I know what you mean. When I changed from the 450# to the 650#, my car rode much harsher.
After all the dicking around that I’ve had with these coilovers, my recommendation to anyone who wants the best performance out of their car would be to leave the stock springs alone and just install the Viking D/A smooth body shocks.
The real magic of the Vikings is their valving and you really need a good DA shock to get the best performance out of your car, at least on the drag strip.

 

and I posted pictures of my car, on lift, at full droop not touching, once again, zero problems.

Joe does these all the time, has none of the issue people ordering from elsehwere run into. So I don't know what he is doing, but nothing but happy customers without all these issues. Mine don't hit the axles, don't have droop issues, no problems at all, verified MANY times.

 

Unreal ....

Again, what brand rear coilovers do you have ... Got a part number ?

 

Vikings, otherwise why would I be posting in here. All viking stuff.

Nope, because I called Joe, said order me the coilovers you have put on 50+ cars without issues, and a few days later they showed up at a great price.

 

He didn't give you the part number for the Vikings he installed on your car?

 

Unreal ....

Or maybe he didn't install the coilovers. You just ordered the coilovers from Joe and they were delivered to your door ... then you installed them.

If that's the case, was there not a part number on the box or on the invoice?

Throw me a bone here ....

 

I picked them up, installed them, and enjoyed them for the past years now. I'm sure years ago there was probably a part number on the box, but they have been on the car for so long, and working without issues that I don't exactly keep that stuff around.

I do know there is no generic part number, and you have to talk to him about what you want. Stock height? Lowered 1"? Slammed? Road race? Street? Drag Race? etc etc etc and then he orders what he knows works. They are not just something you pick out of a catalog.

 

I’m not disputing that, and I have no doubt Joe knows what he’s doing. Mine don’t hit the axles either, but when I tried to install 2” longer, lighter springs, to get more stored energy, they did hit then, as I’ve explained above.
Yes, I could’ve left them alone, but I was trying to get my car to hook better on a very challenging track surface. I could’ve (and should’ve) left the stock springs on it too. Hell, I could’ve left my car stock too, or just got someone to build me a badass ride and post pictures of all the parts it has on it, but where’s the fun in (and learning from) that? Such is the nature of these things: We experiment with aftermarket enhancements and report the outcome on here. Such, I thought, was the very reason for the existence of these forums, no? Otherwise we would just be posting pictures of the cars somebody else built for us, right? I know I learnt a lot on here from you already, so there’s that, too.
The front coilovers on my car admittedly have a bastard part number, but they do look identical to the ones on your car. They could be longer, for all I know, but one thing is for sure, they hit the UCAs badly, and it wasn’t an alignment issue, because with the control arms adjusted all the way out, they still hit, badly.
The car transfers, hooks and runs much better now with the stock front spring and the naked Viking Crusader shocks than it ever did and possibly could have with the front coilover springs on it (and I tried 4 different rates and lengths too).
The one problem, albeit a negligible one, that I have with the rear coilovers on my car is that with the Carlyle spindle, the UCA also hits the spring. I don’t know if yours does that, and to be honest, if I didn’t notice the little nicks on my springs, I wouldn’t have spotted that problem myself. So, I simply put some limiter straps on it. Which, by the way, Viking instructs you to do for all it’s coilovers, so that in the event of violent unloading (although it is hard to imagine how that would happen in the rear) the top doesn’t get ripped off the shock. Go figure.
As far as spring rates go, that’s like just about everything else, including shock settings: it depends on what you’re doing with the car. As far as I know, Ron (the OP) wants to drag race. So, I’m happy to share with him my honest opinion based on my own experience, since that is all I can do honestly.
And I do honestly think he’s worrying too much about the rear coilover spring getting slack at full droop, because, as I said before, that will only happen when he jacks the rear up or if he takes the car hill-jumping or something, in which case a limiter strap is a very cheap fix.
That’s all I have on the matter. Not really trying to step on toes or trying to **** on the tree or anything. I’m just trying to help him out because I already kinda screwed him up with advising him to get the 500# springs, since everyone I know said that you need a ~650# coilover spring in the rear of a C6, which always I thought was the case, until I tried 650# springs myself and it failed, and then I discovered Borg’s table, which I posted above, which helped me understand why it didn’t work.

 

BTW: for ease of reference, below is Viking’s updated application guide for the C6, which they sent to me through my vendor and which is now up on their website.
It should be noted that it differs substantially in terms of spring rates shown in their older catalog (which is also still on their website), and that Viking themselves now recommends significantly lower spring rates for their “DH” (600+HP) and “DL” (<600HP) drag packages, with 450# springs for the former and 400# for the latter.


Note the last 4 digits in the part number, which denotes the spring rates for each.

 

I don't have Carlye rear spindles, so can't comment on those, but no issues in the rear either.

 

I’ve been in contact with Joe, plan on using him when I order mine, won’t be till I get back from deployment but I’ll definitely provide feed back. Pretty much exactly what you said. Tell him specs of the car and how/what your use of the car is gonna be and he takes care of the rest, quoted me prices already and said feel free to call if I wanna get into the specs on what he plans on ordering for my set up. Got quick replies from Joe on here and through email, dude definitely seems to be on his game and has some good bodies off work to prove it, appreciate the recommendations man 🇺🇸🤘🏻

 

I added a few more of the various coil springs and 'Wheel Ride Rates' based on the previous spec sheet that Sammy posted before ...




.

 

That looks about spot on Ron. That’s why I’ve put a set of 8” 425# Hypercos on my car now. I’ll know soon enough how they work. The original 450s that Viking sent me worked fine too, though. Much better than the 650s did.

 

Hi Ron. What did you end up doing? Not that I’m suggesting that you had to do anything...

 

Have never heard anything but good stuff about Joe/CPR.

 

Sammy ... I installed / adjusted:

1.) 8" x 2.5" coil springs in the 400 Lb/in variety.

2.) Hyperco Helper Springs, P/N CS100 (4” L)

3.) Hyperco Spring Dividers, P/N 18DS100

4.) Set compression on 2 and rebound on 3

5.) Got an alignment

I
The car rides really nice now and there is no slop in the coilover springs when the car is jacked up and the rear wheels hanging.

The only problem now is a slight clunking-like noise coming from the rear when riding over a rough road ... I got under the car with all weight on the wheels, and nothing is hitting under there ... springs are not hitting against the axles or against the rear upper A-arms. I can't figure out what is making this noise ... shock piston travel is not at it's max travel either.


Attachment 48334317

 

Hmmn. That’s interesting. I’m starting to realize the longer springs could actually have fit on my car if I had installed them and lined everything back up. They were hitting when I started putting it back together, so I ASSumed they would hit when it was assembled and I was nervous about the spring hitting against the axle. I still have the 10” 400# springs, so if I get bored I may try installing those again at some point.
That noise might just be when the helper springs “stack”, since they’re going to do that very easily, especially with those low shock settings.
I would just have thrown a 9” spring on it, TBH.
I glad that you’re happy with it, though.
Maybe try increasing the compression setting to 5 or 6 (and maybe the rebound to 6 or 7) to slow down the rate at which the shock moves and see if that dampens or eliminates the noise.

 

Sammy ... Thank's for the reply.

You know, I also had that slight clunking sound with the original 500 Lb springs and before I installed the helper springs ... so this has been there ever since removing the leaf spring and initially installing the coilovers.

I will be damned if I can figure it out

 

I forgot to mention that ever since I put the 650# springs in my car, I had a strange noise too, albeit more like a dull creak, on my car. To find out where it was coming from, I put the car up on some 12” high Race Ramp blocks and went under the car and loosened the compression and rebound settings to zero and grabbed hold of the rear swaybar did some rapid benchpresses to bounce the car up and down while a friend of mine used a stethoscope to check it. We pinpointed it was coming from the top spring seat on the passenger side. It seems like when the weight shifts on the car, the spring moves around slightly on the upper seat, causing a creak that sounds like a clunk inside the car. I thought at first it might have been a bad upper bearing on the coilover, but I checked that out when I switched springs the other day and it was fine. I put a little bit of heavy grease on the top of the 425# springs when I installed those a few weeks ago and so far the sound hasn’t come beck, yet. Mind you, I haven’t driven the car on the road as yet, but it was good when I bounced it.
That may be the culprit.