M3/M4 CS Owners Thread

[Zulu Saffa]

Came from a 2018 comp to a 2019 M4cs. Torque difference can really be felt mid range. Car is stock other than wheels/tires/pads/brake fluid. Has a MPE too. No real plans for power upgrades, but looking at camber plates, sway bars, control arms and possible BBK. Thinking I will leave stock dampers for now.

Currently in track set up mode - back to back track days tomorrow and Thursday (H2R and COTA).

Car is phenomenal.

[jmg]

The M3 CS is one of the most beautiful sedans ever designed. It's almost flawless in its muscular elegance. LRG was my color of choice and I wouldn't have it any other way. I sold my M3 CS but I have a feeling that it's going to be one of those cars I will look back in my twilight years and say: "Yup, I had a Lime Rock Grey M3 CS, what a machine! They don't make them like that anymore."

I've had so many great memories in this car. This is the F80 to have. If I could have afforded to, I would have kept it forever:

[RugbyBro]

Originally Posted by Zulu Saffa

No real plans for power upgrades, but looking at camber plates, sway bars, control arms and possible BBK. Thinking I will leave stock dampers for now.

Very nice ride! One thing to consider is that with the CSs BMW made an effort to soften the frontend with less roll/sway stiffness to promote better turn-in, so you may want to maintain a similar relative front/rear stiffness when upgrading the sway bars while retaining stock dampers.

[RugbyBro]

Originally Posted by jmg

[bigj505]

I'm happy someone made a thread. More nice pics to look at

[jtskariah]

Updated my previous post with a detailed list of mods. Let me know what you guys think!

[RugbyBro]

Originally Posted by slcook54

This thread is confirming that something is off with my car. I picked up my CS a couple weeks ago and started my build journal here. I track my E92 1x per month and was excited to see what the CS offered out of the gate. I drove the car back from Seattle home to San Francisco and was honestly shocked how floaty the front-end felt. Texting with Alex, I believe this has something to do with the Dinan HAS kit that the previous owner installed. This is a generic F80 kit, not specific to the CS. Link here.

The description of the kit specifies that it increases the front stiffness by 50% and the rear by only 10%. Aside from the front-end being jarring over bumps, even in Comfort, I'm thinking this adjustment also messed with the F/R balance of the suspension. Taking corners even at 6/10th's, the traction light is going crazy, there is no front-end presence or connection to the road. The front-end is lifting significantly under throttle and inducing understeer.

Racer20 I’ve read many of your posts on the CS suspension setup, all very insightful! Does it seem likely that increasing the front stiffness substantially via springs would induce understeer similar to throwing on a much stiffer roll bar? I’ve seen many of your posts advising base users to swap the rear ZCP sway precisely because the roll balance is off - so I’m thinking the same would happen by over stiffening the front.

[Zulu Saffa]

Originally Posted by RugbyBro

Very nice ride! One thing to consider is that with the CSs BMW made an effort to soften the frontend with less roll/sway stiffness to promote better turn-in, so you may want to maintain a similar relative front/rear stiffness when upgrading the sway bars while retaining stock dampers.

Had this very conversation earlier today at my local indy. Fella said while upgrading the sway bars does work, it can also make the car become unstuck pretty quickly by limiting the roll that much.

I see we have similar taste in track wheels. Apex were out of stock on just about everything at the time I was looking so I jumped on a deal on this forum where a bloke was selling a set of 4, 18" square set up off an M2 that he regretfully sold. At least I am happy!

Whats the rugby background? Diehard Bok supporter here. Loving the 6N at the moment!

Cheers

[CanAutM3]

Originally Posted by RugbyBro

Racer20 I’ve read many of your posts on the CS suspension setup, all very insightful! Does it seem likely that increasing the front stiffness substantially via springs would induce understeer similar to throwing on a much stiffer roll bar? I’ve seen many of your posts advising base users to swap the rear ZCP sway precisely because the roll balance is off - so I’m thinking the same would happen by over stiffening the front.

As I posted previously, stiffening the front relative to the rear will definitely induce more understeer.

[RugbyBro]

Originally Posted by CanAutM3

As I posted previously, stiffening the front relative to the rear will definitely induce more understeer.

Oh yeah I definitely saw that! I was just trying to get Racer20 into the thread since it seems to me that you two have really the best understanding of the CS suspension setup that I've seen over a multitude of threads

Originally Posted by Zulu Saffa

Had this very conversation earlier today at my local indy. Fella said while upgrading the sway bars does work, it can also make the car become unstuck pretty quickly by limiting the roll that much.

I see we have similar taste in track wheels. Apex were out of stock on just about everything at the time I was looking so I jumped on a deal on this forum where a bloke was selling a set of 4, 18" square set up off an M2 that he regretfully sold. At least I am happy!

Whats the rugby background? Diehard Bok supporter here. Loving the 6N at the moment!

Cheers

Bimmerworld TA16s are so under rated! Running a 18x10et33 sq setup but with PAS4s due to the shite Seattle weather... they were really meant to be my track wheels but I might have to pick up a dedicated front set if I keep dailying them. Aggressive poke in the front means my rear wheel arches are not happy!

As for rugby... born and bread England boy who will happily watch Super Rugby over the Premiership 10 out of 10 times I actually only follow Harlequins in the prem because my cousin plays for them. On 6N, France is absolutely on fire... France and Ireland are easily the most entertaining and expansive teams in the contest - great to see France doing so well given their pro league has been dominated by big money owners and mercenaries over the last 10 years. Personally I played in high school, then for a small school in NorCal, then on the NorCal men's circuit for a bit before hanging up the boots due to a laundry list of injuries. Anyway, don't get me started about Rugby... outside of cars that's the other thing I have a devout fanaticism for.

[Racer20]

Originally Posted by RugbyBro

Racer20 I've read many of your posts on the CS suspension setup, all very insightful! Does it seem likely that increasing the front stiffness substantially via springs would induce understeer similar to throwing on a much stiffer roll bar? I've seen many of your posts advising base users to swap the rear ZCP sway precisely because the roll balance is off - so I'm thinking the same would happen by over stiffening the front.

Thanks, glad I can help. Yes, Canut is right. For oversteer/understeer balance, stiffening one end has the same effect as softening the other. The thing that matters is the relative stiffness between them.

Stiffening the front and softening the rear will not be the same in every aspect though, as the ride frequencies, roll gradient, pitch/heave centers, etc. will all be different and have their own effects on the car.

Edit: wait, are you asking if you can adjust the front bar somehow to match the base rear bar? Presumably you could soften the front bar to get a similar roll stiffness distribution, but then the whole car would just be softer and less responsive. That said, I would prefer that over a mid-matched setup.

[RugbyBro]

Originally Posted by Racer20

Thanks, glad I can help. Yes, Canut is right. For oversteer/understeer balance, stiffening one end has the same effect as softening the other. The thing that matters is the relative stiffness between them.

Stiffening the front and softening the rear will not be the same in every aspect though, as the ride frequencies, roll gradient, pitch/heave centers, etc. will all be different and have their own effects on the car.

Edit: wait, are you asking if you can adjust the front bar somehow to match the base rear bar? Presumably you could soften the front bar to get a similar roll stiffness distribution, but then the whole car would just be softer and less responsive. That said, I would prefer that over a mid-matched setup.

Awesome, thanks for jumping in! So the cliff notes version is:

-slcook54's CS is having front end traction issues
-The car came with the Dinan HAS spring setup, which is significantly stiffer in the front than stock (we know that BMW went with the softest base spring setup for the 3CS)
-The car is having front end traction issues when pushed
-Bars and Dampers are stock, so only the springs changed

I think it's just a good discussion to have out in the open because F8X is such a highly and questionably modded platform, that I'm predicting there will be a few future owners that will unknowingly buy CSs with suspension mods that push the chassis out of balance.

[slcook54]

Originally Posted by RugbyBro

Awesome, thanks for jumping in! So the cliff notes version is:

-slcook54's CS is having front end traction issues
-The car came with the Dinan HAS spring setup, which is significantly stiffer in the front than stock (we know that BMW went with the softest base spring setup for the 3CS)
-The car is having front end traction issues when pushed
-Bars and Dampers are stock, so only the springs changed

I think it's just a good discussion to have out in the open because F8X is such a highly and questionably modded platform, that I'm predicting there will be a few future owners that will unknowingly buy CSs with suspension mods that push the chassis out of balance.

Stock suspension going back on and front lip being installed when I pick up e92. Will report back.

[Gtracer]

Just purchased my CS four weeks ago and I'm absolutely in love. I can't get over how refined the car is over the 2018 ZCP F80 that I had previously. I went from a 991.2 C2S to my current M3CS and really haven't looked back!

[jtskariah]

While we are on suspension... is the general consensus to keep the car on stock setup or MP HAS (for a daily driver with some track time)? I am mainly looking for little to no wheel gap, better stance, and improved handling. I keep hearing that a dedicated Coilover setup will always win in these cases. Is this not the case with the M4 CS because of the dialed-in dynamics? What do you guys think about putting in a reputable Coilover kit like Ohlins R&T in our cars (without considering any potential warranty concerns)? Would that be a bad idea or detract from the performance?

Seems like there are some very smart members here when it comes to our cars. Glad to know we have some heavy hitters to help us get things done correctly!

[RugbyBro]

Originally Posted by jtskariah

While we are on suspension... is the general consensus to keep the car on stock setup or MP HAS (for a daily driver with some track time)? I am mainly looking for little to no wheel gap, better stance, and improved handling. I keep hearing that a dedicated Coilover setup will always win in these cases. Is this not the case with the M4 CS because of the dialed-in dynamics? What do you guys think about putting in a reputable Coilover kit like Ohlins R&T in our cars (without considering any potential warranty concerns)? Would that be a bad idea or detract from the performance?

Seems like there are some very smart members here when it comes to our cars. Glad to know we have some heavy hitters to help us get things done correctly!

You can certainly throw on MPHAS - Not sure anyone really knows the exact spring rates, but they are similar to stock. I had it on my old F82 and I liked it a lot but I ran it quite low and it ended up really ruining the ride as I got into the 40k+ mileage range on the car. And I don't mean just from a ride comfort perspective, I mean it became a bit jarring and not confident since the dampers weren't able to properly do their job. Again, I ran mine LOW (like 2 threads left in the front and 1 left in the rear). I'm undecided on if I'll throw them on my CS, if I do they'll stay at max height and I'll use them purely for corner balancing. Pic on this post is after I raised the front a few threads for Seattle to give you an idea of the height I was running - I was also running -2 camber, so the top of the tire is tucked a bit so I had about a finger gap, maybe 1.5 on an angle. If you want to go that low and it's primarily a street/canyon thing, then I think it's better to go with a shock that is designed to run at that height (KW DDC or Bilstein B16).



CanAutM3 & jmg both had MPHAS on their CSs and felt it had a positive impact. And having height adjustability is an awesome feature to have when fine tuning your suspension.

[M3CSinWisc]

^^^ perfect height, in terms of appearance.

Had a Subaru STi that I put a lot of suspension work into (everything short of coils), and it got a lot worse before it got better when I put it back to stock. Too much stiffness (in springs or sways) you lose grip and ride quality, but it looks great. I think the CS has a bit too much gap in the front, but I’m A OK with that because that’s how the M engineers designed it, and who am I to mess with it?

[M3CSinWisc]

Took the car out today for the first time since early November! Just went cruising, listened to music, got reacquainted with how the car feels. Took some backroads w/ curves, and humbly realized that it has such a high performance ceiling that I’ll never be able to attain; even on the curviest of curves, I don’t think I got close to making the car sweat haha

Got some annoying rattle in the AC vent area, but other than that, thing is completely solid. What a machine.

[Wanted_M]

I'll join the party and thanks for starting the CS thread
My wife found the car by pure luck in TX, bought it and never looked back.

Thank god it doesn't have that hideous nose. I will definitely keeping her for a long time


Custom OEM CF hood vent (DB Carbon)


CF interior bits and recently added the window switch trim in CF (DB Carbon).

[f80jruss]

i'm looking to swap my black 763M wheels for the gold ones. anyone interested HMU
818-651-3886

[CanAutM3]

Originally Posted by jtskariah

While we are on suspension... is the general consensus to keep the car on stock setup or MP HAS (for a daily driver with some track time)? I am mainly looking for little to no wheel gap, better stance, and improved handling. I keep hearing that a dedicated Coilover setup will always win in these cases. Is this not the case with the M4 CS because of the dialed-in dynamics? What do you guys think about putting in a reputable Coilover kit like Ohlins R&T in our cars (without considering any potential warranty concerns)? Would that be a bad idea or detract from the performance?

Seems like there are some very smart members here when it comes to our cars. Glad to know we have some heavy hitters to help us get things done correctly!

I really liked the MP-HAS on my CS. It is not easy to compare spring rates because the MP-HAS have progressive rates while the stock spring have linear rates, but the consensus is that their rates are similar to the Comp pack spring rates at the static load point. I found the CS damping to be perfectly suited for the MP-HAS. For sure, the combo was not as stout as an all out "coil over" on track, but I found it struck a nice balance between street and track driving, which was exactly my use case. I liked the fact that I still had the 3 EDC modes at my disposal, perfect for a dual use car. It has to be said that there was some annoying level of NVH with my MP-HAS that were paired with GC camber plate. Nothing major, but some muted clunks when driving at low speeds over small sharp bumps. It is important to get the front-to-rear ride height well balance to optimize the handling balance. I had originally set the front too low relative to the rear, which was suboptimal to put the power down on corner exit. Raising the front a tad resolved the issue.

More pictures here: https://f80.bimmerpost.com/forums/sh....php?t=1533482

Side view with street and track shoes:

[CSBM5]

Probably a good spot to insert Andy Pilgrim's track review? Fun video!

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