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Author Topic: Sways vs. spring rate (long and a little technical)  (Read 15092 times)
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Woofster
I love humanity. It's people I can't stand!
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2005 MSM Ti #1255


« Reply #30 on: March 16, 2011, 05:41:00 PM »

Wanted to show an image of my car being tossed pretty hard into a Chicago box close to the top of 2nd gear to give an idea of how much roll angle the car showed (not much).  I have another photo of my friend's Stock NC on similar rubber (Hoosier A6) in a similar situation for comparison but the gallery is being finicky about letting me upload that image (looks like a sailboat at 30 degrees list). 

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Hydra Nemesis; 550 injectors; Flying Miata Full Intake Kit w/MBC (MAFless) & GFB recirculating bypass valve; Flying Miata DP; Flying Miata Full Exhaust; FMIC 28X7X2.5; Fat Cat Motorsports Elites (single adjustable) 800/500; Racing Beat 1.25" Tubular Front Sway bar w/Brace Kit and Gearheads Gauge Adjustable endlinks; OEM 14mm rear sway bar; FM Frame Rails; HDHCDDHT Rollbar; Hard Dog Harness Bar; G-Force 6-Point Pull-Down Camlock Harness; Ultrashield Rally Sport Seat; Energy Suspension Diff Bushings; Carbotech XP10/XP8 Brake Pads;  Stainless Steel Brake Lines; 15X9 6ULS (Nickel) & BF Goodrich g-Force Rival (225/45/15) street; 15X9 6ULS (Nickel) & Hoosier A6 (275/35/15) track; 15X9 6ULS (Nickel) & Hoosier H2O (225/45/15) wet track; Stewart-Warner Boost Gauge; Thompson Nautilus Air Horn; Mobile 1 0W-30; Redline MT90; Redline 75W90; BEL-tronics Pro RX65. 1/20/08 190.06 HP @ 178.36 Max Torque (Need a new Dyno run because this is inaccurate with current mods!)
"Racing...is life!  Everything that happens before and after is just waiting."  -  Steve McQueen in Le Mans
'95MSM
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Turbo clocked downward, new i/c plumbing


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« Reply #31 on: March 16, 2011, 07:48:55 PM »

I think we all know there are mechanical reasons to increase roll stiffness and there are "feel" reasons, as gtred has posted.  Even if tuning for the driver's preferences, I would suggest that doing it with spring rate is still preferred.  It will also build confidence under braking.
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'05 running gear + '95 body
3.63 ring & pinion FM content: Blouch compressor mod, FM-Link, i/c & no-MAF intake.   BEGi: Stainless SGDP w/ metal core performance cat.   Custom stuff: Compressor clocked downward w/ new i/c pipe, big radius throttle elbow, 2.5" mid-pipe w/ Hushpower II, dual 2" axle-back w/ open Supertrapps, Toyota 4 pc cop ignition

245.2 whp on default FM-Link maps (with OEM midpipe)
'95MSM
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Posts: 6076


Turbo clocked downward, new i/c plumbing


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« Reply #32 on: March 16, 2011, 07:56:01 PM »

Check out the deflection in Woof's rear tire.  If the car was parked at that angle, we should see the same amount of sidewall at 1:00 and 5:00.  Looks loaded up pretty good to me!  Too bad the shadow is masking the front tire.
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'05 running gear + '95 body
3.63 ring & pinion FM content: Blouch compressor mod, FM-Link, i/c & no-MAF intake.   BEGi: Stainless SGDP w/ metal core performance cat.   Custom stuff: Compressor clocked downward w/ new i/c pipe, big radius throttle elbow, 2.5" mid-pipe w/ Hushpower II, dual 2" axle-back w/ open Supertrapps, Toyota 4 pc cop ignition

245.2 whp on default FM-Link maps (with OEM midpipe)
Woofster
I love humanity. It's people I can't stand!
Fifth Gear
*****
Posts: 4758


2005 MSM Ti #1255


« Reply #33 on: March 16, 2011, 08:55:49 PM »

The Gallery finally accepted this photo!
Here's the shot of my friend's Stock NC at relatively the same cornering level (note hand positions in both photos).  The car is always on the podium and, even with the stock roll, handles extremely well.  All four tires are nicely planted...
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Hydra Nemesis; 550 injectors; Flying Miata Full Intake Kit w/MBC (MAFless) & GFB recirculating bypass valve; Flying Miata DP; Flying Miata Full Exhaust; FMIC 28X7X2.5; Fat Cat Motorsports Elites (single adjustable) 800/500; Racing Beat 1.25" Tubular Front Sway bar w/Brace Kit and Gearheads Gauge Adjustable endlinks; OEM 14mm rear sway bar; FM Frame Rails; HDHCDDHT Rollbar; Hard Dog Harness Bar; G-Force 6-Point Pull-Down Camlock Harness; Ultrashield Rally Sport Seat; Energy Suspension Diff Bushings; Carbotech XP10/XP8 Brake Pads;  Stainless Steel Brake Lines; 15X9 6ULS (Nickel) & BF Goodrich g-Force Rival (225/45/15) street; 15X9 6ULS (Nickel) & Hoosier A6 (275/35/15) track; 15X9 6ULS (Nickel) & Hoosier H2O (225/45/15) wet track; Stewart-Warner Boost Gauge; Thompson Nautilus Air Horn; Mobile 1 0W-30; Redline MT90; Redline 75W90; BEL-tronics Pro RX65. 1/20/08 190.06 HP @ 178.36 Max Torque (Need a new Dyno run because this is inaccurate with current mods!)
"Racing...is life!  Everything that happens before and after is just waiting."  -  Steve McQueen in Le Mans
bigx5murf
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« Reply #34 on: March 21, 2011, 02:44:20 AM »

Just finished reading this thread. What an informative wealth of info!

My question now is how does chassis stiffening such as those provided by frame rails, butterfly brace, and control arm braces affect things?
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mr_hyde
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« Reply #35 on: March 21, 2011, 04:16:28 AM »

Big can of worms there.  Grin  When a chassis flexes like it does in a miata (open top), it becomes part of the suspension effectively adding to the spring travel and dampening.  This is not as bad as it sounds a lot of the time but can make the tuning and response of the overall suspension system difficult and unpredictable.  Everything works best when the chassis is stiff and bumps, roll and weight transfer can be handled by the springs and shocks.
-h
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2005 Black Mica #290 8/27/04 w/Factory Hard Top
BEGi Intake, FM Downpipe.  Nice and calm with an edge...

1990 Red - MSM Drivetrain, Adaptronic EMS, Xida 700/400, 15x9 6uls, Full Cage, SGDP w/80mm Corksport exhaust, ~260whp @ 15psi on Forged Rods.  bow2
Build Thread: http://www.mazda-speed.com/forum2/index.php/topic,24668.0.html

2000 BMW M5 - The Falcon - Daily Driver  reddevil

2003 E350 7.3 Powerstroke Ambulance for towing '90MSM to play dates.

1991 BRG - Daughter's daily driver.
bigx5murf
Fifth Gear
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Posts: 2458



« Reply #36 on: March 21, 2011, 03:46:21 PM »

Big can of worms there.  Grin  When a chassis flexes like it does in a miata (open top), it becomes part of the suspension effectively adding to the spring travel and dampening.  This is not as bad as it sounds a lot of the time but can make the tuning and response of the overall suspension system difficult and unpredictable.  Everything works best when the chassis is stiff and bumps, roll and weight transfer can be handled by the springs and shocks.
-h

I remember from your posts, you actually have the frame rails and butterfly brace.  In theory they should both give the coilovers a better platform to work off.  I'm eager to hear your personal experiences and/or opinions w/ this combo relative to handling?

I think Keith from FM only recommends the frame rails on our cars.  I believe he said the NB came w/ something similar to butterfly braces from factory.
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newold_m
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« Reply #37 on: March 21, 2011, 04:43:52 PM »

I gather you have not peeked under your car..: Smiley 

Here is the factory bracing:

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'04 MSM: sold
bigx5murf
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« Reply #38 on: March 22, 2011, 02:03:57 AM »

I've actually removed that brace to install my down pipe.  It doesn't look as robust as the FM butterfly, and i remember it feeling rather light too.  Also, the nuts weren't torque'd on particularly tight either.

Also, when i reinstalled it, I left one nut kind of loose.  Didn't realize till I started checking what was making this "thunk" sound.  Which only happened on really broken'd up road.
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'95MSM
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Turbo clocked downward, new i/c plumbing


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« Reply #39 on: March 22, 2011, 05:28:31 AM »

That particular piece doesn't deserve to be called a brace.

In a nutshell, a stiffer chassis is more predictable when making changes to spring rates, shock dampening and sway bar selection.  Hyde and I both have full butterfly braces, but you have to remove the dip in the exhaust where the dp ends and the midpipe begins.
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'05 running gear + '95 body
3.63 ring & pinion FM content: Blouch compressor mod, FM-Link, i/c & no-MAF intake.   BEGi: Stainless SGDP w/ metal core performance cat.   Custom stuff: Compressor clocked downward w/ new i/c pipe, big radius throttle elbow, 2.5" mid-pipe w/ Hushpower II, dual 2" axle-back w/ open Supertrapps, Toyota 4 pc cop ignition

245.2 whp on default FM-Link maps (with OEM midpipe)
bigx5murf
Fifth Gear
*****
Posts: 2458



« Reply #40 on: March 22, 2011, 06:29:35 AM »

What do you mean by remove the dip?  If I recall, that's exactly where the o2 sensor threads in.  On my dp at least, the o2 sensor doesn't thread in on an angle like the stocker, but rather perpendicular.
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mr_hyde
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Midlife Crisis on Wheels!


« Reply #41 on: March 22, 2011, 09:13:44 PM »

There is a dip at the union of our downpipe and midpipe that goes below the plane of the butterfly brace. I'm not sure why it is there but every aftermarket msm part comes with it also to maintain cross compatibility. I have the section I had cut out and I'll post a picture when I get home.
-h
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2005 Black Mica #290 8/27/04 w/Factory Hard Top
BEGi Intake, FM Downpipe.  Nice and calm with an edge...

1990 Red - MSM Drivetrain, Adaptronic EMS, Xida 700/400, 15x9 6uls, Full Cage, SGDP w/80mm Corksport exhaust, ~260whp @ 15psi on Forged Rods.  bow2
Build Thread: http://www.mazda-speed.com/forum2/index.php/topic,24668.0.html

2000 BMW M5 - The Falcon - Daily Driver  reddevil

2003 E350 7.3 Powerstroke Ambulance for towing '90MSM to play dates.

1991 BRG - Daughter's daily driver.
mr_hyde
Global Moderator
Fifth Gear
*****
Posts: 7213


Midlife Crisis on Wheels!


« Reply #42 on: March 23, 2011, 12:27:30 AM »

Here is the dip being discussed.  This is a BEGI SGDP end attached to an 80mm Corksport midpipe.  I had a buddy at a muffler shop chop it out to allow the butterfly to fit.  At the same time, he moved the flex joint on the Bell pipe behind the O2 sensors instead of in front of them.  This allowed me to use the FM brace to the transmission to make the engine, exhaust manifold, turbo, downpipe and transmission all one solid piece with no flex.  My hope is that this helps a small bit with the 8mm studs on the turbo that like to come loose on the track.  I burned a hole in my favorite pair of gloves torquing those down last summer...  Angry

Note:  Let's not discuss the turbo studs or the dip here further than it pertains to sways, springs and the sister-topic of chassis stiffness.  Start a new thread for that  thumup


-h
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2005 Black Mica #290 8/27/04 w/Factory Hard Top
BEGi Intake, FM Downpipe.  Nice and calm with an edge...

1990 Red - MSM Drivetrain, Adaptronic EMS, Xida 700/400, 15x9 6uls, Full Cage, SGDP w/80mm Corksport exhaust, ~260whp @ 15psi on Forged Rods.  bow2
Build Thread: http://www.mazda-speed.com/forum2/index.php/topic,24668.0.html

2000 BMW M5 - The Falcon - Daily Driver  reddevil

2003 E350 7.3 Powerstroke Ambulance for towing '90MSM to play dates.

1991 BRG - Daughter's daily driver.
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