lotteman

Hey guys,

Lately i've been reading up on different types of shock valving and how it would affect how your car feels on the street vs cornering. I bought a set of used Bilstein PSS's that I plan on revalving to match stiffer springs. Im fairly new to all this damper tech so I feel a bit lost. From what I know so far:

Digressive- shock is relatively stiff < 3 or so seconds and starts to even out as piston speed increases

Linear- shock has a high flow rate at low speeds and starts to decrease flow(at a consistant rate) as piston speeds increase

Progressive- Shock has a very high flow rate at low speeds and begins to decrease flow at an inconsistant rate as piston speeds increase.

I'm trying to figure out what the best valving would be in my situation, a daily driven G35 that sees a hpde/autox 5+ times a year. I would like my car to handle great but at the same time still have a nice ride on these LA streets. Something that would pass the girlfriend/mom test.

A coworker of mine who has been autocrossing for 20+ years explained a how different valving can change respsonsiveness and overall grip. From what i took from his explanations I really like how linear valving sounds. However, im scared this setup might be too harsh on the street. I also notice a lot of people like to run digressive setups, not sure on the reasoning why but it makes sense i guess.

Any input or help would be greatly appreciated guys!

Scott Webb

You might consider contacting Doug Nagy at Streetwise Motorsports. They have a close relationship with Bilstein and lots of experience tuning dampers for motorsports applications.

http://streetwiseparts.com/shock-dyn.../#.UQy2Fo7DLRo

betamotorsports

iTrader: (1)

You can have a car that has a nice ride and handles great but be ready to spend a lot of money on shocks. Most of the off-the-shelf shocks for street cars have too much compression damping because that gives the stiff ride that most drivers (erroneously) think is good handling. In your case a digressive compression curve will allow good control at low shaft speeds (suspension motion) while allowing less relative damping at high piston speeds (bumps).

And ignore shock valving recommendations for Solo use. The Solo world is all about transitory behavior on a smooth surface which has little to do with street use. Shock valving for Solo is also sometimes used a crutch for not enough spring or roll control, depending on class rules.

03threefiftyz

iTrader: (25)

On my full prep BSP solo car I use digressive on front and very slightly digressive, nearly linear valving on the rear...

lotteman

Im really liking how linear valving sounds. The idea of the shock letting the spring do its work on initial turn in then gradually stabilizing the car just makes sense in my head. A digressive valving sounds like it does the complete opposite. Not sure how right or wrong I am but it sounds right in my head. A digressive setup sounds like youre trying to compensate for not having enough spring or you just like really snappy handling.

Maybe I can compromise with a linear/digressive setup?

A little more information for you guys to work with: I plan on using a 784lbs spring front with a 675 or 700lbs spring in the rear(oem location). Ill mostly be on street tires, rs3's at the most. Ill most likely have my bilsteins valved by my coworker. I trust him because i dont know a lot of other people who've made it to solo nationals lol:P Just trying to figure out what valving I like so he could build them.

03threefiftyz

iTrader: (25)

I trophied at nationals last year ....

Mike Bright has valved his custom ohlins set-up with linear all the way around. I've driven it (we used the same spring rates last year), and the front turns slightly better (and it could have been other variables as well), but other than that it was a wash....

For a purely track car (on smooth surfaces) 0-2in/s(velocity) is the most important to look at on the dyno. Since you DD the car, I would probably prefer digressive valving. It allows you run relatively steep initial (low speed) rebound while keeping it reasonable for the daily woes, such as unexpected potholes, etc.

My .02.

lotteman

Maybe you've met my coworker then? name is guy ankeny, drives a yellow s2k

03threefiftyz

iTrader: (25)

Yeah, Guy knows what he is doing. He is joining the dark side in BSP next year....

betamotorsports

iTrader: (1)

Digressive valving is not a crutch for soft springs.

With digressive valving you can set the knee point (where the damping goes from linear to digressive) pretty much anywhere you want, given a good shock. So at lower shaft speeds where you can control roll, you can have a linear (even progressive) valving and then at some higher shaft speed the valving can soften.

Or spend serious money and run triple or quad adjustable shocks and separate low and high speed valving. Given good shock tuning you can reduce the size of your anti-roll bars.