[fleetfoot]

I've got 108,000 miles on my 2013 E92 328i, and over the last 2.5 years I've spent quite a bit of time and money trying to improve steering and chassis feel. My initial goal was to create a car that felt more connected on mountain roads, but then I started doing HPDEs this year so I wanted steering/suspension that was capable but also confidence-inspiring. Here are my thoughts on the various things I've tried over the past 2 years:

95,000 miles: Full Suspension Overhaul - $4,748 (parts+labor)
My shocks were shot, so I decided to replace them and do a bunch of other upgrades at the same time to keep the E92 fun for a few more years before I bought something new. This was basically the ECS Tuning Level 3 kit along with some other stuff. I kept my original sport springs. The main things were:

• M3 control arms
• Bilstein B8 shocks/struts/mounts
• OEM tie rods
• OEM sway bushings
• AKG 95A poly rear subframe and diff bushings

After the install I had the car aligned to M3 specs, with the most noticeable thing being 1 degree of camber up front, which is the advantage of using the M3 control arms. The biggest improvements I noticed were:

1. Fresh shocks/struts greatly improved rebound
2. Poly diff bushing improved shifter feel (didn't expect this one)
3. Ability to accelerate over uneven pavement (like road crests at an intersection) was way better due to the poly rear subframe bushings

However, the chassis felt really spooky in high speed corners. I noticed this change the first time I hit a kink on an interstate onramp at speed. The rear end hopped really weird. I also felt it during my first track day. I suspect that my 3 year old Michelin AS/3+ tires may have had a part in this, or maybe the toe alignment settings. I will mention that the poly bushings resulted in very noticeable NVH increases. I now have a whistling/whining noise from the drivetrain at partial throttle, especially at interstate speeds. But it's worth it IMO.

105,000 Miles: Installed/aligned a fresh set of Michelin Pilot Sport 4S tires - $1219
After running Michelin AS/3 tires the past 6 years (great traction year round), I decided to switch over to summers in the pursuit of better steering feel. I also got the car aligned again and went from 0.15in toe up front to 0 toe. These changes combined totally eliminated the suspension spookiness I felt previously. I didn't notice a major change in steering feel. The new setup worked great for my second HPDE, but I saw some pretty extreme shoulder wear on my front tires, so I started looking for solutions to that problem.

107,000 miles: Installed Dinan Camber Plates - $484(parts+labor)
After doing some research, Dinan fixed camber plates that add ~1 degree of camber seemed like the best solution to reduce tire wear up front on the track. Other adjustable camber plates are known to have significant NVH increases, which I didn't want. I looked at adding thicker sway bars, but this seemed more expensive (especially the labor for the rear) and might not be as effective as just adding more camber up front.

Once I had the camber plates installed, we aligned the car to E92 M3 Competition specs including:

• 2.3 degrees of camber up front
• 1.9 degrees of camber in the rear
• front toe of 0.12 degrees
• rear toe of 0.20 degrees

I think this may have been the biggest improvement of all. Everything feels PERFECT now:

• Steering inputs feel immediate (no slop) and there seems to be more feedback through the wheel
• The chassis is super stable and predictable
• There's tons of front end grip
• I saw acceptable front shoulder wear after track usage
• No increase in NVH
• No wandering on the interstate
• The stance looks more aggressive

A Few Takeaways:

1. I doubt everything would feel perfect without ALL my changes, but if I was doing it again, I might start with the camber plates first, especially since they were the least expensive by far.
2. My 328i steering isn't as razor sharp as my M2, or as communicative as a BRZ, but it's pretty darn good for not being a sports car. I'm super happy with my 328i right now, and it's been great for learning to drive on the track.
3. I HIGHLY recommend the alignment specs below.

[Andy198712]

Great advice thank you!
I’m currently working through my suspenion and i feel that rear end vaugness I think is subframe. I have inserts I’ll try as a short term fix.

But as you found front camber is limited on these (with alignment pin removed) so I’ll look at those plates too!

Thanks!

[david in germany]

I was fighting with my e87 118i for years to improve the feel of the car. I had my 335i MSport with performance package suspension and my wife’s 328i with MSport to compact it to. It always felt nervous (only way I can explain it) I added performance springs Bilstein dampers, etc etc but it never really improved the feel, UNTIL, I coded the car for the performance suspension. Just the coding made the car feel like I thought it should feel and it has a similar feel to my 335i.

[fleetfoot]

Originally Posted by david in germany

I was fighting with my e87 118i for years to improve the feel of the car. I had my 335i MSport with performance package suspension and my wife's 328i with MSport to compact it to. It always felt nervous (only way I can explain it) I added performance springs Bilstein dampers, etc etc but it never really improved the feel, UNTIL, I coded the car for the performance suspension. Just the coding made the car feel like I thought it should feel and it has a similar feel to my 335i.

Interesting. What suspension parameters do you think that coding changed? Other than maybe active steering I didn't think there was anything electronically controlled in the e87/e90 gens. For example no adaptive dampers, e-diff, or electric power steering.

[david in germany]

I know steering tightened up and I believe dtc and brakes were modified.

[neilvan]

Originally Posted by fleetfoot

Interesting. What suspension parameters do you think that coding changed? Other than maybe active steering I didn't think there was anything electronically controlled in the e87/e90 gens. For example no adaptive dampers, e-diff, or electric power steering.

I believe LCI in europe got rid of basic hydraulic steering so its possible it changed some settings for servotronic or adaptive steering and some got full electronic steering(I believe)

Traction control or abs might have changed too but that's about it. Braking and suspension are all mechanical/no sensors so its more than likely a placebo

[Andy198712]

My 2010 e91 325d n57 lci has no steering res so makes sense

[Slade_]

Great info, thanks! Bookmarked for future reference.

[fleetfoot]

Glad this is helpful!

I should also share what I've learned so far on optimal tire pressures. My first track day I ran the manufacturer recommended 32psi front/39psi rear (cold). This didn't feel great, so for my next track day I started with 34/36 (cold), which was better.

My 4th track day, I moved to setting hot tire pressures with a target of 38psi front and 40psi rear after a full session based on my instructor's guidance (he was driving an E46 M3). That setup seems to be ideal with good balance, steering feel, and tire shoulder wear. I measured the tire pressure cold the next morning and it had fallen back to 32/32.

Going forward I'm planning to run 34/36 (cold) for street use and 32/32 (cold) before a track day and then adjust as needed to keep the tires at 38/40 (hot).

[Slade_]

Originally Posted by fleetfoot

Glad this is helpful!

I should also share what I've learned so far on optimal tire pressures. My first track day I ran the manufacturer recommended 32psi front/39psi rear (cold). This didn't feel great, so for my next track day I started with 34/36 (cold), which was better.

My 4th track day, I moved to setting hot tire pressures with a target of 38psi front and 40psi rear after a full session based on my instructor's guidance (he was driving an E46 M3). That setup seems to be ideal with good balance, steering feel, and tire shoulder wear. I measured the tire pressure cold the next morning and it had fallen back to 32/32.

Going forward I'm planning to run 34/36 (cold) for street use and 32/32 (cold) before a track day and then adjust as needed to keep the tires at 38/40 (hot).

May I ask what your wheel set up is?

[bmw335ie90]

Any thoughts on using xdrive front strut mounts to negate the 6mm front suspension lift caused by the dinan camber plates? I am told the xdrive strut mounts are 10 mm more shallow than the regular ones.

From what I have read nobody really reports any NVH from stiffer subframe bushings, only the diff bushings. Is the diff whine worth the stiffer feel in your opinion?

[fleetfoot]

Originally Posted by bmw335ie90

Any thoughts on using xdrive front strut mounts to negate the 6mm front suspension lift caused by the dinan camber plates? I am told the xdrive strut mounts are 10 mm more shallow than the regular ones.

From what I have read nobody really reports any NVH from stiffer subframe bushings, only the diff bushings. Is the diff whine worth the stiffer feel in your opinion?

From my research it seemed like you'd want to do both the diff and subframe bushings. Only doing one could lead to uneven stresses and potential damage. Maybe see if you could find softer poly than my 95A ones?

The slightly higher ride height from the camber plates wasn't a big deal for me. But my wheel gap wasn't super tight to start with. No clue if the xdrive mounts would work/help.

[fleetfoot]

Originally Posted by Slade_

May I ask what your wheel set up is?

I'm still running the OEM M-sport style152 wheels, which are staggered (225/255). If I keep this as a track car, I'll move to a 245 square setup. These photos were pre-camber plates, but it really didn't change a whole lot visually:

[Slade_]

Originally Posted by fleetfoot

I'm still running the OEM M-sport style152 wheels, which are staggered (225/255). If I keep this as a track car, I'll move to a 245 square setup. These photos were pre-camber plates, but it really didn't change a whole lot visually:

Very clean set up.

I’ve always loved that style wheel on the e92. Very oem+.

Currently on style 189s but have my eye on another oem wheel.

[michaelalex17]

I love the steering weight and feel of the e90, but one of the things that makes it not feel razor sharp like a sports car just comes down to the steering ratio. Aside from the m3, the e90 steering requires a lot of input.

Ratio for M3 is 12.5:1, RWD is 16:1, XI is 18.2:1.

[fleetfoot]

Originally Posted by Slade_

Very clean set up.

Thanks! I love having a bit of a "sleeper". It's got all the good performance bits under the hood and behind the wheels (3IM, exhaust, bilsteins, etc.) but to the casual observer it's just another old BMW 3-series.

[fleetfoot]

Originally Posted by michaelalex17

I love the steering weight and feel of the e90, but one of the things that makes it not feel razor sharp like a sports car just comes down to the steering ratio. Aside from the m3, the e90 steering requires a lot of input.

Ratio for M3 is 12.5:1, RWD is 16:1, XI is 18.2:1.

Oh that's interesting about the steering ratio. That could be part of the "sharpness" for sure. However, from talking with bimmerworld, it sounded like the bushing in the "front thrust arm" (I believe this is the "upper control arm") is very important for steering feel, and they recommended a Powerflex bushing, which I didn't install. I'm not sure how the E92 M3 rubber bushing compares to my M2 bushing.

Here's some more info I found on Turner:
BMW’s are known to have failure prone front thrust arm bushings. The flexible rubber bushings, even those found in M performance models, allow significant movement of the front wheels to maximize daily driving comfort, but also allow considerable alignment change. This results in a disconnected and numb road feel, standing between you and a confidence inspiring driving experience. Eventually the fluid filled rubber bushings fatigue and crack due to continual deflection and ozone degradation, and eventually the damping fluid leaks out resulting in complete failure.

I do sorta wish I'd gone with a Powerflex bushing in those front control arms, even though I've already got the somewhat improved M3 bushings. Powerflex might bring the sharpness up closer to my M2?

[fleetfoot]

FWIW, I reached out to Bimmerworld again today. The E92 M3 and F87 M2 control arm bushings appear to be very similar, so bushings probably aren't responsible for the difference in sharpness I feel between my 328i and M2.

I think it makes sense that the difference in steering feel between my 328i and M2 is likely due to differences in steering ratios and power steering type (electric vs. hydraulic). I wonder if electric could be "sharper" due to not having to compress hydraulic fluid?

I suspect overall chassis stiffness and age could be having some impact as well.

[Biginboca]

Originally Posted by fleetfoot

FWIW, I reached out to Bimmerworld again today. The E92 M3 and F87 M2 control arm bushings appear to be very similar, so bushings probably aren't responsible for the difference in sharpness I feel between my 328i and M2.

I think it makes sense that the difference in steering feel between my 328i and M2 is likely due to differences in steering ratios and power steering type (electric vs. hydraulic). I wonder if electric could be "sharper" due to not having to compress hydraulic fluid?

I suspect overall chassis stiffness and age could be having some impact as well.

The steering knuckles have different inclination angles on the E chassis vs the F8X. This is why I swapped to F80 front knuckles. The steering ratios also a big help (I have e92m3 rack which was a great mod.). Also wider front rubber like 255 helps and add some camber. F8X is about -1.7 stock I believe so you probably need more than Dinan camber plates. If you are tracking the car the e9x responds well to -3.5 front and -2.5 rear camber and zero front toe (with firmer or solid front control arm bushings). Also the swaybars are stiffer on the M2. So there’s a lot of things to change.

After I drove a M2 on the track I set about making my e92 handle better. When I drove that M2 I had never driven a car that felt so good in the turns! Now it’s been a few years and I’ve got the car handling great with eliminating all the rubber controls arm bushings with Uniballs (front and rear), solid subframe bushings, extensive chassis bracing (e9x M3 front chassis/subframe plate which M2 has also, e93 front frame brace like the m2 front brace, strut bracing front and rear, etc).

Basically you need to stiffen the chassis, add camber, and get rid of rubber bushings to really make the cars on the next level like the new F8X cars which have these things stock already. What’s interesting is most of the suspension geometry on the e9x is very similar to the F8x. So we have a great base to start with, hence why Shirmer is breaking 7:00 ring times with their e9x m3’s. You just need to bring the updates the new chassis has to the e9x generation.

[Jaronbwall]

And don't forget to add an LSD
I hear Wavetrac sells some good stuff.

[Spyro235]

Originally Posted by fleetfoot

Oh that's interesting about the steering ratio. That could be part of the "sharpness" for sure. However, from talking with bimmerworld, it sounded like the bushing in the "front thrust arm" (I believe this is the "upper control arm") is very important for steering feel, and they recommended a Powerflex bushing, which I didn't install. I'm not sure how the E92 M3 rubber bushing compares to my M2 bushing.

Here's some more info I found on Turner:
BMW’s are known to have failure prone front thrust arm bushings. The flexible rubber bushings, even those found in M performance models, allow significant movement of the front wheels to maximize daily driving comfort, but also allow considerable alignment change. This results in a disconnected and numb road feel, standing between you and a confidence inspiring driving experience. Eventually the fluid filled rubber bushings fatigue and crack due to continual deflection and ozone degradation, and eventually the damping fluid leaks out resulting in complete failure.

I do sorta wish I'd gone with a Powerflex bushing in those front control arms, even though I've already got the somewhat improved M3 bushings. Powerflex might bring the sharpness up closer to my M2?

Edit: I'm a knob. Biginboca mentianion uniballs, same thing!
How has noone mentioned monoball thrust arm bearings (bushings) yet? I had a facebook friend (forum member on the diesel fbook groups) put monoballs in my e70 thrust arms. I'll be having him do my e92's if I stick with that chassis for any amount of time. Monoballs barely add nvh, mostly under hard braking and hard steering the NVH noticeably increased On a straight highway, you'd never know. Steering feel, especially under braking, is improved magnitudes.

[The Nightman]

Monoball tension struts are amazing if you have perfectly smooth roads. Unfortunately the NVH they transmit was not worth it to me on a street car, so I went back to M3 bushings.

On a related note, the M3 strut brace adds a surprising amount of rigidity. I went from the BMW Performance aluminum brace to the M3 one and couldn't believe the difference. Most shocking was the improvement in ride quality on harsh roads. Seems that a more rigid chassis is better at absorbing impacts.