Mazda 2 Front suspension/wheel investigation

[zps2004]

Ok so now that I am back in the states I decided to look into wheel fitment on the 2 to give people a better idea of what fits. This is all with the stock alignment on the car.

Here is the stock wheels on the car.

As you can see there is a lot of room for the wheel and tire to be moved outwards. Here is the same corner with my 15X7 +40 offset TD's with 205/50/15 RE-11's

As you can see there is still some room for the wheels to be moved out before the tire is going close to the fender. I then looked at how it fits with the strut.

Here there is 0.5" of clearance between the strut and the wheel. I then turned the wheel and looked at how close the inside of the tire gets to the inside of the fenderwell. First I turned the wheel all of the way to the left.

The tire has about 1" of clearance from the inside of the frame. You can also see how the frame is cut out in that area for tire fitment. It runs up pretty high, so even with compression the tire will hit the top of the fenderwell before it hits the inside when turning. I then turned the wheel to the left.

With the wheel turned to the left there is plenty of space again about 1" before the tire would hit the fender. So from all of this it is clear that you will hit the strut with the wheel before you hit the inside of the fenderwell with the tire. This is assuming you use a 15" wheel, and have a reasonable tire, no 275/35/15. I then checked all of these with that corner of the car lowered half an inch to see if anything changed. I didn't think it would. Here is how I lowered the front left.

Here is another look of the wheel and tire but with the front corner lower by 1"

Adding some negative camber will obviously help the fitment a lot. I will be looking into that on another day though.

 

[zps2004]

So while looking at all of this I noted some things which would help out our suspension in the front. Firstly when the car was lowered 1" there was only 0.5" of shock travel left before hitting the bump stops.

So I really hope that the instructions for the lowering springs tell you to cut the bump stops.

I also looked at the travel when the strut is in full droop. Overall the wheel has 5.5" of travel from full droop to hitting the bump stop. At stock height it has about 1.5" of compression so there is a lot of droop travel there. A shortened shock/cutting the bump stop will help there a lot.

one of the pictures that I took to show how the tire fits in the fenderwell showed another thing that can help. There is a good amount of room between the bottom of the shock and the axle boot. You can easily have the bottom of the shock be 0.75 inches lower which would add to the available bump travel before bottoming out the shock.

An adjustable shock body would work well here. But this is all looking for the ideal case of suspension. I think by cutting the bump stop you can easily get another 1-1.5" of compression travel. and then since there is so much droop travel you can take another 0.5" off of the shock body as well. That should give you enough travel along with the stiffer springs you usually get with coilovers that you should be able to have good range of motion without any unwanted bottoming out or bump stop hitting. Mazda did a good design for the aftermarket on this.

I also only looked at the front because I am pretty sure that the rear has plenty of travel, and especially with how on a FWD the rear usually doesn't move very much when tuned for performance.

I will also have a video of the rear suspension with and without a torsion beam stiffener. I need to compile everything together first though. I might have it sometime tomorrow.

 

[Slow Paul]

Good investigation. It's interesting that there isn't a whole lotta room when it comes to larger wheels or wheels with more aggressive offsets. But spacers can fit that. As for the .5 inches of suspension stroke on when lowered, that isn't much at all. I think trimming at least a half inch to a full inch from the bumpstop would be welcomed.

 

[Joker2]

Awesome post! I think that I got a bit of heat for going for the same offset. I feel better now. Nice detail and good pics!

 

[DaleNixon]

Thanks for the information!

 

[Greensleeper]

Awesome, thanks!

 

[fam]

Thank You. You sir have removed the stresses of wheel and tire purchasing for me (the toyo r1r's are purposely wider than other tires its size to cheat stock rules, you think id be ok with the wider toyo 205's? or go back down to a 195 (which is probably as wide as a 205)?

 

[Rockin03mp5]

Very informative thread here.

Thanks for all the info.

 

[zps2004]

Actually all of the typical autocross tires, like the R1R, RE-11, Star Spec, RS-3, etc. They are all wider than most, it isn't just a toyo thing. They all do that. That was one thing I was going to take pictures of tonight was how wide the RE-11's are. All of the data I showed was with them and they are wider than most 205's so if you get a normal tire then your easily fine. A 225 of one of the good street tires will fit as well. You just have to make sure you have the correct offset.

I might be able to get that video together tonight as well.

 

[zps2004]

Here is the video. Shows some interesting things. You can see how the rear compresses and droops less with the rear torsion bar. Also you can see that if the car is driven roughly how the rear torsion bar stiffener throws off the balance of the car due to the soft shocks from factory.

http://www.youtube.com/watch?v=dr9sw4Bg5vE

 

[CorkSport]

Its fun to see the stock suspension at work, thanks for posting up the video.

-Derrick

 

[Slow Paul]

Very cool video indeed. Right off the bat you can tell that the 2 needs stiffer shocks.

 

[XCLR8TN]

1:49 - rear tire liftage FTW. Now I'm going to have to tape mine with the GoPro lol! Thanks for all the info! I now understand why under hard braking it's very easy to bottom out the front suspension on a small surface imperfection :/

 

[zps2004]

I might try to mount it in the front this weekend. I have some work to do on the miata though. We will see.

 

[zps2004]

Random other thought. The rear torsion bar I have, is one that DDMWorks built for me. Here it is unpainted.

 

[Racebrewer]

Cool rear bar. What is the size of the bar/tubing?

Thanks,
John

 

[zps2004]

We went with 1" tubing with 0.1" wall thickness. Mainly because we could get it easily and we figures we could mess around from there depending on what it was like. I think we got it good because any stiffer and the rear would be a lot more stiff compared to the front especially with the stock shocks so the car would handle all kinds of messed up.

I have driven a car like that before. My old civic had koni yellows, stiff ground controls, and really stiff bars. Well one of the front shocks blew so I put the stock front suspension in while it was being repaired. That was just scary if you ever had to do an emergency maneuver.

That is why I think that for the rest of the suspension being stock, this bar is stiff enough. We mounted it where we did because there is another bracket welded to the torsion bar as you can see in the picture so where the ends mount are really strong. We know we can fit a 1.25" bar in that same location. That will have to wait until i get a good suspension. If the ABS is really looking at the rear wheel speed sensors though I might not want a stiff rear bar causing the inside to lift though. Only time and testing will tell. I haven't autocrossed the car with the rear bar yet.

 

[Racebrewer]

Thanks.

I have a 22 mm Ford Fiesta front bar to put on and a piece of 1.5" DOM tube to make a rear bar from.

I'll post he results when I get it done. Bilsteins already on the M2.

I wonder if I should do the front or rear bar first? (Just to scare myself)

John

 

[XCLR8TN]

Actually all of the typical autocross tires, like the R1R, RE-11, Star Spec, RS-3, etc. They are all wider than most, it isn't just a toyo thing. They all do that. That was one thing I was going to take pictures of tonight was how wide the RE-11's are. All of the data I showed was with them and they are wider than most 205's so if you get a normal tire then your easily fine. A 225 of one of the good street tires will fit as well. You just have to make sure you have the correct offset.

I might be able to get that video together tonight as well.

I can tell you that the 195 R1R is wider, I think I measured .5" (tread that is actually TOUCHING the ground) wider than the 195 Star Spec. I was extremely disappointed when I received the Star Specs. The tread is nowhere near as squared off or as aggressive looking. Oh well.

 

[Joker2]

The 2 lifts the inside wheel without the rear bar.