Characterization of the OE Suspension Springs
01-20-2011, 06:01 PM
#41
My car is not as low as others in STR, and the rubbing had to have happened in a turn at an autocross. And, my car is very composed over bumps, so it's not very dramatic.
01-20-2011, 06:31 PM
#42
I tried the link, but it doesn't work. I estimated 2:1 since it appeared that making a 1/4" adjustment to my rear spring perch changed the ride height by 1/2".
Since every race track has bumps too, it seems that some bumps should be factored into the bump stop "study". I'll try to remember bringing some dye to my next autocross.
Since every race track has bumps too, it seems that some bumps should be factored into the bump stop "study". I'll try to remember bringing some dye to my next autocross.
01-20-2011, 06:34 PM
#43
Originally Posted by robinson,Jan 20 2011, 10:01 PM
My car is not as low as others in STR, and the rubbing had to have happened in a turn at an autocross. And, my car is very composed over bumps, so it's not very dramatic.
My brother has an S2000, and barely reaches the speed limit, but his wheel / tire combo has removed paint from his fenders.
01-21-2011, 09:02 AM
#45
Former Moderator
Originally Posted by gernby,Jan 21 2011, 09:14 AM
What is a GoPro?
http://www.goprocamera.com/products/?gclid...CFQkSbAodekZRHg
01-21-2011, 09:01 PM
#47
A couple other related things to keep in mind regarding bump stop engagement and fender rubbing...
1. Shock body length in the rear is a factor when lowering the ride height. You really want to minimize bump stop engagement as it is non linear and can quickly overload the tire and induce loss of traction. I have driven a couple, make that three, lowered STR cars locally that were very difficult to drive because the bump stops were engaging causing lost of traction in the rear resulting in a very loose rear. I installed shortened rear shock bodies 1" to allow more travel and lower ride height. You can have Konis shoretned if willing to pay for it. My friend had it done for his Celica. For my setup (Penskes with Penske bump stops) the front tire rubs the fender about the same time the bump stop is engaged..
2. Shock rebound damping if very high can jack down the suspension in a steady state turn even with minor bumps. When I first ran my lowered STR setup the pavement had ripples in it and jacked the suspension down in the front until the tire engaged the top of the fender well. I was running way too much rebound. After softening the rebound it stopped happening.
Short rear shock body
Front ender rubbing
1. Shock body length in the rear is a factor when lowering the ride height. You really want to minimize bump stop engagement as it is non linear and can quickly overload the tire and induce loss of traction. I have driven a couple, make that three, lowered STR cars locally that were very difficult to drive because the bump stops were engaging causing lost of traction in the rear resulting in a very loose rear. I installed shortened rear shock bodies 1" to allow more travel and lower ride height. You can have Konis shoretned if willing to pay for it. My friend had it done for his Celica. For my setup (Penskes with Penske bump stops) the front tire rubs the fender about the same time the bump stop is engaged..
2. Shock rebound damping if very high can jack down the suspension in a steady state turn even with minor bumps. When I first ran my lowered STR setup the pavement had ripples in it and jacked the suspension down in the front until the tire engaged the top of the fender well. I was running way too much rebound. After softening the rebound it stopped happening.
Short rear shock body
Front ender rubbing
01-24-2011, 01:48 AM
#48
UK Moderator
Originally Posted by twohoos,Jan 20 2011, 08:20 PM
I don't think they were wheel rates, but they are "as-mounted" rates, meaning they account for "inactive" coils. A coil can be inactive due to spring-end design ("closed" and/or "ground" wire), spring perch design, and/or suspension preload.
Again, I'm eager to get some direct measurements from someone who has the right resources.
Again, I'm eager to get some direct measurements from someone who has the right resources.
I do have a set of MY02 springs spare, but I guess shipping them to the USA is a bit much
01-28-2011, 11:56 AM
#49
I figured I'd share an interesting discovery I made about the OEM bump stops this week.
Last year I replaced my OEM shocks with adjustable Koni's, and installed the OEM springs on the lower perch. I decided not to cut the bump stops, since I didn't think it would be necessary for the small amount that I was lowering the car (about 3/4"). I autocrossed all year on that setup, but I didn't think I was any faster than I was on the stock suspension. I've pretty much averaged 4th place out of ~15 S2000's (non-SCCA street tire class) before and after I upgraded the shocks.
I decided at the end of last year that I would replace my OEM springs with adjustable perches and Eibach coilover springs (500# front and 450# rear). I didn't lower the front any more than before, but I did lower the back another 1/4". After doing this, the car seemed very twitchy. I liked the way it felt, but it was very easy to kick the back end out on corner exit with slight throttle modulation.
After reading a bit in this thread and others, I decided I needed to trim my bump stops. I didn't expect it to change the way the car handled around smooth corners, but it REALLY did. The car now feels quite a bit softer, and the balance is totally different. My back end is now WAY more planted than the front. I haven't even been able to get the back end to kick out with heavy throttle. My front tires are also rubbing the fender liners on relatively minor dips / bumps. I've NEVER had them rub before.
I think I'm going to have to either put my stock front sway bar back on (I currently have a CR bar), get a stiffer rear bar, or get stiffer rear springs. Actually, I think I really need to get stiffer springs all around to reduce the wheel rubbing.
I kind of got off track there, but the reason why I am posting about this in this thread is because I really think that the OEM bump stops must be engaging a LOT. They might be a signfiicant contributor to the handling characteristics of the OEM suspension even on smooth surfaces. Maybe they are the "progressive" part of the springs...
I just now looked earlier in this thread, and see that INTJ mentioned this very thing.
Last year I replaced my OEM shocks with adjustable Koni's, and installed the OEM springs on the lower perch. I decided not to cut the bump stops, since I didn't think it would be necessary for the small amount that I was lowering the car (about 3/4"). I autocrossed all year on that setup, but I didn't think I was any faster than I was on the stock suspension. I've pretty much averaged 4th place out of ~15 S2000's (non-SCCA street tire class) before and after I upgraded the shocks.
I decided at the end of last year that I would replace my OEM springs with adjustable perches and Eibach coilover springs (500# front and 450# rear). I didn't lower the front any more than before, but I did lower the back another 1/4". After doing this, the car seemed very twitchy. I liked the way it felt, but it was very easy to kick the back end out on corner exit with slight throttle modulation.
After reading a bit in this thread and others, I decided I needed to trim my bump stops. I didn't expect it to change the way the car handled around smooth corners, but it REALLY did. The car now feels quite a bit softer, and the balance is totally different. My back end is now WAY more planted than the front. I haven't even been able to get the back end to kick out with heavy throttle. My front tires are also rubbing the fender liners on relatively minor dips / bumps. I've NEVER had them rub before.
I think I'm going to have to either put my stock front sway bar back on (I currently have a CR bar), get a stiffer rear bar, or get stiffer rear springs. Actually, I think I really need to get stiffer springs all around to reduce the wheel rubbing.
I kind of got off track there, but the reason why I am posting about this in this thread is because I really think that the OEM bump stops must be engaging a LOT. They might be a signfiicant contributor to the handling characteristics of the OEM suspension even on smooth surfaces. Maybe they are the "progressive" part of the springs...
I just now looked earlier in this thread, and see that INTJ mentioned this very thing.
01-28-2011, 12:19 PM
#50
It just occurred to me that anyone who installs lowering springs with OEM bump stops will need to be VERY precise about how much they trim from the bump stops. If they cut too much off the front, they could cause an oversteer problem. Too much off the rear could cause an understeer problem. It really seems like a "good" lowering spring kit should include a set of matched bump stops...