Mazda2 Thread

DaewooOfDeath wrote: I went and test drove a 2. Nice little car and it was fun in a sparkly sort of way. Did feel awfully soft though.

It's not as soft as it feels. The weird bumpstop setup means that once the car starts to take a set, it becomes much firmer and corners quite well.

I drive a car with spine crusher springs. That's why I think it's soft. I definitely found the bumpstops on the test drive.

Well crap. Things have changed for me and it doesn't make sense to keep the 2 now. Anyone want a 2011 sport manual in black with 15k miles located in MO. Will to consider trades of the challenge value variety but need cash mostly to pay off my loan. Want to sell to a good GRM home. Hope I'm not stepping on any toes posting here. I can't put it in the classifieds section as it costs more than $2012.

I bought a video camera form Oregon Scientific for recording autocross with the deuce. The only problem was mounting. Eventually I'll end up with a suction cup mount so I can put it anywhere, but I didn't want to drop $30 on one now. After thinking about it for a few days it occurred to me that right up top and in the center of the car I had a place to screw something in if I unscrewed the antenna first. A trip to HD and one $.68 bolt later and I was set. I went home and mucked about with the drill and some PVC pipe and fittings that I had and the handle bar mount that came with the camera and ended up with this.

I put a few scraps of magnetic sheet under the feet to keep it from scratching the car at drove it up and down the driveway a few times. Seems to be a great camera mount for less than $1. The antenna on the Mazda2 is M5-.8 just in case anyone wants to make something similar.

I hate to post this here, but is anybody actually interested in buying my OEM wheels?

I ordered an aftermarket set based on somebody who was going to buy them, but now it looks like they're bailing on me and I'm kinda screwed. I can ship them and I think I know how to get a decent deal on the shipping. I'll make sure they're packaged well too.

Sending you a PM.
More wheels is better.

Your camera mount is fantastic, Mazdeuce. That is some grassroots thinking right there- inexpensive, simple and easily duplicated.

I was reading on a Subaru forum last night about Steering Angle Inclination (SAI) and it's affect on camber change while turning. The Subaru guys say they have a lot, which leads to a loss of camber in the outside wheel, which leads them to needing to run something like -4 degrees of camber to get it to all work out. I could have broken out the tape measure and measured SAI and caster and tried to model the Mazda2 suspension, but I decided that it was probably easier to just get out the camber gauge and measure it. These measurements aren't perfect, I didn't level the car (which is why my initial measurements don't match) and I didn't use turn plates, though the cement was dirty which sort of counts. This is just to give a ballpark idea of what's happening. I'm turning right, so the left front tire is the one that's loaded.
Turn Left Right
0 -2.3 -2.7
1/4 -2.7 -2.4
1/2 -2.8 -1.8
3/4 -2.8 -.8
1 -2.9 -.2
1 1/4 -2.8 +1.5
So Mazda has SAI and caster working together with the outside tire to keep static camber pretty much constant. Nice. The tradeoff is that from center to full lock the 2 loses 3 degrees on the inside tire. Not cool.
I also read that loss of camber under roll can be approximated on a strut car by guessing that the wheel looses (or gains) camber as an equal to car roll. It's not perfect because there's other stuff going on, but it's worth looking at. My tape measure says the car is about 65 inches wide at the outside of the wheels. I know form messing around with the front suspension that we probably have a maximum of close to three inches of up travel and about that much droop travel. That is, right before you were to tip over, you might have those numbers. Additionally, lets assume that up travel and down travel numbers are always the same as we stiffen springs to reduce travel and roll. They're not, but it's easier to write out a chart if we assume they are. The chart will be travel at one wheel vs. degrees of roll (and camber loss on our outside wheel) for our 65 inch car. And they said I'd never use trigonometry outside of school.
Travel Roll Degrees
3 5.27
2.5 4.4
2 3.52
1.5 2.64
1 1.76
I assume those numbers are a bit bogus as I doubt we're going several degrees into positive camber at full roll. We could be though. Maybe. I guess all of this has let me know that the inside front tire is probably pretty much useless when it's turned. Using a big bar to try and transfer grip to it is pretty pointless. I also need to step up and get a pyrometer so I can try and read tire temperatures. Even better, I need to find some sort of skid pad and drive around that and read tire temps and see what the hell is going on.

Back in the horse and buggy days and dirt track racers the SAI is/was known as KPI ( kingpin inclinaton. The reason for it, According to Steve Smith are three fold, 1) directional stability. 2) to disribute the weight of the vehicle evenly on the entire spindle arm support. 3) to add negative camber to the wheel during suspension bounce so that an excessive amount of negative camber need not be added to the car. I find no 3 quite interesting, particularly when it comes to struts. Lowering of the car can even cause the opposite. Lean, is the biggest problem. as the car leans into a corner any camber gain is negated by the amount of lean. So negative camber has to be added to compensate. When I was tracking my ZX2SR ,I ran 2.5 /3 degrees negative. Tire temperatures were very good. Anothe thing I found that adding caster helps a lot, since it adds negative caster to the outside wheel while going more positive on the inside. It allows running a little less static camber. Steve says up to five degrees is good.

I doubt that the SAI on Subarus is significantly different from othe cars with struts. The lean is the problem.

Your findings are intersting. I have a 2011 Fiesta that I have not gotten around to do any checking. It handles well as is.

Honestly, there's not much I can do with this information other than think about it. Can't adjust caster or SAI really. What it does show is that Mazda (or Ford) set the car up to maintain constant camber in the outside wheel in a corner. We'd like to have is more caster so that when we turn we build negative camber to compensate for body roll. Since the car doesn't do that, we need as much static negative camber as we can get, probably. As well, since the camber change in the loaded wheel is pretty much nothing with turning, we need to work really really hard to keep the car as flat as possible in order to keep the tire in it's happy spot. The reason I was looking at all of this is because of the bump stop spacers that I'm running. I have the ability to run the car on the bumps at ride height if I want to. This will limit me to around 1-1.5 inches of up travel before the rate goes way up and the car won't go any lower. I wondered if I should really try for that or if I should back off a bit. It looks like, in theory, I should try that and see if the other complications that it introduces are of a smaller effect than keeping the loaded tire happy. We'll see.

Oddly enough, you guys are really making me want to buy one of these things. If someone makes a ten page thread on autocrossing Honda Fits I'm going to have to leave the forum.

Mazdaduece,

I think you made a mistake in your reasoning above. When you are turning left, lets say, in order to compensate for body roll and tire sidewall deflection you want the outside, right wheel to gain camber so that the contact patch remains as flat as possible.

Now, think of what happens to the inside tire. The cornering forces are working the opposite way on this tire. The contact patch is rolling away from the outside shoulder and onto the inside shoulder. As such, if the inside tire went negative under cornering, it would have the same grip diminishing effect as your outside tire going positive.

You really want your outside wheel to go negative and your inside wheel to go positive. That's why circle track cars have positive static camber on their inside wheels.

As for KPI, it will make your wheels gain positive camber whenever you turn in either direction but also lends a self centering effect to the steering. In your application, you probably can't change it very much without crash bolts AND camber plates.

The Subaru guys might have a lot of KPI, it's possible, but they also have a lot of positive camber gain due to the angle of their control arms.

As for body roll, the really easy way to measure that is to get your friend to take a picture of your car while you are cornering as fast as you can. Then simply compare the angle of the ground to the angle of your bumper and use a compass.

There's more going on then just the camber gain/loss due to turning. You're right about the inside wheel wanting to go positive in camber with the turn to mazimize the contact patch, and I hadn't thought that all the way through. With the lower arm basically level (which it is on the 2) then roll causes camber loss on both the compressed side and the extended side as well as the camber change due to steering. Then you have whatever camber the tire really wants to be at to perform well.
I really just ran the numbers to see what sort of camber sensitivity to roll and steering the car might have and I think (but I'm not sure) that it will be happier the flatter it is right up to the point where it's too stiff to drive. Maybe. All I have to work with is theory, and now I'll start testing and see where I end up.

Dont forget about body roll. When the car is leaning, its not parallel with the ground, thus also affecting your tire contact patches in addition to whatever is going on with the suspension.

Like you needed another factor to ponder.

EDIT: Im pretty stupid, because I think you and others actually said all that above

Seems to me that this whole situation just reinforces my impression that the car would really benefit from sway bars. Looks like reducing body roll is something we really need to do, and the less we need to rely on spring rates to do that, the better.

I think the car will benefit from reducing roll, but I'm not sure that massive bars is the answer. I'm starting to think that the ratio between bars and springs is important. For instance, say that I double spring rate but keep the bar the same. I reduce roll, but in doing so I also reduce how much the bar twists and how much rate it adds. When I increase spring rate I'm actually reducing the effectiveness of the roll bar. If I put 500 lb springs on the front, I'm not sure you'd even be able to feel if the stock roll bar was on or off. It's not quite the same when you add a big bar and soft springs because the springs still need to hold the car up, so the dynamics are different. I don't think this is quite as easy as a lot of reading makes it out to be. I wish I had a test track.

Max_Archer wrote: Seems to me that this whole situation just reinforces my impression that the car would really benefit from sway bars. Looks like reducing body roll is something we really need to do, and the less we need to rely on spring rates to do that, the better.

Why?

Fords B spec springs are 450 lbs front and 500 lbs rear.

When i was tracking my ZX2SR I ran a heffty rear bar and the car had very litle lean. It already had the Eibach ProKit. springs.and being 1.5" lower it made use of the bump stops. I found offset bushings for the control arm that nearlly doubled the caster.

I just bought one ... 2012 base GX with 5spd

ArthurDent wrote: I just bought one ... 2012 base GX with 5spd

Very cool. Nice color and a great picture.
We have sport and touring down here, what are the trim levels up in the great snowy north?

Starting to do some real work on the STF 2 now that One Lap is over for the year. Just added pics of the seat installs and dyno graphs of the K Sport dampers (temporary solution). AST is working on something more permanent including something clever for the rear....from a BMW.

Details here: Hollis Racing

mazdeuce wrote: Very cool. Nice color and a great picture. We have sport and touring down here, what are the trim levels up in the great snowy north?

We have GX and GS. The GX is pretty basic. Mine doesn't even have an arm rest for the front seats (as I understand it the US ones do). A/C and a block heater were the only options I got.

Right off Mazda.ca

GX

100 hp, 1.5L DOHC VVT 16-valve 4-cylinder engine
5-speed manual transmission
Fuel Economy city/highway (L/100km)†: 6.8/5.6
Brake Override system
ABS with EBFD
Front, side, & side curtain airbags
Engine immobilizer
Brake assist
DSC w/ TCS
Front disc brakes, rear drum brakes
15" steel wheels w/full wheel covers
185/55R15 tires
Spare tire
Body colored front and rear bumpers
Rear wiper and washer
Power door mirrors
Power door locks
Tilt steering
12-volt power outlet
Centre console with 2 cupholders and 1 rear cupholder
Front door storage pockets
Tachometer
Illuminated entry
Isofix child seat tether anchors
Dual front vanity mirrors
60/40 rear seat
AM/FM/CD with MP3 capability
Auxiliary input jack
2 speakers

GS

15" alloy wheels
SAP roof spoiler
SAP Side sill extensions
Chrome exhaust finisher
Fog Lamps
Rain-sensing wipers
Auto headlight control (dusk sensor)
Leather wrapped steering wheel
Silver finish on boots panel
6 speakers

Sounds like the same packages we get. No armrest here either. It's a fun car.

Andy Hollis wrote: Starting to do some real work on the STF 2 now that One Lap is over for the year. Just added pics of the seat installs and dyno graphs of the K Sport dampers (temporary solution). AST is working on something more permanent including something clever for the rear....from a BMW. Details here: Hollis Racing

I'm glad you dropped by the thread. I was following you on One Lap, you did really well.
Did you every figure out the electrical stuff with the seat? If I remember, it has the seatbelt sensor, the weight sensor, and the seat track sensor. Seatbelt sensor is easy. The other two I'm not so sure about.
Also eagerly awaiting your AST solution. Once they build one set......

In reply to ArthurDent:

The armrest is something you have to buy separately. I have it in mine and it took about 30 minutes to put in, though. I assume you can probably get it there too.

You do have a few features that we don't, though, like the auto wipers and lights, which aren't available here at all, and the side sill extensions, which are an accessory you have to buy, paint, and install, just like the armrest.

So I got my wheels on. The +30 C1Ms might be just a tiny bit too low-offset up front, but it's not a deal breaker, and it doesn't rub or anything. They just stick out from the body the tiniest little bit. I'm probably the only one who will ever notice, though. I'll post pics tomorrow, it was already too late by the time I got home today.