Would a non-competitive driver even notice the difference between coilovers and the stock suspension on a street driven C4? TIA...

I can't answer your question from experience but I plan to find out. For the many reasons I want them, the decision's already made. Just haven't spent the money yet. If you've never seen Mo Bandy's site, he has some great info about them on it.
Mo

I'm about to find out too.

I've ridden in Gary's C6Z, there's quite a difference.
It actually rides better, but he's got dual rate coils.
The lighter springs help out on the smaller bumps.
A benifit is that you get better grip.
It's really a win win situation.

The cross talk on the factory spring is also eliminated.

Absolutely not.

Don't waste your money.

The Corvette suspension (leaf springs) is extemely well designed. Coil overs offer you two things - adjustability for corner balancing, and rake adjustment.

I have coil overs on my car, but I do both of the above - currently have 51/49 cross car balance with 3/4" rake. But my car hasn't seen the street since 2003. Well, I do drive it out of the garage to load it on the trailer, but I don't think that counts.

Oh, and I am planning on having different sets of springs for differnt tracks, that's something you can't easily do with leaf springs. But again - for the track.

Coil overs are heavier, BTW.

John,
I'd been toying with the idea of coil-overs as well. Talked to HPS (Roger) and his opinion was that there wouldn't be too much benefit on a street car. For drag racing, he said the factory setup with some different transverse springs would do nicely at a fraction of the price. Now, if I wanted to do road course racing, then he said, it would be a totally different issue and then you would want coil-overs.
Neil

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Not necessarily...

Most of the C4's I know that race still run the leaf springs. I don't know of a single C5 that has gone to coilovers and they are the dominant car in just about every class in which they are eligible.

Clearly, I'm not talking ALMS of Speed GT, I'm talking grassroots NASA and SCCA racing. If you're building a car for the big leagues you're not asking people on the internet for help.

Coil overs have some advantages and some disadvantages. And they are usually severely penaized, so if you were to run them on a track you're most likely pushed into a higher class than a C4 can handle.

But I digress...the original question was regarding street use.

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Did you find the need to upsize your front swaybar? My understanding is the monoleaf front offers about 25% of the anti-sway, (and the rear does nothing because the mounting points are in the center.)

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This is the common practice for a few reasons. I never drove the car with the stock bar so I can't offer you a comparison. However, with staggered tires (275f / 315r) I have very good balance - neutral overall with slight push in slow / tight turns. With 275 square (what I had to run at Nationals) the car is a little tail happy but lap times were similar, just more work to get there. I think I'll be going with less bar in the back (back to the 19mm, or maybe nothing at all) but keeping the larger front bar. We'll see if loosening the back induces understeer.

The car will be much lighter and stiffer in about two weeks, so it will be a complete re-balancing and relearning effort, anyway.

Have you considered adjustable end links, or an adjustable type bar rather than having to change out the swaybar every time?

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Yup. But just like anything, it takes money and time. Aside from the obvious safety equipment going in now I'm focusing first on my brake issues. I know I'm leaving time on the table with the lockups (and fear of lockups)...

In addition, as I'm sure you're aware, C4 parts and support are harder and harder to find. Rippie has a little, Melrose is making some stuff for me off old drawings, and more and more of my car is becoming non-Corvette specific. For the real development, however, the C5 is the car to support, and to some extent, the C6, although it's still a little pricey and therefore less common. Aaron Pfadt has announced an adjustable set up for the C4, and is supposed to let me know when it's out, so we'll see what kind of deal I can swing.

Seems like it'd be easy enough to adapt some other application to the C4 sway bar, then modify the end link mounts.

Do you adjust it by angling the sway bar upward with longer links, effectivelty shortening the lever arms by cosine error? Or by physically changing the end link location on the sway bar?

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My understanding is that adjustable links allow you to preload the bar. You can shorten the link on each side to induce stress into the bar.

I suppose you could also eliminate any preload on the car caused by the bar, but shims would do the same thing. I know my bar changed my cross car balance by almost 1% when it was reinstalled after the last balance. I could eliminate this with adjustable links.

I'm not sure how the adjustable bars operate, it's always been more common on ricer cars than V8's. I suppose it's the same concept, a way to preload the bar to effectively stiffen it.

I could be off on this, I'm a EE, afterall...

I could see using the adjustable links to help cornerweight the car, but I was talking more towards adjusting the roll stiffness. The longer the lever arm is on the bar, the easier your suspension can twist it. Shorter arms = stiffer bar.

Draw a line from your sway bar bushing perpendicular to your end link, this is your lever arm length. Anything that shortens it will increase roll stiffness.

I've had coil-overs about a month. Although the car feels much more stable, I can probably attribute that to the 30mm front swaybar and new shocks, bushings, etc. The coil-overs were probably a waste of $1500, but hey, they look cool!

Check this out...
[url]http://www.c4guru.com/modules.php?name=Forums&file=posting&mode=quote&p=17344[/url]

quote="ghoffman"
We are addressing both the upper front and lower rear debate.
The upper front mount distributes the load over a greater surface area so that the lilkelyhood of cracking is all but eliminated.
The lower rear is a different story. We have no idea what the OE stud is actually made of (alloy wise) but assuming it is a decent alloy steel piece, it is marginal for the loads encountered. Tom Urban measured the piece off of his '95 and I modeled it with COSMOS. The load in this model is 2200 lbs and that is just at the elastic limit (yleld). History indicates that it has not been a problem, as C4's have been running around with coil overs for years, and to do 2200 lbs, you basically have to have slam the one side of the car down at 1.5 g's. On the other hand, the other mounts, can take much more than this and argues for a new design for long term fatigue. Comments are welcome as well as sarcastic remarks!
Cheers,
Gary
"


Well that's good to find out.
Nice to have a real engineering working on this stuff!

Look like if you go into coil bind before hitting the bump stops with the current setup, the mount will fail.

Sound like time for a new mount.

I don't have time to check it all out right now, but I'd be more concerned with the aluminum knuckle failing than the steel mount. The aluminum will carry more bending moment.

1.5Gs on a mount is nothing, consider the shock loads from hitting a speed bump with runflats on there.

I don't recall how much lower the fatigue limits are than the ultimate yield, but it's quite a bit. Less than 50% from what I recall for aluminum. Steel, I'm not sure.

But as you said, if this was a common problem we'd be hearing about it.