E31 coilovers?

[72tpik5]

That is some good looking stuff.

[JDP530]

Ground Control just received my front E31 struts yesterday and will proceed with mods.

Per Riley, with GC:

To my knowledge our kit is all inclusive and will come equipped with rear ride height adjusters placed in board in the factory locations and converts to use with 2.50" I.D. springs.

We shorten the front strut housings to gain ample suspension travel when lowered in the realm of 1.5-2.5 lower than stock. The strut cartridges, depending on the spring rate you should choose, would either be a 1547spgc, a propietary Koni we have made to our valving and length requirements, and a 1289spgc or a 1303spgc in the rear, also a proprietary Koni's we have made specifically to our valving and height specifications.


Should you want to go aggressive on the spring rate and lean more into the race dampers, we also can accommodate such rates with an 8610-1437race front strut cartridge and a 1225spgc in the rear. These dampers can accommodate heavy spring rates and the heavy abuse of a race car when set up properly.


All of our mounts are Ground Control Products, The camber plate I would suggest would be a Hybrid version of a race plate. It features all of the adjust-ability of a race camber caster plate, and still features a bearing for articulation. The two differences are a urethane spring hat, and instead of a cupped washer to carry the load of the vehicle a misalignment spacer that directs the load and the steering duties to the spherical bearing is used instead. This quiets down the NVH transfer through the chassis as well as delivers smooth and quiet steering inputs.

Question from me in regard to spring rates the street/track kit can handle:

The Koni SPGC struts I would put a cap on at 600lbs. The Koni Race struts I would put a cap at 850lbs. The SPGC shocks with an inboard mounted spring (assuming the motion ration is .5 to .6, I would recommend no more than 1500lbs or so. Being that they have are adjustable in the way or rebound damping, I would put the lower end of the strut range at a 300lb spring and the lower range of the shock around 400lbs on an inboard set up such as yours.

[JDP530]

Here is the complete quote:

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Attachment 624731

[rogbmw]

Those look to be very well done. It will be interesting to find out what the ride is like with them.

[killian665]

So how did it go

[JDP530]

I just received suspension kit today from Ground Control. Everything looks great and items were well packed in bubble wrap. The only items not included were dust boots and a spanner for the adjustable rear spring perches.

The rear Konis have the 'button' adjustment where button is located on top of shock body which may not be too difficult to adjust but wheel will need to be removed. I would prefer the click type at top of shock rod so you can adjust shocks from inside the trunk, but I dont know if those are available for the E31. Will have to wait til Monday to find out.

GC also supplies their own shop-made rear upper shock mounts that look really strong and should compliment the reinforcement plates I have already installed.

The front struts were shortened one inch if I am not mistaken and they added a heavy gusset between tube and axle housing. Adjustable camber plates are also included so I hope fitment is correct without having to make any mods.

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[killian665]

Damn that’s pretty. Are the rear shock mount studs pressed in or is that an allen fitting?

[B44DARS3]

Ground control setup is sweet!

[JDP530]

Damn that’s pretty. Are the rear shock mount studs pressed in or is that an allen fitting?

Rear upper mounts are allen or socket head bolts. I am not sure if they are long enough to accommodate the top reinforcement plates, if not, I can replace them. They also included spacers for the bottom eyelets so they fit into lower control arm.

[8eights]

Nice, Would be interested in a front set, I mis the last run when Randy made these.

[JDP530]

I finally finished installing the front GC modified struts and plates. I have the car sitting about 1.5" lower than stock measuring apprx 25.5" from ground to top of fender opening. I have not installed the GC rear shocks and springs yet, but I have driven the car and it is pretty well balanced front to rear with the EDC shocks so the rears are probably good compared to the front EDC struts that were constantly bouncing down the road. Ride is quite firm but not jarring or harsh. Car is new to me so its hard for me to compare this new setup with anything else. Turn-in is crisp with -2.5 camber set up initially. Car was very smooth without any vibration up to 100mph. I am using the Moosehead Eng adjustable pillow balls on the lower (rear) control arms.

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[JDP530]

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[beanerbmw]

I sometimes look for the "Like" button on forums....

[JDP530]

I sometimes look for the "Like" button on forums....

Me too! Where is it? I still haven't found it.

[sfillis2]

Does ANYONE know of a shop. on the East Coast, which install these coilovers? Apparently, there's welding involved?

[JDP530]

The Ground Control kit did not require any welding by owner or installer. Ground Control modifies your struts so all you have to do is install them. If you use the Gecko Racing or other imported coilover kit there will be welding required to shorten stock strut tube and attach the new strut tube to axle assembly.

Here is a thread where someone I believe it's Herzie, used the Gecko kit but I think he's removed the kit because he was having trouble getting spring rates and dampening dialed in correctly for his car. Maybe he can reveal more info on his experience. https://www.bimmerforums.com/forum/s...cko-Suspension

[Goodguyili]

Hey JDP530, any update on the coilovers? Im thinking of doing this so I can lower my ride. I got an enormous gap on the front wheel well i wanna clear. Im running on 18" rims. Have you installed the rear? And how long does it take from shipping your knuckles to getting them back?

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[JDP530]

Hey JDP530, any update on the coilovers? Im thinking of doing this so I can lower my ride. I got an enormous gap on the front wheel well i wanna clear. Im running on 18" rims. Have you installed the rear? And how long does it take from shipping your knuckles to getting them back?

Sent from my SM-G970U using Tapatalk

I'm happy with the way the kit turned out. We did have some fitment issues as I've described above because they couldn't find any engineering notes from years ago. But Ground Control took care of the problems immediately. It probably took at least 4 to 6 weeks, I don't remember exactly maybe a little longer, because I had to send them a pair of struts to be modified and they had to send them out to be powder-coated after modifications.

I'm very happy with the ride and It's a big improvement over stock but not so harsh that you feel all the bumps. Of course, the EDC shocks did not work on my car so I don't know how nice of a ride that would be but I did not want to bother sending them to Europe to be rebuilt. Plus, I was looking for an improved suspension setup with camber plates because I like to drive my car on a track for the fun of it.

[Goodguyili]

I'm happy with the way the kit turned out. We did have some fitment issues as I've described above because they couldn't find any engineering notes from years ago. But Ground Control took care of the problems immediately. It probably took at least 4 to 6 weeks, I don't remember exactly maybe a little longer, because I had to send them a pair of struts to be modified and they had to send them out to be powder-coated after modifications.

I'm very happy with the ride and It's a big improvement over stock but not so harsh that you feel all the bumps. Of course, the EDC shocks did not work on my car so I don't know how nice of a ride that would be but I did not want to bother sending them to Europe to be rebuilt. Plus, I was looking for an improved suspension setup with camber plates because I like to drive my car on a track for the fun of it.

Thanks for your input, I think I might save for it on my 840, would you recomend getting the rear shock mount supports?

[JDP530]

Thanks for your input, I think I might save for it on my 840, would you recomend getting the rear shock mount supports?

Yes, I would recommend the rear shock mount reinforcement plates, especially if you do any aggressive driving or install stiffer springs and/ or anti-sway bars. The plates were one of the first aftermarket parts I installed on my car after reading on here how many people had shock mount failures.

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