OK lets get something strait here zo6style do you have leaf springs or coil-overs? According to your initial post you have coil overs:
Southern Son is running 1100 F and 840 R leaf springs

A 950 lb front coil will have a wheel rate around 440 lbs per inch
A 1100 lb leaf spring (due to the different geometry) will have a wheel rate around 170 lbs per inch

Do you really need a wheel rate that's 2.5 times stiffer?

z06style your wheel rates are around 440 front / 240 rear

Southern Son your wheel rates are around 170 front / 160 rear

For reference from above one of the "stiffer" coil over packages out there the LG coil-overs with the 600 F 700 R springs
They have wheel rates around 278 F and 260 R

Maybe all four wheels are sliding because the car is so stiff that the suspension is not able to soak up the bumps and the tires are just breaking loose?

IMO if you want to get into the ball park you should switch to a 550 front spring so your wheel rates get in line with some of the others above. 550 / 650 will put you at 255 F and 240 R

One more thought, if the car feels like it "dives" under braking that's not because of the springs, it's because of the shocks. Springs are there to support the weight of the vehicle - shocks are a timing device used to control the rate of motion.

I've set-up multiple National Championship winning cars with NASA over the years - not saying I'm an expert by any stretch but I do know a thing or two when it comes to set-up.

 

For the second part of you question I would look at post #32 in the thread below - that is about the best explanation I've come up with on how to measure the trim heights.

https://www.corvetteforum.com/forums...pension-2.html

 

THANK YOU.
Trust that your continued support and advice is profoundly appreciated. I'm committed to learning and solving this challenge.
YES..Im on coilovers w\950#\650#.

1- Q: "Do you really need a wheel rate that's 2.5 times stiffer?"
A: I don't know what I need or don't need rather what I have and where my concern is.
2 - Q: "z06style your wheel rates are around 440 front / 240 rear"
A: IDK...I'm assuming you are referring to "UNSPRUNG" weight

As you know...Sebring is bumpy and challenging where fine tuning could be endless. But that is my home track and where I enjoy my car\driving most.

Thank You

 

As Joel said.......

IF you are running coil overs and not leaf springs you are way off.
You need about 2.0 to 2.20 cycles per seconds at the wheel.
You have 2.48 cps at the front and 1.80 cps at the rear.

You are trying to balance a wobbly card table with a match book cover when the gap under the leg is 1/2 inch.

Just saying.....

 

THANK YOU.

I have no clue what CPS is or how it functions. And I have no clue on the process in which to select spring rate. FACT: The spring rate on this car were provided by the damper manufacturer who claims that such setup is whats recommended for C6Z...So I followed the lead of the Manufacturer who sold this as a package.

 

I understand that you bought a package, but it seems like the package may have been put together incorrectly.

Danny Popp helped in the development of the JRZ shocks - he's always been a leaf spring guy - so my thought would be that the package should have been put together with a 950 lb F and 650 R leaf springs / not coil-over springs.

The picture you sent me shows your RF lifting almost completely off of the ground during hard RH cornering, the reason it's doing that is because the front springs are pushing weight rearward and the 650 lb rear springs have no chance to support all the weight that is getting shifted it's way.

If you put the 550 lb springs on the front it will allow the weight to stay on the front end during cornering and the car will handle much better because the weight will be better distributed.

The numbers I am quoting you above are wheel rates and it's the force that it takes for your wheel to move 1" - when I say your wheel rate is 440 lbs that means 440 lbs per inch - it takes 440 lbs to move your wheel 1" when you compare your current wheel rates to the other ones I mentioned above you can see how much different your set-up is.

Jim is talking about suspension frequency in cycles per second (CPS) - this is a more advanced topic but it does get you in the ball park - this page has a lot of great info about suspension and some of the things we have mentioned here:
http://farnorthracing.com/autocross_secrets.html

As he stated your frequencies are off and if you switch to the 550 front springs it will get your numbers back into the ball park -

I have slightly different numbers than Jim for your car, I have you at 2.55 F and 1.97 R if you change to the 550 lbs springs in front you will be at 1.94 F and 1.97 R which will handle much better than what you have now.

I've mentioned the 550 lb front springs a few times now but you do have several different ways to "fix" the car.

#1 - Quickest, cheapest and easiest - install the 550 front springs and see how it feels, play with shock settings - but at least you're "in the ballpark"
#2 - Talk to who you bought the stuff from, if you were supposed to use 950 and 650 leaf springs with those shocks maybe it's something worth trying.
#3 - Pick new coil over springs rates that will work with those shocks - this would take someone with more experience with the JRZ shocks and what kind of valving is in there - not sure how tight or loose the adjustment range is, really all you need is a copy of the shock dyno graph.
#4 - Sell it and start over all over again

 

Just do what ^ says and you'll be in good shape. He really knows his stuff.

 

Thank You.
I guess I can try 550F/650 and see where it goes...OR attempt to discuss the situation with Danny Popp.

 

Sir,
I forgot to mention. ...JRZ knew that I have and wasn't going to use leaf springs...in fact, they advised/suggested the 950/650 springs by. Eibach...they had complete knowledge of car and setup.

 

I just realized that I was thinking about JRi not JRZ - sorry too many options out there.
JRi shocks were developed by Danny not JRZ, I'm sorry for my confusion.

If the shocks were valved for the 950F / 650R set-up then switching to a 550 front spring would mean that the shocks would need to be re-valved for the new springs.

 

I've been trying to get someone from JRZ to help me but no success. I'm beyond confused and feel that I have been left in the dark after purchasing a fairly expensive upgrade...ugh!

 

Not a bad idea but just remember Danny has a unique ability to 'time' inputs to the action and reaction of the springs. He can do this at triple digit speeds. He has his own built in CPS butt meter. You will never see anyone else drive like Danny.

 

 

With respect to valves... Dampers are adjustable both compression and rrbound.

 

Trust that I appreciate you sharing and applying however, can you please explain how I can do the match on CPS?
What is the formula ?
Do i need spec from Eibach?
Where should I be Front & Rear?
*Ps I'm on slicks with large tires (315F/345R), Katech lip, skirts and large rear spoiler.

Thank you for your assistance.

 

If your dampers are double adjustable with remote reservoir it's very likely you don't need to have them revalved to change springs. I would try a compromise and go down to a 700 lb front spring. Eibach 700 lbs, 8" long, 2.25" diameter. I know for a fact that setup works well. Set your shocks to the recommended starting positions (somewhere in the middle for compression and rebound. Go out for a couple sessions and get the feel of the car. Then start clicking in more rebound 1 click at a time and see how it feels. You don't want to go too stiff on shock settings. It's possible your rebound was already too stiff and unloading your inside rear tire.

Your ride height is not that critical, I run close to stock ride height around 4" off the ground with a slight rake forward (maybe 1/4" lower in front). Check your alignment and go have fun. Your car should handle very well with that setup. You don't need to worry too much about cps, ride heights, etc. Just focus on driving.

 

Although I realize there are those that get great satisfaction from the academic exercise of working the suspension dynamics, without good telemetry from observed feedback you might not get the worth of your effort in return. Race teams change very few items at a time while getting things just right. If you have a sponsor handing out new tires, new shocks, new this and that every time you go to the track it may be worth it but for the most part we track junkies try this tire brand, this scrub, maybe this used set of shocks, try a new alignment setting, swap an item or two in the car that changes weight distribution, new springs, etc..... Actually, I enjoy trying to make a less than perfect car work for me; good education. After all, I am not trying to win multi-thousand dollar purses.

 

Thank You.
YES the dampers F&R are remote adjustable.
Will 700F 650R = slight too much front as I understood that possibly it would be adventurous to have heavier Rear than Front. Nevertheless, I'm not seeking a championship rather FUN while making the most of my investment in equipment.

Thank you and southern for the PM and sincere lessons....great to have your support.

 

Certainly FUN is the goal....while making the most of my investment in equipment. Trust that your support is appreciated and lessons are well taken.
Ps. ..I'm a Virgo. ..so details are attractive to me by nature