Tein Flex Z Spring Rates

[Student Driver]

Originally Posted by churchx

CSG Mike: maybe alignment/camber (which i doubt you running stock) plays role in clearance? Also width aside, his wheels are also of high sidewall and R16. +5.7%/1.4" diameter. You probably have more reasonable sidewall profile to go along the wider width.
So it looks like "meaty tires" in addition to flushness/stance (who knows, possibly also stretch, depending on wheel width) from "looks trends" are prioritized .. i wonder why performance/comfort matters at all for him.

I think he probably just has a tight budget at the moment and is trying to go for a happy medium between function and form. Assuming he no longer has his stock suspension, he may not be able to sell/trade his coilovers without causing him an issue by not having suspension on the car for (x) amount of time. Some people like a nice balance between both performance for tearing up the back roads and looks for hard parking at a local meet. There is nothing wrong with that. And everyone has some sort of a budget so changing his setup just may not be a viable option for him at the moment.

[Leonardo]

Originally Posted by Student Driver

I think he probably just has a tight budget at the moment and is trying to go for a happy medium between function and form. Assuming he no longer has his stock suspension, he may not be able to sell/trade his coilovers without causing him an issue by not having suspension on the car for (x) amount of time. Some people like a nice balance between both performance for tearing up the back roads and looks for hard parking at a local meet. There is nothing wrong with that. And everyone has some sort of a budget so changing his setup just may not be a viable option for him at the moment.

OP said his stock shocks were badly leaking and no longer serviceable.

[Student Driver]

Originally Posted by Leonardo

OP said his stock shocks were badly leaking and no longer serviceable.

lol would have been smart to reread OP's post... OOPS!

[Leonardo]

Originally Posted by Student Driver

lol would have been smart to reread OP's post... OOPS!

Buying a set of stock shocks and reusing his RSR springs, may be the least expensive way to get OP back on the road. I am sure this is not what he wants to do though. But the budget only allows what it does...

[slacker221]

CSG Mike, I am absolutely taking in consideration all of the information I am getting from you guys, hence this post. That is why I am trying to get a technical discussion going to better myself and others when it comes to suspension setup and tunning. Im no expert, and I greatly appreciate the knowledge you guys bring to this forum. If it was not for forums like this, a lot of us would be doing very dumb things with our cars.

Mike, I have a taller sidewall as im running 255/50 R16, so our tires will obviously have a different profile. The tires are not “stretched”, I do not run a bunch of camber. The rims are 16 x 9.5. Also, aren’t the CSG spec Flex A’s firmer than the Flex Z? Im assuming that would factor in to why you don’t rub, but I do. Maybe I JUST GO THAT MUCH HARDER ON THEM CORNERS BRO!?!?! J/K lol

I am asking about running them on the "Stiffest" rebound setting because the car will rub while going over certain bumps on the freeway at 60mph. And I also did it to reduce body roll while cornering, which should also reduce rub from body roll while going over a bump in the road. I figured slowing down the rebound would help with that. Please correct me if im wrong in thinking that. Im no expert and I may be doing something wrong, that is why im here trying to learn.

Apparently people think im going for stance boy setup? That is not what im doing at all, im not going for camber or poke, just a clean setup that is functional for canyon and track use. I will not be autocrossing, I will be mostly drifting at the track, and taking it out to the canyons, so my setup will obviously vary from yours if you are building an autocross and or grip orientated car. I have attached a photo of my car, this is the ride height that im going for, but still get rubbing issues, and rubbing issues are never a good thing.

Im not trying to prioritize looks over performance, hence why im here trying to discuss this. If I was going for looks I would simply remove a couple collars from the coilover, slam it to the ground, add about 15 degrees of camber, and then get 11” wide wheels with 225’s stretched on them. But that’s not what im trying to do.

I went with a widebody setup because I needed to cover some damage to the body of the car, and that was the cheapest alternative at the time. I know you guys will give me more shit about that. But in the end, it is my car, and my build. If you want to criticize me for my poor choices in my build, go for it. No skin off my back. But the purpose of this thread is to learn more about equipment that I currently have, and try to work with that. Why is it so horrible that I want to work with what I have?

X808drifter, What more do I want? I would like to have an actual discussion of what my current options are, besides “Your too low”.

Lets say I do install a set of 8K springs on the flex Z dampers, will it just “ride like shit” or will higher spring rate cause the damper to move faster which can create oscillation or a “bouncy” ride? Maybe since the damper is moving faster, it will cause damage to the shock quickly?

OR maybe going with 8K springs will only slightly stiffen up the stroke slightly to where I do not get oscillation, and will reduce body roll?

If 6K springs are the good fit for our cars, then why do companies make springs in 16k and 18K for our cars? Im not trying to argue, im genuinely wondering why you would need such a stiff spring? Are those paired with much softer damper rates? I Just don’t see a firmer damper and firmer spring paired together working very well on our platform.

Swift sells “Upgrade” springs for the BC BR’s, are the dampers in the BC’s more of a universal valving, or are the BC’s just designed to accommodate different spring rates? Or will upgrading the springs on the BC’s cause negative affects also?

These are things that im trying to learn, I would love some input on the technical aspects of changing the spring rate.

[slacker221]

Originally Posted by Leonardo

Buying a set of stock shocks and reusing his RSR springs, may be the least expensive way to get OP back on the road. I am sure this is not what he wants to do though. But the budget only allows what it does...

Leonardo, I did go over this option, but it was rubbing much worse with the RS-R springs and factory shocks. Even with new factory shocks, having this wide of tires rubs on things, so that is why I need the adjustment of the Flex Z.

[Student Driver]

What about shaving your fenders? Looks like they have a bit of a lip that goes in towards the wheel well. One other option is maybe adding like -1 of -1.5 degrees camber in both the front and rear, that should make your car handle a little better and reduce rub. From the looks of your photo i would guess you have no more than -0.5 camber front and back...

Where exactly does the tire rub? The outside where tire meets fended or somewhere in the wheel well?

[CSG Mike]

@SLackser221

Tuck your wheels in more with a higher offset wheel, and the rubbing will be alleviated. The tire is larger in diameter, and a stiffer setup wont help prevent rubbing with the drastic change you made.

Rebound is how quickly your wheels "drop" when you unload them. Making it stiffer isn't help you any in this case. It does not affect total body roll.

Your car is not functional for canyon and track use, nor is it improving the driftability of your car.

A stiffer spring rate will just result in a harsh riding loosey goosey handling car, because the dampers are unable to keep up with a 8k spring.

The 6k springs are the proper match for **your damper**, not **the car**.

The real fix for you, I think, would to just get properly sized tires.

If you're truly drifting, you should be chewing through tires like nothing; just downsize to 255/45/16.

[churchx]

Mike, I have a taller sidewall as im running 255/50 R16, so our tires will obviously have a different profile. The tires are not “stretched”, I do not run a bunch of camber. The rims are 16 x 9.5. Also, aren’t the CSG spec Flex A’s firmer than the Flex Z? Im assuming that would factor in to why you don’t rub, but I do. Maybe I JUST GO THAT MUCH HARDER ON THEM CORNERS BRO!?!?! J/K lol

I am asking about running them on the "Stiffest" rebound setting because the car will rub while going over certain bumps on the freeway at 60mph. And I also did it to reduce body roll while cornering, which should also reduce rub from body roll while going over a bump in the road. I figured slowing down the rebound would help with that. Please correct me if im wrong in thinking that. Im no expert and I may be doing something wrong, that is why im here trying to learn.

I doubt that most people tracking and if had gone for wider tires/wheels also at same time hadn't proportionally reduced sidewall profile height, for overall diameter to stay same and to not change gearing ratio to taller. Imho your rubbing issues more then probably stems from this, due having noticeably higher tire diameter.

Apparently people think im going for stance boy setup? That is not what im doing at all, im not going for camber or poke, just a clean setup that is functional for canyon and track use. I will not be autocrossing, I will be mostly drifting at the track, and taking it out to the canyons, so my setup will obviously vary from yours if you are building an autocross and or grip orientated car. I have attached a photo of my car, this is the ride height that im going for, but still get rubbing issues, and rubbing issues are never a good thing.

If you wanted to gain more ground clearance, then larger diameter tire imho is not the right way to do it. Suspension travel stays same after all. If larger tire only for "filling arches" and you rub .. maybe worth dialing some coilovers height back, or reduce tire sidewall hight? Certainly you wouldn't think that looks are worth having rubbing setup? Canyon driving shouldn't differ much from daily driving, unless one drives ignoring legal limits. Drifting? Hmm, in most drift setups i've seen much much higher camber, especially in front.

Im not trying to prioritize looks over performance, hence why im here trying to discuss this. If I was going for looks I would simply remove a couple collars from the coilover, slam it to the ground, add about 15 degrees of camber, and then get 11” wide wheels with 225’s stretched on them. But that’s not what im trying to do.

There are many ways wheels won't fit or will require mods that may compromise performance to make them fit. My hunch is that lowering + tire diameter combo is your issue.

...
Lets say I do install a set of 8K springs on the flex Z dampers, will it just “ride like shit” or will higher spring rate cause the damper to move faster which can create oscillation or a “bouncy” ride? Maybe since the damper is moving faster, it will cause damage to the shock quickly?

OR maybe going with 8K springs will only slightly stiffen up the stroke slightly to where I do not get oscillation, and will reduce body roll?

If 6K springs are the good fit for our cars, then why do companies make springs in 16k and 18K for our cars? Im not trying to argue, im genuinely wondering why you would need such a stiff spring? Are those paired with much softer damper rates? I Just don’t see a firmer damper and firmer spring paired together working very well on our platform.

Swift sells “Upgrade” springs for the BC BR’s, are the dampers in the BC’s more of a universal valving, or are the BC’s just designed to accommodate different spring rates? Or will upgrading the springs on the BC’s cause negative affects also?

It sounds like you thought to limit suspension travel by fitting much stiffer springs. Caveats of this:
1) spring rates won't mach damping rates, ride will be s*hit
2) yes, without lot of something to press down (sticky tires+high speed+lot of aero downforce) that may limit travel .. but will make suspension (1.) and even in rest of range where you had no rubbing issues work badly. Very underdamped coilovers .. i don't think you really want that.
There are several much better ways performance wise to not rub then this way, like actually using better fit tires/wheels, using coilovers that are matching springs using in those or revalving current ones (not an option with Flex Z though, that by design are not revalveable).
Proper suspension vendors when offering custom spring rates also offer customizing damping to match. If some doesn't, allow customer to order with unfitting springs, then i wouldn't care for such vendor, as it certainly is only after single sale, not customer satisfaction/offering quality products/long term reputation.
As for very high rate springs suspension .. take note, that it's not worth to compare to rates of suspension of other cars, that have different suspension/motion ratios/mass and so on, but if you'll notice, most relatively high spring rate coilover options are 1) for hella-slamming crowd you claim you are not of, to compensate almost no travel left, 2) for high grip tires / high aero downforce setups, you told, you are not with. Think of something like car with full set of Ace aero, that almost bottomed out on 10K springs. It gone like on rails though with insane cornering speeds. But probably too unusable for daily driving on (bad) public roads, unless one plans to drop spine in pants. Not something how & where you intended to drive.

I suggest to rethink all bits of what you want for car, consider also other options to get what you want, see what might be easier on your budget and better reach your goals. Other coilovers, better fitment wheel/tire choice, different alignment and so on. NOT to try to put overly stiff springs no matter what on current coilovers.

[slacker221]

Originally Posted by CSG Mike

@SLackser221

Tuck your wheels in more with a higher offset wheel, and the rubbing will be alleviated. The tire is larger in diameter, and a stiffer setup wont help prevent rubbing with the drastic change you made.

Rebound is how quickly your wheels "drop" when you unload them. Making it stiffer isn't help you any in this case. It does not affect total body roll.

Your car is not functional for canyon and track use, nor is it improving the driftability of your car.

A stiffer spring rate will just result in a harsh riding loosey goosey handling car, because the dampers are unable to keep up with a 8k spring.

The 6k springs are the proper match for **your damper**, not **the car**.

The real fix for you, I think, would to just get properly sized tires.

If you're truly drifting, you should be chewing through tires like nothing; just downsize to 255/45/16.

I agree that my tire setup is also not optimal, again budget was the issue. I had the corvette wheels sitting around so I decided to use those as they are 9.5in wide. I tried to go with a 255/45 or 255/40, or even 245/45 but was unable to find anyone selling tires in that spec, there are only two manufactures that still make 255/50R16 as this is old tire spec only used on C4 vettes, and older Porsche's.

The rubbing that happens in the front is the tire touching the frame rail at the top of the wheel well. So I dont believe a higher offset, or adding camber will help with that. I do believe that the taller tire profile is my issue as well, but again budget keeps me from buying new wheels/tire setup for now. The rear rubs the inner fender which has already been clearanced and sealed up twice now to reduce rubbing.

The damper adjustment on the Flex Z adjusts the rebound and compression right? or does it only adjust the rebound?

Are you saying my car currently is not functional for canyon and track use? or are you saying that if I change the spring rate, then my car will not be functional?

Also, I will not be drifting on these tires. I have a different wheel/tire setup for drifting. This tire setup will be for daily/canyon cruises.

[churchx]

slacker221: as it rubs on top of wheel well, not on arch or suspension, by logic only way is to space tire lower. Be it by lower diameter tire or .. reducing drop. Doing later as bonus won't require you to buy anything else. Just redo alignment (as changing ride height with coilovers very probably will change camber & toe too). This way you should be able to use full dampers travel without rubbing or having to compromise dampening settings you don't like. All that is needed, is to get over a bit your wished slammed looks of reduced distance between arch & tire. Imho better handling & comfort of more optimal damping settings / non rubbing / better bad road compliance due extra travel / reduced potential extra spendings is worth more then that.
EDIT
though hmm. On second thought it may depend on how height is adjusted on Zs. If not independently, but by preload, then when fully compressed, it still may rub .. then - maybe topmount lift spacers should do better?
EDIT2
"Full-length ride height adjustment system, used for FLEX Z, enables adjustment of ride height by adjusting the case length, without changing the damper stroke length and/or spring pre-load. This has the advantage that the change in ride quality is kept minimal when the height is adjusted."
Seems no problems on that, due independently adjustable height.

[slacker221]

Originally Posted by churchx

It sounds like you thought to limit suspension travel by fitting much stiffer springs. Caveats of this:
1) spring rates won't mach damping rates, ride will be s*hit
2) yes, without lot of something to press down (sticky tires+high speed+lot of aero downforce) that may limit travel .. but will make suspension (1.) and even in rest of range where you had no rubbing issues work badly. Very underdamped coilovers .. i don't think you really want that.
There are several much better ways performance wise to not rub then this way, like actually using better fit tires/wheels, using coilovers that are matching springs using in those or revalving current ones (not an option with Flex Z though, that by design are not revalveable).
Proper suspension vendors when offering custom spring rates also offer customizing damping to match. If some doesn't, allow customer to order with unfitting springs, then i wouldn't care for such vendor, as it certainly is only after single sale, not customer satisfaction/offering quality products/long term reputation.
As for very high rate springs suspension .. take note, that it's not worth to compare to rates of suspension of other cars, that have different suspension/motion ratios/mass and so on, but if you'll notice, most relatively high spring rate coilover options are 1) for hella-slamming crowd you claim you are not of, to compensate almost no travel left, 2) for high grip tires / high aero downforce setups, you told, you are not with. Think of something like car with full set of Ace aero, that almost bottomed out on 10K springs. It gone like on rails though with insane cornering speeds. But probably too unusable for daily driving on (bad) public roads, unless one plans to drop spine in pants. Not something how & where you intended to drive.

I suggest to rethink all bits of what you want for car, consider also other options to get what you want, see what might be easier on your budget and better reach your goals. Other coilovers, better fitment wheel/tire choice, different alignment and so on. NOT to try to put overly stiff springs no matter what on current coilovers.

@churchx Thank you for the insight, this is exactly the kind of info I was looking for. Your right, my thoughts were to try and very slightly reduce travel with a stiffer spring to prevent rubbing. I understand that you want to utilize the entire damper stroke, and that reducing the stroke will almost always reduce shock performance. But I was not sure if reducing slightly with say an 8K spring would not yield such a dramatic affect, but as you guys have explained, it will make the car "Ride like shit".

I did not know some vendors will re-valve the dampers for the "upgrade" springs rates. That is good to know when I go to purchase a more track orientated coilover in the future. I just assumed the dampers all came with the same valving and you could just change the spring rate. This is what confused me from the beginning.

I understand different cars will benefit from other rates and valving. But I was reffering to the swift or other springs for our car that are in the 12-14K range, are those really only used for stance boy setups?

I believe thats whats sets apart the CSG spec Tein's, is that they are more finely valved and have a proper spring for that valving? Correct?


I have been thinking about what I want for my car, hence why im here trying to discuss, and gain some knowledge. Instead of just buying stiffer springs and throwing them on my car.

[slacker221]

Originally Posted by churchx

slacker221: as it rubs on top of wheel well, not on arch or suspension, by logic only way is to space tire lower. Be it by lower diameter tire or .. reducing drop. Doing later as bonus won't require you to buy anything else. Just redo alignment (as changing ride height with coilovers very probably will change camber & toe too). This way you should be able to use full dampers travel without rubbing or having to compromise dampening settings you don't like. All that is needed, is to get over a bit your wished slammed looks of reduced distance between arch & tire. Imho better handling & comfort of more optimal damping settings / non rubbing / better bad road compliance due extra travel / reduced potential extra spendings is worth more then that.
EDIT
though hmm. On second thought it may depend on how height is adjusted on Zs. If not independently, but by preload, then when fully compressed, it still may rub .. then - maybe topmount lift spacers should do better?

@churchx Yes I believe that im going to have to suck it up, and raise my ride height slightly. That seems to be the only option to keep the dampers operating correctly.

The Z has independent ride height adjustment from the preload. So yes I can raise the height without affecting the rebound.

[CSG Mike]

Sounds like your solution is to not turn the wheel as much, or space out your front wheels more.