Todd Morgan

I need to know the softest front spring for my 84 corvette. From what research I've come up with, the 84s have the stiffest spring. I need the softest for drag racing. What's the code for the softest?

Sleazy Rider

courtesy of blackozvette

https://www.corvetteforum.com/forums...84-96-z51.html

MatthewMiller

FWIW, you probably don't want a soft rear spring for drag racing. You certainly would benefit from a soft front spring, though. I would think that stiff rear spring and no rear swaybar would be the ticket at the rear, along with shocks that have lots of compression damping and little rebound damping at all four corners (the old "90/10" shocks come to mind).

Todd Morgan

MatthewMiller

I'd post a "WTB" in the Classifieds section of this forum. Lots of folks have gone with stiffer springs over the years, and probably have a stock soft one laying around. They may not list them because they don't think anyone would be interested.

WVZR-1

Well - not knowing what's actually there now it might be foolish to be shopping for anything. A front spring in an early C4 isn't a simple replacement task. Buying used? You don't know whet you've got until it's installed and 'on the ground'.

What is actually in the car now?


What flavor of 'drag racing' are you doing/attempting? It seems you're maybe relying on what you read vs experience.

***Maybe you 'publish' much more about the car and see what's presented to you for suggestions!! Engine, trans, axle ratio and tires come to mind. There's some very successful 'real drag racers' that post here regularly!!

383vett

For what it's worth, I've been drag racing my 84 since new. I have changed pretty much every part on the car but am still running the stock Z51 front spring. There are a few members faster than me but I am happy with my 1.35 60' and the consistency of my car which enables me to be competitive for the 150 or so runs I make every year. My opinion is to save your money for other mods.

Todd Morgan

Well for starters, I've done enough research to know that the 84 has the stiffest. And I know that the 85 had a way softer spring. And I am one of those real drag racers. I've had cars my whole life. Lol I just need to know what the softest spring is. My car is a true radial car and is quick for what it is. I've been a 1.80 60 ft on true radials with the stock 350. And a softer spring would help.

Todd Morgan

That's a quick 60 but I am willing to bet ya didn't do it on true radials. It's kinda tricky keeping the true radials and making it hook. It hooks good for what it is but ik that you know that a softer spring in the front will help you hook. The 84 from what I've read is the stiffest. I think the 85 was much softer.

Todd Morgan

I can tell you know what your talking about. I'm just keeping true radials on it because the car works really well. I'm just trying to help it out.
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383vett

You are right, the 84 springs are by far the stiffest springs that came on a C4. With double adjustable front shocks, I can control the rebound as well as compression and haven't felt the need to soften the front spring. In an ideal world, coilovers would be the best.

Kevova

What are true radials?

vader86

You can use any spring from 84-87 on the car in front, so go for an 87 base suspension spring.

Or have one made from someone like VBP.

mtwoolford

For a new spring, contact Vette Brakes and Products, they can literally "cook" up whatever you want

WVZR-1

I don't believe that's very likely any longer. I doubt they do their own fabrication and Hypercoil I don't believe does 'custom fabrication' any longer. It would be an interesting question to ask though if OP was interested.

MatthewMiller

So there's some real differences between the info that blackozvet posted (cited above) and the chart that Hib Halverson posted years ago. I think there may be errors in both, in different places. Note that the fist part of blackozvet's post only shows Z51 rates. So unless the OP's 1984 car is a Z51, it doesn't have the stiff 102N/mm spring - it has the much softer 63.5N/mm front spring. That spring isn't a whole lot stiffer than the softest 1984-1987 front spring on the Halverson chart, which is 51.8N/mm. Going through the expense and trouble of installing that spring would only reduce the front rate by 18% - not a big payoff. That is, I think the OP is not going to find a much softer front spring than what is currently in his car, unless his car is a Z51. If his car is a Z51, then by all means he could choose from any other front early-C4 spring and get a big reduction in rate.

On blackozvet's info, the softest front spring for early C4s is shown as 39.9 N/mm. I believe that's wrong. Note that 39.9 is the rate for the softest rear spring on the early C4s. The HKX front spring should actually be 54.0N/mm (from the 1985 FE1). The HMP should actually be 51.8N/mm (from the 1986-87 FE1 and the 1987 Z52), and it is the softest front spring that came on an early C4.

Todd Morgan

True street tires. Not drag radials or slicks

Todd Morgan

Yea I got double adjustables as well. Im just looking for more traction. Like I said it works good just needing to help it out

blackozvet

as MatthewMiller said, there could be the occasional error here and there, keep in mind that the info in my old thread is sourced from a number of different places on the internet, and we all know you cant believe everything you read on the net !

but these were the codes I found (with poundage rates),

FRONT 84-87
BMB 102 n/mm - 582 lbs
HMZ 63.5 n/mm - 362 lbs
HKX 39.9 n/mm - 228 lbs
HMP 39.9 n/mm - 228 lbs
HM2? 57.2 n/mm - 326 lbs
HMN 54.4 n/mm - 310 lbs

my old FE1 spring off my 85 is stamped FJY, this is a 54 n/mm rate (apparantly) and I havent got that on the list - but its the same as the HMN code.

here is the BMB v FJY springs,
note the stiffer springs are always flatter, softer springs have bigger arches, visually you can keep that in mind if shopping for a softer front spring.




if you look around and start asking Im sure you will find something.