Cadillac Owners Forum banner

1 - 20 of 101 Posts

·
Registered
2016 ATS-V
Joined
·
2,271 Posts
Discussion Starter #1 (Edited)
Ground Control has successfully built a coil-over kit for the V! Front and rear drop of 0" to 1.2" +/-. Your choice of spring rate (they have recommended rates). Kits work with stock shocks (the regular FE4 or the stiffer FG2) and will come with custom rear shock mounts to 'fool' the load leveling. Production kits will be available Jan 4, 2006. Price will be $499.

A prototype kit is installed on my car. And I couldn't be happier with it; it's working very well. Their goals were to improve handling (by both lowering the car and using stiffer springs) and not increase noise... they succeeded in both.



Front:
Front setup is very straight-forward, attach threaded spring perch onto the shock body, use Eibach 2.5" coil-over race springs, new top shock mount was built w/new bump stop.

Rear:
GC choose to use the stock rear spring mount points... they said switching to a conventional spring-over-shock coil-over would have changed the suspension geometry too much. And my concern with this would be, without lots of data from GM, there is no way to know if the shock towers are strong enough to handle the weight of the whole car (esp. over the long term).
Custom pieces were made for the top and bottom mounts, the height adjuster is up top, again Eibach 2.5” coil-over race springs. Rear bump stop remains inside the rear shocks.

Spring rate:
They tested a lot of springs: 450lbs, 500, 550, 600… front and rear combo’s (It sounded like building the kit took less time than testing spring rates) For the FE4 shocks, they are recommending 500lbs front and 450lbs rear. GC testing determined that the front FE4 shocks cannot handle more spring than 500lbs… and handling was more balanced with 450lbs in the rear… the shocks can handle 500lbs, but they said they weren’t happy with the “rear wheel frequency” and “the rear didn’t stay as planted” with the 500’s. They need to test the FG2 shocks and will come up with recommended spring rates… they think the FG2 could be pushed to 550-600lbs!

Ride Height:
GC determined that the car is most balanced at 26 7/8” front and rear ride-height - ground to fender lip… (they use suspension based measurements, the 26 7/8” is my translation of their numbers). On my car this was a 0.70" front drop (w/0.5" more possible) and a 0.95" rear drop (cant go too much more with the WW spacers on my rear shocks). I have no rubbing at this height (stock wheels / tire in front, stock wheel / 275s in rear). They said, flat worked best, as all the frame to suspension measurements are the same front-to-rear, meaning the frame is now flat. And the car corner-weighed the best at this height.
They did research the car’s stock rake… they believe the stock rake is not for handling, it was done for aerodynamics (fuel economy?)… But with a coil-over setup, you can setup the car for what works best for you!
For whatever reason (shape of rear fender?)… with the car flat, it looks lower in the rear to me (though the tape measure says it’s not)… I’m not sure if I will raise the rear (just a hair) or not.

Noise:
All springs have urethane mounts top and bottom for noise suppression. Where the stock mounts/bushing were deemed stiff enough they were reused, where they were deemed too soft, custom bushings were made. End result is no noise from the front, and a slight increase from the rear… only perceptible with the radio off. I do have a small squeal from the left rear, I have to talk to GC about this… only one corner is making it.

Road Feel:
Far bigger difference than I thought!
High-speed floatiness – Gone.
Front-end nose dive on hard braking – Gone.
Right/left body sway on uneven pavement, leaving driveways, etc. – Gone. (It feels like I installed stiffer sway-bar.)
And the biggest difference is in steering response… it’s so much quicker now… I didn’t think it would make as big of a difference as it does.

Ride:
The ride is a little stiffer… you know something has changed… but it’s definitely not too stiff. FWIW I asked the wife if she felt a difference… she said no. Given my car is 80% for road-trips, 20% for road-courses, I did not want too stiff a ride… thus my concern w/500lbs spring in some earlier threads… I was wrong… 500lbs is not to stiff… it’s *just right*. Going over pot-holes, freeway expansion-joint, etc… it’s definitely a *bam* now, instead of a *thump* or *whoosh*, but the ride is not harsh at all. (Yes, it’s hard explaining ride quality with sounds)
I don’t have FG2 shocks, but from the threads here, I think ride gets harsher when upgrading from FE4s to FG2s vs. the stiffer springs I have (just a guess obviously).

Handling:
Unfortunately it’s been pouring rain since I got the car back… so I haven’t fully wrung out the car :hide:. But on semi-dry roads, driving 7/10th, the car feels very balanced, I thought is would understeer with the 500/450 springs, it does not… things definitely happen much faster now… more handling feedback once it drys up a little.

Shocks:
GC was very familiar with the V shocks, the “regular” and “performance” models. They said both shocks were very well designed, and Sachs put a lot of R&D into getting the valveing right. They highly recommend using the factory shocks (FE4 or FG2) with this kit. I asked about Koni and Advanced Design. They said they would work with Koni on options… but said Koni has been very difficult to work with lately and extremely slow. About AD, they said “that’s really a race shock… given that you have to rebuilt it, etc… it would not be a good option for this car”. I got the impression we shouldn’t hold our breath for aftermarket shock options. For you guys who absolutely want an adjustable shock… I suggest you call GC directly (talk to Jay or Dale) and put a bug in their ear. And someone with QA1 shocks should definitely talk to them… I think the only change required would be the front shock threaded sleeve (?).

Fooling the rear shocks:
GC will be making a new top mount for the rear shocks… they think they can get a 1.2” drop from the rear with their mount. (Max drop is closer to 1” with WW’s mod.) They are *trying* to come up with a mount that comes apart and adjusts from the bottom… so you only have to remove the rear seat once (to install their mount) and then any future spacer adjustments don’t need seat removal.

Availability:
The kit will include all coil-over hardware, 4 springs (you pick the spring rate, or go with their recommended rate), a custom tool to pop out a bushing from the front shock mount which is reused, the new top mount for the rear shocks, and a giant Ground Control sticker for your windshield (j/k ;)) They have all parts but one in stock… they should have that in by Jan 2… So they believe they can start shipping production kits Jan 4, 2006.
Pricing for the kit: $499. GC will be doing a Group Buy to kick things off... They will be joining as a supporting vendor... until then, that's all i'll post on this.

Finally:
When I went to pick up my car, they had washed it... and apologized if my radio presets were lost as they had to remove the battery... I tell you... it's the little things that make your day... :)

2 thumbs waaay-up :thumbsup: :thumbsup: for the coil-over kit, and Ground-Control as a company.
 

·
Registered
2016 ATS-V
Joined
·
2,271 Posts
Discussion Starter #2 (Edited)
Pics:



On the road:


Front:


Front spring perch:


Front top mount, new bump-stop:


Rear:


Rear, very bottom mount:


Rear, top of bottom mount:


Rear, top mount:
 

·
Registered
2005 Stealth Gray CTS-V, 2009 Black CTS-V
Joined
·
3,570 Posts
As expected, great write-up.

Thanks for the thoughts. :thumbsup:
 

·
Registered
04 CTS-V R.I.P.
Joined
·
1,234 Posts
Great Write Up! I might just save my money and don't get the oa1's or fg2's; pick up the set of springs and sway bars. Thanks!
 

·
Registered
CTS-V
Joined
·
798 Posts
This appears to be perfection in my book... adjustability without re-engineering (and possibly compromising) other factors. And as a bonus, fully compliant with SCCA Steet Touring class regulations regards stock attachment points and component material (i.e. retaining attachment locations and bushing construction materials).

I've already volunteered my V to test mule the FG2/Hotchkis spring rates. With luck we can have recommended spring rates for that configuration established at or just slightly after the expected kit availability time frame. Just in time for the 2006 season... Woo-hoo!

Thanks Dreamin'... U da man.
 

·
Registered
'04 CTS-V platinum/blk.
Joined
·
1,227 Posts
Wow.............I can't even begin to tell you how happy I am right now!!! A HUGE hats off to Dreamin and Ground Control!!! Thanks a ton!!!

Merry Christmas!
 

·
Registered
Lemon Law'd '05 V
Joined
·
1,241 Posts
Dreamin,
I have just welled-up with tears of joy from your thread....thank you. The pictures are incredible, exactly what I expected....beautiful pieces.

So 500lbs was the sweet rate, huh. After I did some research, I thought the rears wouldn't be the same, but I wasn't expecting lower in the rear...perhaps due to the "leveling" of the chassis. And the cornerweighting of the chassis is just a gift from the Heavens.
You know, since I'm on the other side of the country I had no chance to get to GC...I'm so happy you took the time and made the sacrifices to allow Jay and Dale to develop the kit. I also have a real sneaky suspicion that they might just make some money on these...more so from the CTS community than the V guys, I hope they do.

It's nice to see a company take on a challenge and deliver a solid result. I, without a doubt, will delay all other expenses to be in on the group buy...damn, they even deserve full price...it's not like ANYONE else stepped-up and gave us an affordable opportunity at a system like this.

Again, Dreamin, a thousand thanks for your help. Now Cali just needs that testing on the FG2s!!!! Also, fellas, keep in mind that should someone not be happy with spring rates...ie, they are too hard or soft...we can always trade springs. Imagine that, a 2.5inch race spring exchange group. I imagine those that cruise will want softer springs and those that road-race/autox will want stiffer.

Those pictures are addictive...can't...stop....looking....must....find...money.....
-ace
 

·
Registered
Joined
·
523 Posts
Hey when the roads Dry up you have to let me know if the new setup does anything as far as improving wheel hop????
I hope IT MAKES A DIFFERENCE even though it is not likely.
 

·
Registered
CTS-V
Joined
·
1,621 Posts
This has to be the best present I will get for Christmas!
THANKS DREAMIN!:D
Your bottle of Patron Silver is well deserved. GC, do a GP, my checkbook is ready.:)
 

·
Registered
04' CTS-V, 04' Escalade EXT
Joined
·
623 Posts
Wow, great looking set up!
Awsome, what else can be said.
 

·
Registered
Joined
·
8 Posts
Count me in on the group buy. I had a double adjustable GC kit on my M3 that was awesome. The V should be great with this setup. My M3 was night and day different. I only wish I could get it next week while I am off work for the holidays so I had more time to fiddle with the heights. Sincere thanks to all involved in bringing this to reality!
 

·
Registered
1999 Black and Tan STS
Joined
·
753 Posts
This should also be posted in the CTS forum. I bet they could sell 10 to 1 on the CTS over the V series.
 

·
crushing Vs with my Wurm
2013 GT500 - 700+ HP
Joined
·
12,266 Posts
Group buy? COUNT ME IN!!!!

Dreamin. Your dedication to the perfect suspension setup allowed us this opportunity. Thank you VERY VERY MUCH!

F
 

·
Registered
2016 ATS-V
Joined
·
2,271 Posts
Discussion Starter #18
Dooman said:
This should also be posted in the CTS forum. I bet they could sell 10 to 1 on the CTS over the V series.
Someone educate me on the CTS suspension... is the diameter of the front shock the same on CTS and CTS-V?
 

·
Registered
2
Joined
·
381 Posts
Very well done.:thumbsup:
Nevertheless, we :grouphug: should get wildwhl a free set for his groundbreaking work that ultimately led to this great solution. :thumbsup:
 
1 - 20 of 101 Posts
Top