Advanced Suspension Mods

[Dragonhealer]

You are right, it doesn't change anything except it restores regularity of the ball joint. Which isn't necessary on my festiva because I run out of wheel well before running out of ball joint articulation.

However, a custom control arm with ball joint spacer will correct the control arm angle resulting in a better camber/shock travel ratio. But like movin said, this wont affect the roll center, that would require a change in control arm pivot location, which isn't going to happen on this car. Right now the control arm pivot is properly mounted to fill the cars fenderwell but not exceed the room available (Mazda actually did an incredible job matching this). Moving the control arm pivot would require reshaping the fenderwell and moving the strut mount up. That's a lot of work.lol. If I do that it'll be in a car with some internal bracing

Here is a diagram to help explain the ball joint relocation/custom control arm setup.

With the spacer (spacing distance "A") between the knuckle and the ball joint pivot point the control arm angle ( angle "E") is moved to a position where negative camber will increase with suspension compression. This drawing is exaggerated, my control arm angle isn't nearly that extreme. If it was I would have made this part already.

OK, that makes sense

[Dragonhealer]

drooldrooldrooldrooldrool

Was she doing this lap after lap? It seems the chassis is slightly upset. lol.

Yes, every fast lap, but these cars are at a full race build, no elastic in the
suspension at all except the springs and tyres, European Pirelli slicks in
full soft compound, the Hoosier A6 cannot compare to the insane
grip level achieved by these(1). Steady state 1.5 lateral G's were routine,
as were momentary 3.5 G's. The chassis suspension loads were so severe
that multiple sets of ball joints, rod ends, rod inners, hubs, axles, and
pillow bearings were consumed every race weekend. All the Touring class
cars were so affected as we had to run mostly stock parts and the spec.
weights were fairly high (ours was 3075lbs.)

After watching a full race Yaris run, it was decided that the Festiva might
make the ultimate closed wheel racecar.

(1) The soft compound tyres ( yellow ink ) were left over from tyre testing
at High Plains Raceway in 2010, we raced the 2011 season
on medium compound ( green ink ) as the GTS cars were eating tyres
too fast. These did not have materially less grip.

[Advancedynamix]

Guys, maybe I've gotten too old, but I can't see how bending the control
arm up OR down changes the fact that the ball joint is still in
the exact location under the spindle and the pivot point hasn't changed, I can see how moving it fore or aft will change caster, but for the other I'll
need a picture

You are right, it doesn't change anything except it restores regularity of the ball joint. Which isn't necessary on my festiva because I run out of wheel well before running out of ball joint articulation.

However, a custom control arm with ball joint spacer will correct the control arm angle resulting in a better camber/shock travel ratio. But like movin said, this wont affect the roll center, that would require a change in control arm pivot location, which isn't going to happen on this car. Right now the control arm pivot is properly mounted to fill the cars fenderwell but not exceed the room available (Mazda actually did an incredible job matching this). Moving the control arm pivot would require reshaping the fenderwell and moving the strut mount up. That's a lot of work.lol. If I do that it'll be in a car with some internal bracing

Here is a diagram to help explain the ball joint relocation/custom control arm setup.

With the spacer (spacing distance "A") between the knuckle and the ball joint pivot point the control arm angle ( angle "E") is moved to a position where negative camber will increase with suspension compression. This drawing is exaggerated, my control arm angle isn't nearly that extreme. If it was I would have made this part already.

[Movin]

The height would have to change. There is benefit however if the ball joint is
binding. I am right at that limit. If the height changes at either end it does not
matter, simple geometry. Some one mentioned changing the inner mounting
point, that would accomplish the desired effect just fine.

[Advancedynamix]

drooldrooldrooldrooldrool

Was she doing this lap after lap? It seems the chassis is slightly upset. lol.

[Dragonhealer]

Wouldn't I have to bend them upward to do that? (raising the ball joint in relation to the control arm fulcrum point) The festiva control arms are very stout in that area and not only would they be hard to bend consistently, but it would most definitely weaken them. They look to be forged steel, not just cast steel and the section your talking about bending is very short, cold bending them would be difficult and heating them would ruin the ball joint. For me it would be easier to make my own control arms. Other members have built control arms for their Festivas, it's a very simple part. In the future I will most definitely make control arms, but I want to see how far I can take the stock parts first.
Bending the ball joint end downward would result an a more exaggerated angle on the control arm. Bending it upward would allow the control arm to rest more level with the ground.

Guys, maybe I've gotten too old, but I can't see how bending the control
arm up OR down changes the fact that the ball joint is still in
the exact location under the spindle and the pivot point hasn't changed, I can see how moving it fore or aft will change caster, but for the other I'll
need a picture

[Dragonhealer]

Need pics of Carolyn's car!!!!

Karl

Didn't mean to mislead you Karl, Carolyn's secret weapon is in this, as seen at over 100 in "the attitudes" at Miller Motorsports Park.

When asked what it feels like, she said " It feels fine "
http://www.flickr.com/photos/3551904...in/photostream

[Advancedynamix]

Most OEM 15" wheels, especially those on European cars are so over rated for a festiva that you'd have to try to hurt them. Lol. If you pay close attention to the video of tweak " the hills have roads" you'll see I jump off a 4" drop to the dirt where I then e brake the car around at about 45mph and power the car back onto the road. This was done with 45 series tires and that's how I drive the car regularly. Those wheels are still perfectly straight, but I did scratch them up pretty good when I almost flipped the car in the gravel at firebird. Having a featherweight car is awesome.

[Safety Guy]

Need pics of Carolyn's car!!!!

Reading through this handling discussion is interesting, though I have a hard time envisioning exactly what's being said.

As for wheels, there were some 13 X 6" BBS wheels for sale recently, but I didn't get them. I think they were around +20mm offset, which sounded a bit "off" to me. Maybe it's good I didn't get them.

I did get a set of MINI wheels: the "phone dials." They're 15 X 5.5" and supposed to be around 12 pounds each. Centerbore is the same as Honda Civic: 1mm larger than Miata/Aspire. I'm thinking 175/55 or 165/60, but I really don't want too short of a sidewall for the real world pothole dangers that await the unwary!

Karl

[Advancedynamix]

Wouldn't I have to bend them upward to do that? (raising the ball joint in relation to the control arm fulcrum point) The festiva control arms are very stout in that area and not only would they be hard to bend consistently, but it would most definitely weaken them. They look to be forged steel, not just cast steel and the section your talking about bending is very short, cold bending them would be difficult and heating them would ruin the ball joint. For me it would be easier to make my own control arms. Other members have built control arms for their Festivas, it's a very simple part. In the future I will most definitely make control arms, but I want to see how far I can take the stock parts first.
Bending the ball joint end downward would result an a more exaggerated angle on the control arm. Bending it upward would allow the control arm to rest more level with the ground.

[Arnie]

I agree with what's being said here, increase caster. It will help load that inside tire and give more dynamic neg camber (as you already know). But I'd really look into raising your front roll center by bending the control arm ends/ball joint down just a bit. You'll reduce front end roll just through that tweak. I personally don't consider that a non-bolt on mod. Its just slightly modifying a stock piece.

[Advancedynamix]

More caster will certainly do that, and will help on the breaking. What is the best option? Relocate the front anti-roll bar/(trailing link)?

Carolyn's secret weapon is a locker set so tight that you can race with one
axle broken! That and 325 lb/ft of torque!

That inside front wheel.... lets see.. hydrolastic suspension, steering and
body roll inputs, hydrolic pumps, valves...a lot more $$$, more weight,
more complexity......... Citroen !!!

Seriously, except for wider wheels, if you can fit them, I think you are fussing with the last two percent. You have done a magnificent job in a
short time on a limited budget.
We are looking forward to using your
skills on Carolyn's "Grand Am" Monster Slayer Festiva!

Yeah, the front sway bar mounting locations are on removable plates, which could most definitely be altered or replaced with adjustable pieces. Fairly simple.
I'd like to have a nice viscous limited slip in Tweak, and I may have to settle for a helical lsd unless I can get a Mazdaspeed diff to work. Right now it hooks up pretty well for an open diff car with over twice the factory TQ. Just have to see where the limit is.
You left out cantilevered shock mounts driven by stepper motors that are controlled with a programmable self correcting/learning control unit.:p
Thanks! I look forward to helping out as much as I can to construct the monster. You guys help me out a ton, and I wouldn't have been able to fine tune Tweak as fast or efficiently without you. I think we make a great team.

Is it possible the variation is due to too light a rear? I know, defeats the whole premise of weight forward Which appears to work marvelously
in all other respects!)

Actually, the opposite. The rear still has too much weight. It's the momentum of the rear that is bringing it around like a pendulum. This is why I think that being able to run more rake without loosing my caster angle will help. It takes weight off the back, but right now the car feels unstable set up like that (I had a fairly drastic rake angle at the last event on the testing day, but didn't like the way it felt). I also still have some weight I can shed back there too, probably close to 100lbs with glass and the rear bumper and my ultra heavy muffler. After that it'll be time for aero trickery, which should actually be quite effective since the car is so light and punches such a comparatively large hole through the air.

Advance when you say more "Rear Bar".Are you saying stiffer torsion bar? I thought a stiffer bar would keep the car from rotating. I hang up now,& just listen to your explanation...

Yeah, I mean more torsion bar. Stiffer rear bar will cause the car to rotate easier, stiffer front bar will cause the car to push. This is my best explanation on why. More bar in the rear will usually reduce the amount of weight transferred to the outside rear wheel during hard cornering (it stops the outside rear from compressing or squatting), thus providing more traction in the front. More bar will also tend to try and lift the inside rear wheel, since it's the weight of the inside rear wheel and the resistance of it's spring that is acting upon the bar to resist squatting on the outside wheel. All this pressure being applied to the front doesn't come without a loss in grip in the rear. For me, sway bars are a last resort, and Ryal is right in saying that I'm almost at that point, but I still have some tricks up my sleeve. I try to tune the chassis/suspension to it's maximum ability without the use of sway bars, and then I add them when everything else is balanced and working at it's peak. That ensures that I'm not using the bar to correct for other flaws in the setup. The more sway bar you add to a chassis (either end) the less effective the suspension will be at absorbing isolated imperfections in the track/road surface. If I was driving on a NASCAR track this wouldn't be a problem, but road coarses are full of bumps and contours (especially with the way I drive, lol). Above all else, this car is still a daily driven street car, so the suspension must be versatile. Tweak is actually more comfortable to drive on the street than my bone stock 93 Festiva.

[nitrofarm]

Advance when you say more "Rear Bar".Are you saying stiffer torsion bar? I thought a stiffer bar would keep the car from rotating. I hang up now,& just listen to your explanation...

[Dragonhealer]

this is corner 4 where the car felt very balanced. More rear bar would have reduced the amount of speed I could have carried through this corner and corner 3 just before it. I was really gaining ground here on the cars that would out power me up the straight. On the limit the car was a bit tail happy especially in turn 3, which is last place I want to spin (close to 100mph).

Is it possible the variation is due to too light a rear? I know, defeats the whole premise of weight forward Which appears to work marvelously
in all other respects!)

[Dragonhealer]

More caster will certainly do that, and will help on the breaking. What is the best option? Relocate the front anti-roll bar/(trailing link)?

Carolyn's secret weapon is a locker set so tight that you can race with one
axle broken! That and 325 lb/ft of torque!

That inside front wheel.... lets see.. hydrolastic suspension, steering and
body roll inputs, hydrolic pumps, valves...a lot more $$$, more weight,
more complexity......... Citroen !!!

Seriously, except for wider wheels, if you can fit them, I think you are fussing with the last two percent. You have done a magnificent job in a
short time on a limited budget.
We are looking forward to using your
skills on Carolyn's "Grand Am" Monster Slayer Festiva!