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Old 05-05-2012, 04:45 PM   #1
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Default Alignment specs for street

Okay, I've searched all over. 949 Racing, FM, here, M.net, etc. There's lots of different numbers out there, and I'm more than a little confused.

Here's my setup: Tein S springs on KYG AGX shocks. Running 15x6 NB sport wheels, with Yokahama ES100 (195-50R15) tires. I'm looking for a good all around street alignment, and good tire wear. i.e. long tire life is more important than getting the absolute maximum handling. Car is a weekend warrior, being driven to work occasionally and on weekends for fun. Car sees about 50-50 expressway and suburban roads, with the occasional backroads twisties thrown in when I get the chance.

FM recommends the following:
Front
Caster: 5.0 degrees
Camber: 1.0 degrees negative
Toe-in: 1/16", 0.15 or 9 arcminutes total (1/32", 0.075 or 4.5 minutes per side)

Rear
Camber: 1.5 degrees negative
Toe-in: 1/16", 0.15 or 9 arcminutes total (1/32", 0.075 or 4.5 minutes per side)

Toe and caster I don't have any issue with, and plan on going with those numbers - unless someone can tell me why not to. But Camber, I've seen specs from .4* positive (factory) to -1.5* in the front, and -.7 (factory) to -2.0 in the back.

I'm getting an alignment on Monday, and the guy says he will hit any specs I give him. Right now I'm not so sure I know what numbers to tell him.

Any advice?
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Old 05-05-2012, 05:22 PM   #2
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Im running -1.8 all around. I might reduce the rear camber a bit...
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Old 05-05-2012, 06:01 PM   #3
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But you aren't running a rear sway, correct?
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Old 05-05-2012, 06:04 PM   #4
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Front
Caster: 3.5 degrees
Camber: -2.5
Toe-in: 0

Rear
Camber: -2.0
Toe-in: 0

What I'm running, only ran 0 toe at the very strong repeated recommendation by the alignment guy. I'd run -2.0f -1.5r if I did it again though and seriously consider throwing in a tiny bit of toe.
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Old 05-05-2012, 06:05 PM   #5
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levnubhin is running

Front camber -1.8
Front caster 3.5-3.75
Front toe 0

Rear camber -1.5
Rear toe 0

So, why no toe? Also, why so much less caster, but a lot more camber? Lots of places say "as much caster as possible, and 1.0-20 negative camber. What does that get you?
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Old 05-05-2012, 06:30 PM   #6
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Lower caster is for people who have depowered power steering racks, rleete.

If you run power steering or manual, stay at 5. As for toe, it's supposed to substantially increase tire wear for even a tiny bit.
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Old 05-05-2012, 09:27 PM   #7
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Thanks.

I think I'm going to give them the FM specs with no toe in back and UP TO 1/16" toe in front. We'll see how it handles from there.
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Old 05-05-2012, 09:41 PM   #8
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I'd have to dig up the thread, but some mighty big names were stating quite clearly on here that -0.5 more in front is preferred vs. in back.

You should be able to dig it up with a bit of searching, I'll see if I get around to it today.
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Old 05-05-2012, 10:19 PM   #9
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https://www.miataturbo.net/showthrea...109#post458109

Brainy's original post on it. Dug it up just for you rleete.
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Old 05-05-2012, 10:38 PM   #10
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Quote:
Originally Posted by blaen99 View Post
I'd have to dig up the thread, but some mighty big names were stating quite clearly on here that -0.5 more in front is preferred vs. in back.
Broadly speaking, this seems to be a distinction between the AutoX-type crowd and the trackday folks.

Emilio's preference for even camber front to back represents his experience with naturally-aspirated vehicles in a high speed track environment. FM's recommendations are more likely based upon the behavior of a forced-induction vehicle in a street / AutoX setting.

On the red car, I ran -1 front, -1.5 rear, with a stiff solid front bar and no rear bar. This setup handled well without being too tail-happy. On the blue car (no turbo) I've decided that I need to run equal camber front and rear, as this car is far less tail-happy, and because of the lack of power, I'd like to be able to enter turns much faster. Right now, it's understeerey.
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Old 05-05-2012, 10:49 PM   #11
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Quote:
Originally Posted by Joe Perez View Post
Broadly speaking, this seems to be a distinction between the AutoX-type crowd and the trackday folks.

Emilio's preference for even camber front to back represents his experience with naturally-aspirated vehicles in a high speed track environment. FM's recommendations are more likely based upon the behavior of a forced-induction vehicle in a street / AutoX setting.

On the red car, I ran -1 front, -1.5 rear, with a stiff solid front bar and no rear bar. This setup handled well without being too tail-happy. On the blue car (no turbo) I've decided that I need to run equal camber front and rear, as this car is far less tail-happy, and because of the lack of power, I'd like to be able to enter turns much faster. Right now, it's understeerey.
Brainy's in the "trackday folks" crowd now? o.O
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Old 05-05-2012, 11:04 PM   #12
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Well, I'm speaking to origins of thought. I'm not a trackrat either, but I'm starting to recognize the benefits of equal and aggressive F-R camber for a street-driven car with lots of sticky in the tires and not a lot of oomph in the motor.
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Old 05-07-2012, 10:13 AM   #13
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Just got back from Firestone. Very happy with the service there. I got it aligned to FM specs, and they not only hit the numbers, they took me out in the shop to confirm. No hassles, they did it to what numbers I gave them without questioning me. I did have them put it to 0 toe in the rear.

Have to say I like the FM specs. Stable at speed with no twitchiness, yet still very responsive. Tracks straight and true with minimal input. I'll see what it looks like as far as tire wear before I change anything.

Thanks to all who gave advice.
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Old 05-07-2012, 10:24 AM   #14
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Quote:
Originally Posted by blaen99 View Post
Brainy's in the "trackday folks" crowd now? o.O

I'm in the what works for a high-powered-miata-not-a-m.net-cheese-runner crowd.

we have dynamic camber, stiff spirngs and sways, you dont need so much in the rear.

when I had something like -2.5 in the rear, I was forced to remove the rear bar, which sucked horribly.
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Old 05-09-2012, 11:48 AM   #15
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Just remember that toe is what kills tires not camber. If you do a ton of street with the car the small toe helps with trammeling when driving on worn roads. If your more a track guy than the no toe helps with tire wear and reduced drag. Think of toe as if you were stopping on snow ski's. On most setups the toe also changes how the car feels right when you turn the wheel ie the crispness. If you are running a powered rack than you can run max caster no problem. On manual racks you want to run a medium caster setting to help the effort of the rack.
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