BLOWNBLUEZ06

I have built many C5's and C6's for forum members, but don't claim to know much when it comes to suspension. I do have experience installing coilovers and urethane bushings.

I've spent years helping my CF brothers out and rarely ask for it myself. I'm hoping for some good reciprocation here.
I have a 02Z with a RHS 427 and a Procharger F2 blower kit adding roughly 130lbs to the nose of the car. I have a Pfadt urethane bushing kit that I'll be installing in the A arms and sways. I currently have LG GT2 coilovers installed. I ran into a brand new set of Penske 8300 double adjustable shocks that I felt compelled to buy. They're without springs or perches. I've been told that I need 2.250" springs to clear the A arms. The people that sold me the shocks offered to hook me up with springs but aren't necessarily Corvette oriented. This is a 1500hp car that I like to enjoy spirited driving and straight line events but I'm not averse to trying an HPDE some day. I somewhat like the way the car rides now with the GT2 coilovers on it. It could stand to have stronger springs up front.
So what type/rate/weight springs should I put on the car? What's the best way to set up the car without paying 1k to scale it and dial it in? Count turns/threads as I set the perches? Any other suggestions?

TIA

5280Racer

You are right... the vets can't take anything bigger then the 2 1/4 spring. there are many places to get springs and adjusting collars and spring retainers. Typically the rule of thumb is getting a spring that is double the travel of the shock so you never coil bind it. IE; if the shock ahs 4" of travel you want an 8" spring. Also corvettes like to be firmer in the rear end so take that into consideration. at $70 bucks a spring buying a few isn't the end of the world to find the right rate you desire. On my road car I run 8300's as well aggressive tuning and use 900 lbs. front and 800 lbs. rear springs. @ great sources are Gary @ Harbar, or RE suspension for parts.

2MCHPWR

also keep in mind you will want a non-stock upper mount for the pin tops. these are the ones I know of:

• hardbar clevis mounts - reduce travel by 1.5 inches?
• hardbar delrin mounts
• anze mounts

BLOWNBLUEZ06

Thanks for the reply.
With my added ~130lbs to the nose and the battery moved to the rear passenger side, do you think that would call for evening up the springs more? Like 850 front and 900 rears?

I saw Hardbar has dual rate springs. What's the scoop with those?
I tried to call them today and got a cell phone with a full voicemail box.



Thank you for the suggestions. I was looking and only found mounts for shocks with the loops up top. Nothing for the "pin tops", which I'm assuming is the stock threaded rod at the end of the front shocks.
I'll keep trying to call Hardbar.

jwebsta32

Call or email gary and he will surely return either. +1 on hardbar

fatbillybob

maybe I don't know anything but I'm pretty sure a car set up for straight line is different from a car set up for hpde. I don't think there is a compromise for both. I would be surprised if anyone could tell you what to do because your car strays so far from the average vette with 1500hp. I don't see how you are going to get any answers until you do the hard work of testing your setup. That is really hard. You need to be able to run consistent laptimes at the limit with a bunch of sets of new tires. If you are driving spirited and sub threshold even stock will work fine. You might like the way something feels sub threshold and that might be absolutely undrivable at the limit. That makes for something you don't want but may have thought was a good idea before testing. All that stuff with scaling a car and doing the chassis math is just the beginning to get you to the point where you can do testing.

crimlwC6

What about keeping your GT2s and calling up Lou and telling him what you have and him sending you the proper shocks...and then giving me the Penskes! Seriously, though the 1st part would save you money, time, frustration and you all ready like the suspension you have. If not, send me the GT2s!

2MCHPWR

I think hardbar doesn't make the delrin mounts and sold the design to Banski or something like that:

https://banskimotorsports.com/Pin_Top_Shock_Mounts.html

BLOWNBLUEZ06

Thanks for your input everyone. I apologize for not following up sooner. My life's been crazy lately.

As it turns out, the seller accidentally misrepresented these shocks as 8300's when they're actually 8100's. They're working to make it right or will refund my $ if we can't agree on the terms. It seems the 8100's have a lot of room for improvement and that's what Penske took care of when designing the 8300's. From what I understand, they're still great shocks and with some valving changes, will still be the best shock I've ever encountered by far. I'm still working to figure out the smartest moves based on my needs. Dyno tuning, revalving, rebuilding with new seals since they've been sitting so long etc....
I've tried to contact Gary with Hardbar with no luck. The phone went to a full voicemail box and as of yesterday, his website is down . I hear great things about him, so I hope he's ok.

I appreciate the tip for the delrin mounts from an alternate source. I'll be looking them up.

My general plan is to hopefully find a happy medium between performance and expense with these shocks and get them dialed. I'm going to most likely finish the assembly of my car, get it weighed and then run some numbers to determine the best spring for my situation. Since he didn't post up in my thread and I'm not sure if he cares to remain anonymous, I'm reluctant to mention his name, but a forum member that I have mad respect for contacted me via PM and offered to run through all the calcs with me to help me determine the best spring combo once I get the weights.

Thanks again for everyone's help.

mountainbiker2

I was dealing with Guy Ankeny for many years when I had Penske's. He will always get back to you, even on Sunday's.
http://ankenyracingenterprises.com/ourcustomers.htm

Steve A.

RBbugBITme

You can also call Penske Shocks or Phoenix Performance would probably be even better. If you find a clevis style upper mount instead of the pin style you shouldn't have to worry about the loss of shock travel like the LG GT2's, you're floating piston will be in your 8300 canister and the shock itself will have more available stroke.