freetors
freetors Reader
9/17/18 6:47 a.m.

I've been spending some time codriving with a fellow at our local autocross events in an E street class NB Miata. He made a run at nationals this year but we are planning on making a much more serious effort next year. He already has the 1-1/8" Racing Beat solid bar on the front and we are still getting body roll in excess of our static camber. Photographically verified. The outside tires are going positive camber. So as the the title says, who makes the stiffest front sway bar that will work on a 2000 miata? The small fortune racing bar was interesting but it's way too much money and they list no specs for so I can't math out its stiffness. I come from the s2000 world, where I guess the owners are just nerdier, and the stiffness of pretty much every bar out there is known, in lbs/in of displacement. It's hard to find info like that in the miata realm.

Kylini
Kylini Dork
9/17/18 7:24 a.m.

After some googling (grain of salt):

Also grain of salt: http://www.fatcatmotorsports.com/FCM_Ride_Harmony_NB_Mazda_Miata_Online/FCM_Ride_Harmony_NB_Mazda_Miata_Online.htm

According to the 2nd link, the tubular 1.125 Racing Beat should provide 857 ft-lb/deg stiffness, so the Small Fortune might go stiffer. I'm not sure which torsion bar they currently sell/include in their kit.

Dusterbd13
Dusterbd13 MegaDork
9/17/18 7:43 a.m.

1 ton suburban front sway bar cut and welded on the arms to fit?

Motorhome maybe?

I know addco used to do custom stuff like this as well.

frenchyd
frenchyd SuperDork
9/17/18 7:56 a.m.

In reply to freetors :

If an 1 & w/8th isn’t big enough stop using solid bars. That’s adding too much weight to the front end. Bend up some 1&1/4 tubular steel. Bend it to the required shape and weld whatever ends you are currently using.  

Then take it to a spring shop.  Truckers break springs all the time and almost never buy new.  Tell the heat treater what steel you used and he will have it properly heat treated for you.  

If the rules allow it use a variable clamp so you can adjust according to what the tires are doing that weekend. Moving the clamp as little as an 1/8 of an inch can often make the difference. 

moxnix
moxnix HalfDork
9/17/18 8:52 a.m.

The bar that comes with the small fortune racing kit is the 1.25” diameter x .125” wall center bar.  You might be able to talk with them and get a different one i you buy direct from them I don't know.  A new center section is about $150.

captdownshift
captdownshift PowerDork
9/17/18 9:09 a.m.

Home Depot, they sell it under "steel rebar" it's about $28 for 12ft. 

ProDarwin
ProDarwin PowerDork
9/17/18 9:14 a.m.

 

Angle iron + welder

 

I'm a little surprised you are ending up with positive camber though, given the Miata camber curve.  Especially on street tires with the RB big bar. 

freetors
freetors Reader
9/17/18 9:40 a.m.

In reply to ProDarwin :

I'll post the pic when I get home. The problem is not only not enough bar, but also not enough spring rate, but we aren't allowed to change those.

I have some ideas where I could legally kill both of those with one stone. But it'll be kind of a bastardised mod.

codrus
codrus UltraDork
9/17/18 10:09 a.m.

FWIW, the 1.125 Racing Beat bar is tubular, not solid.  They also sell a 1.25" tubular front bar, listed as being for "NB2".  It bolts up to the NB1 just fine, though.

http://www.racingbeat.com/Miata-1990-2005/Sway-Bars/54106.html

 

freetors
freetors Reader
9/17/18 11:49 a.m.

Ok so I was mistaken in the op. The current bar is racing beats 15/16" solid bar. We're going to try out their 1-1/8" tubular bar and go from there. 

KyAllroad (Jeremy)
KyAllroad (Jeremy) PowerDork
9/17/18 1:14 p.m.

Since you are in there, upgrade the end links of the sway bar to get rid of the flex.

And i’m pretty sure the extended ball joints are class legal, that should get you plenty of camber.

Pete Gossett
Pete Gossett MegaDork
9/17/18 4:07 p.m.

I’m out of touch with Street class & not we’ll versed in NBs - do they suffer the weak front swaybar mounts like the NA, and are the Racing Beat swaybar braces legal in Street class?

buzzboy
buzzboy Reader
9/17/18 4:10 p.m.

Are there any rules stating you can't have two? Double  up on sway bars. Add the stock bar on to the current bar.

Stefan
Stefan MegaDork
9/17/18 4:51 p.m.

Sounds like you need more static negative camber. 

Keith Tanner
Keith Tanner MegaDork
9/17/18 5:31 p.m.
Pete Gossett said:

I’m out of touch with Street class & not we’ll versed in NBs - do they suffer the weak front swaybar mounts like the NA, and are the Racing Beat swaybar braces legal in Street class?

Actually, it's the NB with the weak mounts. Nobody even thought about sway bar mounts until the NB came along and started tearing mounts apart.

Our lower ball joints are definitely legal for Spec Miata, dunno about ES. Loads of camber, though.

Floating Doc
Floating Doc HalfDork
9/17/18 5:59 p.m.

I'm following this with great interest.

Certainly plenty of body roll in my NB2.

I expect it to be be a lot more pronounced when I get some decent tires.

freetors
freetors Reader
9/17/18 6:14 p.m.

Here's the car in question.

In reply to KyAllroad (Jeremy): Endlinks are already spherical bearings. Extended ball joints are not legal in scca street classes. Actually any method camber addition begotten by replacing parts is not allowed. It must be all standard parts and the range of adjustment you can get is what you are stuck with. Sidebar; strut based cars can usually add camber bolts if the factory service manual specifically allows it for correcting camber after a collision.

In reply to Stefan: Front camber is already maxed out. Rear isn't, but it's on my list of things I want to do.

 

Fun fact, we also preloaded all the bushings (except the lower control arm inner bushings since they have to be aligned at ride height) to try to get maximum lowness with factory springs.

red_stapler
red_stapler Dork
9/17/18 6:15 p.m.

Can’t you play with the bumpstops in Street?   Adding some stiffer MCU ones would be as good as increasing the spring rate.

The biggest swaybar isn’t going to limit bodyroll but pick up the inside front tire.

freetors
freetors Reader
9/17/18 6:27 p.m.
red_stapler said:

Can’t you play with the bumpstops in Street?   Adding some stiffer MCU ones would be as good as increasing the spring rate.

The biggest swaybar isn’t going to limit bodyroll but pick up the inside front tire.

We can change bumpstop stiffness, but not rate, as long as they are equal to or shorter than oem. We already have stiffer bump stops.

I am of the school of thought that for a rear wheel drive car, having a weight transfer bias that nearly picks up the inside front is the way to go. My STR s2000 is set up this way and many others are too in the same class. It drives freaking fantastically.

According to solostorm we are sustaining 1.1g in the miata in the corners. I think with a little more work it could be even better!

Floating Doc
Floating Doc HalfDork
9/17/18 7:25 p.m.
 

I am of the school of thought that for a rear wheel drive car, having a weight transfer bias that nearly picks up the inside front is the way to go. My STR s2000 is set up this way and many others are too in the same class. It drives freaking fantastically.

According to solostorm we are sustaining 1.1g in the miata in the corners. I think with a little more work it could be even better!

The reason I'm not going to just throw parts at my car: I don't know anything yet about the theory behind the engineering.

I need a mentor.

Keith Tanner
Keith Tanner MegaDork
9/17/18 9:32 p.m.

Once you pick up a wheel, all remaining weight transfer takes place at the other end. I've seen some BMWs set up that way, but I don't know if I've ever seen a Miata work successfully with air under the front tire. Could be a strut vs double wishbone thing, and I could be wrong.

I remember talking to a successful Spec Miata builder a few years ago about setup. He used to "accidentally" bend his upper control arms to get more camber.

freetors
freetors Reader
9/17/18 10:06 p.m.
Keith Tanner said:

Once you pick up a wheel, all remaining weight transfer takes place at the other end. I've seen some BMWs set up that way, but I don't know if I've ever seen a Miata work successfully with air under the front tire. Could be a strut vs double wishbone thing, and I could be wrong.

I remember talking to a successful Spec Miata builder a few years ago about setup. He used to "accidentally" bend his upper control arms to get more camber.

I will never claim that it's the end all be all in rwd car setup, but it is a formula that I know that works well. For the record, I don't think my s2k's inside front has ever become airborne with my setup. But I know it gets pretty close. According to my spreadsheet it should have less than 100 pounds load on while turning.

I did the alignment on this particular miata and I was really wishing we could do some things like that when we maxed out at a mediocre ~1.4*. But ethics got the better of us. There are so many parts of the car I can think of to tweak to edge out more camber and you'd would never be able to spot it by looking at it. But an astute competitor could measure it!

freestyle
freestyle Reader
9/17/18 10:26 p.m.

There a wealth of research on this on miata.net for NA and NB autocross setup. When I raced in STS there was a recipe for what works at a national level.  As I recall custom valved shocks and very specific alignment were the solution to winning in street class. This has all been done before and documented. 

 

https://forum.miata.net/vb/showthread.php?t=541008

ProDarwin
ProDarwin PowerDork
9/18/18 7:29 a.m.
Keith Tanner said:

 I don't know if I've ever seen a Miata work successfully with air under the front tire. Could be a strut vs double wishbone thing, and I could be wrong.

I imagine compared with BMWs this is a CG height/track width issue... 

Floating Doc
Floating Doc HalfDork
9/18/18 9:52 a.m.

In reply to freestyle :

Thanks for the link. Lots of useful information there. Unfortunately, the last post was from months ago, after it deteriorated into two and a half pages of someone arguing that his illegal clutch was actually legal.

Since then, everyone has migrated over to fake book. I'm not a user, not going to join.

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