I'm replacing the Gymkhana spring in my 80 with composite. I've decided to use VBP. The question now comes down to 330# or 360#. I know what the descriptions say - ride focused at 330#, more handling focused at 360#, but I'm looking for true seat of the pants description. Obviously having always had the the Gymkhana a harder ride was just price paid for handling. I never found it objectionable, but then the last time I drove the car and distance (even back and forth to work) was 2004. Now being 59 I may not be so tolerant . That aside though if the composite at 360 will ride smoother than the Gymkhana and handle better, I'd probably go that way.

Also, experience based guidance on shocks. Cost wise I don't feel like paying the extra for an adjustable set. So just what people have found works best with the 330 vs 360 in a non-adjustable set.

Thanks,

 

I installed a 330# spring, in the '79 that my wife used to own. However, that was selected based on the discussion I had with the tech line, at VB&P.........

 

Consider the entire system. I guess if you keep the spongy front springs then the 330 would be OK for a "comfort" ride package. But I'm also 59 and I very much enjoy a more performance capable combination of 550 fronts and 360 rear. I'm seriously considering moving up to a 420 with more sway bar. The ride I have now is just fine, but we have pretty good pavement around here.

You have to decide what kind of driving you'll do and the condition of the roads. Got a lot of potholes back there?

 

This is a timely thread. I'm just getting ready to order springs. I was going with 550# front with 330# rear but should I use the stiffer rear spring with those front coils?

 

I'm sure most will confirm that the 330 is too soft. I went from the 7 layer steel spring to the 360 (mine actually measure closer to 350 when tested) but now when going over a dip the rear dives just noticeably more than the front* and I've got slight understeer when pushed hard. For this reason I think I may move up to a 420.

I also have Bilstein Sports shocks and about the stiffest sidewall tires on the market so I get some pretty solid impact/rattling on ruts and washboard that I can't specifically attribute to springs. But hey, it's a Corvette!

*(edit: I may be a lot lighter in the front than the average C3)

 

Also, experience based guidance on shocks. Cost wise I don't feel like paying the extra for an adjustable set. So just what people have found works best with the 330 vs 360 in a non-adjustable set.

Thanks,[/QUOTE]


For basics, nothing much better than Bilstein HD in front and Sports in back. I was actually hoping the Sports would be a little stiffer, being used to Konis in back for the previous 30 years. Maybe I'm just going with the flow, but I don't know of anything currently better.

 

My 78 L-82 4 speed was an OEM gymkhana suspended Sport suspension car that had the 292lbs 7 leaf steel spring and 550 coils in the front....It rode pretty hard when new. In 1986 I switched to the VBP 360 monospring and the car immediately rode MUCH better but with the KYB Gas A just shocks was too bouncy on the highway. In the mid 2000's I switched to Bilstein HD's all around with the 550 springs in the front and the improvement was dramatic the rear was still too bouncy. Around 2008, I switched to Bilstein Sports in the rear only with Bilstein HD's up front which is the combo I have today. The car rides firm, but not harsh. I still wish that the rear spring was slightly stiffer and if I ever need to replace the 360 spring I would go for the 420 composite. Most folks who ride in my car that are not C3 owners cannot believe how well it rides and handles....

 

Years ago I had VBP make a #340 for me to use on the 74 BB.....I ended up using it on my 82 "dd" w/Gymkhana suspension......I am very satisfied with that spring......but of course on rough roads and such.....you will feel it......on the highway.....around the turns....and good local roads......it is just fine........

 

I run this combo in my 70 that I autocross.
Several other C3 autocrossers in my club run the same set up with good results. One 69 frequently an FTD with it.

 

The key to maximizing the ride benefit of the 360 composite without any handling penalty are the SHOCKS. I would not recommend any mass market shock but only a premium one like Bilstein or QA1.

 

Hello JB, I pretty much knew you'd be chiming in here. I'm pretty sure four or five years ago your advice led me to some of the parts I have now. Thanks!

But before I pull the trigger on the 420lb rear and bigger front sway bar combo, I am hoping to find reasonable approximate determination on the following question. How much of the rear end softness I'm feeling is due to frame flex??? A four point roll bar is not out of the question.

Sorry to hijack your thread, I hope the OP has got some useful feedback.

Steve

 

On my car, it is the nature of the composite spring, not frame flex, in my personal opinion. Do you have a front spreader bar? If not, get one from speedirect...$100....best value for the money on a C3 for little dollars

 

I have 4 Bilstein Sport shocks to go with the springs when I do that project. I like to lean on my car a little, I live on a mountain that's fun to come up but I'm getting old, too, and don't want to jar out my teeth which I mostly still have.

 

I run 550/360 springs, and QA-1 single adjustable shocks. The notion of going to 420 in the rear has occurred to me, but the roads in Pa are horrible. Not much better that cow paths with a bit of chip and tar on them.

With the QA-1 shocks you can tune the ride from fairly soft to bone jarring hard just but turning the **** on the shock. I think that would be a great option to try, even if only on the rear to start with. Most of the ride feel comes from the rear I think. I have made adjustment to just the rear shocks, and you can really feel a difference.

 

This ^^^^ may be the way to go for me rather than switch out my perfectly still fine 360 composite. My question though is that if you dial up the QA1's does the ride becoming punishingly hard losing the benefit of the composite. I should start a thread to see who has a 360 composite with Bilstein Sports that then switched to rear QA1's and the difference?

 

Oh yeah, got that spreader bar. That and gusseted lower control arms, Global West uppers with 6* caster, heim joint camber arms, sticky 9.5" summer tires and some poly bushings and motor mounts. New bushings and bearings throughout. It's night and day better than the old worn out stocker it used to be.

 

When I installed my QA-1 shocks I played with the dial settings before installing, and with the lowest setting I could move the shock like an accordion fairly easy. On the hardest setting the shock would not move in my hands. I decided to just set them at halfway and install. I left that setting for quite a while, but later dialed down to the third from the lowest setting. I like that better for a decent ride.

Knowing I can dial in more if I want to get competitive is a huge plus, and like I said I can reach under the rear and make changes without even jacking the car up.

 

Hello all. No, I didn't abandon the thread. I've just been busy all day. I am really impressed by all the contributions here. I think I'm convinced the 360# will be the way to go. The question then is Bilstein Sports or the the QA-1's. Hitting then various thoughts posted:

Solid ride - well as one person commented, hey, it's a Corvette whether 16 yrs old when I first drove one or 59 now.

PA roads - been driving them for 34 years and I bottomed the poor C3 more than once. I think it's worth the bumps for getting the handling the car was born for.

On the issue of the front suspension, I'm sure this will be incomplete without some work there also. But this is a progressive rebuild. I started with the brakes figuring after 13 years off the road making sure it would stop before I cranked it up would be wise. Now I'm at the differential. Sticking with the Dana 44 for now, but a rebuild (I found a couple broken clutch pack clips) and switching to 3.36 from the current 3.08's. Since it's been pulled out it's the best time for all the rear suspension work. After this is a conversion to an overdrive transmission. And then I'll get to the engine and front suspension. The recommendations on the front suspension are definitely appreciated for my future work.

So thanks everyone thus far. It is all much appreciated.

 

I went with a shortened #330 mono spring.
I don't think it's too soft.

I have heim joint trailing arms and strut rods and I use Koni adjustable shocks. The car rides comfortably and not at all harsh.
I am extremely happy with my setup.

My car is simply a cruiser. Meaning I don't race it. I just drive it hard and enjoy it. No high horsepower brute here. Build it the way you would drive it.

It's all in the set up.

Craig

 

I might be slightly out of sequence but I did my '72 vert some 20+ years ago......VBP 360 in rear, 460 in front later got smart and out Billy Stein sports all around......but the largest improvement is WHEELS AND TIRES '89 vette wheels 275/50/17 in back....255/50 in front.....2.5" wheel ADAPTERS.....fenders were flared by previous owner.....

after that, went to RACK steering winter 01-02...

and added the cross support a year or so later......

for a street driver, you can't beat that combo....drives like a DREAM.....

HAVE to ditch the stock rear steel springs....those leaves rub like KRAZY and so make a hell of an inertia impact that is just ROUGH riding....