MCS Suspension Talk & Setup Tips

[5thscaleracer]

Hello everyone I would like to know if anyone has experienced this.

Car info:
M3CS
Suspension MCS 2WNR GC camber plates with rear coil over shock.
Stock sway bars
stock bushings
SPL Sway bar links f/r

Issue:
Under hard braking the rear end picks up and gets very light to a point that the rear starts to do it's own song and dance. It feels like rear brakes are locking up. But whats happening is that the rear shock lacks the droop. Under hard braking there isn't enough weight or force applied to the rear wheels to maintain traction?

Hard braking as in entering T1 @ bigwillow going from 120mph to 80mph.

My proposed solution:
1. Lower the car more all around so there is enough droop in the rear
2. Stiffen the front shock settings
3. Grow some balls and don't brake as hard?

looking for thoughts and ideas to bounce off other people with a similar suspension setup.

Thanks in advance

[coolmody]

Spring rates? Alignment settings? I have a very similar setup, but don't experience this. .2 deg of total toe in at the rear and APR rear wing.

[5thscaleracer]

Originally Posted by coolmody

Spring rates? Alignment settings? I have a very similar setup, but don't experience this. .2 deg of total toe in at the rear and APR rear wing.

I have no Aero aside from the stock CS carbon bits.

Spring rates
800F
700R

Alignment

Front
Camber -3.25
Caster 7.7
Toe 0

Rear
Camber -2.7
Toe .1* In

Curb Weight 3792
50/50 cross distribution.

i need to put the car back on the rack and verify chassis ride height. The suspension has settled a little over the past week of usage.

[5thscaleracer]

Problem solved!

I was an idiot and didn't setup rear sway bar preload correctly. The sway bar links were tightened down when the rear suspension was unloaded.

This caused the sway bar to actually apply a downward force (creating a lift) on the rear end at all times vs being neutral.

I made this discovery when attempting to adjust ride height and there was resistance created by the sway bar.


problem solved have a good day everyone!

[coolmody]

That's more rear camber than I would run. I typically go between 1.8-2.0 especially since you have high spring rates. Remember camber helps in corners, but reduces performance under braking or acceleration.

[5thscaleracer]

Originally Posted by coolmody

That's more rear camber than I would run. I typically go between 1.8-2.0 especially since you have high spring rates. Remember camber helps in corners, but reduces performance under braking or acceleration.

Understood

This is actually the alignment specs that work for the track i will be visiting next.

My alignments are based on tracks so it's constantly changing.

DIY Alignments using hub stands is the best way to get it done.

With the swaybars properly loaded the issue is gone.

My normal track car is a 16V Merc but the F80 is seeing less garage time and more track time now. It's the 3rd stepchild that needs attention in 2022/2023 track day season.

[F80Speed77]

Checking out your springs rates, what front sway bar do you use and what setting?

I have FEAL 441+ with a full coilover rear and I'm running 800F 600R. I have the 30mm H&R bar at full stiff and I'm wondering if I had a little too much push mid corner to exit as I think my mid corner speeds were a little down this year. I don't have adjustable rear endlinks so perhaps they were causing bind? The car isn't super low in the rear though.

[5thscaleracer]

Originally Posted by F80Speed77

Checking out your springs rates, what front sway bar do you use and what setting?

I have FEAL 441+ with a full coilover rear and I'm running 800F 600R. I have the 30mm H&R bar at full stiff and I'm wondering if I had a little too much push mid corner to exit as I think my mid corner speeds were a little down this year. I don't have adjustable rear endlinks so perhaps they were causing bind? The car isn't super low in the rear though.

I am running Stock M3CS bar front/back not sure what size they are but i felt that the car didn't need a bigger bar.

Usually bigger bars on non aero cars will cause a push if you only do the front. Push usually mid corner maintaining throttle which is why you usually go larger in the rear to balance it out.

Right now i have more oversteer mid corner on power so i end up throttle steering as needed.

try the softest setting on the front bar see if that gets rid or some push.

i doubt sway links would make a hug difference.

[RSXDC5]

Adjustable sway bar endlinks enable proper corner balancing and best performance from the package.

[eXstasy]

Originally Posted by 5thscaleracer

Problem solved!

I was an idiot and didn't setup rear sway bar preload correctly. The sway bar links were tightened down when the rear suspension was unloaded.

This caused the sway bar to actually apply a downward force (creating a lift) on the rear end at all times vs being neutral.

I made this discovery when attempting to adjust ride height and there was resistance created by the sway bar.


problem solved have a good day everyone!

Glad you figured this out. I seem to have a similar problem though.

I have a base M3 but swapped in a rear OEM ZCP rear sway a while back. I installed SPL rear end links, and even adjusted to their shortest position, I cannot get them in without pushing up on the bar.

The ZCP bar in its natural resting point in the OEM bushings seems to have slight preload, applying a downward force. This is with the rear suspension fully loaded on ramps.

Is the rear of my car too low? Do I need to change out the OEM bar bushings or get aftermarket?

Current ride height with 19" wheels, measured from center of fender to bottom lip of the wheel:

Front 619mm (24 3/8”)
Rear 597mm (23 1/2”)

I didn't really want rake but it looks like I will have to raise the rear a bit.

[jfritz27]

Originally Posted by eXstasy

Glad you figured this out. I seem to have a similar problem though.

I have a base M3 but swapped in a rear OEM ZCP rear sway a while back. I installed SPL rear end links, and even adjusted to their shortest position, I cannot get them in without pushing up on the bar.

The ZCP bar in its natural resting point in the OEM bushings seems to have slight preload, applying a downward force. This is with the rear suspension fully loaded on ramps.

Is the rear of my car too low? Do I need to change out the OEM bar bushings or get aftermarket?

Current ride height with 19" wheels, measured from center of fender to bottom lip of the wheel:

Front 619mm (24 3/8”)
Rear 597mm (23 1/2”)

I didn't really want rake but it looks like I will have to raise the rear a bit.

Would prob just try raising rear first as you said. FWIW (obviously different suspension setup), for MCS installs BW recommends setting the rear 1/4" higher than the front (the reference measurement being taken ground-to-metal underneath the rocker panel near the front and rear jack points)

Edit: .... and they recommend setting the front so that there's a ~1" gap between top of tire and fender arch

[uncle ben]

Originally Posted by jfritz27

Would prob just try raising rear first as you said. FWIW (obviously different suspension setup), for MCS installs BW recommends setting the rear 1/4" higher than the front (the reference measurement being taken ground-to-metal underneath the rocker panel near the front and rear jack points)

Edit: .... and they recommend setting the front so that there's a ~1" gap between top of tire and fender arch

Any idea what they reccomend for dampner settings when starting out?

[jfritz27]

Originally Posted by uncle ben

Any idea what they reccomend for dampner settings when starting out?

Yep (obviously for 2-way -- their sheet kind of implies a remote setup as it mentions the canisters. So I suppose for 2WNR -- what I have but not yet installed -- these could be slightly different, but prob fair starting point nonetheless). From full soft:

Front: bump 9, rebound 10
Rear: bump 7, rebound 9

[RSXDC5]

Top of wheel arch to floor, 24in f&r
Bump/Rebound scale off of many different things, grip/aero/spring rate/tire stagger or square/track surface/etc.

On MCS 2wr, with a 305/325 stagger on a 100 treadwear track tire (oem sways), I like:
F: 5C 11R
R: 3-4C 11R

[jfritz27]

Originally Posted by RSXDC5

Top of wheel arch to floor, 24in f&r
Bump scales off of many different things, grip/aero/spring rate/tire stagger or square/track surface/etc.

On MCS 2wr, with a 305/325 stagger on a 100 treadwear track tire (oem sways), I like:
F: 5C 11R
R: 3-4C 11R

Thanks for this

Maybe we could keep this thread alive... if so inclined would be cool if others using this setup could chime in about their experiences with their preferred settings, with specifics as to why you changed what. And of course including other necessary details of your setup like RSXDC5 mentioned. I'm sure those of us like myself who are first venturing into the world of an adjustable suspension would appreciate it! Even if your setup differs in some of the details, getting a sense of the thought process on our specific platform could be helpful (I've done a lot of reading about the theory, but like everything else in-practice is another story).