What are the advantages of a C4 over C3 suspension? I'm in the planning stages of a build, which will have creature comforts, like AC, LS motor, R&P steering, etc. I'm looking for a nice ride, it will not be a track car, more like pro touring.

I've been checking out some of the frame builders, who have turnkey systems with frame, updated brakes, C4 suspension, R&P steering, etc. They are pretty expensive. They also have C5 and C6 suspensions which are way over budget for me, so this is not even a consideration.

Is a C4 suspension that more superior, or can a C3 suspension be modified to get most of the benefits of a C4? Again this is not going to be a track car, ride quality is the primary consideration.

 

I owned an 84 for about 13 years and now a 74 and I can say the 84 had waay better handling than the c3... everything about it handled better , cornering steering... yes C4 suspension is superior... the c3 suspension was released in 1963...(same frame and suspension as the c2) Now as far as styling?... c3 hands down.

 

Anything can be modified.
The rear suspension on the C4 is where the bulk of the magic happens - the toe curve is much better.

If you're not hitting the track it doesn't really matter. Modern wheels and tires will take you most(95%+) of the way there for casual driving.

That said, I'm running the ridetech rear coilover setup and damn does it autocross nicely.

 

Ride, handling, and weight savings. No disrespect, Bellaire, but you'd be ahead of the game purchasing a C4 and making that car what you want it to be than trying to modify a C3 to handle and ride like at C4.

 

And that suspension originally developed in the late 50's (don't forget the "lead time" in Detroit), a time when a "wide" tire had a tread width of 4". The suspension geometry of the C4 is vastly superior.

 

Instead of putting money into a new frame and C4 suspension why not put airbag suspension on the C3? This would give you a nice around town ride like you want.

I think I saw someone offering air bag kits for the C3 at Carlisle one year.

 

Changing the frame with the C4 suspension will be around 15 - 20K from what I can tell.

What about retrofitting a magnetic selective ride control system from a new Corvette or Cadillac? You would need the shocks and the computer box to control it but the conversion has been done C5s. Not sure how the C3 geometry will do but would be interesting to see.

 

No disrespect taken, I have a body and a title. No frame, motor, etc

 

I'm sort of building a Grand Tourer rather than a Pro-tourer...

I had a frame- a nice rust free one...

Since you don't have a frame- all bets are off!!!

Anyway- I looked at all the options for the rear suspension when doing mine.

C4- a lot of fabricatio0n - but the brakes are a down grade over stock C3.

$ 1)Nice composite spring-rebuild everything else
$$ 2) Mono Dual mount Spring Kit
$$ 3) Vansteel Coilover (w/ offset trailing arms)
$$ 4) Sharkbites- nice look-use old trailing arms
$$$ 5) Ridetech-wasn't an option -not available when I did my suspension-price will take your breath away- nice upgrade on the diff mount



I went w/ the Vansteel coilovers. I had a bent trailing arm-So it just made sense- almost a bolt in- a little welding- parking brake is relocated- and can easily add the wider tires as the arms are offset.

For the front- I originally went w/ the Vansteel's semi-coil overs- and was just going to rebuild the stock A-Arms-

But splurged and when the the VanSteel tubular A-Arms and full coil overs.

They were more expensive than the transverse mono spring.

Unfortunately car is still on blocks - so I don't have a comparison to stock - but did drive my 73 stock suspension for 2000 miles this year and 3000 miles last year for the Hotrod Power Tour- and it really was not that bad-and its just got a composite spring....


P1010601.jpg~original by Richard Hayes, on Flickr

Coilovers=




Semi-coil overs-

 

I know this video kind of sucks (quality is horrible for some reason - possibly autofocus) but skip to 1:15 and watch the caliber of cars I am passing on the track. There are cars that out power me and I am not claiming to be the fastest but there are not too many in my run group that get around me in a session. I am outhandling M3s, C5 & C6zs, 911s, etc. Much of this can be attributed to driver confidence but turning low 1:40s at Road Atlanta on a 255 tire is no small feat.


This was when I had VB&P monoleaf springs front and rear with 255/40-17 tires (granted 60 utqg tread wear.) This was also on stock sized brakes with Wilwood D8-4 calipers on all 4 corners.

I have now upgraded to full coil-overs front and rear and will be back out this weekend on 295/30-18 100 utqg tires, along with 14" Baer brakes all around. Unfortunately not the same track for comparison purposes.

All of this is to say, the C3 suspension can be a bad little package if you spend a little time and money on it.

 

I have the VBP Performance Plus full kit, offset trailing arms, and 275/40/ZR17 Nitto tires front and rear.

Would like to hear a comparison from you between your old and new suspension setups even though the tracks are different.

 

Basically, what all the examples illustrate is that a stock C4 suspension is superior to a stock C3 suspension BUT a worked over C3 suspension can be VERY good and certainly a match for the C4 suspension not to mention newer cars with much more sophisticated suspensions. FWIW, the stock C4 brakes suck relative to a stock C3 brake system with the exception that the C3 brakes are heavy and contribute to unwanted unsprung weight at each wheel but its tough to beat 4 piston fixed racing calipers at each wheel with vented front and rear 12 inch discs versus the C4 brakes with 11.5 front vented single piston floating caliper and 11.5 rear solid disc with a single piston floating caliper...starting in 1988 the big brake package offered 13 inch front vented disc and dual piston floating caliper, better but not great.

 

I have a 365 lb fglass rear spring, Bilstein's, 550 front springs, spreader bar and bolt on roll bar with 17" wheels. For touring and fun driving I am quite pleased with this setup. If I were autocrossing then would upgrade to some of the above systems mentioned.

 

Other than for bragging rights (how much is that worth to you?) it's very hard to justify going to the trouble if you're not chasing lap times. In addition to upgrading to modern tires are a number of tweaks you can perform on the C3 chassis/suspension that will take it a lot further than you might imagine, and they needn't cost a fortune. ...nor do they all come in a box. My $.02


TSW

 

It changes everything now that You have a Car project with out a Frame and You are looking to built a Touring car. As long as the Body You have is pretty rust free and a worth wile contender for a build then I would definitely be considering an aftermarket Frame. The Touring Car Market is heating up and values of well built cars are to. The high cost of the frame will be offset if the car is ever sold.
Interesting the C4 rear suspension is actually a copy of a C3 design. John Greenwood developed the design to overcome some of the inherent design problems with the C3 for road racing and offered Cars built to race and kits to modify street cars. When GM developed to new C4 they used the same basic design.
The Frame builders are now offering C5-6 front suspension which has been modernized and is a bit better design than the C4. However the C4 uses forged Aluminum parts and the newer cars cast Aluminum. Forged parts have a much better look to them.
The C5-6 uses a rear Transaxle with the Transmission in the rear so some major body work is needed to fit. The C4 Dana 44 Rear ends have been sought after for a long time and command a high price to purchase. However with the demise in C4 Values entire cars are selling for less than a good Dana 44 used to sell for.
Good luck on the build.

 

Ive heard this before but after driving my c4 for 13 years and putting over 25k on it with out ever having to touch the brakes (which stopped on a dime btw) and having to redo the "New" calipers on my c3 after sitting just one year because they leaked.... I'm not so convinced of this statement... the corvette was designed for the street so in that respect the c4 brakes ....

the brakes on my c3 work well but you see plenty of people who have upgraded due to their weaknesses.

 

Jeff AKA "jb78L-82" said it best-
"FWIW, the stock C4 brakes suck relative to a stock C3 brake system with the exception that the C3 brakes are heavy and contribute to unwanted unsprung weight at each wheel but its tough to beat 4 piston fixed racing calipers at each wheel with vented front and rear 12 inch discs versus the C4 brakes with 11.5 front vented single piston floating caliper and 11.5 rear solid disc with a single piston floating caliper...starting in 1988 the big brake package offered 13 inch front vented disc and dual piston floating caliper, better but not great."

My stock 73 stops fine on the street- but on my 71 I blinged it out w/ some bigger Wilwood rotors and calipers.




Why just stick w/ Corvette stuff- Here's a BMW IRS- Stock is handling over 550HP- just four mounts and it's in!!! Nice -neat -clean package- and can be purchased relatively cheap....



Richard

 

I'm not saying the C3 brakes cannot be problematic requiring some maintenance on some cars but that the basic C3 brake system is head and shoulders above an 84-88 C4 system in braking ability, not reliability....can't argue with physics...see my earlier post. 4 piston fixed calipers at 4 wheels with 11.75 vented rotors will stop better with equivalent tires as a basic C4 everything being equal...including weight of the cars. BTW... With the exception of ss caliper s in 1985, I have never touched my c3 brakes except changing brake fluid in 30+ years of driving the car. Even 88+ c4s with the 13 inch front 2 piston caliper had 11.5 solid rears with a single piston caliper...physics.

Going to a 4 piston fixed front Willwood caliper AND 13 inch rotor on the C3 will improve the brakes (mostly due to the 13 inch rotor, more clamping force) but to really improve the C3 brakes you need to go to a 14 inch front rotor with a 6 piston caliper like the C6Z06. GM knew the C4 brakes were weak which is why they came out with the "big brake" package in 1988 on the C4. My 94 Mustang GT had Front 12 inch single piston floating calipers (like the C4) and solid rear 11 inch rotors with a small single piston floating caliper (like the C4) and I upgraded the front brakes to Cobra dual piston floating calipers with 13 inch rotors. Are these brakes better than they were? Yes. Better than my stock C3 brakes? NO

My 78 with the stock brakes, Performance Friction Pads all around, Stainless steel braided brake hoses all around, and 255/45/17 Zr ultra high performance tires will easily outbrake a stock C4...I have driven 84-88 C4's and 88+ C4's..no comparison..again Physics will not lie.

 

Well all I have to offer is that I actually owned both a c3 and c4 and I understand the suspension and tires being superior may have been the cause but my c4 stopped better than my c3 does so I have to say they must have engineered something right in the newer more reliable modern style braking system ... as a package it handled and stopped better.
Hopefully when I get my 18" rims and tires I will regain some of that feel on my c3 that I had with the c4 and maybe see some advantage.. That and a borgeson steering upgrade.

 

Thanks for your reply to my thread. I really lucked out on the body, it is excellent, straight, never hit from what I can tell, no rust, and has a complete interior with newly done seats, new carpet in the box, and all new wiring harnesses in the box. The paint even looks good.

I have noticed the touring car market heating up on the televised auctions as well. Lots of Chevelles and Camaros. The corvettes seem to be mainly C1s and C2s,, and the ones done right are bringing 70 to 100k plus. Not sure where the C3s fall in the mix.

I have contacted several of the frame builders for quotes on a turnkey system. prices are consistent from builder to builder and run about 40k. Everything is top shelf, nothing left out, all you have to do is drop the body and paint.