Suspension for dry tarmac rally

Hi all,

What are the considerations for coilovers for dry tarmac that is not crazy bumpy but definitely can have bumpy sections, has lots of elevation changes, crests, on and off camber turns, and sometimes ripples and crumbled tarmac?

Over the years I've tried a lot of circuit spec dampers - Nitron R3's, Ohlins R&T, JRZ's, Tractive's, etc. My thinking now is for a modified road car (Porsches, GR Yaris, etc), you want soft springs (but still stiffer than OEM), adjustable ARB's, and longer travel. The longer travel is especially hard to get in the front because most of the time you are on Macpherson struts's with 1:1-ish motion ratios. I find you really need more droop travel with rebound on the softer side so that your wheel really follows the road. For example, you go over a crest and as you go down in elevation the front wheels unload and go into droop. If you run out of droop travel then no matter how great the damper is, your tires aren't on the road.

I wanted to compare notes with people on here. Do you agree/disagree?

How much total free suspension travel do you want especially in the front? 10cm? 12cm? 15cm? I find circuit dampers sometimes is 8-10cm and it's way too short. The rear is usually quite ok with circuit dampers because the motion ratio is way below 1 so there's enough wheel travel.

Typical modified road cars are 1400-1500kg. What type of spring rates do you like especially in the front? In a Porsche with a light front end I think 80 N/mm is a good sweet spot. Tons of forums love 110 N/mm but I find that way too stiff. For front engine RWD cars like BMW's I'm thinking 110 N/mm or so. I've driven 80 N/mm BMW's and find that just a tad soft.

I'm concentrating on the front end because I find the front end by far is the most important. That's your drive under braking, your roll stiffness under trail braking, etc. Then you just pick a rear spring for balance after you pick the front.

What do you guys think? I'm especially interesting in knowing how long you think the total free travel needs to be, and what type of compression to droop ratios you run. The HPA course's rule of thumb of 66% compression 33% droop I find there isn't enough droop for circuit type of dampers.

Anyone know what the usual travel length of tarmac rally suspensions are from the likes of rally spec dampers like Reiger, Samsonas, etc?