Coilover height affect of performance

[PNW Avant]

This is a fundamental question about coilovers and their performance at different heights. I have the Koni streetsport coilovers and I find the ride to be quite jarring during city driving, but actually quite pleasant during highway or arterial speed driving.

My question is, when I raise the coilovers, is there any affect of performance of the suspension (besides raising the center of gravity and the associated affects)? I'm wondering if changing the neutral position of the strut closer to the center of its range changes its performance characteristics (i.e., if you are really low, the strut is stiffer because it is near the end of its range). Any input on this?

I ask this question because I am wondering if raising the coilovers will result in a slightly better ride. I'm at about 25 all around and not really happy about the ride after about 8k on the coilovers. I'm additionally considering replacing all shock mounts, sway bar links, etc, to try to smooth things out. Otherwise, I think my only other option is to go with another brand/model like KWv3 to get the comfort and performance I'm looking for.

[32_d3gr33s]

This is a fundamental question about coilovers and their performance at different heights. I have the Koni streetsport coilovers and I find the ride to be quite jarring during city driving, but actually quite pleasant during highway or arterial speed driving.

My question is, when I raise the coilovers, is there any affect of performance of the suspension (besides raising the center of gravity and the associated affects)? I'm wondering if changing the neutral position of the strut closer to the center of its range changes its performance characteristics (i.e., if you are really low, the strut is stiffer because it is near the end of its range). Any input on this?

I ask this question because I am wondering if raising the coilovers will result in a slightly better ride. I'm at about 25 all around and not really happy about the ride after about 8k on the coilovers. I'm additionally considering replacing all shock mounts, sway bar links, etc, to try to smooth things out. Otherwise, I think my only other option is to go with another brand/model like KWv3 to get the comfort and performance I'm looking for.

If you are really low, there is very little room for the shock to absorb the bump because it is nearly all the way compressed. raise the suspension and the ride becomes a little smoother. I was slammed on st coillovers with stock wheels. So much so that i was scraping the bottom of my car on driveways and such. The ride was absolutly horrid. Raised it slightly and the ride became so much nicer. probably 1/4 of an inch made all the difference for me.

[Abuck35]

ummmm don't street sports have adjustable dampening?

[evo_ski]

I can say firsthand that varying the height on vogtland gts varies the ride tremendously. Not in straight line performance or how they feel just cruising around, but when mine were at around 24.75 I think under hard corners the rear bump stops would come into play and cause the front corners to dive super heavily. You kinda got the double turn in feel to it. It would turn in semi hard and then once you pushed it to a certain point after the front rolled enough it would bite again super hard and be on complete rails. After raising it to around 25 1/8 for winter that completely stopped the double turn in. They now feel like a normal suspension as far as cornering goes and they will bite pretty evenly throughout the corner. My old FK Silverlines that blew were not like that since they didn't use bump stops, so you could raise or lower it without changing how anything felt.

[b6onboost]

Raising them will help with ride quality.

My concern is your expectation of how a performance suspension is going to handle city/harsh roads. Most will fell like butter on smooth highways, but on harsh city roads they are going to cause a more jarring ride. Its the nature of the stiffer springs. That being said, Stasis/Koni SS have some of the softest springs of any aftermarket coilover. They are truely 'street' coilovers. They really don't ride much different than OEM sport, so long as they aren't completely slammed. My friends, who own other modded cars with coilovers, get in my car and comment how ridiculously smooth mine are while being just as low as them. I'm at ~ 25in, zero fender gap. So if one of the mildest and smoothest coilovers for the B6 is too jarring for you and your driving conditions, don't know what to tell you. Even though my coilovers are really smooth, I can personally say that I would not want them if the majority of my driving was downtown or on harsh roads.

[diagnosticator]

One aspect of this is that the angularity of the lower control arm, in relation to the coil over, varies with ride height. This effects the leverage of the control arms on the coil over as the suspension responds to bumps. With lower ride heights, the effective leverage due to angularity is reduced, increasing the force of bumps before the suspension reacts. This is involved with the harsh ride you described, as well as the compression damping adjustment.

[Abuck35]

Thank you for adding that last part. I know my response didn't speak to the fundamentals of your question but I have the same coils and the same ride height. With the struts and shocks set one click off full soft the ride quality is nearly as smooth as stock. So if u wanna keep the same height just make em softer.

[PNW Avant]

Thank you for adding that last part. I know my response didn't speak to the fundamentals of your question but I have the same coils and the same ride height. With the struts and shocks set one click off full soft the ride quality is nearly as smooth as stock. So if u wanna keep the same height just make em softer.

Great info guys, thanks for all the input. Everything put forth seems to be consistent with my experience and expectation.

I think at this point I just need to raise it up a little bit and perhaps adjust the dampening. Abuck, can you describe how to do this? I thought the Streetsports needed to be opened up to be adjusted, is that correct? I have the owners manual but I don't believe it describes adjustment.

[JoshDub]

You have to compress the shock all of the way and twist the rod. I am pretty sure it has to be done out of the vehicle. I never played with mine though.

[evo_ski]

To my knowledge since the adjuster is on the top of the strut you pretty much just undo the 3 engine bay bolts, drop the strut tower down enough to see it/turn the knob and then bolt er back up. Rears I believe are the same but I can't say for sure. Mine are non adjustable, so I don't have any experience, but perhaps this might help. Not sure if that is set up exactly the same as your struts though.

[Abuck35]

Josh Dub is right. I've done mine twice when I first installed them. You don't have to open them up. You take the shock off the car, and push the rod the whole way down. Then turn it to the right or left via allen key. It will click everytime you hit a different setting. There are only five, but each one is noticeably different. When I first put them on I had it set to one click off full hard, and it was ROUGH lol.

[dougyfresh]

This is a fundamental question about coilovers and their performance at different heights. I have the Koni streetsport coilovers and I find the ride to be quite jarring during city driving, but actually quite pleasant during highway or arterial speed driving.

My question is, when I raise the coilovers, is there any affect of performance of the suspension (besides raising the center of gravity and the associated affects)? I'm wondering if changing the neutral position of the strut closer to the center of its range changes its performance characteristics (i.e., if you are really low, the strut is stiffer because it is near the end of its range). Any input on this?

I ask this question because I am wondering if raising the coilovers will result in a slightly better ride. I'm at about 25 all around and not really happy about the ride after about 8k on the coilovers. I'm additionally considering replacing all shock mounts, sway bar links, etc, to try to smooth things out. Otherwise, I think my only other option is to go with another brand/model like KWv3 to get the comfort and performance I'm looking for.

The short answer is Yes to what is in bold for the coil-overs you have.

When you get into the Ohlin's dampers and other such coil-overs like the PSS9s and V3s then you have the ability to adjust compression and rebound dampening to dial the ride characteristics in for a given ride height.


I can tell you from experience that Ohlins dampers with the compression and rebound damping dialed in with a ride height of 24" fender to ground with 19inch wheels (actlsub9's old b6) is a far better ride than my STaSIS/Koni Streetsports with factory settings at 25.5" fender to ground on 19inch wheels. I will be getting some Ohlins SLs when I fell like spending over $2k on new coil-overs.

[dougyfresh]

ummmm don't street sports have adjustable dampening?

Rebound only.

No compression damping adjustment.

You are limited. You want to dial in both rebound and compression for the most optimum ride characteristic.

[Turbavanttro]

I will be getting some Ohlins SLs when I fell like spending over $2k on new coil-overs.

If you stay on top of the classifieds, you can get a deal on Stasis Motorsports...I got mine for $1200 and Stasis rebuilt all four of them and provided new springs, and I'm still well under $2k.

Just thought I'd add, if your Koni coilovers use progressive springs, then as you lower the coilover, it will result in a progressively higher spring rate/stiffer feel. You can tell they are progressive if the distance between each of the active coils is not equal. For linear springs (equal distance between active coils), the effective spring compression rate would be the same as you go lower.

Rebound only.

No compression damping adjustment.

You are limited. You want to dial in both rebound and compression for the most optimum ride characteristic.

As you go lower, wouldn't the more important adjustment to maintain ride quality (as you lower a coilover) be to lower the compression rate of the shock since the shock is more compressed at the lower static ride height?

[dougyfresh]

The STaSIS/Koni streetsports have a progressive rate front spring and a linear rear spring.

[evo_ski]

Just thought I'd add, if your Koni coilovers use progressive springs, then as you lower the coilover, it will result in a progressively higher spring rate/stiffer feel. You can tell they are progressive if the distance between each of the active coils is not equal. For linear springs (equal distance between active coils), the effective spring compression rate would be the same as you go lower.

Doesn't the spring compress equally no matter what height your coils are at rest though? I always thought that was how it was, but I really don't know, just trying to learn some more info here. Thanks!

[PNW Avant]

Doesn't the spring compress equally no matter what height your coils are at rest though? I always thought that was how it was, but I really don't know, just trying to learn some more info here. Thanks!

This is consistent with my understanding...raising or lowering the coilovers just repositions the perch (i.e. how far up or down the bottom of the spring is in relation to the strut/shock body). Force upon the spring should remain unchanged throughout the range of adjustment.

[PNW Avant]

Again, thanks for the input guys. I think first step will be to raise the car up to 25.5" or so. Next will be to replace shock mounts to see if some clunks and bumps go away (140k on these parts). Finally I'll make a dampening adjustment 1 click softer. If none of those work, I'll probably be in the market for some fully adjustable coilovers.

[PNW Avant]

Raising them will help with ride quality.

My concern is your expectation of how a performance suspension is going to handle city/harsh roads. Most will fell like butter on smooth highways, but on harsh city roads they are going to cause a more jarring ride. Its the nature of the stiffer springs. That being said, Stasis/Koni SS have some of the softest springs of any aftermarket coilover. They are truely 'street' coilovers. They really don't ride much different than OEM sport, so long as they aren't completely slammed. My friends, who own other modded cars with coilovers, get in my car and comment how ridiculously smooth mine are while being just as low as them. I'm at ~ 25in, zero fender gap. So if one of the mildest and smoothest coilovers for the B6 is too jarring for you and your driving conditions, don't know what to tell you. Even though my coilovers are really smooth, I can personally say that I would not want them if the majority of my driving was downtown or on harsh roads.

Thanks for this input. I think you may have hit the nail on the head here.

[Turbavanttro]

Doesn't the spring compress equally no matter what height your coils are at rest though? I always thought that was how it was, but I really don't know, just trying to learn some more info here. Thanks!

Most of the coils I've seen for the B6 don't have separate height/preload adjustibility. Which means changing height means changing the spring pre-load. Correct me if I'm wrong.

The effective spring rate should increase progressively throughout the majority, if not all of its full length of spring compression. Considering the average coilover provides about 1 to 3 inches of ride height adjustment, and the amount of compression the spring is subjected to when going from full high to full low, I suspect the difference in spring rate between full high-low is fairly significant.

[diagnosticator]

Another factor involved, is that as the suspension ride height is lowered, the spring preload is increased. This stiffens up the suspension from the increased spring preload alone, disregarding and effects from control arm angularity changes. With the higher spring preload, the force on the suspension required to compress the springs further is high also, compared to an increased ride height with lower spring preload.

[Turbavanttro]

^^^That's exactly what i was getting at. Some coilovers have separate pre-load adjustment and height adjustment, which seems like a very good thing since pre-load is a major factor in how a system is designed to function. Most if not all of our options don't have them separate.

[PNW Avant]

^^^That's exactly what i was getting at. Some coilovers have separate pre-load adjustment and height adjustment, which seems like a very good thing since pre-load is a major factor in how a system is designed to function. Most if not all of our options don't have them separate.

Ah, I'm not at all familiar with preload. But after a quick google search, your comments about preload seem accurate. Great to know, thanks for pointing that out! I am fairly confident my Konis do not have seperate preload and height adjustment.

[evo_ski]

Wow i had no idea i just assumed that the spring would react the same regardless of height. Thanks for the info guys!

Sent from my DROID BIONIC using Tapatalk

[a4darkness]

A bit late here but can certainly attest to CO height directly effecting ride characteristics (and quality) with my Vogtlands (standard + RS4 Rear Sway). And that's actually not the worst thing ever, as it allows for a good ability for one to adjust the ride to their preference.

I've actually stopped measuring and am now just eyeballing each side. It's odd b/c if you adjust one corner and it effects others... sometimes you need to move the others and sometimes not.

The latest round of adjusting occurred over the past two months... dropped the front end a bit but went too far. Looked hot, bounced like mad on the highway.




So I raised the fronts up and it was better, but still wonky.




Brought the rears up a tad (actually just the driver's side, the pass didn't need it afterward) and it smoothed things out a bit.



So now I'm thinking about bringing both the rears up about .25" and lowering the fronts by maybe a full turn or two at the very most. And then never touch it again. Until I touch it again.

The comments about turn in have got me thinking about how the different heights have effected this particular aspect. While I can't really specify a particular height and it's turn in characteristics I will say that adjusting the rears does help, or so it seems.

[evo_ski]

This summer i am thinking about testing my modified front bump stop theory we talked about. I think that will be perfect. Basically I would be adding a little material to the top of the front bump stops since it seems like the rears hit first which causes the front end to dive in corners and once it contacts the front bump stops it rides on rails. I think a small chunk of the stock bump stops added on top might be perfect.

Sent from my DROID BIONIC using Tapatalk