What makes it a rally car? The suspension.

I’m going to break into a topic that is critical for your success in rally, costs a lot of money, was once a bit controversial on rallynotes, and a subject I’m still learning about after 7 years in the sport: Suspension.

Suspension makes the car a rally car: Regular street car struts / shocks are just not designed to take the abuse and friction that rally cars can see. First is the springs: Often 100+ pounds more force then a street car with more inches of travel. Second is the side loading: Engineers wish for a strut centered directly over the wheel that only travels up and down at a perfect 0° angle. The reality is camber, caster, toe, rotation, and side loading. The center of the tire is 4″ from the bottom of the strut, it’s at a 10° angle to the ground, the pivot for the control arm changes this angle as it goes up and down, etc. Then you go over a giant jump into a tight right hand turn – fully unloaded to fully loaded in 2 seconds. All of that energy has to go somewhere.

The first way to overcome these issues is with an inverted shock / or strut. This takes the single point of stress that is a narrow 14-19mm rod, turns the assembly inverted (upside down) and protects the damper. Now the side loading is spread over a 50mm housing and the damper piston is happily sealed from the elements. The second way is to give the damper a higher volume of fluid with a separate reservoir. It takes longer to heat up more fluid and it cools outside of the strut. You can control how fast or slow that fluid moves into the reservoir giving you adjust-ability. This is why ‘remote reservoir inverted adjustable struts’ are used in rally.

“But Kris said that he finished a rally on stock struts!” Yes. I did. It sucked. You just can’t go anywhere near as fast as you can on a proper rally setup. Unfortunately it took me a long time to get there with the P-Car (Ze’Neon). I was making a pretty good show in rallycross and had survived my first two rally events on stock dampers when I started to work with Bilstein in 2006. Their sponsorship for us consisted of a set of inverted motorsport inserts. (Just the part on the left, not the whole strut on the right.) It was up to us to have the strut housings machined as Bilstein did not make 1st Gen Neon struts. With a budget of “less than no money” I had someone with some experience build a set of housings out of stock struts. This was a miserable failure (Read the complete Rim of the World 2006 story here). Looking back, I downplayed it as much as I could to not let my new “suspension” sponsors down. The truth was the damper rod bolt shot out of the bottom of the strut INTO the CV joint on one side after the housing failed. I lost all the seals and bearings on all 4 struts, and my buddy Harry became my personal hero for rescuing us with stock spares. As far as Bilstein is concerned, their equipment is awesome! It was the cheap housings that caused all the drama. Bilstein replaced the broken rod for me, later re-valved the rears, and those dampers are still on the rally car to this day! The combination being a set of Bilstein PT cruiser fronts (that accept the motorsport inserts) and a reworked set of rear housings. Even though it works, and was able to get us a championship winning setup, this hodge-podge mismatch of housings and inserts is not something I ever want to go through again.

What should it cost? What should your budget be? I’d start at $1500 – $2000. If someone says to you they have a new rally suspension setup for less then $1000, you are going to get what you pay for. Non-inverted, junk coil-overs, with thin metal housings. Save up for the real thing!

Being able to open up a catalog and order rally struts for the 2GN (after the fiasco with the P-Car) was rewarding. Hot Bits has a ton of applications for all kinds of cars. Their full on rally setup is expensive, but you get a lot for your money. Hot Bits RSI Rally includes Camber plates, bound/rebound 35/40 way adjustable, inverted dampers, adjustable coil overs, and an out of the box rally setup that helped us set 3rd fastest times @ NNR in a brand new rally car! If you’re considering building a car, consider very carefully what options you have for an “off the shelf” rally suspension setup.

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5 Responses to What makes it a rally car? The suspension.

  1. Mark Lewis says:

    I just found your website recently and F.B./Liked it today. Glad to see your common sense input. Not much rally info here in North Carolina, let alone events. I am planning on building a purpose built car for some club level rallycross events in 2013. Thanks for your input.

    • Kris says:

      Hey Mark – Thanks for checking us out! (and the Like) You may be surprised to learn that one of the NASA Rally Sport directors lives in North Carolina! Have you heard of this: http://sandblastrally.linaracing.com/ Should be decently close to you and gets a TON of entries! (Bikes and Cars). Send us pics of the rallycrosser when you race! – Kris

      • Mark Lewis says:

        Kris: THANK YOU so much for the Sandblast Rally info. I will be glad to keep you updated on the Rallycross project.

        Mark

  2. Mike Houston says:

    Mark, I am also in NC. Attend Sandblast every year for the past 5 years. There is also THSCC in the Raleigh area of NC. I am working on transforming my SRT4 into a Rallycross Car. But just taken time since right now it is my DD.

  3. Mike houston says:

    Kris,
    Great Write up! I am on BC Coilovers right now. but my plans are to change those out next year for some hotbits. Since BC doesnt do any Dirt / Gravel research , Development.

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