Adjustable control arms for Miata

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Dan133
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Adjustable control arms for Miata

Post by Dan133 »

Ok... In order to have a shot at winning smallbore without becoming an appreciably better driver I am now looking into control arms that will allow me to increase the amount of negative camber in my NB miata. Does anybody have any knowledge they'd be willing to share about the different options? Information on the internet seems to be much slimmer than what was available for shock/spring upgrades.

Respectfully Awaiting Enlightenment,

Dan
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Re: Adjustable control arms for Miata

Post by echan »

I know that when Joe Seward and I increased the negative camber on the TR6, it made a world of difference. Although, I'm sure one can get to a point where negative camber doesn't help anymore and may even hurt you with less tread on the road.

We also increased the caster which is also good. I think of caster as negative camber on the wheel that's needed when you turn. So to me, the more caster the better.

Just out of curiosity, if you get those special control arms, can you dial in more positve (less negative) camber for street driving and then dial in more negative for the autocross? That way you can still enjoy the car as a street car? Both the TR6 and the Sprite aren't really fun to just drive around on the street. It seems the more the car deviates from stock the less "streetable" the car becomes.
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Re: Adjustable control arms for Miata

Post by Dan133 »

I don't know, Ed. This is a feeler thread. I would assume that adjustable would mean just that. I would hope to be able to adjust in extra neg camber for an autocross and then back it out for street driving. I don't want to turn the car into an autox only vehicle. That is why I'm not stripping the interior and the 'tupperware'.
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Re: Adjustable control arms for Miata

Post by Dan133 »

And I don't think that I really understand how caster works(what it does). But mine is maxed out according to the shop that does my alignments.
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Re: Adjustable control arms for Miata

Post by konkilr »

Castor allows the top of the wheel to tilt as you turn. Think of it as how a skier leans to turn. The tires tilt adding camber on the outside wheel and reducing camber on the inside wheel. The more caster the better for autocross. I custom modified the suspension on the SUXASS to get the caster angles I wanted.

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Re: Adjustable control arms for Miata

Post by eage8 »

Adjusting camber at the autocross and then adjusting it back might cause alignment issues. i know with my cars if I add camber it does stuff to the toe... but my cars also just have mcpherson struts.

but yeah, you'll want to also try to get some arms that can add additional caster at the same time, I don't see why they couldn't make arms that did that.

EDIT: now that I thought about it, it'll mess with toe for the same reason mine does. you tilting the hub and the tie rod mount is static so there for the hub is going to pivot on the tie rod and change toe at the same time.
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Re: Adjustable control arms for Miata

Post by Dan133 »

I see what you mean, Eage. When I lowered the car on the Ground Controls I picked up a little toe out in addition to a little additional neg camber. I guess the question would be where the tie rod connects to the hub.
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Re: Adjustable control arms for Miata

Post by eage8 »

I'm pretty sure the tie rod connects to the hub on the front of the hub on the miata. so if you were to add camber you would get more toe out like you did when you lowered it. I added a lot of camber to my RX-7 at an auto-x (with camber plates) and it didn't feel right. I think I got way too much toe out. I would suggest just adding in a significant but not extreme amount of camber and just keeping it that way (maybe like -2 degrees)
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Re: Adjustable control arms for Miata

Post by echan »

Like Jake said, "the more the caster the better for autocross." I really don't thing of any negative except that the steering wheel is heavier as you increase caster. One way to think of caster is to think of a motorcycle vs. a chopper. The chopper has tons more caster than the motorcycle and as the chopper turns the wheel the wheel leans to the side. However, turning a chopper is heavier than the motorcyle (assuming equal handle bar length).

When we stripped 200 pounds off the TR6, those that drove the car thought the steering was super light and fast. In reality is was light because of the reduced weight but not any faster than stock steering ratio. The difference in ratio was just an illusion. Then we changed to Jaguar upper ball joints with shims to increase caster. It made the steering heavier but the overall effect was to bring the feeling about stock, which is a little heavy (or as Denise Dersin would say "I can't turn this car's steering wheel").

It makes you realize how the old cars had big steering wheels for added torque and all the race car drivers had big forearms to turn the car - gives really meaning when they say "it's a man's car" because only muscle men can turn the car!
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Re: Adjustable control arms for Miata

Post by Dan133 »

does anybody have any experience with this product or something similar? http://www.awrracing.com/blog/2009/05/1 ... -for-miata
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Re: Adjustable control arms for Miata

Post by konkilr »

No experience but that product looks great. However I dont see it being a real needed item. The front end is the end to concern most with. When the rear starts getting real loose, then I would consider those arms. You need something like that for the front that allows caster and camber adjustment.

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Re: Adjustable control arms for Miata

Post by Claff »

I think it'd be easier and cheaper to just become an appreciably better driver.
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Re: Adjustable control arms for Miata

Post by eage8 »

Dan133 wrote:does anybody have any experience with this product or something similar? http://www.awrracing.com/blog/2009/05/1 ... -for-miata
AWR is great. Everything the sell is really nice, I have a lot of their stuff on/waiting to be put on my RX-7. It's a shame that's only for the rear end it doesn't look like they make one for the front.

If you do end up getting those, I would get the ones with the mazda comp bushings. delrin is too stuff for the street and mazdacomp are just a bit stiffer than stock.

in my experience you don't need/want a lot of camber in the rear though. that's one of the things that's wrong with my RX-7 right now, I have way too much camber in the rear and I'm actually trying to get rid of it because I can't get enough grip.
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Re: Adjustable control arms for Miata

Post by eage8 »

After a quick google search I found these:

http://www.epmiata.com/store/Suspension/TMDKCA000.html

they look decent, but I'm not sure if you'd be able to adjust caster, you might be by adjusting the 2 sides in opposite directions.
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Re: Adjustable control arms for Miata

Post by milkmandan »

http://949racing.com/tubularcontrolarms90-05miata.aspx

for the money you'd get a larger gain from going to 275's on a 9" or 10" wheel IMO. CSP cars don't get to use custom control arms.
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Re: Adjustable control arms for Miata

Post by konkilr »

Increasing castor will make any tire work better. You may not need as wide of a tire when you have enough castor.

A trick we always do to subaru's is by removing some of the rear camber. This is one of the main causes of understeer in a subaru. The rear just grips too much.

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Re: Adjustable control arms for Miata

Post by moxnix »

milkmandan wrote:CSP cars don't get to use custom control arms.
Yes they can if they want.
Solo Rules wrote:15.8.H. Camber kits, also known as camber compensators, may be installed. These kits consist of either adjustable length arms or arm mounts that provide a lateral adjustment to the effective length of a control arm. Alignment outside the factory specifications is allowed. The following restrictions apply:

1. On double/unequal arm (e.g. wishbone, multi-link) suspensions, only the upper arms OR lower arms may be modified or replaced, but not
both. Non-integral longitudinal arms that primarily control fore/aft wheel movement (e.g. trailing arm(s) or link(s) of a multi-link suspension) may not be replaced, changed, or modified.
I don't know if any of the CSP cars are running them or not yet but it would not surprise me if nothing else just for the weight savings.

What is the problem you are trying to solve?
Can you not get enough camber or do you just want to be able to adjust it back and forth for street driving?
How much are you currently at?
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Re: Adjustable control arms for Miata

Post by Dan133 »

I am looking for more ultimate grip. The Miata is inherently tail-happy and i am currently maxed for neg camber in rear. Understeer is not my problem with this car as it currently sits. Of course as soon as I get the rear to stick better I will drive faster until the front starts to slide and then will need a solution to the understeer. A vicious circle. But soooo much fun!
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Re: Adjustable control arms for Miata

Post by david.valeri »

Dan133 wrote:I am looking for more ultimate grip. The Miata is inherently tail-happy and i am currently maxed for neg camber in rear. Understeer is not my problem with this car as it currently sits. Of course as soon as I get the rear to stick better I will drive faster until the front starts to slide and then will need a solution to the understeer. A vicious circle. But soooo much fun!
I have a minor bend on one side of my front suspension so it is maxed out camber wise. I think I need more negative camber in the front based on the tire temperatures I have taken at a couple events and the wear pattern on my front tires, but I'm not ready to take the plunge yet. Before either of us spends money, I would be willing to exchange pit crew duty with you to get good tire temperature measurements from all four corners. I can't always get in and out of the car fast enough with the harnesses so I would be happy to help you out if you would help me out.

If you know your tire temperatures, you can figure out if t is an air pressure thing, an alignment thing, an insufficient heat in the tires thing, or a ham-fisted driver ting.

Additional caster has the advantage of adding camber only in a turn so you maintain more contact area during straight line braking. The disadvantages are increased steering effort. Since you have power steering, that is probably not an issue for you. Here is a picture of castor angle: http://en.wikipedia.org/wiki/File:Caster_angle.svg. For me, with the smallest steering wheel there is and no power steering, adding more castor probably isn't a good idea.

Have you tried running without the rear sway bar or adjusting the tire pressure front to rear bias?

As for the aftermarket control arms, you can still adjust castor using the eccentric bolts on the lower control arm in the front. If your camber is maxed out in the negative direction, then adjustable upper arms like the one from epmiata can help to pull the upper ball joint inwards and get you more negative camber. Alternatively, the lower arms from 949Racing let you slide the lower ball joint outwards achieving the same goal.

Here are the ones I have found that haven't been listed already:

1) http://www.flyinmiata.com/index.php?dep ... %20%20LEFT. Looks to be the same as the ones at 949, but at half the cost.
2) http://iscracing.net/miatasuspension.html ISC offers eccentric delrin bushings for the upper control arm, but I heard bad things about clearances around the spring as well as the settings slipping and changing your alignment.
3) Somebody makes a blue powder coated set that I can't seem to find again. It may be the ones on epmiata.
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Re: Adjustable control arms for Miata

Post by moxnix »

Dan133 wrote:I am looking for more ultimate grip. The Miata is inherently tail-happy and i am currently maxed for neg camber in rear. Understeer is not my problem with this car as it currently sits. Of course as soon as I get the rear to stick better I will drive faster until the front starts to slide and then will need a solution to the understeer. A vicious circle. But soooo much fun!
How much camber is max? Depending on springs and ride height that can be anywhere from ~1.5 to 4+
I would be looking at alignment, spring rates, and sway bars before I went to new control arms.
Have you used the suspension design spreadsheets on FCM to see what you current Front Roll Couple is?
david.valeri wrote: 1) http://www.flyinmiata.com/index.php?dep ... %20%20LEFT. Looks to be the same as the ones at 949, but at half the cost.
They are the same price as the 949 racing ones (They are sold as singles on FM for $350 and as a pair on 949 for $700) You will need a pair anyway.
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Re: Adjustable control arms for Miata

Post by david.valeri »

moxnix wrote:
david.valeri wrote: 1) http://www.flyinmiata.com/index.php?dep ... %20%20LEFT. Looks to be the same as the ones at 949, but at half the cost.
They are the same price as the 949 racing ones (They are sold as singles on FM for $350 and as a pair on 949 for $700) You will need a pair anyway.
Oh. I see what they did there. With their fancy subtraction.
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Re: Adjustable control arms for Miata

Post by eage8 »

Dan, do you have aftermarket sway bars? I've seen several guys that put the stock rear sway bar back on for the same reason you're describing, lack of rear grip. On my rx-7 I'm going to an even greater extreme and removing the rear sway bar entirely.
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Re: Adjustable control arms for Miata

Post by konkilr »

We treid removing the rear sway on the suxass but saw no difference over a stock rear sway. We prefer to keep the sway on. The only testing we did was checking droop travel and there was no difference. Try jacking a rear corner and measure the height the fender reaches before the tire comes off the ground. Then disconnect the rear sway and check again. This will tell you if the bar is making a signifigant difference or not. In our case the larger bar was causing us to lift an inside rear tire causing wheel spin. We needed to keep the rears planted to come off the corners better.

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Re: Adjustable control arms for Miata

Post by kyle.bowker »

The AWR RUCA are primarily for people runnning very low ride heights (<11.5" from center of the hub to the fender lip) who want to dial out excessive negative camber. If you want more camber than what your factory eccentrics will allow the offset control arm bushings should get you all that you need. The trick to winning small bore with a Miata would be 6ULs wrapped in sticky rubber and a short rear end ratio. And good driving.
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Re: Adjustable control arms for Miata

Post by eage8 »

kyle.bowker wrote:The AWR RUCA are primarily for people runnning very low ride heights (<11.5" from center of the hub to the fender lip) who want to dial out excessive negative camber. If you want more camber than what your factory eccentrics will allow the offset control arm bushings should get you all that you need. The trick to winning small bore with a Miata would be 6ULs wrapped in sticky rubber and a short rear end ratio. And good driving.
I don't think there really is any secret... bottom line the better you prep a car the faster it'll be. and more camber definitely won't hurt.
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