Need help chosing a proper coilover setup.
Sep 4, 2013, 07:14 PM
#91
Evolved Member
Thread Starter
iTrader: (9)
Join Date: Mar 2006
Location: CT
Posts: 597
Likes: 0
Received 0 Likes
on
0 Posts
...On a side note, I just pulled the trigger and ordered a set of these, freshly rebuilt by Eibach for $1100 shipped - 0 miles on the rebuild.
They can be seen here: https://www.evolutionm.net/forums/sa...coilovers.html
Sep 5, 2013, 06:23 AM
#92
In general, as you increase the spring-rate, you also should bias the shocks more towards rebound. Why? Because the stiffer springs will resist upward (bump) movement more, so you need less compression damping; plus, the stiffer springs can store more energy that needs to be controlled, so you need more rebound damping.
There's a simple (and , therefore, over-general) rule that says you first calculate the amount of low-speed damping required to be, say, at .75 of critical, but then multiply the compression by 2/3 and multiply the rebound by 3/2. (This is the 2/3 & 3/2 rule.) Because damping is geometric, instead of arithmetic, you multiply the values to get the new overall value, and 2/3 times 3/2 is 1, so you are still at the same overall value.
Now, the 2/3 & 3/2 rule is meant for moderate spring-rates. As you start to move towards really stiff, you need even more bias towards rebound. The one thing that you have to watch out for is "packing down," which is when you have so much rebound that the shock doesn't re-extend after each bump, so the shock keeps compressing more and more, "packing down" the spring. This is very, very bad, because a packed-down spring is stiffer than a spring at rest, so the car becomes more like a go-kart (i.e., something with no suspension at all). But as long as you don't go so far as to pack the suspension down, more rebound to control the stiffer springs is best for tarmac handling.
Well, those curves for the front shocks are close to 1:1, not 2/3:3/2 or better. The amount of rebound seems OK for 8kg springs, but that's too much compression. Rather than "give" when the fronts hit a bump, the nose will rise up. That won't be nice for the passengers; that's not the best for handling either. Hence, my comment that it would be nasty.
There's a simple (and , therefore, over-general) rule that says you first calculate the amount of low-speed damping required to be, say, at .75 of critical, but then multiply the compression by 2/3 and multiply the rebound by 3/2. (This is the 2/3 & 3/2 rule.) Because damping is geometric, instead of arithmetic, you multiply the values to get the new overall value, and 2/3 times 3/2 is 1, so you are still at the same overall value.
Now, the 2/3 & 3/2 rule is meant for moderate spring-rates. As you start to move towards really stiff, you need even more bias towards rebound. The one thing that you have to watch out for is "packing down," which is when you have so much rebound that the shock doesn't re-extend after each bump, so the shock keeps compressing more and more, "packing down" the spring. This is very, very bad, because a packed-down spring is stiffer than a spring at rest, so the car becomes more like a go-kart (i.e., something with no suspension at all). But as long as you don't go so far as to pack the suspension down, more rebound to control the stiffer springs is best for tarmac handling.
Well, those curves for the front shocks are close to 1:1, not 2/3:3/2 or better. The amount of rebound seems OK for 8kg springs, but that's too much compression. Rather than "give" when the fronts hit a bump, the nose will rise up. That won't be nice for the passengers; that's not the best for handling either. Hence, my comment that it would be nasty.
Sep 5, 2013, 06:43 AM
#93
Evolved Member
Thread Starter
iTrader: (9)
Join Date: Mar 2006
Location: CT
Posts: 597
Likes: 0
Received 0 Likes
on
0 Posts
In general, as you increase the spring-rate, you also should bias the shocks more towards rebound. Why? Because the stiffer springs will resist upward (bump) movement more, so you need less compression damping; plus, the stiffer springs can store more energy that needs to be controlled, so you need more rebound damping.
There's a simple (and , therefore, over-general) rule that says you first calculate the amount of low-speed damping required to be, say, at .75 of critical, but then multiply the compression by 2/3 and multiply the rebound by 3/2. (This is the 2/3 & 3/2 rule.) Because damping is geometric, instead of arithmetic, you multiply the values to get the new overall value, and 2/3 times 3/2 is 1, so you are still at the same overall value.
Now, the 2/3 & 3/2 rule is meant for moderate spring-rates. As you start to move towards really stiff, you need even more bias towards rebound. The one thing that you have to watch out for is "packing down," which is when you have so much rebound that the shock doesn't re-extend after each bump, so the shock keeps compressing more and more, "packing down" the spring. This is very, very bad, because a packed-down spring is stiffer than a spring at rest, so the car becomes more like a go-kart (i.e., something with no suspension at all). But as long as you don't go so far as to pack the suspension down, more rebound to control the stiffer springs is best for tarmac handling.
Well, those curves for the front shocks are close to 1:1, not 2/3:3/2 or better. The amount of rebound seems OK for 8kg springs, but that's too much compression. Rather than "give" when the fronts hit a bump, the nose will rise up. That won't be nice for the passengers; that's not the best for handling either. Hence, my comment that it would be nasty.
There's a simple (and , therefore, over-general) rule that says you first calculate the amount of low-speed damping required to be, say, at .75 of critical, but then multiply the compression by 2/3 and multiply the rebound by 3/2. (This is the 2/3 & 3/2 rule.) Because damping is geometric, instead of arithmetic, you multiply the values to get the new overall value, and 2/3 times 3/2 is 1, so you are still at the same overall value.
Now, the 2/3 & 3/2 rule is meant for moderate spring-rates. As you start to move towards really stiff, you need even more bias towards rebound. The one thing that you have to watch out for is "packing down," which is when you have so much rebound that the shock doesn't re-extend after each bump, so the shock keeps compressing more and more, "packing down" the spring. This is very, very bad, because a packed-down spring is stiffer than a spring at rest, so the car becomes more like a go-kart (i.e., something with no suspension at all). But as long as you don't go so far as to pack the suspension down, more rebound to control the stiffer springs is best for tarmac handling.
Well, those curves for the front shocks are close to 1:1, not 2/3:3/2 or better. The amount of rebound seems OK for 8kg springs, but that's too much compression. Rather than "give" when the fronts hit a bump, the nose will rise up. That won't be nice for the passengers; that's not the best for handling either. Hence, my comment that it would be nasty.
Sep 5, 2013, 07:14 AM
#95
Evolved Member
Thread Starter
iTrader: (9)
Join Date: Mar 2006
Location: CT
Posts: 597
Likes: 0
Received 0 Likes
on
0 Posts
Thanks for all your help. I feel like I've been educated on some things.
...On a side note, would you say these were a better purchase than some FA?
Last edited by CtSilver03Evo; Sep 5, 2013 at 09:52 AM.
Thread
Thread Starter
Forum
Replies
Last Post
MRevolutionX
Evo X Tires / Wheels / Brakes / Suspension
25
Mar 21, 2016 11:03 AM
GTWORX.com
Evo Tires / Wheels / Brakes / Suspension
96
May 15, 2014 11:36 AM
project_lancer
Lancer Tires, Wheels, Brakes & Suspension - Sponsored by The Tire Rack
47
May 19, 2013 03:18 AM
kensuke
Lancer Tires, Wheels, Brakes & Suspension - Sponsored by The Tire Rack
45
Mar 23, 2013 03:31 AM
trinydex
Evo Tires / Wheels / Brakes / Suspension
23
Sep 17, 2009 12:44 PM