Big front bar vs big rear bar?

[Doc_speeder]

I'm looking at getting a 2 and prepping for STF in the spring, so naturally I've been researching all the options. I really appreciate the great info that Andy Hollis has put up as I doubt anybody could start with much better than what he's got for a setup.

I do have quite a bit of experience and (ancient) history with Rabbits and Golfs. It seems like a lot of the fast guys in those used to, or still do, run a huge front sway bar, and huge rear springs with no rear bar. The reasoning is that even though in theory a big rear bar with lots of rear roll stiffness seems like it would be better, a big front bar can help with negative camber loss in a camber challenged car like a FWD VW chassis.

It would seem like the 2 is pretty darn similar to an early Mk1 VW chassis. Has this approach been tried out on the little Mazda? I'd really appreciate some input from some of you fast STF guys on this one, even just out of curiosity.

Thanks all

 

[CorkSport]

I'm surprised no one has chimed in on this. I ran a rear upgraded rear bar with the stock front in STF for most of the 2011 season and the car was good. I was really surprised when I got to test out our larger front swaybar and it increased the effectiveness of the rear bar when it was installed. I haven't tried out a mazda 2 with an even larger bar so I am not sure what I would be result would be.

-Derrick

 

[Doc_speeder]

That's the kind of info I was looking for. In my experience you can run into issues with a big front bar with no LSD if you have a torquey car. I think maybe the 2 is not such a car lol.
I think that likely once the inside rear tire is off the ground, the rear bar is doing all it can, and there may be some benefit of a larger front bar. It seems like the front bar is relatively easy to change in the 2?

 

[Racebrewer]

Actually, the front bar is a PITA to change. At least the first time. Second time would be pretty easy.

To change the front bar, the front subframe has to be dropped a ways so that the bar can be un-bolted and snaked out. The new bar gets snaked back in, bolted down, and the subframe has to be bolted back in the same place.

My mistake was trying to drop the subframe as little as possible. I had to keep going back to drop it further. Bite the bullet and drop it about 5-6 inches the first time and it will be much easier.

The second issue is that it is possible that the subframe may return to a slightly different position. That would result in the need for a suspension re-alignment.

Mine returned to the original location so no problem. However, before dropping it, I had put "witness marks" on the body with some Sharpie marker pens so I was ready to wrestle the subframe back in place if needed.

I had the car supported on jackstands under the body and dropped the subframe with a floor jack. Corksport may have detailed instructions for their front bar on their website.

John

 

[eyeballs]

From my experience so far, I think bars at both ends could be beneficial. I've got the corksport stuff front and rear, but stock dampers and a mild spring upgrade. I was surprised at how much more grip I got from the front end with the corksport bar, but I wonder if I had auto-x friendly spring rates if I'd still see that type of response. I think an even larger rear bar could be beneficial as I'd still like rotation to be a little more eager, though I also don't have a much camber as I should. I'd want to know how the car behaved with a stiff coilover setup before advising on a front bar if you are going all out. Don't forget about the urethane bushings for the rear either.

I agree on the front bar being a PIA on this car. I gently lowered the front subframe with the floor jack but then moved the jack away once the subframe bottomed out. Pulling off the front wheels makes getting to those subframe bolts easy. I did have difficulty getting the subframe back in the exact place. The original marks from the bolt heads are easy to see.

 

[CorkSport]

I think camber really is the key with the swaybars installed. I have the maximum negative camber on the shop b-spec car that crash bolts can give you and it is pretty close to -2 degrees. I think for autox 3 or more may be better.

-Derrick

 

[eyeballs]

Camber is key regardless. And like doc said....the nice thing about adding a larger bar up front (on the macpherson setup) is you get that reduction of dynamic camber loss. Of course the downside is with the susp being less independent, there's the question of how big do you go before you start loosing grip. And I think that is largely dependent on the dampers and spring rates.

 

[CorkSport]

I was not able to over power the Kumho EXS on the local autox courses with the bar we offer unless I had the steering angle to high (or to fast) on a wet course. Dry courses I cannot remember under steering, when I approached the limit the back of the 2 would drift out.

-Derrick

 

[Andy Hollis]

You have to look at the whole package, bars and springs. You can do it with either...or both. Indeed, combating the lousy dynamic camber of the strut suspension at the front is the #1 priority. Right alongside that is lowering the cg. And they are related...the lower the cg, the less body roll due to less weight transfer. Win-win.

In my case, I killed both birds with one stone: springs. By going with a high front spring rate, I was able to lower the car substantially w/o bottoming, as well as combat the remaining body roll. I still ended up running 3 degrees of negative camber, though that delivers wheelspin at times. Especially on bumpy surfaces.

From there, I added rear roll stiffness until the car was properly balanced. In fact, I had three different setups depending on surface and weather. A simple rear spring change was the difference. Normally, I'd do that with an adjustable rear bar, but the twist beam does not make this possible. Changing rear springs is really easy. I can do it between autocross runs. 5 minutes.

The car has had most of the autocross stuff taken off of it, and I've been doing it in stages to see how the balance and the street ride quality changes. Right now, the car is nicely balanced for aggressive street driving with the 550 front springs on the K Sport fronts and the complete K Sport rear setup, along with the Racing Beat rear bar. I've also raised it up a couple of inches, and reduced front camber to -1, with zero toe.

The whiteline/powerflex front bushing setup is still in there and makes a huge difference in feel. The car is much more precise with those installed. And I'll never take the AWR motor mount out. That thing rocks.

I even took the car out to the track the other day when my daughter was in town so she could get some track time. It was quite good, despite being was less radical than it was when autocrossed.