Side launching from a 40roll WTF

[Properstyle]

So lets talk suspension components that likely need to be replaced. I have 2009 DCT LCI E90M3 that I recently supercharged. The car is on Broadway static coilovers but raised up quite a bit right now. only lowered down to having no gap between the wheels and fenders height wise. Any way I installed the ESS 625kit blower in December and had it tuned by frank smith the car makes 525whp with 341tq. I've been running 19x10 19x11 265/30/295/ Falken 453s when I first started using these the car would dead hook 50 in 2nd gear which was right in the power band. Of course as they became bald they had less grip. I had the car realigned pulled out a bit of camber and was back to nearly stock specs now running -1.9 rear camber with only a touch of toe to maintain tire scrub. I switch to a set of PSS after and it could be by pure timing the car started launching to the left when ever I punched it in the power band. The launch was pretty violent and I felt like if I was on top of the car I would have wrecked. I figured this was just a flook and maybe i was on the crown of the road. But no matter what road or how I hit the gas once power came on the car would kick the rear to the right and launch to the left. Tires don't feel like they are spinning and I'm not leaving any thread. Normal driving showed no change but 2nd gear was not do able with out feeling like I was going to wreck the car.

I figured it might be time to do the subframe and had solid rear mounts installed with 75d AKG diff bushhings put in. The car feels a bit more stable but i am still getting the side launching when punching it from a 50. My car only has 77k on it as a 09. Has anyone had a issue with sloppy grip on the PSS? I wondering if the problem is actually the tires and not the suspension components. Don't get me wrong the car takes off hard enough to keep up for the first 2 gears with a upgraded turbo f80 from a 40 and a 65 but side ways motion really does makes me unconfortable.

the car is now 1inch higher all around from these photos.

[thekurgan]

Let's talk differential. How much "friction modifier" is present in the diff.

[Chojin]

Always have your car aligned after putting on new tires.

[Properstyle]

Originally Posted by thekurgan

Let's talk differential. How much "friction modifier" is present in the diff.

what ever comes in the bottle from the factory bmw diff fluid.

Originally Posted by Chojin

Always have your car aligned after putting on new tires.

going for another alignemnt next week.

[dragonsi]

Does it kick to the right and then to the left every time? Are you trying to correct it when it goes right or are you holding the wheel straight, or is that what you meant by if you were on top of the car?

Have you tried messing with the dampening settings since you raised it? Also maybe double check the preload on the springs. PSSs have a much stiffer sidewall than Falken 453's.

Also, if you are experiencing any consistent wheel hop, be careful, you don't want to blow your diff.

Does it favor one side, at least if you punch it from a roll?

[aira]

My car slides to the left with PSS as well. Haven't had experience with other tires.

I just floored it and you could kinda see it kick out here.

https://www.instagram.com/p/8qnqGZEPsK

[Properstyle]

Originally Posted by dragonsi

Does it kick to the right and then to the left every time? Are you trying to correct it when it goes right or are you holding the wheel straight, or is that what you meant by if you were on top of the car?

Have you tried messing with the dampening settings since you raised it? Also maybe double check the preload on the springs. PSSs have a much stiffer sidewall than Falken 453's.

Also, if you are experiencing any consistent wheel hop, be careful, you don't want to blow your diff.

Does it favor one side, at least if you punch it from a roll?

on the car it actually seems the pss have softer side walls. ( my only test) rocking the car. On the falken 453s the side wall didn't flex, on the pss you can move the car about 1/2 from side wall flex.

The steering will naturally seems to turn to the right as the car kicks out and then the dcs corrects the car but it feels like I have to be on top of it. I'm calm while driving and just let the car spin but it very very unnerving when it happens.

It doesn't wheel hop. I know not to stay in it if that was to happen. If I soften the damping it doesn't seem to be as bad but it always goes to the same side no mater what road i am on.

[W Cole]

My car with the 625 kit and 295 wide PSS wants to swap ends as well. It usually happens while shifting. I figured it was normal for a car of this power level with the stock differential?

[Patrón]

Remember my pm exchange with you, or my question asking what gear you were starting your races in? 3rd at 40 or 50 isn't too bad at all but 2nd at 40 or 50 throws me almost completely sideways with the wheels spinning. I have to try very hard modulating the throttle and wheel to keep it straight. I've determined the only solution is r compound tires ( which I will not do) or upgrade my trailing arm bushing material and subframe bushings. My tires are old but plenty of tread and seem to be in good shape (80%+ tread left) & they are 305/30s on 11in wheels. I'm on Bridgestone Potenza re-11s which have a very good reputation for traction. If I keep my foot floored from a 2nd gear hit and switch to third at redline it will continue to spin the tires up to the 4th change(again, if floored). Like my friend jokes, "first world problems". I really feel the only solution is r888s, pilot cups or similar and I'm not willing to go that route since I drive it every day.

[Longboarder]

Something is wrong and it's not the tires. I have stock zcp suspension with MRF subframe bushings running PSS on stock ZCP wheels. I change alignments occasionally going between street and track use. My car hooks from a roll in any gear including 1st gear @ 570 wheel and goes perfectly straight 100% of the time. Only spins a little when it is very cold in December and January months.

Seems like your suspension/alignment out of adjustment.

[pbonsalb]

I would try no slip modifier in the diff.

[xaappx]

Nice car. Get a front lip and side markers.

[squartus]

Like they said depends on gear, I punch mine at 40mph in 2nd and ill spin my 315,s pretty good falken azenis. Alot will have to do with road and tire temp as well

[81bear]

I'd focus on making sure tires are warm, at a suitable PSI, and a good stretch of road.

[Hujan]

Originally Posted by Longboarder

Something is wrong and it's not the tires. I have stock zcp suspension with MRF subframe bushings running PSS on stock ZCP wheels. I change alignments occasionally going between street and track use. My car hooks from a roll in any gear including 1st gear @ 570 wheel and goes perfectly straight 100% of the time. Only spins a little when it is very cold in December and January months.

Seems like your suspension/alignment out of adjustment.

This would be my guess as well. I'm no expert but I would put my money on toe being out of whack. Toe can really dramatically effect the stability of the rear end, especially on high-horsepower applications.

[Longboarder]

Originally Posted by squartus

Like they said depends on gear, I punch mine at 40mph in 2nd and ill spin my 315,s pretty good falken azenis. Alot will have to do with road and tire temp as well

It is a very common misconception that the wider the tire, the better it will hook up in a straight line.

This is why a Tesla can launch so hard on skinny 195's. Width has nothing to do with it.

The rubber compound and flex of the sidewall are the physics behind it. The wider a tire the better lateral grip it can produce...that's why road racers need as wide of a tire they can get.

I guarantee that with stock 265 PSS, you would straight line hook way better than with your 315 Falkens. Hell, you could hook better using a 225 r888s.

[81bear]

Originally Posted by Longboarder

It is a very common misconception that the wider the tire, the better it will hook up in a straight line.

This is why a Tesla can launch so hard on skinny 195's. Width has nothing to do with it.

The rubber compound and flex of the sidewall are the physics behind it. The wider a tire the better lateral grip it can produce...that's why road racers need as wide of a tire they can get.

I guarantee that with stock 265 PSS, you would straight line hook way better than with your 315 Falkens. Hell, you could hook better using a 225 r888s.

I'm going to need you to elaborate on this concept a bit more. I can understand having too wide of a tire for a specific wheel which can cause a reduction in the contact patch to the road hence reducing the grip potential. But you've lost me with the notion that supported wider tires won't improve forward grip only lateral? As for the the Tesla example I always thought it had to do with their weight and were it was placed? Kinda like the 911 and its rear engine make up providing better traction out of the corners...

Edit: this is assume the tire compounds are similar

[Properstyle]

Originally Posted by Longboarder

It is a very common misconception that the wider the tire, the better it will hook up in a straight line.

This is why a Tesla can launch so hard on skinny 195's. Width has nothing to do with it.

The rubber compound and flex of the sidewall are the physics behind it. The wider a tire the better lateral grip it can produce...that's why road racers need as wide of a tire they can get.

I guarantee that with stock 265 PSS, you would straight line hook way better than with your 315 Falkens. Hell, you could hook better using a 225 r888s.

The tire compound on the pss similar to the Falken 453. That I know to be true even on motor I spun more on 295/30 pss then I didn't on the Falkens at 275/30. I've fliped between both in both sizes on the same wheels. Pss are not all they are cracked up to be. They just last for a long time and have great laterial grip but straight line traction nothing spectacular. If Toyo made the ra1 in a 19 I would run it but they don't. The r888s grips but are loud as hell other wise I would buy them and the nt-01 would have to be a 305 which is to wide for how aggressive my rear tires are. To use

[dparm]

Originally Posted by pbonsalb

I would try no slip modifier in the diff.

I would proceed very carefully with that. If anything, it will make the LSD less predictable since the locking will not be gradual. There is a reason limited slips need FM, and it's not just to reduce noise.

Anyway, you can read on how the LSD works right here:
http://www.gkn.com/driveline/about-u...coLok-engl.pdf

[ekbusdriver]

Longboarder is correct.
Something is amiss in the suspension. Even if bushing is slightly more worn than the opposite side will cause a pull to one side.

[pbonsalb]

Originally Posted by dparm

I would proceed very carefully with that. If anything, it will make the LSD less predictable since the locking will not be gradual. There is a reason limited slips need FM, and it's not just to reduce noise.

Anyway, you can read on how the LSD works right here:
http://www.gkn.com/driveline/about-u...coLok-engl.pdf

Even BMW says try it without and use the FM version or add FM only if needed. I am not suggesting running RL 75W140NS, for example.

[dparm]

Originally Posted by pbonsalb

Even BMW says try it without and use the FM version or add FM only if needed. I am not suggesting running RL 75W140NS, for example.

Even if you buy the non-BMW branded stuff, Castrol Syntrax LS (formerly SAF-XJ), it contains LS additive. The BMW stuff is merely Syntrax LS with even more FM.

I've never seen any literature from them that says you can use a non-FM 75w140 back there, so please tell me where you read that.