Floaty M4 post mods..

[DallasLife345M]

I have an interesting dilemma. I just recently got my M4 ZCP back after adding KW HAS, Dinan strut ball, PS4's (295/30/20 and 265/30/20), and spacers (2mm rear, 10mm front). My car seems more floaty and less connected now. I did similar mods on my 15' M4 and 18' M3 CS and both felt more rigid (harsh) and connected to the road post mods. The only difference is on my other two M's I didn't use PS4's, I had some track tires on my 15' M4, and standard PSS's on my CS. Any ideas? I don't think it's the Dinan strut ball. I really think it's the tires.

[BlackF82]

I am interested to know about this as well. I had the 19's on my M4 and went to the 20's (666m), the car seemed to have gotten more "floatier". Then, I had KW HAS installed with 12mm spacers all around, the car got even more "floatier". Its not as bad when I put it in sport+ but enough to notice it really quick. I thought I was making shit up but seems like we have a similar issue. All tires were/are MPSS.

[evoix]

I had the same problem. Car felt unstable at higher speeds and around corners. I took my spacers off and got an alignment. Car felt so much better.

[WestBankM4]

Alignment is absolutely key here. I installed MP-HAS and spacers on my M4 CS and let me tell you, I was regretting the purchase. It was way worse than OEM specs, after two weeks seat in period, I took it to BMW for an alignment.

Now it's way better than OEM in terms of flex, turn-in, and stance. The alignment was the key.

[jpy1980]

Probably alignment, but have you checked your tire pressures?

[PsychCA]

I second the above statements: alignment is the key to your mods.

[Reddevils7]

you should always get an alignment if you change the ride heights

[DallasLife345M]

I'll get an alignment and see if that resolves the issue. I don't think it's the spacers, had them on my previous M3/4 and didn't cause this issue. However, I still think it's the tires, I'm at 32-33 PSI now, will bump to 35 PSI today and see what that helps any.

[VChenz]

Make sure you get the before and after alignment report.

[BlackF82]

I had an alignment done right away and balanced all 4 wheels.

I think I'll upgrade to coilovers in the future, I love stiff rides.

[Billy_BMW]

Alignment won’t fix vertical instability, which is usually down to the dampers and/or softer tyres. The PS4S is a softer construction than the PSS and other track tyres, which can upset, ‘soften’, the steering feel and overall stability. Have a look at the threads in the tyre forum.

[DallasLife345M]

Originally Posted by Billy_BMW

Alignment won’t fix vertical instability, which is usually down to the dampers and/or softer tyres. The PS4S is a softer construction than the PSS and other track tyres, which can upset, ‘soften’, the steering feel and overall stability. Have a look at the threads in the tyre forum.

I think you are spot on. I'm gonna look into getting different tires and selling these. Anyone want to buy them? Less than 100 miles!

[JamesGames]

Originally Posted by DallasLife345M

I think you are spot on. I'm gonna look into getting different tires and selling these. Anyone want to buy them? Less than 100 miles!

Your issue isn't the tires. It's the dampers paired with the HAS. I personally ran springs / stock shocks and ripped them out within the next 1000 miles for coilovers. While some may feel they are acceptable , everyone is different and preferences are different. But the tires are not going to fix your issue.. The stock dampers are made for the stock height / springs and are not ideal IMO. Certainly acceptable but coilovers fixed that issue for me. I guarantee changing tires aren't going to do much, PS4S tires are great tires for the street.

I've ran RE71R / PSS / PS4S / Hankook Ventus on the F8X if that helps.. PS4S were my favorite out of all of the tires for the street.

[swagon]

With less than 100 miles, the tires are barely broken in. They're still basically brand new.

Get the alignment, check your tire pressures, take off the spacers and report back. I would say the KW HAS are the culprit though, there have been numerous people dissatisfied with them. Don't modify for the sake of modifying - especially powertrain and suspension...

You previously had a CS - if you liked its handling and ride comfort, it is not difficult to replicate that. Some CS owners on here run M Performance HAS with good success, too.

[DallasLife345M]

I disagree the culprit is the KW HAS or spacers. I installed KW HAS and spacers on my 15' M4 and 18' M3 CS and it was actually more stiff (harsh almost) and both cars handled and cornered better. However on the CS I kept the stock PSS and on the 15' M4 I ran RE-71's. The closest thing I can compare it to is once on my 08' 335i I swapped my run flats for non-run flats and that car turned into a floating boat, immediately turned around and got run flats re-installed. In addition to feeling floaty it also feels heavier - not sure how to explain it, I did go up in rear's from 285 to 295, it's an inch wider in the rear. I went up to 35 psi on all 4 tires for a test, not any better.

[65fastback]

Like you...I am running a set of Ps4s 265/30/20 & 295/30/20 on 666 rims. have had oem mpss on the car as well as MPSS all season's alpina. i luv Ps4s my fave street tire.

Iam lowered on eibach springs and 12mm front 10mm rear spacers.

My personal experience is at higher speeds i get ZERO float the car gets even more glued and connected ...i have a real hard time believing the Ps4s are causing the floaty feel your experiencing.
You prolly know this but...A 295 ps4s does give a bit quieter ride & more sidewall than a 285 mpss so maybe your feeling that?

Ive also heard people think their car goes faster after putting a K&N sticker on and oil change the mind is a powerful thing!

[BlackF82]

Originally Posted by DallasLife345M

Here is my troubleshooting plan.. Next week I am switching back to OEM PSS Star Spec tires and getting an alignment, then will test. If that doesn't improve anything I will remove the spacers and test again. If that fails to resolve the issue I plan to order coil overs and replace the KW HAS. I really think it's the tires. I will report back next week..

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[fiveohwblow]

Originally Posted by DallasLife345M

I disagree the culprit is the KW HAS or spacers. I installed KW HAS and spacers on my 15' M4 and 18' M3 CS and it was actually more stiff (harsh almost) and both cars handled and cornered better. However on the CS I kept the stock PSS and on the 15' M4 I ran RE-71's. The closest thing I can compare it to is once on my 08' 335i I swapped my run flats for non-run flats and that car turned into a floating boat, immediately turned around and got run flats re-installed. In addition to feeling floaty it also feels heavier - not sure how to explain it, I did go up in rear's from 285 to 295, it's an inch wider in the rear. I went up to 35 psi on all 4 tires for a test, not any better.

Completely agree. I just installed kw HAS on my 15 Friday evening. Finally got a chance to drive it today and my lord is it planted. Firm. I haven’t had the chance to get an alignment yet but will do so soon.

I am running re71r’s for point of reference.

Also, I have asked and no one comments which makes me scratch my head. I keep hearing the dampening of the factory shocks is what causes this. Why does no one also take into account this is editable via the CS, GTS adaptations etc. who has run a HAS kit and utilized one of these? I would assume it makes a world of difference... seems the solution isn’t rip it all out but tell the electronics to behave in a manor in which you’ve modified it....

[horsepower_and_hounds]

I would be willing to bet all the floaty feeling people have is the dampers are not correctly mated to springs.... spring or HAS lowered cars. On coil overs the same applies or the dampening vs rebound are not set right along with bypass shim stack. Out of all the springs I have tried the MS seem to work the best so far

[forgemarco]

Make sure you give the tyres a chance to bed in properly, they can feel a bit weird when new.

[THEROK]

Friends don't let friends lower on stock shocks. The only reason to go HAS is because you don't or can't spend the money for a proper adjustable coilover package.

So some of your need to learn that technically they're all coilovers stock or aftermarket on your f8x.

The real difference is you want to "upgrade" to adjustable coilovers (e.g. shock compression and rebound).

Spacers suck too btw.

[SpdJunkie]

I had the same problem. Geometry was off front to rear. Front was way too low. Raised the front up just a little and the floatiness went away. I was finally able to feel the improvement in handling because of the KW HAS.