When I see spring rates of 800 lbs mentioned for a Miata I immediately think of the quote from Colin Chapman ( or maybe Smokey Yunik) that says "Any suspension will work if you don't let it"
When I see spring rates of 800 lbs mentioned for a Miata I immediately think of the quote from Colin Chapman ( or maybe Smokey Yunik) that says "Any suspension will work if you don't let it"
Keith, do you have a sway bar recommendation for the FM Fox suspension? I will wait until I have whatever new suspension installed with new wheels and aligned and adjust from there, but if there is a proven formula, I'm all ears...
Sway selection for the Fox depends on what you're doing with alignment, as noted before. On my car with the 750/500 springs, aero and a high power/weight ratio, I'm running the FM front bar and a MSM rear combined with 949 alignment settings. The mechanical grip is set up a bit more for oversteer than is the current fashion, but I have it set up with a bit more rear aero grip. Makes it easy to turn in slow corners and stable in fast ones.
We tried 1100 lb front springs back in 2003 when we were trying to make a car work. They're still sitting on the shelf on the shop.
I came to a realization today. I'm currently cruising around Denver in a loaner BMW X1. And the suspension is crap. I think it's trying to be sporty, but the overall ride quality is not something I'd consider DD quality on an aftermarket Miata suspension. It's not as good as a set of 750 lb springs on Foxes. My E39 M5 is in a different league in both body control and ride quality even though it's 15 years old with 117k on it and riding on steamroller tires.
This may be why people are so happy with 800 lb front springs on street Miatas. The standard of comparison has shifted. I'm using things like the M5 as my benchmark, but that's not what others are necessarily comparing them to. This is not an old man "things aren't as good as they used to be" rant, because there's no technical reason for the X1 to have crap suspension. It was BMW's choice for some reason.
I've noticed a lot of new cars have horrid suspension. Soft springs, but excessive low speed compression damping to make it feel "sporty". So it's compliant on huge bumps but rides like crap on small rough spots. And they're usually pretty under-damped in rebound. I had a pretty new Ford Fusion rental at one point where hitting a certain dip in the road about 55 would shove it to the bumpstops, rebound to several inches above ride height and then settle and bounce back up again before it calmed down.
For some reason, that harsh / floaty combo seems to be the new "normal", but in reality, it's awful. Goes right along with very light, very fast ratio steering in my book. Why the heck does a Civic need a rack so fast that it's barely over 2 turns lock to lock (and it's HARD to go straight on the highway with steering that fast unless you keep a very light touch on the wheel and never hold it).
NOHOME wrote:
Colin Chapman, paraphrased. Comes from a notebook of his that's on display in a museum.
Thanks again for the info, folks. After pondering with Keith had to say in this thread plus talking to a few suspension gurus, I decided to give FM Fox a try with the standard spring rates. The prevailing thinking on 700lb plus springs essentially boils down to the idea that I will want them should I decide to drive on full R comps, but otherwise don't need that much spring, as long as I have enough travel. The extra travel of the FM Fox setup, plus the new higher recommended ride heights should guarantee enough travel. If 550 doesn't get me there, it is comforting to know the Fox shocks can handle higher rates.
I'll post back after I've had a chance to install and baseline them.
In reply to Keith Tanner :
I'm currently looking at upgrading my wheel and tire package on my 99 NB. Its an under developed SSM car that I have been autoxing competitively for my first full season this year, after a several years in ESP and then a few in BSP with my air cooled 911. Now that I am used to the car, I'm finding that if im too aggressive on corner exit the back end washes out, and the tires progressively get worse and I end up slowing down. Current springs are 500/350 with FCM Bilsteins. RB 1 1/8 front bar, stock 11mm rear. I'm on 15x9 6UL with 225 A7, and I feel like I'm just asking too much of the tire considering the power. Our local event site is very bumpy, and so this softer set up seems to be working well, I just feel like the tires are giving up at the limit.
Ive been told that a move to larger wheels and tires would require a spring rate change, but I am nervous about upsetting a very well balanced car. The plan was to move to a 15X11 wheel and a 275, which may be overkill, but I do not want to upgrade again a year later if I go with 10's and its not enough. This may be slightly off topic fom the OP question, but it does sort of make me wonder about the soft VS firm discussion and would really like some input from folks with more experience with the NB Miata.
Cheers!
In reply to tripower4speed :
You can step up two sizes on your Hoosiers and stay with the 9” wheels you already have.
That’s the easiest answer and as you said, the car IS well balanced still. So don’t change anything else just now and get a set of 275s. Also, what pressures are you running? My CSPish car with 275s on a 9” wheel is down to 21f and 19r. Softer tire gives more compliance and grip, especially on a rougher course.
You “may” try taking the rear bar off entirely, personal preference but I found it just made the car oversteer more.
In reply to tripower4speed :
Honestly, I'd recommend you talk to Emilio over at 949 Racing. He's got more experience with your sort of use case than I do. He and I will agree that your suspension is currently holding you back.
Jeremy, if you got oversteer by removing the rear bar, it's probably because you're now rolling on to your bumpstops.
In reply to Keith Tanner :
Umm, I probably wasn’t clear. With a rear bar in place the car oversteers. To tame the rear end I had to take the bar off. It’s pretty common in cone dodging circles.
Okay, that makes more sense. Yes, cone dodgers seem to set their cars up with softer roll stiffness in the rear than track or street cars.
In reply to tripower4speed :
You need extra travel on the rear, which you can get with extended top hats. Your springs are a bit soft too. What’s your alignment settings?
I’d love to hear back from SteveDallas to see how the FM Fox setup worked out for him.
Thread necro:
I ran the Fox coils with 500/375lb 8" springs at a rallycross last week and we were 4th out of 12 in modified RWD after 5 runs. I've never run on dirt before. They are fantastic, end of story. I wound them up to a bit over stock ride height.
This thread is originally from 2016 but since it was bumped I'll say that I have the FM Fox setup for a street/track setup on my rotrex NA and I absolutely love them. Best coilover for mixed use IMO.
Running Xida Race setup here. Believe the hype, it's incredible.
And since the last time we visited this thread, I've turned that 750/500 Foxy track car into a street car for occasional use. It works better than it should, although it's clearly a car with performance priorities.
But I've also been playing with higher rear rates on the NA/NB Foxes and have been quite happy with the results. Hasn't been made the default yet, but 550/450 is getting thumbs up from anyone who's tried it.
calteg said:Running Xida Race setup here. Believe the hype, it's incredible.
Also running the Xida Race coilovers, with the 800lb front/500lb rear springs. Night and day transformation on how the car is when autocrossing. Incredibly fast and much easier to drive than on the FM/VMAXX Classics. And honestly, I don't think that it rides any worse on the street. Pricey, but worth every penny.
It's probably worth noting that the Xida Race cost more than 3x as much as a set of V-Maxx Classics :) The V-Maxx are a great value for the money but they're sure not in the same league as the Xida or Fox.
Keith Tanner said:It's probably worth noting that the Xida Race cost more than 3x as much as a set of V-Maxx Classics :) The V-Maxx are a great value for the money but they're sure not in the same league as the Xida or Fox.
Oh, that was not a dig at the Classics. They were good when my car was a mild 1.6L-powered mostly-street car on 205-width tires. When I went to 250whp and 245-width 200tw tires and was autocrossing it frequently, I was really just overwhelming them. But I was surprised that doubling the spring rate really had no noticeable effect on ride quality.
Of course all the people who own Fox and going to rave about them and Xida is no different, but has anyone owned and used both extensively? I think everything I read points to either Fox or Xida being the top dog. Xida probably the best for shaving every last 1/10th racing and Fox being great for a dual purpose car. Also I suppose use cases can be different and what I think is acceptable ride quality on the street (and how good/bad the street/track is of course) is almost certainly different than other people.
I've had the chance to drive both, and I think you've got a pretty good assessment of the two. I think the Fox work better in more conditions than the Xidas, but the latter are hyper-focused on lap time on a set up track car, especially when built to a specific recipe. The "Supermiata" platform is pretty well developed.
Keith Tanner said:And since the last time we visited this thread, I've turned that 750/500 Foxy track car into a street car for occasional use. It works better than it should, although it's clearly a car with performance priorities.
But I've also been playing with higher rear rates on the NA/NB Foxes and have been quite happy with the results. Hasn't been made the default yet, but 550/450 is getting thumbs up from anyone who's tried it.
Just noticed this... Interesting! So, if you're changing the F/R ratio this much, would I benefit from running a stiffer spring in the rear (currently 750/500)?
I guess it's cheap enough to experiment with different rates.
That's what I'm doing. My V8 car is a little bit of an outlier so I haven't don't too much testing of the new rates on that one, but it would be worth a shot. You'll want an alignment and sway bar setup to match, don't just stick the big rear springs in there.
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