FCM E46 M3 Ride Harmonizer suspension spreadsheet - aka Flatride !!!

[nervous24]

What specs did you have for the "infinite range" GC bar? I'd like to play around with them in the flat ride spread sheet.

Also wondering what weigh reduction mods you made to the car? I'm at 3550# with driver and 5/8 tank of gas. I'm a pretty average size guy (~200# when in the car), but you have about 300# less weight!? I was thinking my car was a little heavy when I saw the initial weights, but its still lighter than the factory curb weight by about 110#.

Oh, I don’t currently have the GC front bar. I am running the Turner bar on full stiff with a stock rear bar. I had the same thinking has Ian and I’m happy to hear that if I decide I want to raise my FRC after an upcoming event that my plan will play out just the way I thought it would. The car feels pretty damn great at present but I’m curious what it’ll be like on the track.

As as far as weight reduction goes, you shouldn’t feel bad. My cars diet has been substantial since it’s a track car. The only things behind my buckets are a half cage, rear glass and my suspension reservoirs. I deleted the sunroof (AJ Hartman panel, the only true cf option) and plenty of other things. Hell, I even had the parcel shelf chopped out when the cage went in to help offset the jungle gym a touch. Saved like 13-15lbs, I forget which.

This photo was taken just after picking it up from the fabricators

[duracellttu]

I do Finance for a living... and this spreadsheet is overwhelming. This is the first time I'm seeing this and I dont even know what to do with it.

Check out Obioban's thread above. It's really informative. I've spend a lot, A LOT, of time with the spreadsheet over the past couple of months. If you need help walking through it let me know. I'm happy to help you out.

[Obioban]

I do Finance for a living... and this spreadsheet is overwhelming. This is the first time I'm seeing this and I dont even know what to do with it.

This might help:

https://nam3forum.com/forums/forum/main-forum/e46-2001-2006/9123-e46-m3-suspension-setup-or-how-to-not-downgrade-your-car-with-suspension-mods

[x Spades x]

I do Finance for a living... and this spreadsheet is overwhelming. This is the first time I'm seeing this and I dont even know what to do with it.

[duracellttu]

I’ve been debating pulling my Turner bar in favour of the GC piece. Gonna feel things out on track in a few weeks before pulling the trigger.

Last time out my frc was like 72.1% (currently at 74.6%) so I’m hoping for a positive change with the current setup. The GC bar would offer an adjustment range of 76-80.3% which would surely keep things in line if I felt I needed it.

Also, for those that may be curious, and because most don’t post all of this info when discussing their setups, my car weighs in at 3251 with driver and a little over 1/2 tank of gas. I run 400/800 (2.12Hz/2.39Hz) for 13% FR and the aforementioned 74.6% FRC.

What specs did you have for the "infinite range" GC bar? I'd like to play around with them in the flat ride spread sheet.

Also wondering what weigh reduction mods you made to the car? I'm at 3550# with driver and 5/8 tank of gas. I'm a pretty average size guy (~200# when in the car), but you have about 300# less weight!? I was thinking my car was a little heavy when I saw the initial weights, but its still lighter than the factory curb weight by about 110#.

[nervous24]

A large part of the reason I went with the GC front sway is that the bar is infinitely adjustable within its adjustment range. So, it fell in spec per the spreadsheet, and then I could dial it in to my taste specifically by changing the arm length.

I’ve been debating pulling my Turner bar in favour of the GC piece. Gonna feel things out on track in a few weeks before pulling the trigger.

Last time out my frc was like 72.1% (currently at 74.6%) so I’m hoping for a positive change with the current setup. The GC bar would offer an adjustment range of 76-80.3% which would surely keep things in line if I felt I needed it.

Also, for those that may be curious, and because most don’t post all of this info when discussing their setups, my car weighs in at 3251 with driver and a little over 1/2 tank of gas. I run 400/800 (2.12Hz/2.39Hz) for 13% FR and the aforementioned 74.6% FRC.

Despite the high frequency (mainly a track car) it is remarkably pleasant and composed when on the street. I run almost full soft up front (MCS 2W) with splash of compression in the rear to manage the springs. Front settings are 1C 1R and rear is 6C 1R. Still playing with the rear comp to be sure I’ve got the optimal damping but it’s fine for now.

Prior to my current setup I have run, in order:

stock suspension + H&R springs @ stock weight

MCS 1W + 800/900 @ 3400lbs w/driver + 1/2 tank
(not fun AT ALL!)

The car as currently composed is as good as its ever been and I attribute that to the suspension harmony that FR has afforded me.

[r4dr]

Be careful about tunneling in on one number and/or looking at that number in a vacuum. Every suspension setup is a compromise.

2% flat ride is still flat ride, it's not like either you have to be at *x*% flat ride at *y* speed otherwise the car will be bucking like a bronco. If you look at Shaikh's 330i entry on there, he runs 425/800 for 8% flat ride on what seems to be a dedicated track car (there are clips of it on his YT channel). I don't have personal experience with TCK Konis (only GC) but I've been told they're valved on the softer side as a philosophical decision versus GCs. He could also be limited to 700 in the back because of what dampers that kit runs.

All I'm trying to say is looking at 400/700 as a 2% flat ride and nothing else is kind of missing the rest of the picture. Just like how Obioban is adapting his "perfect world" flat ride numbers to the capabilities of his dampers. Personally I wonder how 350/700 would work but I have no idea if that will end up being too soft up front for the track.

[duracellttu]

This past week I have been emailing TCK about spring options. I was wondering if he sold other spring rates, not listed on his site. Specifically for the rears.

I wanted to know if he could get 750# rear springs in the barrel shape. He told me that the SA damper wont support anything above 700# springs in the rear.

His recommendation was 400# fronts and 700# rears and that it had "great balance". This was after I told him I had a TMS front sway and OEM rear.

The flat ride calculator shows that to be a 2% flat ride (2.04Hz Front / 2.07Hz Rear) with 76.4% FRC. Sounds like that will have a bit of a harsh ride. Thougths?

[Obioban]

I was (am) working within the constraints of what my shocks can handle and what sways exist (to get the oversteer/understeer balance right without having no rear bar).

[duracellttu]

Shaikh just replied to my email and said he'll start posting on here soon.

Talking about spring rates kind of defeats the purpose of the spread sheet! The point of it is to target frequencies. Frequencies are influenced by spring rates, but also by wheel offsets, corner weights, unsprung mass, etc!

I'm currently at 1.92hz front, 2.06hz rear, with 4647 lb-ft/deg (off bump stop) of front roll stiffness and 1237 lb-ft/deg (off bump stop) of rear roll stiffness (vs 1688/809 off bump stop stock).

But, the springs and sways that got me there are unlikely to be the same as what would get you there.
(in 3071 lb car that's a bit front heavy and no longer has the counterbalancing battery on the passenger side, with my wheel offsets/sizes, 350 FL, 325 FR, 700 LR, 628 RR-- staggered left/right so I have equal frequencies left right)

After playing around with the spreadsheet a little more, I am trying to understand how people are choosing the Hz delta between the front and the rear. There is a section in the spreadsheet for "Flat ride calculator based on target road speed".

Obi, when I punch in your rear ride freq of 2.06 Hz, the flat ride calculates to a target road speed of 125 mph, to get 1.92 Hz in the front. Is there a reason you chose this? Is it for a flat ride at max speed on the track? I 'm having trouble determining what to target.

As a basis for comparison, 60 mph target road speed, with 2.06 Hz rear freq calculated --> 1.75 Hz front freq. Similarly, the stock suspension is set to 1.53 Hz rear / 1.27 Hz front for a target road speed of 40 mph.

[r4dr]

Playing around with the targeted road speed table towards the bottom left, assuming all things stock in an E46 M3 coupe, can you conclude that BMW targeted 40 mph as the road speed for their factory flat ride? That would make sense given how cars are driven on the street, so if you wanted to skew towards high-speeds on the track you would target 80+? So perhaps a compromise dual-duty car would target 50-60?

[TosM3]

hmm interesting will read up

[Obioban]

A large part of the reason I went with the GC front sway is that the bar is infinitely adjustable within its adjustment range. So, it fell in spec per the spreadsheet, and then I could dial it in to my taste specifically by changing the arm length.

[mrgizmo04]

Interesting, is there a target FRC based on rwhp ranges? I’m sitting at 340rwhp and trying to figure out my new setup specs.

That comment was more generalized to different chassis, like Miatas are probably around 60%, s2000 might be mid 60s, our cars mid 70s, etc.

I can't tell you that if you have headers and CSL airbox you should target 76% instead of 75% and if you are FI you should target 80.

Obviously chassis tuning is part of it, but if you have 800hp, you will run wider rubber and softer springs etc in rear.

[mrgizmo04]

Ah thanks. Yes I misunderstood it.

Curious to know everyone's spring/sway setup. I personally am against the philosophy of sway bars in general because I like suspension articulation so I'm running stock sways and 500 front/600 rear Eibach springs. It sounds like I should drop down to the a ~300 spring rate front to go flat ride.

Flat ride is more of a concept between front and rear axle based on frequencies to have the car settle evenly after going over a bump at a certain speed. Yes you will need to either drop the front rate, up the rear, or both.

If you do that, you will have a much tighter rear end (😉), and oversteer prone chassis, which you will have to counter with bigger front bar.