andyng

Well, tried to search on this topic but couldn't find anything...

I'm from Malaysia and drive a Proton Putra 1.8dohc 4G93P...exactly same as the Mitsu Mirage Asti (Coupe). In Malaysia, the Putra (mirage asti) shares many parts as the Wira (lancer), therefore tapping the same resources for performance parts...

question is, me and my friends are happy with a local coilover manufacturer's product quality and build, but not happy with the settings recommended for us.

So, we are trying to find out what are the bound and rebound damping rates for a lancer/mirage coupe 1.8 using:
1. 7kg/mm linear front and 5kg/mm progressive rear springs
2. 8kg/mm linear front and 5 or 6kg/mm progressive rear springs

What we have felt is that the above spring rates are quite correct, but can;t get a matching damping rates.

Hope you experts here can help point us in the correct direction. then we can just ask the manufacturer to set those dampings for us.

The coilovers are of height adjustable type, twin tube design, 250mm length springs. Weight of car is about 1100kg i think. driving conditions are like tarmac rally or spirited road use...not track settings.

Thank you in advance for reading this topic.

Confused...

urbanknight

iTrader: (14)

try Tein (www.tein.com) they have various spring rates and dempening levels, including dual spring setups. As long as one of their sizes fits your car, they could send you some matched springs to your dampening, or offer you shocks with adjustable dampening to match the springs.

andyng

we already have the coilovers in the car, just that we need some numbers for damping rates for us to work on...usually they are in kg/F (whatever that is) measurements, tested using strut damping dyno machines. I don;t think any of the major manufacturers will reveal their numbers, so i seek the advice of fellow enthusiasts who have found their suitable settings and have had them tested on the dyno machine to get a reading of the damping rates. we decided not to get any imported sets due to the lack of a local agent who can service or recondition them with proper equipment. and we don;t get to choose springs rates or whatever settings we want, just can get whatever is available off the shelf...sad but true...

urbanknight

iTrader: (14)

ouch, sorry to hear that. Unfortunately I have no idea what dampening rates I have. Unless you want to ship me your dyno maching, I just go by level 0-16. Maybe someone else on here knows the numbers.

andyng

yeah...quite unfortunate we are here in Malaysia in terms of performance parts...what are your spring rates anyway? I hope someone here can give us some direction...i wish i had a dyno machine myself...

one more question...i used to use 5kg front and 4kg rear springs with a certain damping...if anyone can tell about the corresponding increase in damping rates according to increase in spring rates, it would help too...like every increase of x% spring rate should follow with y% increase in damping rate...or every 1kg increase spring rate, should follow with ?kg/F increase damping.

am i confusing you guys? or am i confusing myself...

sdhotwn

iTrader: (2)

I think most of us on here tune by experimentation and adjustment not by actual hard numbers.

Hopefully I have some time tonight. But then I'll be able to go through and do some calculations and give you numbers that will indicate what damping rate will make you critically damped (not overdamped, or underdamped), and some ranges for overdamping. That would probably be about the best I can do for you!

urbanknight

iTrader: (14)

If this helps, off the Tein site the kit for the 02/03 Lancer OZ has 7kg front and 5 kg rear. But I imagine the stock springs are much less.

sdhotwn

iTrader: (2)

Your critical damping coefficient (the minimum amount of damping possible without generating oscillation) = 2*mass*(springrate/mass)^(1/2)

So then units would work out t kg*(N/m*kg)^1/2 So that's that more or less... if you have more damping than that.. you are overdamped which is typically desireable for suspension applications (being underdamped results in "bounce").

I don't have enough time to be of more help.. hope that is at least of some use.

andyng

sdhotwn,

sorry for not understanding your formula (i'm a maths idiot) but how do you calculate "2*mass*(springrate/mass)^(1/2)" and "kg*(N/m*kg)^1/2" and what about the piston speed factor?

...what i have done is print out some graphs from the JIC website and try to estimate the numbers from the graph and try to match with the spring rates, then simulate for the mirage CA4A.

for everyone's benefit, check this out:
http://www.jic-magic.co.jp/file/product/j_index.htm
but translate with www.babelfish.altavista.com

thanks...

sdhotwn

iTrader: (2)

I don't know if it works out for what you need.. but was the best I found in the time I had to search. Just take your vehicle mass (kg's) and spring rate (Newtons/meter) and plug it into the equation of 2*mass*(springrate/mass)^(1/2) That will give you a number that has funky units. I didn't/don't have time to verify what the units condense down to.... but that gives you a damping coefficient... that's about all I have at this point.. but what you have done with the graph is probalby better anyway as theoretical is usually not the most accurate way to go.

andyng

thanks!

anymore websites to refer to where i can check technicalities of damping and also damping curve charts...?