I've been looking into doing this since '01, and personally I like TT's setup. But I have to play devils advocate and bring up the idea of any weight loss advantage to the C4 setup. I talked to Paul Newman @ Car Creations about a year ago and he claimed his frame mods with the C4 running gear brought the weight of a C3 down to around 2800lbs with a small block.
Is there really that much of difference in the weight? I could see maybe a couple hundred lbs, but considering most C3's come in around 3200 - 3400 lbs that's more than I expected.

 

Skidpad isn't very meaningful. If you want to know, though, I was playing around with an accelerometer the last time I went autocrossing. It registered about 1 g (0.96 actually) on my first very conservative run. Unfortunately, I messed up the settings after that, so I don't have any more data. I know that's not a really a skidpad, but the idea is close enough. I have Pilot Sport tires, by the way.

Also, my car is certainly not sluggish to turn with stiff springs, shocks, and sway bars, but the tradeoff is a very rough ride. The flimsy frame doesn't help either.

 

From what I am reading I think I can mod a c3 to do what I want which really is a relief. Thanks for all the info guys.

 

well for a pre 80s car it could be considerable, the C4 aluminium parts are really light especially the driveshaft, halfshafts and the various control arms & rods. The spindles & hubs are also much lighter than the C3 stuff but I personally feel their brakes are junk and the rotors really thin. The major disadvantage of the C4 setup is the track width requiring you to run neg. offset wheels (yuck on C3) or some hefty flares, that would look cool but totally screw up the scrub radius and make steering harder (not that much of a problem IMO because the C4 steers too light as it is)

 

I made a few mods & the handling is great!................................Vette Brakes & Products-
.. -Stainless steel ‘O’-ring calipers
-Dual-mount composite monospring kits,front & rear( lowered Vette 1.5 inches)
-Tubular upper & lower A-arms
-Smart Struts
-HD tie rods
-Spreader Bar
-KYB GR-2 shocks
-HD Spicer U-joints
-Energy Suspension-Hyperflex poly bushings -American Racing Torq Thrust II 17 x 8" wheels,4.5 BS
-Kumho 245-45-17" rubber -Hawk HPS (high perf.street) brake pads

 

The swing arm geometry of the C3 results in the rear end "steering" during cornering. You have two choices:
1) Go to a multi-link suspension for the rear using either the C4 suspension or Guilstrands version (bolts & welds into C3 frame)
2) Make the "steering" help you instead of hurt you. Greenwood gives a good description of the modifications required to the rearend in his VIP (vette improvement program) article - can be found on the internet.

Also getting the ride hieght is really important on a C3 for best handling.

 

Smart Struts

 

What did you do for the steering??

 

Nothing yet,other than remove the bump stops.I'm considering power rack-n-pinion,or Flaming Rivers' close-ratio steering box replacement which is alot less cash...but my steering response seems just fine as is.I'm not planning any road course racing in the near future anyway

 

While my steering is tight there are situations like running very fast down a secondary road and the steering is twitchy. Also on high speed sweeper turns you seem to need to correct the turn a number of times. I seem to overturn and I need to constantly correct.
I am going with the steering box.

 

Hey Kevin,
would you like some advise from a non biased - and experienced hand?
I have a C-4 with completely stock suspension setup. My brother has a C=3 with all of the handling goodies - 305 tires VBP front and rear setups - steeroids rack and pinion - you name it - he's got it. When we go out on the track it isn't even close - He eats my dust bigtime in the curves! And if we switch cars - the same result - the stock C-4 puts the heavily modified and pricy C-3 to shame!

I know thats not the politically correct thing to say here in the C-3 section - but thats the way it is - in the real world - sidfe by side tests!

Now he has played a little with his engine - (458HP) and beats the crap out of me on the long straights - but since we built the thing for straight line top speed - his 2.73 rear end is a real handicap getting out of the corners and into the straights - so if I want to beat him - and **** him off - I go real slow through the corner - and with a 5 speed I get a good quick launch out of the corner - by the time he straightens it out and gets on the gas - it's to late - he gets even - but has to back off!

Any way - if you are looking to build a handling machine - your better off starting with a C-4 - If you want a cool looking car - go with the C-3 - way more hip than the slightly modified firebird they called the C-4.

Carl Johansson

 

By secondary road,do you mean not paved? I havent had to do any correcting yet,but I really havent had it out on alot of different road surfaces.I parked it for a little longer this year than planned,because I needed to do some brake work...I just put 4 new stainless O-ring calipers & Hawk HPS pads on last week. -Remember also,my 79's lowered at all fours,using 245-45-17's(I'm planning on going to 255's in front-265's in back).Although it rides great,I have to be very mindful of "potholes" (hits pretty hard w/stiffer suspension) & sudden surface elevation changes,or I could scrape(mainly into & out of parking lots)

 

Why would you remove the bumpstops?

 

Thanks Carl. I think I will take better looks and a little less cornering anyday.

 

What bump steer problem??

In Corvette Handling, A Performance Handbook, Herb Adams states, "The factory designs in a certain amount of bump steer to make the car understeer: the engineers call it "roll steer." A slight amount of roll understeer is beneficial, and stock Corvettes have the right amount. Unless you change the control arms, their pivot locations, the front knuckle or the steering linkage, you don't have to worry about bump steer."

Do you guys know something that Herb didn't?

 

Bit your tongue My car doesn't see gravel roads. Nearly every road here is paved. The secondary roads are paved with a coarser pavement but pavement none the less and very light traffic. You can really make time on these roads, no traffic, almost never see a cop but they can be rougher, the corners tighter. While they are not posted the acceptable speed is 50 mph. I like to double that.
Our stock steering is noted for being very poor and anyone really looking for handling get rid of the stock system. Steriods or a box seem to be the 2 options. Regardless of price I am going with the cheaper box because I feel it is better.
If you car is really that low the steriods might not have enough ground clearance. The steroids is $1249 and a Jeep box is $675.
I believe in a little more ground clearance and a little softer sprung car and worked with longer spindles and a heavy speedway bar.
I will add one to the rearend this winter,

 

How about this one-> Power Steering Box
-From Flaming River Industries-
-NEW POWER STEERING BOX

Trivalent Chromium Free Plating offers ten times the corrosion resistance of a painted box.
Features Unique Tech billet cap included.
Rack and Pinion Valve Spool for SMOOTH, PRECISE steering and handling.
Four Bolt Mounting Pattern also interchanges to early three bolt application.
Available in four ratios (12:1, 14:1, 16:1, 17:1) to fit virtually any application with the steering feel you prefer.
NOTE: Ratios are approximate - input shaft 3/4-30 spline. -- FR1560 Power Steering box 12:1 ratio, plated w/ billet cap Only $489.00 They also have one specifically for C3's withe 16:1 ratio

 

After the suspension was changed,lowered around 1.5",and larger wheels were added...I had to make about a 3 point turn to do a U-turn in my lane.So,the stops,or whatever theyre called,were Sawzalled and now my turn radius is great! Better than before the work

 

Your talking about your steering stops??? Lowering the car wouldn't affect them. If anything the big tires would hit sooner then a stock set. I would think you would need the stops to prevent the tires for hitting the inner fender. There are two stops per wheel, the welded on one at the back and the oversized bolt head on the front. Both are located on either side of the lower ball joint.

 

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