Sprung corner weights, motion ratios, and hertz

[Visceral]

Hey all,

Attempting to engineer the correct springs/damping for my E90 for AutoX, street, and track fun.

I've been searching all morning, but cant find if anyone has added up, calculated, or just has heard what our front and rear sprung corner weights are (with room for a tire/wheel weight, naturally).

Also, mu understanding is that we have motion ratios in the .96r/.56f zone.

Also, do people have frequencies that are working well for them? 2hz? 2.5?

Thanks in advance. There isn't a lot coming up in searches.

[SYT_Shadow]

I'd love to know.

I'd like my suspension tinkering to be a bit more advanced than what it currently is:

[Visceral]

Background:
http://eibach.com/eibach/img/ers-14s...nworksheet.pdf has the math. I'm looking for a frequency of approximately 2hz and then to calculate the critical damping for that.

[Fitzpadj]

Many a people have done this for lots of different platforms and I have never seen it be right. Find your local fast guy/shop and duplicate his setup and test/change from there.

[Visceral]

Originally Posted by Fitzpadj

Many a people have done this for lots of different platforms and I have never seen it be right. Find your local fast guy/shop and duplicate his setup and test/change from there.

I know what the "go fast" setups are. 600/900 or 700/1000 and the MCS triples from BW. Thats $8400.

Great. Check. I'm working through the math with my son to teach him the science, and we need the variables.

If you aren't going to approach it scientifically and you purchase 3-way adjustable shocks, you will either-

1. get lucky; your go fast shop hit the nail on the head, front AND rear.
2. chase your tail around in circles trying to adjust and "feel the difference"
3. chase your tail around in circles buying more parts.

The first step in approaching 3-way shocks scientifically is to get the numbers, study the system, and then come up with a hypothesis, that way when the system is off, you have an idea how to adjust it.

The go fast shop has no idea what tires, what sway-bars, what wheel weights, what vehicle weights, what ride heights, etc etc etc exist in my system. They wont hit the nail on the head for my car.

[ThunderMoose]

Considering DJ holds multiple east coast track records and is the only guy I know with the nads big enough to stay flat (>137 mph) through VIR climbing eases, I'd be more than happy to take his settings and plug them in with no questions asked.

However, if you're trying to teach your son the math, keep searching this forum, because I have seen a few threads posted here with the math and the variables you're requesting.

[Pig Farmer]

Do a quick search for the user name "Orb". Back in the day, he posted a lot of information on the e9x (M and non-M) suspension.

[Visceral]

Originally Posted by ThunderMoose

However, if you're trying to teach your son the math, keep searching this forum, because I have seen a few threads posted here with the math and the variables you're requesting.

And I'm practically family with Tommy Milner, but I didn't ask him which shocks are best for my Corvette.

I'll keeeeeep searching.

[SYT_Shadow]

Originally Posted by ThunderMoose

Considering DJ holds multiple east coast track records and is the only guy I know with the nads big enough to stay flat (>137 mph) through VIR climbing eases, I'd be more than happy to take his settings and plug them in with no questions asked.

Wow, flat out through the VIR climbing esses is insane! I guess big aero, real slicks and massive balls?

[SYT_Shadow]

Originally Posted by Visceral

I know what the "go fast" setups are. 600/900 or 700/1000 and the MCS triples from BW. Thats $8400.
.

This is what I have in my setup of the track car but I'm not there yet, tuning it is a hit or miss even with the provided baseline settings.

I'll have Mr Kline give us a baseline and hopefully have Randy drive the car afterwards

[Visceral]

Originally Posted by SYT_Shadow

This is what I have in my setup of the track car but I'm not there yet, tuning it is a hit or miss even with the provided baseline settings.

I'll have Mr Kline give us a baseline and hopefully have Randy drive the car afterwards

Whats your swaybar config? It's really hard to quantify the swaybar spring rate as an addition.

Also the motion ratio of the rear shock and spring are different... so NBD, but one more translation.

[Visceral]

Originally Posted by Pig Farmer

Do a quick search for the user name "Orb". Back in the day, he posted a lot of information on the e9x (M and non-M) suspension.

Thanks! Orb has some good numbers, but some of the numerical assumptions for his calcs isn't shown. He also headed into the great cyber-unknown about 4 years ago.

I appreciate his conclusions tho. It point more to 550/900 than 700/1000, but I dont know what his tires were or his swaybars. People have apparently pushed spring rates higher in the last 4 years as remote dampers can control it well (like the MCS).

He was a fan of JRZ tho, and I'm suspicious of that

[SYT_Shadow]

Originally Posted by Visceral

Whats your swaybar config? It's really hard to quantify the swaybar spring rate as an addition.

Also the motion ratio of the rear shock and spring are different... so NBD, but one more translation.

Yet to be installed. The Hotchins front/rear setup

Although the 3W is not properly set up, it's still 3s faster than the oem zcp suspension

[SYT_Shadow]

Originally Posted by Visceral

Thanks! Orb has some good numbers, but some of the numerical assumptions for his calcs isn't shown. He also headed into the great cyber-unknown about 4 years ago.

I appreciate his conclusions tho. It point more to 550/900 than 700/1000, but I dont know what his tires were or his swaybars. People have apparently pushed spring rates higher in the last 4 years as remote dampers can control it well (like the MCS).

He was a fan of JRZ tho, and I'm suspicious of that

Hahaha, i second your jrz comment!

[roastbeef]

all this hair-splitting and math to use 3-way coilovers and you're going with a cheap brembo retrofit caliper?

[Visceral]

Originally Posted by roastbeef

all this hair-splitting and math to use 3-way coilovers and you're going with a cheap brembo retrofit caliper?

Dude, you really are triggered that I'm not rushing out to buy (or try to buy) a $7k big brake kit.

If looking to understand how the math lines up to a set of spring rates some guy who answered the phones suggests is hair splitting...

guilty.

[roastbeef]

not triggered, its just unusual.
lots of time, energy, and thought going into your suspension to be right and seemingly zero thought and research put into the brakes.

[Visceral]

Originally Posted by roastbeef

... seemingly zero thought and research put into the brakes.

Just because I came up with Brembo Z06 calipers, F80 rotors, and some cooling you think I didnt put thought into it. There are way too many people who wear their heart on their sleeve in the M3 brake debate; and yet half the fast BMW guys at the tracks around here are using stock calipers and rotors. This forum is not the best help in a scientific brake discussion. It's OK, I just know when to look elsewhere.

[roastbeef]

Originally Posted by Visceral

Just because I came up with Brembo Z06 calipers, F80 rotors, and some cooling you think I didnt put thought into it. There are way too many people who wear their heart on their sleeve in the M3 brake debate; and yet half the fast BMW guys at the tracks around here are using stock calipers and rotors. This forum is not the best help in a scientific brake discussion. It's OK, I just know when to look elsewhere.

its a lot of time and money for something that might work rather than paying a little more for something that has been proven to work. i'm not suggesting to go blow $8k on ap's or pfc's either.
which hard motorsport parts did you get? are you getting custom heat shields done to implement the ducting? its going to be a mystery if any oem shields are going to fit, even if the f80 rotor hat offset is the same as the e90's.

[Visceral]

I got the cooling kit with the backing plates.

"HARD Motorsport Brake Cooling ClubSport Kit with M3 Backing Plates"

We'll see, but the F80 offset it the same.

[Fitzpadj]

Originally Posted by Visceral

I know what the "go fast" setups are. 600/900 or 700/1000 and the MCS triples from BW. Thats $8400.

Great. Check. I'm working through the math with my son to teach him the science, and we need the variables.

If you aren't going to approach it scientifically and you purchase 3-way adjustable shocks, you will either-

1. get lucky; your go fast shop hit the nail on the head, front AND rear.
2. chase your tail around in circles trying to adjust and "feel the difference"
3. chase your tail around in circles buying more parts.

The first step in approaching 3-way shocks scientifically is to get the numbers, study the system, and then come up with a hypothesis, that way when the system is off, you have an idea how to adjust it.

The go fast shop has no idea what tires, what sway-bars, what wheel weights, what vehicle weights, what ride heights, etc etc etc exist in my system. They wont hit the nail on the head for my car.

You have to understand where I am coming from, I have seen lots of engineers and math critical people (I am in Corporate Finance) spin themselves into a tizzy about "mathematically correct".

Unfortunately the mathematically "correct" settings seem to rarely work out in the real world. Hence why Pro Teams go to the track ballparked by their motorsports engineers and then play with spring rates from there. I don't blame you and I give you great respect for trying to teach your son good valuable teachings; I just have seen many go down the path and be completely off based on their findings.

Go at it, just make sure you do a gut check on your numbers to see how they compare to shop recommendations like Bimmerworld and Turner Motorsports who have tested with these actual platforms and gone up and down on the springs to find the right balance. And just because Tommy Milner likes it at 800/900; doesn't mean you will be fastest at those rates. At our Non-Pro level; confidence in having the car work the way you like it to is worth far more in seconds than a perfect setup.

[Fitzpadj]

Originally Posted by Visceral

Just because I came up with Brembo Z06 calipers, F80 rotors, and some cooling you think I didnt put thought into it. There are way too many people who wear their heart on their sleeve in the M3 brake debate; and yet half the fast BMW guys at the tracks around here are using stock calipers and rotors. This forum is not the best help in a scientific brake discussion. It's OK, I just know when to look elsewhere.

Not to double down, but it seems you are very insistent you are correct and no no one else is; I hope this is an attitude that changes when you get to the track as we are all here to have some fun