catman78

iTrader: (15)

Hi all,

I'm picking up some used Bilsteins that I'm gonna send out for re-valve before install.

My current setup is:

Robispec springs
245/40/17 Star spec's
Master Bushing kit
Whiteline Bumpsteer and RCK.

Should I get them valved same as stock or something different?

Car is a DD with some HPDE events thrown in.

Thanks for the suggestions in advance.

n2oiroc

iTrader: (33)

get the spring rates from robispec and get them revalved.

erald01

iTrader: (5)

where do you send them for revalving, i wonder if i shoud send mine out too

theEVOdream

iTrader: (41)

http://www.bilsteinus.com/products/s...e/service.html

this link should answer your question

Iowa999

iTrader: (1)

www.bilsteinus.com

Most people ask for more low-speed compression damping.

Iowa999

iTrader: (1)

jinx!

catman78

iTrader: (15)

Originally Posted by SmikeEvo
Stock: F: 180, R: 225. 0 drop.

Robi site states 20% stiffer upfront and same in rear.

So Robi springs s/b

216 front, 225 rear.

Iowa999

How does your recommendation translate to revalve specification?
Do I just list the form along with Robi Spring rates?

Smike

iTrader: (8)

Give them the max rates that the springs have. They will do the rest of their magic.

madmax199

iTrader: (20)

Ask for them to be valved at 65% critical damping and go as digressive as they can. You will thank me later! Oh and tell them Max (the world challenge BMW guy) sent you!

catman78

iTrader: (15)

madmax199

Should I just type that into .pdf form under or do I need to give them #'s?

Revalve Specifications/ Work Request Information:

madmax199

iTrader: (20)

Ask to speak to Ramone, he's the shop manager. You still will have to fill the work request form/spec but he will tell you how to fill it acoording to your demands!

FERNO

iTrader: (4)

Some good info in here. I'm still waiting to get my first set back but I may follow these suggestions for my spare set.

Iowa999

iTrader: (1)

I've seen people say this before, but there's something I don't quite get. This involves the difference between bounce and rebound damping. Are you asking that the shock produce 65% of the force required for critical damping during both rebound and compression?

madmax199

iTrader: (20)

The 65% number is a balanced compromised between being underdamped(around 50%) and overdamped (70+%). Simply put, the critical damping has to do with the oscillation of the springs and the rate they are controlled by the dampening curve.

Without being overly technical, any disturbance to the system will cause it to oscillate until the springs and dampers are done reacting. A 65%-70% critically damped shock will dampen out the oscillation with limited overshoot and control the spring's natural frequencies without too much bouncing up and down.

The reason 70% is not often recommended is because, through testing, racers have found out that, unless the surfaces are silky smooth, things becomes a little problematic over junctions and bumps so 65% is a nice compromise for all kind of surfaces. Ballers still go out and revalve at 70% for certain tracks but most, including me, use the magic 65 on pretty much any track and any car. I have my dd, Auto-x toys, and even the company car when did the world challenge(back when privateers and small teams stood a chance).

For the techies, this is how Critical Damping is calculated:

Critical damping Cc = 2 * SQRT( K * W / g ) . . . where K is some kind of spring rate (lb/in) and W is the weight (lb) of the mass that's "vibrating". g is the acceleration due to gravity (386.4 in/sec^2)

Iowa999

iTrader: (1)

Please be overly technical.

My question was whether you set both rebound and compression damping to 65%, as opposed to, for example, setting rebound to 70% and compression to 60%.

ps. when you wrote that 70% was "overdamped," I assume that you mean that this is excessive damping (i.e., bad for handling and/or ride), and not that it's actually, technically, overdamped, yes?