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

[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.

[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#.

[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.

[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

[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.

[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]

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

Wow, yeah that is gutted! Looks great! Now I don't feel so bad hahaha. I basically have a full stock interior. Removing the sunroof and going with a slicktop CF roof definitely helped though.

[Obioban]

Wow, yeah that is gutted! Looks great! Now I don't feel so bad hahaha. I basically have a full stock interior. Removing the sunroof and going with a slicktop CF roof definitely helped though.

My car is ~300# lighter than stock. ~200# of that comes from 4 mods:
1) cf roof
2) fixed back seats (cobra nogaros— still leather/heated and allow back seat access)
3) lithium ion battery/battery cable delete
4) light weight stereo/stock stereo harness delete

The other 100# is the result of many small 1-5 lb changes.

I could easily knock another 50# off with a lighter than stock muffler and back seat delete, but ruining the civility/practicality isn’t worth it to me.

[Will]

My car is ~300# lighter than stock. ~200# of that comes from 4 mods:
1) cf roof
2) fixed back seats (cobra nogaros— still leather/heated and allow back seat access)
3) lithium ion battery/battery cable delete
4) light weight stereo/stock stereo harness delete

The other 100# is the result of many small 1-5 lb changes.

I could easily knock another 50# off with a lighter than stock muffler and back seat delete, but ruining the civility/practicality isn’t worth it to me.

What was the contribution of #4 (the light weight stereo/stock stereo harness delete)? I know you had a thread on the old m3f, but I forgot the specific number(s). Thanks.

[duracellttu]

My car is ~300# lighter than stock. ~200# of that comes from 4 mods:
1) cf roof
2) fixed back seats (cobra nogaros— still leather/heated and allow back seat access)
3) lithium ion battery/battery cable delete
4) light weight stereo/stock stereo harness delete

The other 100# is the result of many small 1-5 lb changes.

I could easily knock another 50# off with a lighter than stock muffler and back seat delete, but ruining the civility/practicality isn’t worth it to me.

I checked off #1 on this list. Which was easily the best weight mod you could do on the car.

On the old forum we had a weight / weight reduction thread. Any chance you have approximate weight savings associated with this list? Might be worth starting a separate thread on this again.

[Johnvu]

I have had experience with two set ups: 8k front and 14k rear, oem front sway and no rear sway Ratio: 1.01, and FRC: 70ish. I took the car to the track on this setup and it felt pretty good, but there was a good amount of body roll.

I just recently changed out toa tuner front sway bar at full stiff and oem rear sway. Bounce Ratio: 1.01 and FRC 75.4 (with the sway bars) . I did a shakedown run with some friends on some fun country roads and I have to say that there was a pretty huge difference. The car feels way more responsive/ sharper on turn in, which took some getting used to. The car definitely felt like it was more predictable as well.

All in all, I really love the flat ride calculator. The ride is still pretty damn comfortable and it doesn't bounce around like the some other cars I've been in. My only regret on my current set up is not using this calculator before ordering my coilovers.

When I upgrade my fortune's from 500s to 510s, I am going to up the rear springs rates. With that being said, Is there a good target for the bounce ratio? 5%, 10%, or 15?

[Obioban]

I checked off #1 on this list. Which was easily the best weight mod you could do on the car.

On the old forum we had a weight / weight reduction thread. Any chance you have approximate weight savings associated with this list? Might be worth starting a separate thread on this again.

1) ~45 lbs
2) 59 lbs
3) ~50 lbs
4) ~45-50 lbs... mostly wire

[e46m3_06]

Well I really like the idea of this spreadsheet but its not mapping to what I feel on the track. My car with driver is about 3100(fully stripped with roll cage). I'm using 650/650 springs, rear in stock location, and GC front ARB with no rear bar at all. According to this spreadsheet I should be understeering like mad. I've been considering reducing the rear springs cause I get a bit of oversteer after a while although its fairly neutral at the start of the day and session. My FRC should be 86.8% which would be way too much understeer. I'm still way faster than a street car but looking to get a better as some cars in my class seem to be out cornering me. Any ideas?

[Obioban]

Well I really like the idea of this spreadsheet but its not mapping to what I feel on the track. My car with driver is about 3100(fully stripped with roll cage). I'm using 650/650 springs, rear in stock location, and GC front ARB with no rear bar at all. According to this spreadsheet I should be understeering like mad. I've been considering reducing the rear springs cause I get a bit of oversteer after a while although its fairly neutral at the start of the day and session. My FRC should be 86.8% which would be way too much understeer. I'm still way faster than a street car but looking to get a better as some cars in my class seem to be out cornering me. Any ideas?

Perhaps you’re running out of bump travel, and your rear bump stops are engaging first, ramping up the rear rate and causing oversteer? Could be too little travel, could be too much rebound causing the rear to jack down.

[e46m3_06]

Hmm it seems with a 650 spring and GC Konis and a lightened car that it wouldn't have much chance of bottoming out. Also it doesn't seem like the oversteer is such an instantaneous event like a bump stop collision. But I can try the ziptie test this weekend to verify. The GC dampers only have a rebound adjustment and I haven't really experienced much change with adjustments. I don't know what spring rate the dampers were built to accommodate since I'm not the original builder and GC can't seem to provide the data with the info I can supply. That could be an issue as well so I'm starting to think about changing dampers.