I've posted the following on the C2 board and thought I would do the same here too:

So I've had my 64 vert for 6 years now and it's an old-school resto-mod and I love it except the ride quality...hard bounce. I love the handling characteristics, though. I just can't seem to get the ride quality dialed in. I feel every bump, little or hard.

Here are the mods to my C2:
- modified ZZ4, EFI, 700R4, 400 Hp / 400 Tq
- 82 vette Rear diff, VBP Performance Plus suspension with QA1 adj shocks
- Disc on all 4.

Back in the spring, I picked up a fully restored to original specs 72 coupe. I like the ride quality (comfort). The handling sucks. Steering is no where near as precise as my C2. Feels like a lot of body roll/sway when turning corners. Power sucks with 1/2 the HP and 3.08 rear gears vs my 3.55.

So I want to upgrade my suspension on the C3 (along with HP & Tq), but don't want to end up with the harsh ride of the C2. Do any of you have suggestions on what direction I should take regarding the suspension. VBP performance plus, coil overs, etc?

The driving intent is just for fun, no plans for racing.

If you've got ideas on how to improve the C2 ride quality I'm all ears. The QA1's were the recent attempt to make improvements, and I got a small amount. My concern here is that maybe the backend is too light with the aluminum rear-end. I may have to totaly change out the spring rates (I've done once already). The front doesn't feel right either. Part of my handycap here is that I'm no expert on what is good or bad. I've only road in 2 other C2's in the past 10 years.

 

easy change I would start with a spreader bar in the front with Bilstein sport shocks on all four corners and then a 330 lb rear fiberglass monospring in the back. That's what I have done with my 72 so far and really like the improvements. All from VBandP.com

Sully

 

Softer springs for ride quality, allows the wheels to move quickly. Maybe keep the stock springs as you like the "comfort" they currently give. the 550lb springs GM put in as part of the performance package are too stiff for comfort and were designed to reduce wheel travel and therefore bumpsteer.
Good shocks to control the wheel movement, I have the Bilstein sports and am happy with them.
Sway bars to keep it flat. Start with adding a rear one.
You can sharpen up the steering by going manual, R&P or borgeson and while you're at it, fix the bumpsteer with blocks on the ends of the steering arms.
Then start going mad with things like the spreader bar or coil overs

 

Before throwing more money at it, first I'd play with shocks a bit more. Not specifically familiar with QA's, but I've had a bit of experience tuning double and multi-adjustable Koni, Penske and others. I assume your's are double-adjustables. What adjustments have you tried so far, including out of the box, and where are you now?



DO NOT just slap on a rear bar without determining if you actually need to shift balance towards oversteer from where ever it is now.

 

Before gas shocks were developed, auto designers thought that really stiff springs were required to get good handling. Well, that may have been true then, but once gas shocks were available, they could be matched with softer springs and get both ride quality and road handling from the same setup. The C2 frame is nearly the same as the C3 frame, so both versions need about the same components to function well.

If you have the optional suspension package in your C2, you need to go back to milder springs and then add the gas shocks. Bilstein sports, if you are really into the road handling thing; or Bilstein heavy-duty shocks if you want the best combination of ride and handling.

 

I have a 78 L-82 4 speed (66,000 miles) that came with the gymkhana suspension from the factory. I have been playing with the suspension since 1983 to improve the ride, handling, and steering for 29 years now usually replacing stock components (ball joints, tie rods, idler arm), upgrading the OEM design with better components (poly bushings, spreader bar, lowered front 550 front springs, blue printed/rebuilt OEM steering box, shocks (Bilsteins), 360 composite rear spring, competition adjustable struts with heim joint, not bushings etc). I almost always have replaced/upgraded suspension components piece by piece so I know what that specific component does to the handling, steering and ride. For Example, put a 360 composite spring on in 1986 and that was the only component I did at the time.

First the C2: Not sure I understand your description of the suspension on the C2 which is pretty much exactly like the C3. You said it has a VBP plus suspension but has QA-1 shocks? This suspension kit does not come with QA-1 shocks but Bilsteins. I assume the QA-1's are not coil overs since the VBP's kit has transverse front and rear springs. Correct? What are the spring rates you do have? The C2's are much lighter than the C3's so spring rates will effect the handling and ride more than on a C3. From the Avatar picture, I see after market rims and tires on the C2. What size, speed rating etc? I would call VBP and find out which Bilstein is used for that suspension, Heavy duty or Sport (30% stiffer than the HD's). I would consider the Heavy duties since you want a nice ride but need to check with VBP on the spring rates to avoid a bouncy ride.

For the C3: Below is 25 years of trial and error on my 78 and it is simply a great handling, steering, and riding C3. PM if you want more specifics. As for the steering since it is all original, I would have GTR 1999 (Gary Ramadei) from New Haven, CT Blueprint/ rebuild the OEM box which I am sure is toast at this point. My steering is fantastic now. I know good steering since I have 5 other cars with Rack and Pinion including a 2010 Z06 i bought new and a 2012 Lexus IS 350 F Sport! Below is a summary from another post I commented on:


Here is my setup:

Front:

Blue Printed/rebuilt Gary Ramadei OEM steering box
Speed Direct spreader bar
Poly upper and Lower Control arm bushings
550 springs, 1 inch lower than stock
OEM 1 1/8 inch sway bar with Poly endlink and mounting bushings
255/45/17 ZR ultra High Performance Summer only tires
Bilstein HD shocks

Rear:

360 monospring with poly cushings
Competition adjustable strut rods with heim joints
3/4 OEM type sway bar with poly bushings
Bilstein Sport shocks
255/50/17 ZR tires like in the front

The car rides, steers, and handles better than 99% of the C3's I have been in. I still would stiffen the rear just a tade with a 420 spring.

Fellow forum member, Karol, recently rode in my 78 and he could not believe how much better my car rode than his 78 L-82 4 speed with the base suspension (including the base steel spring) and 255/60/15 tires! You would never think that reading and hearing some folks comments about poly control arm bushings, low profile Z rated tires, high composite spring rates etc. My car simply rides MUCH better than the OEM suspended cars, Gymkhana as well as base!

 

Yup. What he said.
If you are looking for comfort, Hyperco makes a 200 lb rear composite spring that duplicates the factory spring rate of the later C3s. They call it EZ Ride. I believe Eckler's and Van Steel both sell it.
The stock rate front springs (280 lbs) will also help.
The next step is a SLIGHTLY larger front stabilizer bar (maybe 1"), and a mild (9/16" or 5/8") rear bar.

 

As I have noted in other posts, composite springs have a very different ride quality from the OEM steel springs-a 300 lb composite is MUCH softer than a 300 lb steel spring which is the reason GM used steel transverse leaf springs with MUCH lower spring rates than the comparable aftermarket composite springs-you can't compare the spring rates to each other. I think that you are looking for a C3 with a decent ride but not giving up too much on the handling side? I have a friend with an 82 C3 with the OEM 198lb transverse rear COMPOSITE spring and his car is so soft and floaty you would think that it is an 80's cadillac! Sounds like a 300 lb rear composite with Bilstein HD shocks and 460 Lb front coils would be appropriate for what you are looking for matched with the Sport/Gymkhana front sway bar (at least 1 inch, my 78 has a 1 1/8 inch front bar-rear bar can be determined later).

i re read your original post on the C2 and you mention the QA-1 Coli overs with the VBP Plus suspension? You don't have transverse front and rear composite leaf springs with coil over shocks, do you? That would be a VERY stiff suspension!

Still confused!

 

jb,

You miss-read my post. I have QA1's that are adjustable....not coilovers.

I sorted through the receipts that I have from the PO and found that he put NAPA shocks on it. There's an opportunity for improvement right there.

Are you suggesting that I put the 300# on my C2 (with the 82 rear end)?

And are you saying the C3 should be:
- 300# Composite with Bilstein shocks on the rear
- front and rear sway bar
- for the front, it sounds like replacement coil with Bilsteins

 

You will get a ride improvement by reducing the unsprung mass of the car. Wheels/tires/brake disks/calipers/a-arms - anything that is NOT supported by the springs.

The ride will be smoother. Force equals mass times acceleration. When the wheel/tire is deflected by a bump then the unsprung weight of the tire/wheel/brake/suspension components (mass) is accelerated into the sprung mass of the car. The less the unsprung mass is, the less the force directed to the car (sprung mass). The less the force, the smoother the ride.

Conversely on a dip (or hole) a reduced mass will be accelerated more rapidly downward (by the force of the spring) keeping the tires in better contact with the ground.

Reducing the weight of the wheel/tire/brake disk has this effect also, but, in addition lighter weight wheel/tires/brake disks have less inertia to overcome and can accelerate the car faster.

If you are going to take weight off a car, the reducing the unsprung mass will have the greatest ride improvement effect with reducing the tire/wheel/brake disk gaining the most in performance.

 

 

On the C2 the VBP Plus suspension came with Bilsteins, not sure which ones, heavy duties or sports. I would talk to VBP and ask but yes I would think that Bilsteins would help. There has not been a single car I have put Bilsteins on that the ride and handling have not improved.

On the C3, I can't recommend a rear composite spring rate on the forum but it sounds like around 300lb/in would be acceptable to you with ride and handling. As I said above, the front bar depends on what you are trying to achieve. Generally C3's without a sport suspension have too little front bar. I would wait on the rear. Yes, 460 front coils with Bilstein HD's. Just my opinion, not gospel!