment, etc.

In any case, I'm also putting in whiteline toe link and trailing arm bushings this weekend, albeit for a different reason. I'll post my thoughts after I get through it.

As long as your thrust angle is zero you should be fine.

I do feel as we lower the car it starts to throw things out of whack as well. Obviously depending on how low you go, one will need a new alignment. I suspect this might play a role for some.

[cvc 22349a]

Originally Posted by feuer

E-diff will kick in after the rear began to step out already. Only remedy would be true LSD.

Not in my experience. If anything, an LSD exacerbates that problem. Solid subframe and diff bushings are the remedy.

[feuer]

Originally Posted by cvc 22349a

Not in my experience. If anything, an LSD exacerbates that problem. Solid subframe and diff bushings are the remedy.

Could be due to either launching on uneven surface, off corner balance after coil overs, some suspension part failure or alignment.
Open diff will spin only one wheel, or at least spin it more, compared with LSD.
So I do not think that LSD would make it worse.

[weehe126]

Figured i'd update this. I believe my problem was my tires. I had NT05s and was having the problem. Switched to RE71r and everything is fine now. The tires grip way better, but when I do roast them there is minimal kickout and essy to control.

[cvc 22349a]

Originally Posted by feuer

Could be due to either launching on uneven surface, off corner balance after coil overs, some suspension part failure or alignment.
Open diff will spin only one wheel, or at least spin it more, compared with LSD.
So I do not think that LSD would make it worse.

The op was talking about the rear end kicking out to the right, car steering left under hard acceleration i.e. dog leg, rear steer. An LSD improves traction thereby exacerbating that problem. That problem is rooted in the disconnect (soft subframe and diff bushings) between the chassis and rear subframe and diff/axles. Eliminate the disconnect and you've got a 335 that tracks straight under hard acceleration. I can't live with all that nvh on a street car so I modulate the throttle and only nail it in 5th or 6th gear.

[feuer]

Originally Posted by cvc 22349a

The op was talking about the rear end kicking out to the right, car steering left under hard acceleration i.e. dog leg, rear steer. An LSD improves traction thereby exacerbating that problem. That problem is rooted in the disconnect (soft subframe and diff bushings) between the chassis and rear subframe and diff/axles. Eliminate the disconnect and you've got a 335 that tracks straight under hard acceleration. I can't live with all that nvh on a street car so I modulate the throttle and only nail it in 5th or 6th gear.

I have installed few VWETISH kits and plates on 135i and 335i with various combination of upgrades and increase NVH is barely noticeable.

[whosdady]

I think I may have solved my issue... I'm not pretending we all have the same problem. I switched out my 9 year old trailing arms (with corresponding bushings) and things feel much tighter.

[justpete]

Originally Posted by whosdady

I think I may have solved my issue... I'm not pretending we all have the same problem. I switched out my 9 year old trailing arms (with corresponding bushings) and things feel much tighter.

Yep, that's a common cause as the trailing links with worn bushings will cause toe-out under hard acceleration leading to stepping out, if not worse. Spherical bearings instead of bushings will take care of it for good without increasing NVH.

[whosdady]

I replaced the trailing arm bushings with powerflex black.