Ground Control Spring options

[derbo]

All this talk with suspension changes with LivesNearCostco and threadjacking made me want to make a new thread about changing spring rates on the Ground control coilover system.


So far I have seen 3 options for coilover springs with custom spring rates:


HyperCo
Swift
Ground Control


Now I'm not sure what the spring sizes are.

I am assuming they are 2.5in ID springs but I'm not 100% on the lengths. Anyone know?

[derbo]

Just called Ground Control and they said it is 6" 2.5ID front spring and the rear is a 7" 2.5ID spring. The Koni Yellows that come paired with the GC Coilover system can take up to 600lb/in springs before they need revalving.

[LivesNearCostco]

I think the GC rears tend to get shorter as the rates go up, like 6.5" for a 550 lb/in rear spring instead of 7" for the 430 lb/in spring. GC also supports both 2.5" and 2.25" rear springs--if you switch to 2.25" you have to get a different gold adjuster nut and possibly a different white plastic cone for the back. I think the GC fronts are always 2.5" ID but am not 100% sure.

The highest rate I see in their GC-branded spring list (http://www.ground-control-store.com/products/category.php/CA=214) is 550 lb/in but they also sell the Eibach 2.5" ID race springs up to 1400 lb/in and 2.25" ID springs up to 2100 lb/in or more (4000 lb/in?).

[derbo]

Talking to the guy on the phone, he also said they can custom order any spring rate you desire at whatever length :)


At $59.00 its probably the cheapest option.



Where did you get the idea that they run shorter springs for higher spring rates? I'm just curious cause I'm intetionally trying to get the same length springs so I don't need to change my ride height :)

[LivesNearCostco]

In their own branded springs (made by Eibach), spring rates >430 lb/in are only available in 6" or 6.5" lengths. The 2.5" ID Eibach 7" springs are available in rates from 275 to 700, but if you use a stiffer spring with the same free length, won't it give you a higher ride height because it compresses less? With an 800 lb corner weight, the 430 lb/in spring would compress ~1.86" while the 550 lb/in spring would compress ~1.45".

[derbo]

i guess a higher ride height wouldn't be too bad as long as long as the ride height raises the same all around! I'm most likely going to call GC and get something along the lines of 450/500. Waiting on a friend to see if he can get me a set of swift springs for cheaper than GC.


Maybe even go 450/550


But i'm emailing back and forth with GC to see what my options would be. :)

[derbo]

440/550 seems to be the most popular option in the Area here.

440lb/in 6" spring for the front
550lb/in 6.5" spring in the rear

Hyperco doesn't list anything lower than 600lb/in in their catalog for a 2.5" ID 6inch spring


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[danewilson77]

derbo....do you think tracking your car...is why you need a new clutch soon?

[derbo]

derbo....do you think tracking your car...is why you need a new clutch soon?

No. The clutch as been low since I got it from the previous owner. I've been milking it and it's getting high finally.


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[danewilson77]

No. The clutch as been low since I got it from the previous owner. I've been milking it and it's getting high finally.


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OK.

HTC Thunderbolt+TT

[LivesNearCostco]

Derbo you gotta let me know how you like the 440/550 spring rates. I'm thinking of going higher, and Murph is talking about like 500/600 rates or more. But I assume he's talking Solo Nationals in Lincoln on AST double-adjustable dampers (wasn't he on AST 4200's?). And I need to do a few more AutoX and track days on my current 375/430 springs first.

[derbo]

I got a few different responses from GC. Jay@GC said that the struts can handle up to 800lb/in and at that point you should be on race dampers anyways.

He suggested 550 be the absolute min for the rear for racing. I'm following the next step up at 440/550.


Friend has a supplier than get me 6" or 7" swift springs. I'm torn from getting a 7" or 6" 10kg/mm for the rear. Otherwise, it would be with GC which is the cheapest option.

[LivesNearCostco]

Did he say struts or shocks can handle 800 lb/in springs, or both? Because in the front the spring rate is pretty much what the strut sees, but in back the shock sees something like only 63% or 67% of the spring rate because of the lever action of the upper control arm. With 800 lb/in rear springs, the rear shock only sees about 536 lb/in. With 550 rear springs the rear shock would see around 368 lb/in. (This is me pretending to know something about BMW suspensions.)

[derbo]

Sorry I didnt clarify myself.


1. What is the maximum spring rate allowed before the struts need to be
revalved to handle the springs?


The front, up into the 600-700s, the rear, up close to 800. After that, you should be in race dampers anyways. Ignore what people say about the damping, GC designed them.

This is exact quote from him.

[LivesNearCostco]

If they have similar valving, that makes total sense. Thanks for sharing. I did an AutoX yesterday and while the 375/440 rates felt good, there were a few tight turns where I felt like higher rates would help. At least a month before my next track day (Buttonwillow), so maybe I should do that before deciding on higher spring rate.

[LivesNearCostco]

Derbo, I just ordered the 550 lb/in springs from Ground Control. Guess that means no M3 strut bar for me until at least next month!

[derbo]

so you are runnin 375/550?

[derbo]

I'm actually waiting on my buddy's friend for a quote from swift. I'm most likely going to order swift springs for my car.

[LivesNearCostco]

Well that's the advantage of coilovers... as long the ID is the same and the length is right, you can use anybody's coilover springs.

Still running 375/430. For the front I bought used 6" 440 lb/in springs from someone on m3forum.net, plan to use them with the new 6.5"/2.5"/550 springs from GC.

[derbo]

agreed! I'm excited for you. Hopefully you don't rub either ;). I'm most likely going with a 6" rear 10KG/mm spring. Someday we will see each other at a trackday and do shotgun rides to see the differences.

[LivesNearCostco]

If I did my math correctly, that is 560 lb/in while mine will technically be a 547 lb/in. Means you're a little more HARD CORE than me! I read a thread somewhere claiming Swift springs are more responsive than GC/Eibach, Hyperco, or VVS/Vogtland springs, but have no idea if it's true.

[derbo]

Swift only comes in metric spring rates so its 448/560 as the spring rates goes. I know that swifts have less coils and allows for a larger stroke without binding but I do not know how it will differ in responsiveness on the same similar rates. I guess we will find out. The price difference the swifts from the GC retail springs is so close I rather pay the extra for the swifts.

[derbo]

ordered my swifts! hopefully they dont shipp from japan..:X

[LivesNearCostco]

Congrats! My GC 547 rear springs just arrived. Old 440 fronts are at home. Tonight might be a good night to pull the struts! But now looks like won't have another track day until April 21-22.

[derbo]

Congrats! My GC 547 rear springs just arrived. Old 440 fronts are at home. Tonight might be a good night to pull the struts! But now looks like won't have another track day until April 21-22.

We need to do a button willow day so we can meet halfway lol

[LivesNearCostco]

Installed the 440/547 springs last night. On smooth roads it feels the same as the 375/430 springs. But I haven't pushed it yet nor have I hit any bad roads, just a few speed bumps around my place and a dip at the parking garage. I need somewhere I can drive fast safely...

Yes! I will get up to Infineon someday but not sure if it will be this summer. Any chance you might do Buttonwillow with NASA April 21-22? I'm pretty sure I will be there at least Sunday, since I probably cannot do Buttonwillow April 13 with the BMW CCA. Or are you more of a Speed Ventures/Trackmasters person?

[derbo]

I mostly deal with NCRC ncracing.org and my next track day is infineon 5/12 with speed ventures.

I never raced with NASA or BMW CCA yet.


Let me know what about the results :)

[LivesNearCostco]

IMHO, BMW CCA track days are the safest and most expensive. I've done 4 Speed Ventures track days but never NCRC.

So far on smooth roads my new springs feel the same as the 375/430. Rough freeways are slightly more annoying now. Speed bumps at a certain speed range are okay, but above that speed (maybe 8 or 10 mph?) speed bumps have been quite painful with either set of coilover springs (compared to stock springs). I was going to AutoX on Sunday to see how they felt but now I'm volunteering to help with the Street Survival teen driving clinic held the same place and day as the AutoX, so I probably won't get to drive the course on Sunday.

[derbo]

That doesn't fair well for my stiffer setup haha. What do you mean by safest?


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[zhpnsnv]

I've tried a few outfits for track days. CCA is the safest in that they put you with an instructor until you prove you don't need one. They enforce the rules. It is not the wild west on the track unlike other courses. I'm totally fine with the wild west but only with experienced and respectful drivers. Teenagers in Mitsubishi evos bombing through mid corner passes like they're playing gran turismo is not fun. Porsche club does a nice job, too.

[derbo]

Well I'm glad my experience with NCRC and Speed Ventures has been great and I've been in groups where there aren't crash lunatics thinking we are RACING each other.


Can't wait for my springs to show up and I can get cracking and installing them to report back :).


BTW Costco,

How did the springs affect your height without adjustment?

[LivesNearCostco]

I think the right answer is to maintain the same ride height I should have left the rear adjusters where they were and lowered the front adjusters two turns. Unfortunately I didn't do the math until after swapping the springs so I raised the rear adjusters one turn and lowered front adjusters one turn. Rear was clearly higher than before so a few days later I lowered rear adjusters back down one turn. I think the front is also still slightly higher than before and I will probably lower them one more turn.

On paper the new front springs will compress 0.31" less than the old ones and that should be about 2 turns. The new rears should compress 0.5" less than the old but the new ones are 0.5" shorter, so I should have left them alone.

What is the free length of the new springs you ordered?

[derbo]

I ordered all 6" springs. I will raise the collars on both 2 turns.

[LivesNearCostco]

Assuming your current springs are 6" front and 7" rear, that sounds good for the back but for the front I say lower 1-2 turns, not raise 2 turns. Going to a stiffer spring of same (free) length requires you to lower the perch to maintain the same ride height.

Another perspective on how my springs feel is the 375/430s felt okay on the street (except speed bumps) but on the track they felt a little soft. Not that I know what a well-sorted E46 should feel like, but it just felt like there was more body roll than needed. The 440/547 feel a little harsh on bad roads but hopefully will feel perfect on the track.

[derbo]

Good eye. I meant to say I would lower the front and raise the rears. LOL. The rears are more of a pain to raise than the fronts so I'll work to get 565mm fender to lowest edge of the rim like I set it up before. Once that is dialed in, I'll work on the fronts to 570mm. :)

[derbo]

Just installed the swift springs along with the reinforcement plates as well.

Currently the ride height is 575mm front and 565mm rear. I will lower the front a little more to get back to the same ride height if I am not happy with the stance of the car in the daytime.


Currently the car rides very nice with the new stiffer spring rates of 448/560. The swift springs actually take the bumpers better than the eibach springs and seem to be on par with the little bumps. Larger bumpers there is a definite difference in feel. Since my tolerance is relatively high, its not too bad and on the freeway it felt great with the difference of 100lbs between front and rear vs the old 55lb difference.

[LivesNearCostco]

Derek, how many track days have you done on the new Swift springs? Do you ever wish for more spring rate, or wish you could go back to the softer springs? I'm riding on GC/Eibach 440/547 lb/inch springs, similar to your rates, though your springs are Swift. Have been thinking of trying stiffer springs... saw some used 525 front and 650lb rear springs for sale. Or could just buy the 650lb springs for my rear and move my current rear 547lb sprins up front.

When I drive nice roads (most of the time) I am sure I could handle higher spring rates. But when I drive on a bad road my current spring rates are very annoying and I think I should stay with what I have and not try to go stiffer.

Or I could just save the money for your HKS exhaust.... deep exhaust tone > stiff suspension! Wait didn't you already package it up for somebody?

[derbo]

Derek, how many track days have you done on the new Swift springs? Do you ever wish for more spring rate, or wish you could go back to the softer springs? I'm riding on GC/Eibach 440/547 lb/inch springs, similar to your rates, though your springs are Swift. Have been thinking of trying stiffer springs... saw some used 525 front and 650lb rear springs for sale. Or could just buy the 650lb springs for my rear and move my current rear 547lb sprins up front.

When I drive nice roads (most of the time) I am sure I could handle higher spring rates. But when I drive on a bad road my current spring rates are very annoying and I think I should stay with what I have and not try to go stiffer.

Or I could just save the money for your HKS exhaust.... deep exhaust tone > stiff suspension! Wait didn't you already package it up for somebody?


John, (is that how you spell it?)

I've done 3 track days on the Swift Springs. I have 6" 65mm 8k and 10k springs. I think I should've gotten a 7" spring for the rear as I think my car is still too low in the rear. I may purchase a new 7", perhaps you are interested in the 65mm 6" 10k for the front?

Being that I live in the city, I believe my 8k/10k setup is a perfect compromise from comfort and track performance. I haven't done a new trackday with the LSD setup with the OEM M3 rear sway so I'm unsure how my setup is right now. Prior to the LSD setup, the car rotated very well and performed like a champ. I think the car felt more neutral after the swift springs, where the GC springs were closer to understeer conditions.

Only track I did a repeat before and after the swift springs was Buttonwillow CW13
10/23/11 2:11:25
11/23/12 2:08:64

Problem is I made numerous changes were done to the car between the two years besides the springs..:
-M3 Fuel Pump Baffle
-GruppeM Intake
-E92 M3 Motor Mounts
-RE transmisson mounts
-RE RTAB Shims
-Recaro SPG
-Brake ducts
-Brake Titanium shims
-Clutch Delay Removal





The HKS was packaged for Bruce but he didn't want it because I painted it flat black and he didn't want to deal with the hassle of removing the paint and damaging the SS finish.

[LivesNearCostco]

Thanks. 2:08 is quite a respectable time at Buttonwillow 13CW, and so is 2:11. What kind of tires were you using? My best time is 2:17.xx, first set with Hankook R-S3 tires on a 78F day, then again using Continental ExtremDW on an 85F day (later it went to 102F and my times got slower). I would like to think if I went back now with R-S3 tires on a day that wasn't too hot, I could do 2:13 laps, but not sure. That's one reason I want to get better tires and try it (along with my new front swaybar).

My current springs at 440/547 lb/in work out to 7719/9596 gm/mm, so a bit lower than your 8000/10000 setup. If I upgrade to 525/650, that's 9649/11400 gm/mm, higher than your current rate.

[derbo]

2:11 was on RE11 255/35/18 All around

2:08 was on Star Spec Z1 245/40/17 all around.

another variable to take into consideration :facepalm.


Are you on stock brakes?

[LivesNearCostco]

I just tried the 525/650 lb/inch springs for a few days and it definitely feels more harsh on bumps and expansion joints than the 440/550 springs. My springs are about 20% stiffer in front and 18% stiffer in rear, and maybe overall it feels 15% harsher on bumps. My 9-year old daughter complained today about the bumpiness when I was driving her around, whereas she never complained about it on the 375/430 or 440/550 springs.

Will try a few track days with the 525/650 springs then decide if I should go back to 440/550.

[derbo]

Have you considered getting swift springs? my 440/550 swift springs felt softer than the 375/415 eibach springs on bumps.

[LivesNearCostco]

Did think about it but not seriously. Was looking for used springs, found some Eibach and Hyperco, but don't remember seeing any Swift springs for sale. It's certainly possible the Swift claims about their springs being more responsive are true. I will be at Thunderhill this weekend with CCA and hopefully it will be dry and a good time to test the 525/650 springs on track. The alternative is to go back to 440/550 lb springs and just raise the ride height a little to help keep me off the bump stops in hard turns.

[derbo]

What size springs are you running?

sent from a Moto X

[LivesNearCostco]

6" length, 2.5" inner diameter. I know GC can do 2.25" I'd springs in back by changing the adjuster rings, but not sure they can do any size other than 2.5" ID in front because sleeve has to fit over the strut.

Edit: I see the GC Camber plates do support 2.5", 2.25" and 60mm ID springs, but I still suspect for their own front struts on BMW E46/E36 they need to use 2.5" ID springs.

[derbo]

Are you using 6" all around? I was considering getting a 7" 550lb swift spring in the rear. The rear seems really low right now even at a fairly high perch setting.

[LivesNearCostco]

Yes, 6" length 2.5" ID all around. My previous rear springs were 6.5" length. The 6" are a little short, not for ride height, but for fear they might rattle around when going over a big bump and hitting full droop. Both springs let me achieve my desired ride height but with the 6.5" spring the adjuster was 3 or 4 turns up from the bottom while with the 6" spring the adjuster is about 5 turns from the top. With the 6.5" rear spring, it was work to raise the adjusters to the desired ride height unless I disconnected the shocks--I had to use the adjuster wrenches. With the 6" spring, I can raise the adjuster easily by hand (no wrenches) even with shocks connected.

Assuming you have shortened rear shocks, I think a 7" 550 lb rear spring might require you to disconnect rear shocks to raise adjuster to desired position, then use jack to raise wheel and control arm up high enough to reconnect the rear shock. Good news is your rear springs will never be loose and will always be under some tension. Downside is you might have to disconnect rear shocks whenever you want to adjust rear ride height.

[LivesNearCostco]

Went back to the 440/550 springs yesterday. Definitely more comfortable than 525/650 on freeway expansion joints or bumpy surface streets. The stiffer springs were great at the track and on smooth roads but were annoying me a lot on this one freeway I often drive to and from work. One disadvantage is since I'm back to 6.5" rear springs, if I raise the back the springs are still under some tension so changing rear ride height is harder. If I disconnect rear shocks then the rear springs are loose and it's easy to change the rear ride height.

I was looking forward to trying AutoX on the stiffer springs, but after about 2 months on them, I wimped out. At least I still have my stiffer front swaybar.

[derbo]

Went back to the 440/550 springs yesterday. Definitely more comfortable than 525/650 on freeway expansion joints or bumpy surface streets. The stiffer springs were great at the track and on smooth roads but were annoying me a lot on this one freeway I often drive to and from work. One disadvantage is since I'm back to 6.5" rear springs, if I raise the back the springs are still under some tension so changing rear ride height is harder. If I disconnect rear shocks then the rear springs are loose and it's easy to change the rear ride height.

I was looking forward to trying AutoX on the stiffer springs, but after about 2 months on them, I wimped out. At least I still have my stiffer front swaybar.

I totally didn't see this. The problem I think is that swift only makes a 7" and a 6". I noticed my ground control perches are cupping and no longer flat. I already ordered the new tear drop perches but am waiting for new camber bolts ( and the fight to remove the one bolt) before installing the rears. From your experience john, I will have a hell of a time with a 7" spring adjusting proper height.


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[LivesNearCostco]

By teardrop perches do you mean the reinforcement plates that sit on top of the upper control arms, or the gold collars that adjust up and down?

I think adjusting with 7" springs in the back won't be bad as long as you raise the entire rear end and disconnect the shocks. Assuming the 7" springs are same rate or higher, you will move the spring perch 1/2" lower (or more). In my case, when going from 6" 650lb springs back to 6.5" 550lb springs, I kept the adjusters at the same height because the longer springs are software, so the springs are slightly compressed at full droop--and thus hard to adjust--unless I disconnect the shocks.

[JB3]

By teardrop perches do you mean the reinforcement plates that sit on top of the upper control arms, or the gold collars that adjust up and down?

I think adjusting with 7" springs in the back won't be bad as long as you raise the entire rear end and disconnect the shocks. Assuming the 7" springs are same rate or higher, you will move the spring perch 1/2" lower (or more). In my case, when going from 6" 650lb springs back to 6.5" 550lb springs, I kept the adjusters at the same height because the longer springs are software, so the springs are slightly compressed at full droop--and thus hard to adjust--unless I disconnect the shocks.


I totally didn't see this. The problem I think is that swift only makes a 7" and a 6". I noticed my ground control perches are cupping and no longer flat. I already ordered the new tear drop perches but am waiting for new camber bolts ( and the fight to remove the one bolt) before installing the rears. From your experience john, I will have a hell of a time with a 7" spring adjusting proper height.



Thread revival.

Where is the best place to buy Swift springs? Edit: best price and fast shipping.
And what is the verdict on spring length for Swifts with GC?

I'm about to call GC and I'm trying to source the Swifts. Had them on my Evo in 2011 and quite honestly, they are the "Jesus setup" with Bilsteins for that car, and I would love to try them with the GC Koni coilover kit setup.

[derbo]

Thread revival.

Where is the best place to buy Swift springs?
And what is the verdict on spring length for Swifts with GC?

I'm about to call GC and I'm trying to source the Swifts. Had them on my Evo in 2011 and quite honestly, they are the "Jesus setup" with Bilsteins for that car, and I would love to try them with the GC Koni coilover kit setup.


I had a friend that knew someone who worked at swift so I bought them directly from them.

Front 448lbs/in
Rear 560lbs/in

I went with 6" all around but I lost a fair share of adjustment for height in the rear. The front was fine as there is alot more adjustment. I ended up getting a 7" pair for the rear 2 years later to get my adjustment back when the springs sagged in.

GC uses a 2.5ID spring so be sure to get a 65mm ID swift spring. Swift also does not sell half inch increments. They only sell full inch heights.

Hope that helps!

sent from my phone

[JB3]

Thanks Derek, you already gave me the rates in metric, :) I am waiting to hear back from Smilez if he can get a good price on them before I call GC. Thank you for the ID info as well.

Would you say that if I wanted to only go slightly lower than stock I should go with the 7" rear spring right off the bat? I will never want to go real low (no more than 1" lower than stock, optimally), but after reading this thread, I was concerned about tension, having to loosen the rear shock, and all the other stuff you guys talked about with the 7". Is it easy to adjust with the 7" and are the coils far enough apart for bump?

Will the 6" front still go high enough to not be slammed in the front? Again, I'm seeking .75 - ~1" drop

[derbo]

Thanks Derek, you already gave me the rates in metric, :) I am waiting to hear back from Smilez if he can get a good price on them before I call GC. Thank you for the ID info as well.

Would you say that if I wanted to only go slightly lower than stock I should go with the 7" rear spring right off the bat? I will never want to go real low (no more than 1" lower than stock, optimally), but after reading this thread, I was concerned about tension, having to loosen the rear shock, and all the other stuff you guys talked about with the 7". Is it easy to adjust with the 7" and are the coils far enough apart for bump?

Will the 6" front still go high enough to not be slammed in the front? Again, I'm seeking .75 - ~1" drop

If you look at my current car pics, you can see where my car sits. The 7" rear springs allows the perch to be somewhat in the middle setting where as the 6" spring forced my perch to the highest setting it could be. Once you set your height, you will rarely adjust it and IMO I prefer the spring to be properly seated than moving around like the 6" spring.

I don't think ground controls will allow ONLY a 1" drop. I'm not even sure what I have, nor do I care. LOL. I've been planning to raise my rear up more as the front is fairly high at this point.

[JB3]

http://imgur.com/MNQ1prY

Ah I see. I had to revisit your pic. That rear shot makes the front look slammed. The front shot looks reasonable.

Thanks for the info on the 7" rear being in the middle of the adjustment.

Sent from my OnePlus One.* Regularly foiled by autocorrect. But duck it.

[derbo]

http://imgur.com/MNQ1prY

Ah I see. I had to revisit your pic. That rear shot makes the front look slammed. The front shot looks reasonable.

Thanks for the info on the 7" rear being in the middle of the adjustment.

Sent from my OnePlus One.* Regularly foiled by autocorrect. But duck it.

http://i.imgur.com/M2CbptU.jpg

Yea the front isn't slammed at all. I get poked at by my "parking lot stunner" friends lol. I actually think I should raise the car on both ends tbh. Better for track days :)