[Lucky'sM5]

My GC setup is finally here and looking to install this weekend. My questions involve the rear adjustment or lack of ease of adjustment. I have noticed on a few the BC setups,that there is an extension bar that comes up through the rear shelf near the speakers. A buddy of mine with a 335i and the bilstein set up cut out access through the trunk and placed a plug in the hole. I know the e39 does have a ton of wiring running through the side wall in the trunk, which leads to the second question.

Question 1 - Is there an extention bar or anything similar that GC owners have used to change the rear set up a little easier?
Question 2- can you cut access through the trunk to get to the strut?

I don't plan on changing too often but i do want to drive a bit to get the feel of the car before I set it and forget it, however, I would like to not have to remove the package shelf a few weeks later to readjust if necessary. Thanks for your help in advance!

 

[Rhino]

You will need to cut a hole in the parcel shelf, However, IIRC the speakers will still be in the way. I don't think there is a simply solution short of removing the speakers permanently or some serious fabrication work.


Cheers, :cheers:
Rhino

 

[Lucky'sM5]

I feared that would be the case. I am going to try a few thing this weekend and hopefully come up with a solution. Thanks for the quick reply!

 

[josiahg52]

Yeah, unfortunately you have to drive around for awhile with the back seat taken apart until you make the final adjustment. It's totally worth it in the end; you're going to love them. Good luck!

 

[RoundelM5]

Will the BC coilover extension adjuster thingy attach to and control the GC setup in rear? I believe (according to Vivid Racing) that you can buy the BC extensions separately for $40.

What spring rates did you choose and how do you intend to use the car - lots of track time? very little? none?

 

[Lucky'sM5]

After speaking with Trevor and Jay a few times I chose the 430 from and 350 rear. She is a daily driver and I hope to do maybe 2 or 3 track events a year but that all depends how fast I can get her track ready in my mind. I lived in San Antonio before I moved to Dallas and sold my track cars to help the move. I found a 90degree adjustment knob that I think might work to access through a cutout in the trunk. My only fear is it comming loose and interfearing with the springs. I plan to put Mia (that's my cars name) on the lift at 9am tomorrow and will do everything in our power to find a reasonable solution. I don't think I'll be changing the set up much, but I'm in the "better have it and not need it than need it and not have it" mode. I will also be changing the front and rear bushings and the pinch bolts for the struts. I will take as many pics as I can and try to post on Monday. Wish me luck!

 

[RoundelM5]

Sounds great - good luck with the install. Got a pic/details/source on the adjustment tool? My GC coilovers just arrived and I'm planning install in the next week or so.

I went with 550F/400R but I'm tracking 12-15 days per year so wanted a bit more manners on track. Can't wait to hear how your install goes!

 

[Lucky'sM5]

I don't have the adjuster in my hands, my buddy has it at his shop. I believe it was tabbed by him in the same principle of the 90 degree screwdrivers. I wish I could track it that much but I don't have another daily at the moment and my wife would not be happy with me taking our truck to work everyday and leaving her at home. I really like a stiff ride that handles the twisties but didn't want to jar my fillings loose on some of the roads that lead to my place of business. I do want to drive in a set up like the one you chose to see if it would be an option for an extra se of springs and or worth it to change out for track time. I have access to a lift and plethora of tools for free so it is a little easier to work on her. I'm like a kid on Christmas eve and can't wait till I wake up tomorrow!!!!

 

[RoundelM5]

Well sneak outside and do the fronts today - they are very easy...probably an hour each or so (maybe two then one if you've never done it) and that way you will get your fix and only have the rears to do tomorrow!

Please be sure to post a pic of what you end up with for the rear tool/access and any thoughts/experience. Thanks!

Yeah, I went round and round on spring rates and err'd on side of more stiff. If they are too much, particularly in front, I may just grab another set of springs. We'll see!

Good luck tomorrow (and/or today)!


Sent from my iPhone using Tapatalk

 

[jamiepeers]

I always thought Groud Control Coilovers were designed as such so you could adjust them without removing the rear shelf??

 

[josiahg52]

I always thought Groud Control Coilovers were designed as such so you could adjust them without removing the rear shelf??

As far as I know, the GCs are actually one of the few (if any) adjustable kits that REQUIRE you to remove the shelf to adjust.

 

[lugnuts]

ca't wait to see the install pics.

BTW what are the stock spring rates?

 

[RoundelM5]

BTW what are the stock spring rates?

GC lists two choices on their website re: "which kit" as either "family/street" or "track/school"

I think the track/school setup has varied a bit over the years, particularly on rear spring rate, based on discussions with/posts by others. Currently, 430F/350R is what they offer "standard" now unless you discuss/request otherwise. The kits that used to be available from D/A were 430/380 I think and a number of folks have also received 430/325. That said, you want a different spring rate, just ask.

I'm not actually sure what the rates are for the family/street setup as I wasn't interested and never asked.

You do not need to remove the rear deck to adjust the rears; however, you do need to remove the rear deck speakers (yeah, i know, not exactly a great choice either). For this reason, I will try to fab up something to enable adjustment through the deck/from trunk. If not feasible, I guess I'll be driving around without a rear deck for a month or so until after my April 11-12 track days.

 

[lugnuts]

thanks for the info.but I was more wondering how do those rates compare to the factory M5 spring rates. I like the factory ride but a slightly stiffer ride would be ok too.

 

[RoundelM5]

oh, sorry, I read "stock" as in "stock" GC rate...

OE springs are progressive rate so it's not a direct comparison as these are linear rate springs. You may be able to find full load rating of OE springs on here but I don't know it. I'm guessing approx 200 at most given that Dinan springs are "a little over 200." That said, some of the suspension experts may know

 

[lugnuts]

no problem it was good info as I am considering getting the GC's. just need to figure out what spring rate is right for me before I buy.

 

[Lucky'sM5]

I went round and round for months between the kw, bilstein, gc, bc an a few other lower end like k sport and xyz for months. The gc's really were the most practical set up for performance and money. You get camber plates new bump stops and rear mounts fully assembled from gc with the option on spring rates and the struts matched. All the others all the extras are extra. I'm on my way to the shop now to install. I will be doing the coilovers, bushings and a left front window regulator! Happy times!

 

[jamiepeers]

As far as I know, the GCs are actually one of the few (if any) adjustable kits that REQUIRE you to remove the shelf to adjust.

Well, not according to CA Automotives website. States there clearly that you can remove the suspension from under the car, thus leaving the rear shelf in place, albeit more difficult to adjust than say BC units, it means you don't have to have half of the interior out of the car

See below and follow the link.

Koni Single Adjustable Rear Shocks
with shortened damper rods preadjusted to match rear spring rates using our shock dyno. The Koni rear shocks are adjuistable for rebound, however it is not simple. The Ground control rear upper mount allows (forever) maintanence and adjustment without removing the package shelf and 200 assorted parts by allowing the rear suspension to be removed from BELOW the car.

CA: Chassis, Suspension & Steering Upgrades

 

[Lucky'sM5]

According to gc you don't have to remove the package but you have to remove the speaker and cut an access through the pannel. You still have to remove the speaker to get to the rear strut.

 

[Lscman]

My GC setup is finally here and looking to install this weekend. My questions involve the rear adjustment or lack of ease of adjustment. I have noticed on a few the BC setups,that there is an extension bar that comes up through the rear shelf near the speakers. A buddy of mine with a 335i and the bilstein set up cut out access through the trunk and placed a plug in the hole. I know the e39 does have a ton of wiring running through the side wall in the trunk, which leads to the second question.

Question 1 - Is there an extention bar or anything similar that GC owners have used to change the rear set up a little easier?
Question 2- can you cut access through the trunk to get to the strut?

I don't plan on changing too often but i do want to drive a bit to get the feel of the car before I set it and forget it, however, I would like to not have to remove the package shelf a few weeks later to readjust if necessary. Thanks for your help in advance!

Supposedly the latest Koni for E39 setup sold by GC allows adjustment from below, but it probably isn't easy. If you are not satisfied with relying upon the historical data posted about koni tuning, why not just leave the package shelf removed for a few weeks after the install? The access hole idea isn't very useful with no external adjustment. The 3 series units were likely custom modified for external adjustment.