Lower your car, make sure to get an alignment

[—kung fu jesus—]

That is how a lot of the upper level coilovers work. On mine, the bodies thread into the lower mounts for height adjustment without detracting from the stroke. The fronts have an extra inch of adjustability because the lower mounts have an adjustable heim joint. The lowest I have taken my car was 10.75" in the front. I figured I had another 1.5" left. I measure off the pinch welds now and the car is higher that that now.

You would do your rear suspension a huge favor to run taller tophats in the rear with your current setup. slamming the shock bodies into the bumstops when they bottom out can damage them and cause them to leak.

[blenderblast]

This thread is surprisingly informative.

[I<3flippyheadlights]

This thread is surprisingly informative.

I KNOW!

And KFJ, I don't bottom out often... actually not at all. But it feels more "bouncy" in the back and I guess that could mean I'm hitting my bump stops. Its not that bouncy (like cut springs on a honda) but it is slightly noticeable when going over a few bumps.

[— MazRoadAdmin —]

OK, just trying to get the mindset.

Generally, that is a bit too much toe out in the front. The wheels will also toe out even more when the suspension is compressed. I am guessing the car is pretty sensitive to bumpsteer.

More camber in the rear than the front isn't too stable, especially with that much difference between the toe angles front and rear. I don't know Loren's numbers, so I can't compare his to yours, but if you have only an inch of suspension travel, you're defeating the mechanical grip of the suspension design.

Trying to match your static settings to his dynamic settings, I get that, but it is the wrong idea. Look at this site that shows you the camber curves at different heights:

http://www.virkki.com/jyri/miata/camber/

His front toe is a little aggressive, but still streetable. I'd have set it closer to 1/16-1/8 but our first test run was with it at 1/4 out and Gavin LOVED the way it felt, so I didn't want to take it all away. We're only talking 3/32" per side, which my trig calculator tells me is about 0.23 degrees.

More camber rear vs. front is a fairly typical Miata setup, and often more than 2/10ths. When someone comes to me with no idea what they want, and I know that they don't have a lot of performance driving experience, I generally set their car up to NOT oversteer. Hence a little bit more camber in the rear, and adequate toe-in. After he's had time to live with that for a while and can tell me whether or not it over or understeers, we can fine-tune it to his liking.

The graph you linked to doesn't make your point. The camber curve doesn't change with ride height. The CAMBER changes with ride height, that is by definition, the camber curve and it is determined by the geometry of the control arms.

That graph actually explains WHY I set his camber as aggressively as I did. Look at their default numbers. at 13.5" ride height (stock), if you have 1.5 degrees negative camber, at full compression (10"... I'd be surprised if you get that far with a bump stop, but we'll use that number) you'd have about -5.5 degrees of camber. (a little more in the rear than the front)

Now, if you change your starting ride height to 12", but kept the static alignment at -1.5, you only reach -4 degrees at full compression! To maintain a stock level of dynamic camber, you have to dial in more static camber BECAUSE the camber curve doesn't change.

At a 12" ride height with -2.5 static camber (as demonstrated by the nifty tool you linked to), you get -5.0 degrees at full compression. Still a little less than stock, but I don't recommend running much more than -2.5 degrees of camber on the street.

But, hey... suspension tuning is a mysterious black art... there's more than one way to tune a suspension. Feel free to do something else.

If you want to change the actual camber curve, you have to start monkeying with the lengths or mounting points of your control arms.

[bokehmon]

^... mind explaining the differences in caster?

I gotta agree with KFJ on this one - it seems a little off. Your alignment will differ to your suspension setup.

Saying that you don't lose travel when lowering could be mis-interpreted. You can only have as much "travel" (stroke) as you have room to the metal of the tub, otherwise your tire will bottom before the suspension.

[— MazRoadAdmin —]

Because I didn't need to adjust the front camber, I just checked the front caster and it wasn't too far out so I left it alone. If I had made adjustments to the front alignment eccentric bolts, I'd have tried to get the caster more even.

And it's true, your setup will determine your alignment requirements. In this case, his springs are actually not THAT stiff and he's on stock swaybars. So, body will roll pretty readily until it hits the stops (which is only about an inch of travel maximum). His dynamic camber requirements should be the same as that of a stock suspension.

Anyway, those are the choices that I made. You don't have to agree with them.

THE POINT of this thread was that when you lower your car, the FRONT TOE changes drastically. Gavin lowered the front of his car by about 2 inches, gained a bunch of static negative camber in the front, and as a result, his alignment was TOED IN massively in the front. That's why he posted this thread, to be sure people were aware of that. It happens every time, and anyone who lowers a Miata needs to know it... he didn't know, and he wanted to share that fact.

[—kung fu jesus—]

Thanks, Loren! I like to hear the reasoning. I'm not here to dispute it. Your explanation is very good!

The graphs show what the camber angles are at static and what they will go through travelling though their arc.
I am no means a suspension guru, but a lot has rubbed off on me through osmosis over the years.

The camber settings are very close to each other front to rear, so I don't really see a big deal. The toe settings are a bit odd, but now that I see you were trying to make the car understeer prone, I undertand. More in the rear, more than flippy's settings, have really bizarre characteristics at higher speeds. I am still trying to imagine what the toe settings set as they are will go through durning their travel

The danger, for the user, comes in when the rear shocks start getting into the bumpstops and bottoming out. That effectively overrides the springs and rates go from whatever the s-techs are to ∞. At that point, the alignment settings in the rear stop factoring and become static (they can't change anymore because the suspension isn't moving anymore).

There are others out there that are FAR more knowledgeable than I am in this stuff and would take everyone here to the wood shed on this stuff until our brains implode.

[I<3flippyheadlights]

This thread is now beyond the scope of my knowledge. I will sit back and watch. Thanks for chiming in Loren, I tried my best to explain what we did but, I didn't know all of it.

[VagaXt]

If you want to change the actual camber curve, you have to start monkeying with the lengths or mounting points of your control arms.

Actually, you effectively change the lower arm length by moving the eccentric bolts (the bolts holding the lower control arms to the subframes). Effectively, you change the camber curve that way.

[VagaXt]

And to the OP, at 11.5" fender-to-hub ride height in the front on your NA (based on your car info in your profile), I can see what you and Loren are trying to do with having your front toed out since he know that your car will have toe-in-induced change when you eat though your front damper (shock) travel whenever you load up your front suspension dynamically (under braking/cornering). However, I don't think it is necessary.

My concern is that Loren's assumption is purely contingent on you having sufficient bump travel in the front end. With you on Konis (spring preload adjustable ride height only), I assume you are losing some front bump travel lowering your car to 11.5".

Through personal experience at that front end ride height and using various Miata coilover setups, you will either be limited by damper bump travel (hit bumpstop) or the chassis itself (tire/wheel hitting the top of the wheel well). I am betting you will have the former situation. This will limit the amount of toe in you will have under load in the front end.

In regards to your front toe settings, I see anything other than 0 toe unnecessary for a performance street-going HPDE (track) car since I suspect the front tires your car will spend more time rolling with toe out. With 3/32th toe out per side (which is 3/16th total on the axle), it is acually a great auto-x setting since you get that quick darty steering feel, but at the cost of accelerated tire wear and a bit of rolling drag.

[— MazRoadAdmin —]

Actually, you effectively change the lower arm length by moving the eccentric bolts (the bolts holding the lower control arms to the subframes). Effectively, you change the camber curve that way.

You do, it's true. But, not very damned much.

[—kung fu jesus—]

Not much at the mounting point, a lot more out at the wheel.

[— MazRoadAdmin —]

Not much at the mounting point, a lot more out at the wheel.

I'm all for learning something. Please explain how much the camber changes due to adjustments at the eccentric bolts and how you came to the conclusion that it's a lot more at the wheel.

[—kung fu jesus—]

Are you being facetious?

[— MazRoadAdmin —]

Not really. You're stating facts as if you know something. Spill it!

(meanwhile, I'm searching around trying to find answers for myself, it's an interesting topic... and not a simple one)