: Gc Guys, Spring Rates From Mark.....



vettethret
03-06-07, 02:29 PM
I've been on the phone with Mark from GC for about 30 minutes going over what I'm looking for. I was very happy with his willingness to help me figure this out. The car is going on the ground. 2.5" in front and 2.75" in the rear, this is how I've been running all my cars for 10 years in case that comes up. I will be running the DND racetech shocks which are basically the hal 12 way adjustables.

Mark gave me a suggestion of running 8" springs instead of the normal 10" since I'm going down so far. I cant have the wheels jamming up in the wells so he suggested 850lb fronts and 800lb rears. I have a Viper thats dumped on Motons so I'm use to a hard ride. My biggest concern is not bottoming on the wheels wells. The guys running the more aggressive set ups, what do you think of these rates? By going to an 8" spring in front, will it be enough to keep the front of the car up? Mark actually suggested I post up and get some advice from the guys that have gone this route.

Thanks in advance:thumbsup:

rand49er
03-06-07, 03:49 PM
If you're goin' that low, better go a million in front and a million fifty in back. :eek:

vettethret
03-06-07, 06:39 PM
Anyone?

05CTS
03-06-07, 09:05 PM
By lowering your car that low your are limiting your on springs and spring rates. If you go to soft, your coils will bottom out on one another causing coil bind and will also cause your wheel to bottom out as well in the fender. If you go to 800 lbs springs your ride is going to extremely stiff for street use but it's probably your only option going that low. Why don't you go to less of a drop and gain better ride quality. We use a minimum of 800 lb springs on our older vette road cars. We start out beginners on 600# springs and gradually move them up to 1000# springs.

vettethret
03-06-07, 09:18 PM
By lowering your car that low your are limiting your on springs and spring rates. If you go to soft, your coils will bottom out on one another causing coil bind and will also cause your wheel to bottom out as well in the fender. If you go to 800 lbs springs your ride is going to extremely stiff for street use but it's probably your only option going that low. Why don't you go to less of a drop and gain better ride quality. We use a minimum of 800 lb springs on our older vette road cars. We start out beginners on 600# springs and gradually move them up to 1000# springs.

I've driven nothing but Vette/Vipers and have had them all lowered like this for almost 10 years. I have run coil overs on every single one. Motons, pfadts, rippies and lg coil overs. I dont mind a stiff ride at all. When people ask me why I run my cars so low, I ask them, why do some guys like fat chicks?:suspect: I run all of my cars like this and probably willwhen I'm 80. I understand suspension dynamics and limiting travel. Since there is really no true coil over made for this car, I am building my own system here. I know some guys are running agressive set ups. I wont go less of a drop because thats not what I'm looking for. It would probably be for the best, but I guess I'm just not that smart!:)

05CTS
03-06-07, 10:06 PM
Than IMO you should run the 800# springs:thumbsup:

wildwhl
03-06-07, 10:56 PM
Just a thought, and Mark should know, but 2.5" lower should not require 2" shorter springs since with 10" spring at max height (i.e. slightly below stock) I still had the entire collar to lower with in the front.

The rear is another story though.

Good luck with your lead sled ride!

WW

chev4life
03-06-07, 11:13 PM
You must throw up pics of this thing when you get it done! I was running 750's on an old cam '95 Z28 of mine and I had it sitting so low I bumped lane markers with the air damn when I drove :D

vettethret
03-07-07, 12:19 AM
Just a thought, and Mark should know, but 2.5" lower should not require 2" shorter springs since with 10" spring at max height (i.e. slightly below stock) I still had the entire collar to lower with in the front.

The rear is another story though.

Good luck with your lead sled ride!

WW

Thats what I thought about the front. I've seen some almost tucked with the 10 inchers. He said it wouldnt be a problem to put 8 inch springs in the back and 10 up front. Does anybody see a problem with that combo?:thumbsup: :highfive:

vettethret
03-07-07, 12:31 AM
You must throw up pics of this thing when you get it done! I was running 750's on an old cam '95 Z28 of mine and I had it sitting so low I bumped lane markers with the air damn when I drove :D

Thats funny. My old man gave me his 75 el camino and within two months I had it so low, if the road was slightley concave I would tear the blue reflector right out of the ground and it would roll down the street!:thumbsup:

vettethret
03-07-07, 03:23 PM
Where's all the guys running the stiff set ups?

Dreamin
03-07-07, 06:13 PM
Thats what I thought about the front. I've seen some almost tucked with the 10 inchers. He said it wouldnt be a problem to put 8 inch springs in the back and 10 up front. Does anybody see a problem with that combo?:thumbsup: :highfive:

No problem with mixing spring lengths... you dont need 8" in front, with the 10" you can probably lower the car 3"+. You will need 8" in the rear... with the 10" you'll get maybe 1.5" max drop.

There's all sorts of room in the back, but in the front, with a 2.5" drop, I think you'll hit the wheel well liner... there's just not that much room...but you can always adjust the fronts up.

You'll need one heck of a stiff shock to handle that much spring... Check with DND to make sure their CTS-V shocks are designed to handle 800+ lbs springs, all with the 2.5"+ drop... The DND shocks were designed for the stock springs (400 lbs), and to run at the stock car height. All shocks have a "sweet spot" range where they like to run, the DND's were designed to run at stock height, +/- the suspension travel, say 1". Now you want their shocks to run 2.5"+ below their design, with say .25" travel... the shock valuing spec's can get out of whack running shocks out of their "sweet spot"... i.e. compressed so much all the time.

You'll need beefier sway-bar endlinks (with such a big drop, the endlinks wont last, even with the stock bars)... you can get the Z06 endlinks for the front sway bar, and you'll need to fabricate rear end-links...

vettethret
03-07-07, 09:08 PM
No problem with mixing spring lengths... you dont need 8" in front, with the 10" you can probably lower the car 3"+. You will need 8" in the rear... with the 10" you'll get maybe 1.5" max drop.

There's all sorts of room in the back, but in the front, with a 2.5" drop, I think you'll hit the wheel well liner... there's just not that much room...but you can always adjust the fronts up.

You'll need one heck of a stiff shock to handle that much spring... Check with DND to make sure their CTS-V shocks are designed to handle 800+ lbs springs, all with the 2.5"+ drop... The DND shocks were designed for the stock springs (400 lbs), and to run at the stock car height. All shocks have a "sweet spot" range where they like to run, the DND's were designed to run at stock height, +/- the suspension travel, say 1". Now you want their shocks to run 2.5"+ below their design, with say .25" travel... the shock valuing spec's can get out of whack running shocks out of their "sweet spot"... i.e. compressed so much all the time.

You'll need beefier sway-bar endlinks (with such a big drop, the endlinks wont last, even with the stock bars)... you can get the Z06 endlinks for the front sway bar, and you'll need to fabricate rear end-links...

Thanks very much for the response dreamin. I'm going to stick with the 10's in the front. Even Mark didnt know if the 8"s would work in front. I'm just not sure wether to do 750/800 or800/850. I talked to Denny at DND at length and I need to call him back. I was talking to a very helpful guy at a shop in wisconsin (creative engineering) and his customer is running a 900lb front spring and a 700lb rear. He said he wanted to go stiffer in the front, and he could barely move the back at 700lb. Its a street car that sees track duty. Will the zo6 endlinks work in the back?

Thanks again for your help, trying to get this figured out this week so I can order.:thumbsup:

rgd
03-07-07, 10:50 PM
I have the set-up you are going to. QA1 shocks are the shocks DND is building wth. You are right right you will need the 8" springs. I have mine set up the opposite 800 front 850 rear, have not switched them around to see if performance changes though.

May I make one suggestion if you don't have the shocks yet. Have DND replace the stock oil with a thicker grade oil (in the shock) it will be better. Mine work fine but they are always set at max 10 or 12 clicks. With thicker oil you should be able to set them more centered around 6-8 clicks. (best guess)

My $0.02. FYI I am at 26" at the wheel wells, not sure what that equates to as you are measuring. Only slam fender wells ... not any more. lol

thanks
rgd
luck:thumbsup:

vettethret
03-07-07, 10:54 PM
Thanks rgd, I suggested that to him and he said hes got the valving "dialed in". looks like I need to go over that with him again. If you were used to a stiff ride in a sports car, could you drive your car as a daily or is it insanley stiff where you couldnt?

Thanks for your imput.