Suggestions for more travel and better traction on dirt?

[F3BZ]

struts are all the same across all models. any spring should fit since struts, caps, vibro insulators are all the same. ford shows 5 different springs and 3 differnt wire diameters (.393, .397, .401) leading me to believe that some of the springs that show the same wire diameters might have a different # of coils. ford doesn't show any other info in the parts list other than corresponding color spot for each spring.
kia shows different springs and struts for the 3 door, 4 door 5 door and combi models. i don't have any specs on them but i do know that the 5 door rear spring is stiffer than a festiva and i have a front spring for a combi and it has 2 xtra coils and is 2" longer than a festiva front coil. maybe the combi rides a little higher than the others. something i'll have to look up in the brochures.

[Sid_RallyX_82]

K, I have a few questions here...
1) what is the stock spring length for a '91 L w/ AC?
2) I have an idea here... I'm gonna probably build some coilovers, but what do you guys think about utilizing two springs one each strut; one light, to manage normal travel over terrain and for body roll; one heavy, to absorb large bumps and landing off jumps. Would that be practical?
3) if it IS practical, what lengths/rates ball park should I be looking in to get the most possible travel out of the struts?
Thanks guys! You're so much help for us newbies

[Advancedynamix]

I don't have the lengths written down, but I do know that there are longer options that would probably work better on dirt. In fact, the BF 323 GTX (Mazdas purpose built rally car) are longer than a festiva, and they bolt right up with kia rio strut mounts. The spring rates are too heavy for a festiva and the spring diameters are too wide as well, but a little custom fab work would solve that issue and allow the festiva springs to be used.
Kia Rio front struts bolt right up and are also longer than the festiva or aspire shocks. Use the festiva springs and you'll probably hook up pretty good over the rough stuff.

[azgtx]

Yes, correct on the long shafts...as we had to deal with. I used Tokico Illumina's on the GTX's stuffed into the Tokico Dirtra (short for dirt track) tubes..they are from the Toyota Mr2 and VW Corrado. The old Tokico Dirtra's are no longer available. I do think you can still get the oem struts for the GTX from Mazda. They were either built by Tokico or KYB.

[Sid_RallyX_82]

Charlie, you've also suggested KYB Golf MkII front struts to me. What can I expect from each the MkII, Rio, and Aspire struts?

[Advancedynamix]

The valving will be different on each of the different choices. It also tends to be slightly different from one manufacturer of shock to the next.
Even if I had the shock dyno graphs for each shock, that info would be useless until you get some time in the car on the track and decide what it's doing and what you need it to do. I would start with good quality stock suspension and drive it as hard as you can practicing all the different obstacles and terrain you'll see in competition. Then post up what your thoughts are and what you would like.
The difference between a championship winning FIA world Rally car and your every day hatchback isn't just a multimillion dollar budget, it's track time and R&D.

[Sid_RallyX_82]

Alright, if I could take a side track and talk about the rear, considering how much toe would change over rough terrain and potentially make handling unpredictable, would suggest less camber? Or is the another way of having more camber with less dynamic toe through travel? Yes, I know this will depend on specific conditions and exactly how I make use of the car. Just looking for more bits of knowledge that I can piece together later on

[Advancedynamix]

If your camber and toe are set to zero then the changes will be slim to none. However, the toe change with camber from beam articulation can improve the predictability of the chassis dramatically. I've found this to be a big advantage in the handling of these cars. It can work like a very complicated multi link 4 wheel steering system, except it's just a simple flex beam.
The trick is to set your camber and toe so it will do what you want. If you start with say 1 degree negative camber and 1/16 total toe in with 2" of droop, you'll shouldn't notice instability over the crests, but you'll get a little help in the corners from the camber, when the car leans over. As the beam articulates, the outside wheel will toe in as the inside toes out slightly. This is not going to be drastic, but it does reduce scrub and help maintain traction. I've been working with trailing beam style rally cars since the mid 90's. Back then we were using VW Golfs, but the Festiva is a better car in my opinion.

[Sid_RallyX_82]

Ok, say I want more travel for rough terrain (if you can't tell, this has been my main focus ) and allow for... less than maximum droop. Idk how much that will be cuz I still need to reduce weight and play with ride height... What is stock travel length? Any way, say I have a fair amount of droop and I'm sliding through a turn and go through dips and bumps. If I have -1*, the change from toe in to toe out should be minimal? And allow predictability?
Sorry, I feel like this was a bit scrambled but I'm too tired to edit

[Advancedynamix]

You won't want to lift the car much for clearance. These cars are already plenty high enough for rally terrain from the factory. Also, lifting the festiva much causes other geometry issues, that can make the car feel nervous at high speed.
If you lift the car, your already reducing droop. Negative camber improves stability, as does toe in (to a point). If you only have an inch of droop and 1 degree of negative camber and 1/16 toe in, you'll have more stability over rough terrain than a stock festiva if all your other settings are equal.

As the rear suspension moves downward through its stroke (when the car becomes light over crests or jumps, or the wheel settles in a hole or rut) the negative camber will toe the wheel out. The more negative camber, the more drastic the transition will be. As the suspension compresses upward through its travel (landing from jumps, body roll, bumps ect) the negative camber becomes toe in.
Now, to fully understand the effects this has on the vehicles handling cherictaristics, you must consider the weight transfer taking place during each event of suspension movement. Typically, when the suspension is in a droop state, the wheel that it is attached to is unloaded and has less effective over the cars direction than the loaded wheels. Also, slight changes in suspension geometry will not be noticeable on loose, or rough terrain. Fussing over a degree of wheel attitude when your hammering the car over sand or gravel is foolishness.

More importantly, what happens when you drive the car now at high speeds over the terrain your racing on? Building a car on paper, without a good baseline to start from is a fools chore.

[Sid_RallyX_82]

Alright, you say "start with good quality stock suspension". I have the factory setup. Everything is still good. If I drop my ass on either bumper and jump off it quick, the car will rise back up just slow enough that it does not bounce at all. Does that meet your criteria or do you suggest replacing with all new Festiva KYBs? Or other brand

[Advancedynamix]

That should work. Plot out a practice coarse and start recording lap times and learning how the car reacts on the obstacles. When you get to know the coarse and the car well enough, then you can begin to refine the chassis to suit your needs. Until then you have no idea if your making a change for the better.
All to often, I'll test drive people's "fully built race cars" that have all the trick parts, only to run slower laps than I did in the car when it was stock. This is because driving fast has nothing to do with a spec sheet of trick parts, but it has everything to do with a user friendly machine that allows the driver to focus on the task at hand. Learn your machine, and focus on improving only what is necessary to accomplish your goal. That is the method for building a competitive race car.

[Sid_RallyX_82]

Well, that's exactly why I wanted to lift it about two inches or so. My course has occasional harsh dips and a few sections with large boulders sticking part way out of the dirt and I have to slow down a lot more than I want to through there. Maybe heavier springs and bumpstops will help enough