rear sway vs no rear sway FCM calculator
#1
rear sway vs no rear sway FCM calculator
I've been reviewing the rear sway vs no rear sway, and it seems to be about 50/50 with what people choose to run.
Here is one thread https://www.miataturbo.net/showthrea...ate+calculator
Using the fcm calculator I was shooting for about a 61% F/R bias.
http://fatcatmotorsports.com/FRC_TUT...S_TUTORIAL.htm
Does the sway matter as long as you reach the desired bias?
i.e 400/250 with stock sway(61%) or 450/300 no rear sway(63%). The bias is basically the same (I don't think I would notice 2%, since it is an ideal estimate), but I like the idea of a little stiffer spring.
Here is one thread https://www.miataturbo.net/showthrea...ate+calculator
Using the fcm calculator I was shooting for about a 61% F/R bias.
http://fatcatmotorsports.com/FRC_TUT...S_TUTORIAL.htm
Does the sway matter as long as you reach the desired bias?
i.e 400/250 with stock sway(61%) or 450/300 no rear sway(63%). The bias is basically the same (I don't think I would notice 2%, since it is an ideal estimate), but I like the idea of a little stiffer spring.
Last edited by miatauser884; 12-20-2011 at 06:28 PM.
#3
Boost Czar
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I run teins with stock rates so 7/6K, with a 7/8" bar on the stiff setting, and the stock rear 12mm.
This brings me to like 51% FRC, or something. I love it; and that's coming from a calculated 60% (450/250). I don't want to change I thing. I'd have vairous other rates, ratios, and sway bar combos, and they all either pushed like a snow plow or were uncontrollable.
I agree with Sav, autoxing without the rear bar was impossible, I couldn't turn "nimbly". Any hairpins were a joke.
This brings me to like 51% FRC, or something. I love it; and that's coming from a calculated 60% (450/250). I don't want to change I thing. I'd have vairous other rates, ratios, and sway bar combos, and they all either pushed like a snow plow or were uncontrollable.
I agree with Sav, autoxing without the rear bar was impossible, I couldn't turn "nimbly". Any hairpins were a joke.
Last edited by Braineack; 12-20-2011 at 03:31 PM.
#9
OK, what bias is everyone else running? Brains bias surprised me. I thought the FCM thing was the bees knees. What should I be shooting for as far as bias? The FCM calculator suggests my current setup is a touch over 51%. I thought this felt a little tail happy in high speed cornering at the track. The car didn't loosen neutrally, but the back end started to break loose. However this was on a tight off camber turn. I was able to throttle steer easily on longer sweeping turns.
So rear sway in it is, now which one: FM front bar, stock rear with 450/300 nets 59.3%. FM rear bar 53%. Based on Brains review, keeping the the FM sways and changing springs seems like the way to go.
So rear sway in it is, now which one: FM front bar, stock rear with 450/300 nets 59.3%. FM rear bar 53%. Based on Brains review, keeping the the FM sways and changing springs seems like the way to go.
Last edited by miatauser884; 12-20-2011 at 06:50 PM.
#10
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that same bias in y8s car is pretty oversteery, but his rs2s are dead, they have no grip. maybe my car just has no power.
it's probably because of how my front bar is set. but then again he has an NB and a tubular front bar
id have to actually drive it myself again to tell the difference.
it's probably because of how my front bar is set. but then again he has an NB and a tubular front bar
id have to actually drive it myself again to tell the difference.
#11
OK, what bias is everyone else running? Brains bias surprised me. I thought the FCM thing was the bees knees. What should I be shooting for as far as bias? The FCM calculator suggests my current setup is a touch over 51%. I thought this felt a little tail happy in high speed cornering at the track. The car didn't loosen neutrally, but the back end started to break loose. However this was on a tight off camber turn. I was able to throttle steer easily on longer sweeping turns.
So rear sway in it is, now which one: FM front bar, stock rear with 450/300 nets 59.3%. FM rear bar 53%. Based on Brains review, keeping the the FM sways and changing springs seems like the way to go.
So rear sway in it is, now which one: FM front bar, stock rear with 450/300 nets 59.3%. FM rear bar 53%. Based on Brains review, keeping the the FM sways and changing springs seems like the way to go.
I don't really know if that makes sense, but that's the way I understand it.
As for a % number, if you look at xidas 800/500 add in the 1.125" RB hollow and either stock rear or 14mm mazdaspeed rear, you will find thats about 59-60% on the NB. I think thats pretty close to the setup that Emillio runs on the enduro cars (I don't really know what they ran), so thats a naturally aspirated car at ~150 hp.
if you are churbo'd you will need to put in other people's turbo setups in your general application and go from there.
#13
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I have those same spring rates and sway bars. The stock rear bar is on the car and the FM hangs on a hook in my garage. With the FM rear bar the rear has a slightly greater tendency to step out if you overcook a corner and I found myself tiptoeing through certain turns at VIR. With the stock rear bar the handling balance is more neutral, breakaway is much more predictable, and the car generally inspires more confidence IMO.
#14
Boost Pope
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Simple answer:
Set up suspension with stock rear bar in place.
Drive car.
Too much power-on oversteer? Disconnect bar.
Personally, I disconnected my rear bar after an... incident occurred on the street during which much tire smoke was generated and a small tree was uprooted by my rear bumper.
Set up suspension with stock rear bar in place.
Drive car.
Too much power-on oversteer? Disconnect bar.
Personally, I disconnected my rear bar after an... incident occurred on the street during which much tire smoke was generated and a small tree was uprooted by my rear bumper.
#15
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I don't care about the FCM set-up, 949's info is the king of fast cars around here. I don't like auto-x, but I could not enjoy a car with a soft swaybar. I'm running 700/400 springs, RB front sway, FM rear sway on middle setting, and the 949 alignment.
The real answer is the set-up that allows you to get the car in and out of the corner clean, fast, and comfortably. John drives my car a lot and we both agree that it's predictable and easy to drive, but my car is a tough stiffer in the rear and it's all personal preference. Follow Joe's logic.
The real answer is the set-up that allows you to get the car in and out of the corner clean, fast, and comfortably. John drives my car a lot and we both agree that it's predictable and easy to drive, but my car is a tough stiffer in the rear and it's all personal preference. Follow Joe's logic.
#16
In layman's terms, what does each hole in the FM ear bar represent. I just put it where Shaike said to, which made it the least intrusive (softer) iirc.
What does moving the bar from one position to another accomplish, and what is it doing to the geometry? I plan on running the stock sway since the softest setting on the FM seemed to cause oversteer in cornering. W
What does moving the bar from one position to another accomplish, and what is it doing to the geometry? I plan on running the stock sway since the softest setting on the FM seemed to cause oversteer in cornering. W
#17
I shoot for 57 on a lower hp Miata and 60 if you have a turbo. If you can't get the right bias with a rear bar them pull it until you can get a new set of springs. Changing the holes changes the spring rate of the car. I making this up as an example but let's say the three holes in a rear sway are 600, 650, and 700lbs. The stiffer you run the car the looser it will get. Sway bars are a tuning aid.
#18
In layman's terms, what does each hole in the FM ear bar represent. I just put it where Shaike said to, which made it the least intrusive (softer) iirc.
What does moving the bar from one position to another accomplish, and what is it doing to the geometry? I plan on running the stock sway since the softest setting on the FM seemed to cause oversteer in cornering. W
What does moving the bar from one position to another accomplish, and what is it doing to the geometry? I plan on running the stock sway since the softest setting on the FM seemed to cause oversteer in cornering. W
changing the attachment point, changes the arm length. by changing the arm length you are effectively changing the leverage point where the force is applied on the sway bar. the shorter the arm, the stiffer the bar.
Use your sway bar to fine tune balance. Ideally you would have an "infinitely" adjustable sway bar, but thats not really possible, so you make do with 2-3 settings. This is also not just 3 settings, as one side on stiff and one side on lesser will average out and is completely kosher to run (from my readings at least). Not sure about the mazdaspeed bar, I would assume that its one setting, but I seem to have enough adjustability in my front bar for all the balancing I need. That may change as I get faster though, I still have to take this setup out to CMP which is probably my strongest track at this point.
#19
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Moving the attachment point further away from the fulcrum point increases the effective length of the arm, which has the same effect as softening the bar.