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Assuming all suspension parts are in perfect working order as OEM factory parts you won't notice the difference on the street.
Spring rates / shocks will give you a feeling of harsh or smooth on the roads. From factory smooth to VB&P harshness (550) & 360 rear springs. Depends what you what from your car.
Now what I call harshness depends on the quality of the roads. We here in Canada get a lot of rough pot hole roads every spring, the VB&P kit is very harsh compared to the factory rubber / softer springs on these roads. But at the track which is new and nice and smooth the harshness goes away and at time seems soft in hard corners.
Do you want it to handle track days ?
Then you need to upgrade rubber to poly, stiffen all the springs, add thicker sway bars, proper alignment , tight steering parts and most importantly get much better tires.
The tires are the biggest change that you will notice.
If you will only drive on the street with 15" tires factory spec parts are just fine. If you have a flexing old tired frame a spreader bar can help.
I have the complete VB&P Street & Slalom kit with SPC upper arms, poly everywhere, spreader bar.
To give you an idea of handling changes.
1. VB&P Kit with 255 15" T/A Tires (1:41 laptimes)
2. add michelin 245 18" super sport tires (1:36 laptimes)
3. added 275 18" Nitto NT01 tires (1:32.8 laptimes)
The tire is the contact point between the car and the road.
I have a similar setup as above on my 72' with the Nitto 555's.......it handles phenomenal for a 1972 automobile......crazy tight even with stock steering setup........
My next mod when I can afford it will be the Wilwood calipers.....shaves 8-9 lbs. per wheel.....
Jebby
Last edited by Jebbysan; Nov 12, 2017 at 11:45 AM.
To the several of you who have the 360 lb monospring on the back, would you swap to the 420 lb if someone gave it to you for free and elves did the work in the middle of the night?
I'm looking to replace the steel springs in my '79 and my '80. Since they aren't compatible with each other, I have to get it right the first time with both.
The only member I know running #420 spring in the rear is George. He has a big motor and tracks his car often.
How much power do you have and how fast do you intend to go?
Hopefully the forum can help?
To the several of you who have the 360 lb monospring on the back, would you swap to the 420 lb if someone gave it to you for free and elves did the work in the middle of the night?
I'm looking to replace the steel springs in my '79 and my '80. Since they aren't compatible with each other, I have to get it right the first time with both.
I have had the VBP 360 composite in my 78 OEM gymkhana suspended C3 since 1986, replacing the GM Sport 7 leaf steel spring. Even back then all these years later, the 360 composite was a revelation in ride comfort versus the OEM steel spring. Originally I had KYB Gas A Just shocks in the rear with the 360 and the ride was too bouncy on the highway since the KYB's could not adequately damp the 360 composite. I eventually switched to Bilstein Heavy Duty in the back with this spring and although better in terms of damping, I still felt that the 360 spring was too bouncy. I switched the rear Bilstein HD's in the rear to the Bilstein Sports, in the rear only ( I run Bilstein HD in front with the 550 coil springs) and the ride today is perfect..NOT harsh at all-firm but very compliant over bumps. I have one of the best riding C3's I have been in (I have been in or driven many over the years) along with the steering response and handling.
With all that said, I personally would go to a 420 composite if I was to change my 360 with MY suspension as outlined earlier in this thread for a little stiffer feel in the rear.....My 2012 Lexus IS350 F Sport AND my 2010 Chrysler 300 (with Bilstein HDs, Mopar Strut tower brace, Eibach V8 sway bars, 245/55/18 ZR tires) BOTH ride much stiffer than my 78 C3....I prefer a ride that is slightly stiffer in my cars, obviously....
Last edited by jb78L-82; Nov 12, 2017 at 01:11 PM.
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
I ran the 360# spring in my '69 for a few years. Major improvement over the steel spring (both in ride and handling). Sold that spring and put a 420# spring in it, as I like a firm ride and I do track days when I can. The 420# spring still has a decent ride quality to it on the street.
I presently have the C4 500# Z51 spring under the car (I put a C4 suspension under the car a few years back). Even this spring seems smoother and more comfortable than the original C3 steel spring.
To the several of you who have the 360 lb monospring on the back, would you swap to the 420 lb if someone gave it to you for free and elves did the work in the middle of the night?
I'm looking to replace the steel springs in my '79 and my '80. Since they aren't compatible with each other, I have to get it right the first time with both.
If I didn't already have the 360 lb spring, I'd probably pay the extra $$ and go with the VB&P adjustable composite spring. If you're going to take it to the drags or just want control over the spring weight it's a good option.
You can make it softer for general driving and then on drag days move it a couple notches to increase the pressure.
Adjustability costs $$$$, though.
I got a crazy good deal on the 360 lb spring on here and it was 1" shorter on both sides so I don't regret going the route I had. Just in an ideal world where money was no object the adjustable composite VB&P would be my choice.
Adam
Last edited by NewbVetteGuy; Nov 12, 2017 at 05:40 PM.
I'm still waiting for George & Skunk Works to chime in.
Attacking the first line of my post is not the best way to start any discussion.
I'm still open to good advice from those that know!
I track my car... and love smoking C6's and 7's....
Up front 550 springs cut 3/4 coil Bilstin Sports all poly and the largest sway bar they make:-) with rac-n-pinion steering.
back fiber spring, 360 i think... bilstin sports, second largest rear sway bar they make:-) all ploy.. the aluminum pancakes for the rear diff... 18" custom made Centerlines, 180 tread ware tires (still burn through 1st 2nd and 3rd:-( ) 650 hp 427sbc... cooling upgrades as well... full drive train,,, and yes, of course brakes,, 14" hats on all 4 with wildwood calipers and knee brake proportioning valve with hydroboost and so so much more. and yes... smoking C4.5,7 and 7's... We have 5 corvettes we race,, the C3 is at the top
Last edited by pauldana; Nov 13, 2017 at 03:03 PM.
I ran the 360# spring in my '69 for a few years. Major improvement over the steel spring (both in ride and handling). Sold that spring and put a 420# spring in it, as I like a firm ride and I do track days when I can. The 420# spring still has a decent ride quality to it on the street.
I have a similar experience with the rear monospring......I ran the 380# in my '69 for years, and recently switched to a 420#. Nice firm ride, no autoX, but drag race every now and then. I have QA-1 adjustable rear shocks, so I can make the ride softer (street) or firmer (track) as I wish. The right shocks are the key to tuning this spring, IMO. Looking back, I would have gotten the 420# originally.
