It has been a while since i am trying to figure out the process of carefully choosing components for my 240's coilover setup. However i stumbled on a problem that seems to be nowhere explained, so thought of posting a thread about it.
From what i have seen there are a few things to calculate before ordering parts to make sure you got the proper springs and strut inserts, so to define the length, spring weight, strut valving etc.
So:
1) We got a set of springs calculated with various ways
2) We got a set of coilover stuff to install on our car
3) We also got old or new stiff struts (revalved or adjustable)..
The question is: How to choose or better calculate which setting on our adjustable strut to use, or what kind of valving to order, so to match the spring rate properly ?
Most people from what i have seen just install the whole system and "by feel" they say if it is over or under damped. But this can not just rely on feel. Not all of us are racing drivers so there should be a correct starting point. Of course it probably depends on what you are doing with your car, but still, there should be some limits that you should not cross and become over or under dumped !! That is what i am trying to figure out.
Lets set an example to analyze so that anyone who replies can talk about the same thing:
We have springs 10 inch long on the front, 350 lbs/inch (=61.29 N/mm or 6.25 kg/mm), and 11 inch long on the rear 200 lbs/inch (=35.02 N/mm or 3.57 kg/mm).
Struts: lets say we have a set of KONIs (info from Dave's site)
So the front are COMP: 157 REB: 213-427 @ lets assume 0,5m/sec (=500mm/sec)
And the rear are COMP: 259 REB: 494-990 @ lets assume 0,5m/sec (=500mm/sec)
A little comment here: On DB site there are some compression and rebound numbers and some computerized DYNO sheets. On some numbers the results are given in lbs (such as above statement by Michael) and some others in Newtons (N). I am not sure if they have been converted though or is a mistake.. My assumption though is that especially the DYNO'ed numbers refer to kg at 500mm/sec, since for example on the dyno sheet for the front R-sport struts for 524.57 mm/sec is 3610.0N and for -528.80mm/sec is -967.6N. These values divided by about 10 to convert N to kg he writes for reb/comp: 360/100
After all these:
1) Do the KONI's mentioned above fit the springs described ? Rear should be more difficult since they are offset positioned related to the axle.
2) Since KONIs are adjustable: What is the limit for becoming underdumped ? For front and rear
3) What is the limit of being overdumped ? Also for front and rear
Sounds like a university exam, however i think solving this would help a lot of people !
From what i have seen there are a few things to calculate before ordering parts to make sure you got the proper springs and strut inserts, so to define the length, spring weight, strut valving etc.
So:
1) We got a set of springs calculated with various ways
2) We got a set of coilover stuff to install on our car
3) We also got old or new stiff struts (revalved or adjustable)..
The question is: How to choose or better calculate which setting on our adjustable strut to use, or what kind of valving to order, so to match the spring rate properly ?
Most people from what i have seen just install the whole system and "by feel" they say if it is over or under damped. But this can not just rely on feel. Not all of us are racing drivers so there should be a correct starting point. Of course it probably depends on what you are doing with your car, but still, there should be some limits that you should not cross and become over or under dumped !! That is what i am trying to figure out.
Lets set an example to analyze so that anyone who replies can talk about the same thing:
We have springs 10 inch long on the front, 350 lbs/inch (=61.29 N/mm or 6.25 kg/mm), and 11 inch long on the rear 200 lbs/inch (=35.02 N/mm or 3.57 kg/mm).
Struts: lets say we have a set of KONIs (info from Dave's site)
WHAT ABOUT KONI SHOCKS?
While I have not yet used Koni shocks on a Volvo 240, I will add the following info for comparison. This comes from 240 owner Michael Yount:
"I've spent a lot of time talking with the tech folks at Koni about their Sport shocks for the Volvo. They are MUCH stouter than the Bilstein HD's. The front struts offer 157/213 lbs. damping compression/rebound. The rebound is (3-way) adjustable - and the 213 is the minimum. They will adjust to 427 lbs. of rebound damping. The rears are MUCH more stout because of the motion ratio - the spring is 27" from the pivot point - the shock is only 22" away. Their rear shocks offer 259/494 lbs. of damping in compression/rebound, and the rear rebound will adjust up to 990 lbs. of damping force."
So the front are COMP: 157 REB: 213-427 @ lets assume 0,5m/sec (=500mm/sec)
And the rear are COMP: 259 REB: 494-990 @ lets assume 0,5m/sec (=500mm/sec)
A little comment here: On DB site there are some compression and rebound numbers and some computerized DYNO sheets. On some numbers the results are given in lbs (such as above statement by Michael) and some others in Newtons (N). I am not sure if they have been converted though or is a mistake.. My assumption though is that especially the DYNO'ed numbers refer to kg at 500mm/sec, since for example on the dyno sheet for the front R-sport struts for 524.57 mm/sec is 3610.0N and for -528.80mm/sec is -967.6N. These values divided by about 10 to convert N to kg he writes for reb/comp: 360/100
After all these:
1) Do the KONI's mentioned above fit the springs described ? Rear should be more difficult since they are offset positioned related to the axle.
2) Since KONIs are adjustable: What is the limit for becoming underdumped ? For front and rear
3) What is the limit of being overdumped ? Also for front and rear
Sounds like a university exam, however i think solving this would help a lot of people !
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