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      10-14-2015, 06:00 PM   #1
bgregg
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Ground Control coilover conversion kit

GC has a coilover conversion kit for the M235i that uses the stock struts/shocks and therefore the stock EDC. The kit involves new springs, spring perches, camber/caster plates, front bump stops. Basically a sleeve-over type arrangement on the front.

The kit therefore does not require any 'EDC delete' electronics or recoding to avoid error messages.

The kit is height adjustable, all the way to stock height if desired.

The kit allows a choice of several types of springs to be specified by the customer: street, track, race. All springs from Eibach, I believe.

This kit comes with the upper camber/caster plates.

This kit assumes the stock dampers are good enough to keep and therefore match up with a different spring. I could believe that is true for a street setup, but would wonder for a more aggressive setup. Or you could put your own choice of aftermarket damper in there instead, but then deal with the EDC delete also.

You may not find this on the GC website yet (for the F22). But I inquired and find out it is available already. I think it is on the website for other models of BMW.

Anybody have experience with these on 2-series or another BMW model? I can't contribute any firsthand experience. It would appear that the benefits are choosing ride height, but keeping EDC functionality. At a price point above just a spring swap, but well below a full coilover kit.

Last edited by bgregg; 10-25-2015 at 11:38 AM.. Reason: link arms not part of kit; bump stops are part of kit
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      10-15-2015, 02:14 PM   #2
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GC does not have a very good reputation for quality around here. If you want to use the car, and save money just get the blistien coil overs.
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      10-15-2015, 06:12 PM   #3
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Quote:
Originally Posted by bgregg View Post
GC has a coilover conversion kit for the M235i that uses the stock struts/shocks and therefore the stock EDC. The kit involves new springs, spring perches, camber/caster plates, and linkage arms to the swaybar. Basically a sleeve-over type arrangement on the front.

The kit therefore does not require any 'EDC delete' electronics or recoding to avoid error messages.

The kit is height adjustable, all the way to stock height if desired.

The kit allows a choice of several types of springs to be specified by the customer: street, track, race. All springs from Eibach, I believe.

This kit comes with the upper camber/caster plates.

This kit assumes the stock dampers are good enough to keep and therefore match up with a different spring. I could believe that is true for a street setup, but would wonder for a more aggressive setup. Or you could put your own choice of aftermarket damper in there instead, but then deal with the EDC delete also.

You may not find this on the GC website yet (for the F22). But I inquired and find out it is available already. I think it is on the website for other models of BMW.

Anybody have experience with these on 2-series or another BMW model? I can't contribute any firsthand experience. It would appear that the benefits are choosing ride height, but keeping EDC functionality. At a price point above just a spring swap, but well below a full coilover kit.
This is super interesting. I know some people haven't had a great experience with GC, but they've done right by me, even after their old camber plate design ate one of my struts.

I think I might consider this in the future -- I'd be very interested in retaining the stock EDC function of the car, but have some of the adjustability of a coilover, along with some paired springs.
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      10-18-2015, 09:24 PM   #4
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kit picture

Around $1074 shipped. scroll down for actual pictures

Last edited by bgregg; 10-24-2015 at 09:42 AM.. Reason: take out temporary placeholder
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      10-20-2015, 11:56 AM   #5
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that's so close to coil overs, plus its GC, there engineering is questionable at best, customer service other than LP has been awful. Search the web, tons of problems, up to you Just my 2 cents.
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      10-22-2015, 04:00 PM   #6
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According to Ground Control, I am the first F22 kit purchase request. They had previously done the F30 so the kit will be similar. They specified 425 lb/in front springs and 650 lb/in rear springs to meet my particular request.

One thing I like is the full catalog of springs is available, so it is possible to get what you want. I needed two things in particular from a kit: ride height pretty close to stock for my taller track tires, and camber plates to achieve -2.5 in front. Most coilover kits, with the exception of KW Street Comfort Kit, do not meet my ride height requirement. This kit with the included camber plates is exactly what I needed.

I will post a picture here during the unboxing. Since I am within driving distance of Ground Control, I can always go there in person, but not planning to have to do that. So far, I am getting the support over the phone for questions in a very timely manner.

I also learned that the stock swaybar link arms are compatible with their kit. More information coming on the install experience.
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      10-22-2015, 04:39 PM   #7
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i just installed UUC sway bar end links in front because stock ones broke while i was steering with TCkline coilovers, had GC camberplate and it destroyed left strut twice, one was OEM and other was Bilstein. i hope they fixed it but i wouldn't go to them again.
The only thing is Camberplate will increase noise.
i got used to it, but women will hate it.
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      10-22-2015, 04:46 PM   #8
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Quote:
Originally Posted by bgregg View Post
According to Ground Control, I am the first F22 kit purchase request. They had previously done the F30 so the kit will be similar. They specified 425 lb/in front springs and 650 lb/in rear springs to meet my particular request.

One thing I like is the full catalog of springs is available, so it is possible to get what you want. I needed two things in particular from a kit: ride height pretty close to stock for my taller track tires, and camber plates to achieve -2.5 in front. Most coilover kits, with the exception of KW Street Comfort Kit, do not meet my ride height requirement. This kit with the included camber plates is exactly what I needed.

I will post a picture here during the unboxing. Since I am within driving distance of Ground Control, I can always go there in person, but not planning to have to do that. So far, I am getting the support over the phone for questions in a very timely manner.

I also learned that the stock swaybar link arms are compatible with their kit. More information coming on the install experience.
Interested to see how this turns out. Keep us posted.
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      10-22-2015, 05:38 PM   #9
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Good question about the swaybar end links. I was thinking the upgraded springs would be doing a much better job of keeping the suspension flatter, thereby making the swaybar work less hard.

I was not planning on any swaybar changes or any end link changes, but will see how it all pans out. End links are cheap enough that it wouldn't be a big deal to upgrade them.

On the camber plates, I don't know if all problems are now resolved? Or if I will join the unhappy list too later on. Only had fixed camber plates on my Cayman S (made by Tarrett Engineering), because it too had inadequate camber in stock form. Those ones were not noisy at all.
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      10-22-2015, 07:12 PM   #10
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Quote:
Originally Posted by bgregg View Post
Good question about the swaybar end links. I was thinking the upgraded springs would be doing a much better job of keeping the suspension flatter, thereby making the swaybar work less hard.

I was not planning on any swaybar changes or any end link changes, but will see how it all pans out. End links are cheap enough that it wouldn't be a big deal to upgrade them.

On the camber plates, I don't know if all problems are now resolved? Or if I will join the unhappy list too later on. Only had fixed camber plates on my Cayman S (made by Tarrett Engineering), because it too had inadequate camber in stock form. Those ones were not noisy at all.
I have the new plates. I haven't had any issues with them, and they do make a bit more noise, but nothing awful.

With regard to doing endlinks/swaybars, just keep in mind that doing the sways on this car is very labor intensive, as you need to drop the front and rear sub frames to get at the bars. I had it done. Worth it, but huge pain in the ass.
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      10-22-2015, 11:02 PM   #11
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Quote:
Originally Posted by bgregg View Post
On the camber plates, I don't know if all problems are now resolved? Or if I will join the unhappy list too later on.
The move away from a urethane bushing to a spherical bearing for the sliders has most likely eliminated the risk of snapping off the strut's shank stud. Anyone who has GC plates with urethane bushing sliders needs to change to spherical bearing sliders ASAP!

There are still some who question GC's use of an older OEM bearing and a custom spring perch vs. using the stock perch/bearing combo (a la TCKline) vs. a needle bearing solution (a la K-MAC) vs. whatever Vorshlag cooks up.

My GC plates are working pretty well for me notwithstanding a little extra NVH. I'm watching the perch bearings carefully, because it doesn't take many miles to fill them with grit, and jacking up the car can cause them to separate, which can cause damage to the carrier.

Quote:
Originally Posted by bgregg View Post
Only had fixed camber plates on my Cayman S (made by Tarrett Engineering), because it too had inadequate camber in stock form. Those ones were not noisy at all.
I'd be really excited to see fixed -2deg camber plates with stock-style urethane bushings and stock perches for these cars!
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      10-22-2015, 11:07 PM   #12
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There have been a number of people that have tried parts of this kit individually, such as camber plates only. Or prior versions of camber plates before the current generation. So it is hard for me to really sort out all the information in proper context.

I am thinking there were definitely some growing pains for GC to work out. So I am coming on the scene a bit down the road from all of that. So I may be the first to try the full kit on M235i.

UPS delivery tracking says the kit arrives tomorrow, so I'll post pictures of what it looks like in the current implementation. I assume the springs are all off-the-shelf 2.5" ID coilover springs straight from the Eibach catalog. I like linear spring design the best, so that is a positive for me.

What I have read from others, is that the Comfort, Sport, Sport+ settings don't have that much of a difference from each other in ride quality after the kit. Maybe still a small difference, but much more subtle since the springs may be more dominant than the damping of the struts. So I'll confirm that point later on.

Quite true what liquidpaper said about complexity of swaybar installs: I want the springs to do most of the job of body control and control of dive under very hard braking. The swaybar job is either adding/subtracting remaining oversteer or understeer, if any, which I may just live with what I end up with. BMW decided to really bury those swaybars.
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      10-23-2015, 10:20 AM   #13
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Thanks rwalker for the tip about being careful to monitor the grit buildup and also do you take any precautions in jacking up the car? I am trying to get a visual in my mind of what that will look like for the perch bearings.
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      10-23-2015, 11:02 AM   #14
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Quote:
Originally Posted by bgregg View Post
Thanks rwalker for the tip about being careful to monitor the grit buildup and also do you take any precautions in jacking up the car? I am trying to get a visual in my mind of what that will look like for the perch bearings.
unfortunately, there isn't really anything you can do when jacking to prevent separation

the best option is to use ramps to get the car in the air whenever possible, to keep the front suspension loaded

new bearings are only $10, but R&R is a 2 hour project :-(

attached is a pic of separation of the slider + bearing from the spring perch; this isn't harmful in and of itself, but if the bottom bearing race stays with the perch instead of with the slider, balls can dislodge, and/or the races can be crushed when load is re-applied

the issue here is that the M235i places almost no load on the spring perch when the strut is at full droop, further: the load it does apply isn't squarely applied when you're running a lot of camber (the lower and upper perches aren't square when cambered up)
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      10-23-2015, 11:11 AM   #15
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the below pictures from Pparana illustrate a worst case

note that this is not the right way to disassemble the front suspension (Pparana has shorter springs that provide zero load at full droop), but it shows how the top race (yellow) wants to stay with the slider (grey, top), whereas the bottom race (black, or not shown) tends to stay with the perch (red)

note that the sides of the yellow race/retainer should be square, but are flared (failed)



Last edited by rwalker; 10-23-2015 at 11:17 AM..
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      10-23-2015, 12:35 PM   #16
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Quote:
Originally Posted by rwalker View Post
The move away from a urethane bushing to a spherical bearing for the sliders has most likely eliminated the risk of snapping off the strut's shank stud. Anyone who has GC plates with urethane bushing sliders needs to change to spherical bearing sliders ASAP!

There are still some who question GC's use of an older OEM bearing and a custom spring perch vs. using the stock perch/bearing combo (a la TCKline) vs. a needle bearing solution (a la K-MAC) vs. whatever Vorshlag cooks up.

My GC plates are working pretty well for me notwithstanding a little extra NVH. I'm watching the perch bearings carefully, because it doesn't take many miles to fill them with grit, and jacking up the car can cause them to separate, which can cause damage to the carrier.


I'd be really excited to see fixed -2deg camber plates with stock-style urethane bushings and stock perches for these cars!

Its not the grit that causes them to separate it is load. They are sealed until the case splits. Once the case splits open, that's when you get more noise, worst case is failure. I would suspect this bearing is what caused the urethane failure. The load for the shock (strut) is minimal, the load on the spring is much greater.

Think about it this way, you can push a shock (strut) with your hand, a spring you have to stand on. Your also dealing w McPherson strut design, so the shock, strut combo is the upper control arm, which carry's even more load.

If you live in NY or any state with safety inspections, or MOT ext overseas, those bearings would be a automatic fail.

I cant really stress how dangerous they are once separated, you could hurt yourself, someone else, or the car.
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      10-23-2015, 12:38 PM   #17
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Quote:
Originally Posted by Liquidpaper View Post
I have the new plates. I haven't had any issues with them, and they do make a bit more noise, but nothing awful.

With regard to doing endlinks/swaybars, just keep in mind that doing the sways on this car is very labor intensive, as you need to drop the front and rear sub frames to get at the bars. I had it done. Worth it, but huge pain in the ass.
LP check those bearings for separation, the plates are pretty quiet until they separate. You need to get both wheels off the ground and unloaded. With your springs you should be able to check with no issue since your lowered. If separated replace or remove asap.
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      10-23-2015, 12:47 PM   #18
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Quote:
Originally Posted by Pparana View Post
Its not the grit that causes them to separate it is load. They are sealed until the case splits. Once the case splits open, that's when you get more noise, worst case is failure. I would suspect this bearing is what caused the urethane failure. The load for the shock (strut) is minimal, the load on the spring is much greater.
I'm not sure I agree with you on load.

My understanding: The strut bears all of the suspension's lateral load. The spring bears vertical loads.

When you have a lot of camber, the perch bearing is only subject to lateral load relative to the strut caused by non-parallel perches. The perch bearing is not used for strut top location.

What I think causes the failure with urethane bushing: bending of the shank stud back and forth relative to the shank, leading to hardening and breakage. The spherical bearing fixes this by ensuring there's no bending load on the stud, only the normal lateral load for location of the top of the strut.
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      10-23-2015, 01:49 PM   #19
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on a true macpherson strut suspension geometry that would be correct. Most if not all are a pseudo McPherson strut suspension (2r is Pseudo McPherson with fictive steering axis). The top of the plate takes the load after the spring. Which in the case of your gc plates the energy has to pass through the the bearing to the plate.

Shocks dissipate the frequency of the spring rate to maximize contact and comfort. Take the spring out, and set the car down on the shock, it would be completely compressed. That may help in visual?
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      10-23-2015, 02:29 PM   #20
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Originally Posted by Pparana View Post
LP check those bearings for separation, the plates are pretty quiet until they separate. You need to get both wheels off the ground and unloaded. With your springs you should be able to check with no issue since your lowered. If separated replace or remove asap.
I've had a few mechanics check since I had the plates installed in June. No separation, so, so far so good.

The plates made some more noise right when I got them installed, but I am 95% sure that is due to the spherical rather than urethane bearing.
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      10-23-2015, 04:02 PM   #21
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Quote:
Originally Posted by rwalker
the below pictures from Pparana illustrate a worst case

note that this is not the right way to disassemble the front suspension (Pparana has shorter springs that provide zero load at full droop), but it shows how the top race (yellow) wants to stay with the slider (grey, top), whereas the bottom race (black, or not shown) tends to stay with the perch (red)

note that the sides of the yellow race/retainer should be square, but are flared (failed)


Same as my case, cant be arsed to post pics again.
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      10-23-2015, 11:12 PM   #22
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The rear of kit

2.5" ID coilover 650 lb/in Eibach springs in the rear, with height adjuster:


Comparison to stock rear spring (not part of kit, only for reference):

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