Ground Control Coilover Conversion (HAS) Kit

[F80Speed77]

Hi everyone, I didn't see a dedicated thread to the GC HAS Kit anywhere so figured I'd start one.

First let me say that for the price this is going to be one of the best handling mods you can do to your F8X especially when equipped with EDC. For ~$1300 you are getting the following...

GC's Excellent Camber Plates
Eibach F&R 2.5" Race Springs (Potentially to your specification)
New front bump stops
Heim Style Front Endlinks
Coilover Sleeve Kit for Front Height Adjustment
Rear Ride Height Adjusters

This is pretty much what my kit looked like


We'll get the bad out of the way first. This kit is a pain in the ass to install if you don't have a large press that can push the new coilover sleeves down onto the damper body. I did it with a hammer and it was a great work out, my biceps doubled in size, but it took about an hr+ per side just to get them hammered down. I would definitely find a friend with a press if I had to do it again. Other than the hammer the sleeve process everything is pretty straight forward and easy.

One more gripe and we'll get to the good. The kit does not come with a helper springs and 100% needs it if you plan to use a 6" tall front spring. I had to purchase a set which added $130 onto the cost of things which was acceptable because of how cheap this kit is. You could maybe talk to Ground Control during the order process to see what they can do but I went through a third party dealer (Bimmerworld) and was going to be charged extra.

Here is what everything looks like installed on the front.


Alright time for the good! My kit came with a 6" 450lb front spring and an 8" 800lb rear spring. I elected not to install the rear springs because I wanted to see how the car felt with the OEM 575lb rear spring. Turns out it feels pretty good! Around town overall ride quality hasn't significantly diminshed, there is more road noise transmitted to the cabin probably from the camber plates but it isn't significant either. I had the car out to an autocross event over the weekend and I really liked the balance it had, exit oversteer felt more manageable and I could feel the front end start to wash away a little if I overdrove into a corner which carried over a little midcorner. It felt absolutely hooked in the 5 cone slalom we had at this event! I'm running a ton of front camber with the camber plates set to around -4.0deg and the grip from the 285/35/19 square RE71R setup felt great. I had 16 runs at this event and my caveman tire temp reading of feeling up the tire did not indicate the front inside edges were overheating. Also if you are familiar with the RE71R the center tread black did not show significant wear which was nice.

I'll have the car on track at Gingerman this weekend to hopefully report back more news and maybe experiment with the higher rear spring rate. Here are some more pics!

[erictrainer]

Nice setup! What kind of wheels are those?

[F80Speed77]

Konig Ampliform 19x10 square +28

[biofluke]

I'm really surprised I don't see more people getting this kit. It seems to be a HAS kit that's actually made for track driving, which is exactly what I've been looking for. However, the lack of reviews and feedback has made me hesitate about getting it.

Also, I've seen a million threads about recommended spring rates. Did you put in the stiffer rear spring before the track this weekend? Are those spring rates what Ground Control recommended? Was the 5" spring an option or the standard size? I'm surprised they don't have a helper spring option on their website if it requires it.

I keep hearing people say recently that these cars can be over-sprung and that lower spring rates work better for a street/track setup. I've seen spring rates all over the place. I tend to get analysis paralysis when it comes to decisions like this. But then at the same time, I look at the B16 Damptronic (another setup I'm considering) and wonder if they even provide enough info on it or if it would even work well as a track setup.

Very tempted to give this kit a go. I wonder how well they would pair with B6 Damptronic shocks.

Thanks for your review!

[F80Speed77]

To answer some of you questions, I was in a hurry and with all the covid stuff going on BW said they had a kit in stock spec'd that way so I just ordered it figuring we'd be changing stuff as the season went anyway. I'd recommend talking to Ground Control and ordering from them. The 800lb rear spring was a recommended setup by Ground Control but with all the motiony ratio stuff going on in the back of the car going from 575-800 probably isn't as crazy at sounds. I'd bet having a bigger front bar, which I don't have, would make that bigger rear spring work well.

GridLife Gingerman Post Event Follow-up!
So we didn't change the rear spring rates, I had a pro-driver hop in the car and he was lapping at a super-competitive pace and liked the forgiveness the car had with these rates so I vowed to not change anything until I was closer to his times lol. He agreed with the very neutral sentiment and you could steer it out of turns with throttle very nicely and the diff would make you feel like a hero. Grip was excellent on entry and mid corner but was still having issues with power application on exit. Might need to try lower hot rear pressures next time or maybe go even higher with front spring rate? The RE71R is a pretty stiffly sidewalled tire so maybe different tires could help on that front too?

[sc_tr0jan_m3]

Looks hopeful but I'm very interested to hear more reviews. I love my GC race plates on e46 track car so it sounds like this is more track oriented than the rest out there.

[Iceman51sn]

Thanks for that detailed write up. I had no idea about this kit until I saw your post and now I'm really intrigued. Wish there were more reviews out there but again really appreciate your write up on it. Keep us posted as you continue to rack up the miles on it!

[F80Speed77]

End of Season Notes!
I gradually lowered the car to max low over the season (the coilovers have some nice adjustment but with the helper springs and springs rates I have I never went full stanceboi lol) but lowering the car removes the pre load on the spring and the 3" helper springs I installed were too short. I've ordered 50lb 3.5" tender springs which I think will work a little better compared to the essentially zero rate helper springs I had.

I eventually switched to a 650lb rear spring after adding a front sway bar which I've been running in the full stiff sitting. The car has really nice balance now at fast tracks like Road Atlanta and Road America! It did feel a little pushy in some slower turns at Gingerman but weather wasn't ideal there. I haven't tried the 800lb springs yet.

Still pretty impressed by what this kit offers at it's price point! This car was great to drive across the thousands of miles I traversed this year driving to racetracks. We'll see what's in store for the offseason!

[m3elmo]

curious did you ever code your shocks to CS specs or are they zhp

[F80Speed77]

No coding that I'm aware of.

[jacobhorn]

I also have the GC HAS kit insatlled on my 2017 F80 M3 Comp Package + EDC, and I love them.

They are absoultely the best option for affordable, track-ready suspention for F80s. The fact that GC will provide custom spring rates at no cost is a bonus!

I love the ease of height adjustability and ofcourse the adjustable front camber plates. The diamater of the front springs are a bit narrower than the popular KW HAS kit, so no rubbing on front tires, even when fully lowered on my 275/35/18 track tires at full speed around an aggressive road course.

There is definitely more sound/road noise from the sitter suspension components, but that is to be expected from any/all similar setups.

I highly recomend this setup for those looking for a more adjustable, aggresive setup for the street and track, for less money than any other comparable suspension setup.

[vrptstyly]

Any more insight on this kit gentlemen? Anyone pair the EDC CS coding with these? Not sure it would be much different than experiences with other kits. Looks like this might be the kit for me. Recommended spring rates?

[F80Speed77]

Spring rates are totally dependent on what your plans are for the car. You'll want a 6" tall spring for the front (with 3.5" tender springs) to get the most adjustability and an 8" spring for the rear. I'm using the H&R front sway bar in the stiffest setting with 500lb Front and 800lb Rear springs and it rides pretty darn nice in Comfort mode still. This is a slightly more track oriented setup.