TCracingCA

The simplest answer depends on whether you are street driving or track!!

On a track- you will never find perfect handling at the limit everywhere! So you have to approach things broken down into objectives- an overall fast lap, having an advantage in certain areas for passing, and tire wear duration! Naturally if you tune for fastest lap, you hope you coincidentally develop a passing advantage and good tire wear is how most do it! I personally think the guys that can get turn entry and exit at the optimal are the ones that win. In those heavy transitionary moments where things like cross weights, weight transfer, corner weighting, individual wheel tuning etc are worked on! So do you throw it away everywhere else to make that big passing move each lap in a particular turn or section, because you find it is follow the leader around most of the turns and onto and down the straights! That is where track testing comes in. And running practice laps with competitors! Thus you will be forever chasing the setup!
As I get older, I am on any type of track less and less and going back to my Canyon Running passion! So I know my road section (TC- Turnbull Canyon) Raceway between Hacienda Heights and Whittier (if you want to know what I am all about- go to Pelican Forum onto the Mulholland thread I think Pg 339 is me)! and I know it probably better than any other human on planet earth.
I actually am moving into cheap Formula cars now purely for fun and plan to take a Malibu GP or Go Kart mentality to it, and just show up, drive it through an Autocross or around the track and if not good, play with it without killing myself! Therefore I know just enough to not embarrass myself!
My new approach to having street capable superior handling is getting the same new approach as my Formula Car approach. One I am on street tires on potential rough roads! , therefore it would "not" be good to set it up to race car specs! So I am developing two setups, from a one car suspension. Call it soft and heavy! But putting maximum suspension tunabity into the car! Basically mark, write down, measure each, to switch back and forth! So basically if I was to choose to just drive it everywhere with a setup, then there would be a helluva lot of compromise and vulnerability if caught on the street or caught on the street where the most critical component (my tires) is placed into being the most compromised! I just have to decide if that is what I want to do! No I don't want to give it up or give it away! On the street if I run into a modern Porsche GT-3 RS, I just want to leave the guy with an impression of Wow! That thing surprised the heck out of me, I wasn't expecting that! On my end I wish I could have had the race setup and tires for the encounter! I do have to factor in better street tires, speed ratings than what I can buy in my size for my vintage ride! Now if it happens more than once, or some Z-06 can embarrass me, then I probably will drive it around everywhere on the Michelin TB-15s or on the Race Hoosiers! Now if the GT-3 RS said meet me up on Turnbull Canyon road, I would get a great big smile on my face! If at Willow Springs racetrack, no one in the entire Country would embarrass me there either!

So the question to reach your tuning goal, is what the f**k do you want to do with it and where?

ignatz

The short answer is autoX. I'm going to chase down The SkunkWorks reading suggestions. And as he suggests, I'll have to get the car past its limits to know what to do to it. Certainly makes sense. As per my Question 3, I guess I will have to decide myself if there are enough advantages to double adjustable shocks.

TCracingCA

If pure Autocross and no street operation, then just put heavy springs on it and shocks that will keep it from bouncing. Dial in camber based on reading across the tire face with a cheap temp gun. Go to a big parking lot and drive around in both directions for 70 seconds and then do those temp readings as prep to simulate any course! If you don't feel like doing the springs, then get big sway bars proportionally front and rear and buy and tear up more expensive tires!

Autocross is usually set up on basically mostly flat venues! Because it is mostly flat, the above suggestion and because it is flat, you don't need fancy double adjusts either! Naturally the organizers will set up one fun and interesting section like over a drainage area, so just line those up square with a heavy suspension, so you don't end up fly or spinning! If you were doing multiple tracks or radical canyon running over rough surfaces, then get expensive stuff! For autocross you don't need them!

TCracingCA

Ok let's look at the way the Corvette was designed!

The Corvette roll stiffness front and rear ratio was designed to give understeer! As they went up in sway bar size to increase roll stiffness to gain better handling, they kept the ratio the same front to rear to keep the understeering characteristics. So that is what was happening with the stock provided bar diameters. Actually the front bar is traditionally slightly oversized, to maintain the understeer characteristic.
When you push the car toward its limit, the IRS and rear steer tends to transition to oversteer especially when you get on the brakes going into a turn. So you get larger tires, but for the bar set-ups, some like to reinduce that ratio back toward understeer as they get into performance driving. The comfort feel they get in normal driving.

Since our cars are front engine, most of the handling is affected by the front and what is happening there! Understeer usually wouldn't necessarily allow for the fastest lap times, pushing and plowing.
It kind of sucks that Corvette handling is so roll bar influenced.

jb78L-82

This explanation is exactly correct!

A couple of additions:

Many folks use the term oversteer in broad terms but there are many different reasons oversteer can occur. Front To rear sway bar/spring imbalance, trailing throttle oversteer, steady state oversteer, throttle on oversteer (just about any engine configuration car will oversteer with enough power), braking hard in a high lateral corner-mid corner (this one is a major blunder on the street or racing for any car). Most drivers to your point are much more comfortable with understeer although understeer is most often not the fastest way around corners.

One last point is that the SBC C3's are actually not a front engined car since all of the engine is behind the centerline of the front axle and is more to the middle of the car than the front. The BB C3's are most definitely a front engine car. In fact the front to rear weight balance on the SBC C3's is close to 50:50% F:R. (my 78 C3 is actually 48% front:52% rear). The BB C3's are nose heavy with a weight bias 51-52% front: 48-49% rear. The 2 engine configurations are very different with the SB C3's considered the better handling of the 2.

TheSkunkWorks

Tho the same basic dynamics apply, AX (inclusive of Solo 2) and RR typically differ in what handling characteristics best suit one or the other. In the former, you're going to be dealing with a lot more tight, "point & shoot" turns and switch-backs as compared with the latter, with few if any genuinely fast bends.

In the limited time I've spent AX'ing in various cars (relative to my time RR'ing), other than having found a slight to moderate oversteer bias desirable, the single characteristic I've found in need of tuning has been the overall transition time it takes a car to "take a set", especially in quick switch-backs. With a lot of damping, some AX turns may not last as long as a car takes to reach steady state cornering which, depending on the layout, can be good or bad. Sometimes, you may actually want to have the shocks slow down transitions so much that they constructively limit suspension movement, while others you may want the to free up the car in order to get transitions over with ASAP.
You'll just have to see whether moving one direction or the other helps you get thru the more important turns of a particular course.

The good news is that even single adjustables will give you some space within which to tweak "set time", as well as a bit of area in which to manage fore and aft weight transfers. So, there's a chance you might achieve a level of performance that satisfies your needs without worrying about finer aspects of shock tuning which would require double adjustable or higher shocks. HTH

TCracingCA

For most non-race drivers, the car feeling comfortable to them is more important to driving it fast while handling than a whole bunch of parts suggestions!

The engine setback and positioning in the. Car does help with polar weight shift from the effective center of gravity point. It is one of the factors that separates the essentially a production car chassis from other production car chassis to make it a Corvette.

TheSkunkWorks

Nope, nope, and not necessarily.

Both the SB and BB sit behind the C3's front axle, with either mass being distributed ~85% front and ~15% rear. An iron BBC with aluminum heads, intake and water pump is only ~90# heavier than an L82. Add an aluminium block to the BBC, and it's the SBC that's the heavier of the two.

Using factory weight specs from the 1978 model year as an example:

Stock:
Front 1682, rear 1875, total 3557, front 47.3%, rear 52.7%

Same car w/iron BBC w/aluminum heads, intake & water pump:
Front 1758.5, rear 1888.5, total 3647, front 48.2%, rear 51.8%

Deltas:
Front +76.5, rear +13.5, total +90, front +0.9%, rear -0.9%

Even with the additional ~75# of iron heads, the BBC would still end up with a F/R weight distribution of 49% / 51%. So, the BBC isn't exactly a supermassive black hole. But, thanks for playing.

.

TCracingCA

Yes a shock that can settle the suspension (springs) quickly and smoothly during radical changes of direction is good! When I say single adjusts are good enough for Autocross, Slalom, Solo 1&2 or Gymkhana events or whatever you call them, naturally the winning cars usually are running the more expensive and sophiscated parts, but not always!

We should go go back to the base definition of a Sway Bar/Roll Bar/Anti-Roll Bar is they are installed primarily to make a car corner flatter. They resist the weight transfer produced or induced during cornering. They resist body roll and put tractive forces on the outside tire! The major problem is getting too stiff of heavy of a bar. Thus to much resistive force causes the inside wheels to lift in a corner and you can go to extreme understeer at the front where the majority of the handling occurs! Basically you just want the back end to successfully follow where the front end wants to go! Thus as things are changing oversteer or understeer from the back end, that could cause a big problem or give you an advantage!

For most I kind of would suggest as big a bar if you don't have the springs that will not cause an unweighting of the inside tire. Then add a rear bar that will allow the initial understeer characteristic at high speed entry and braking (naturally best to try to keep understeer at all non-race speeds)! But a rear bar that allows a smooth transition out of understeer thru neutral to oversteer with out snapping out or breaking traction (naturally to the adhesion of the tire or spring pressure forcing the footprint to the ground.

Naturally you can see I am a heavy spring advocate! They force footprint, they resist weight transfer while still allowing independent wheel movement. The problem is heavy springs can be harsh reacting and harder to control or regain their control. Thus on rough roads or uneven surfaces they can skip and launch causing an actual loss of footprint or tire tracking to the ground. Etc
Lighter springs are easier to control and track the ground better, which can benefit tire contact to the ground which is good, I call it dancing over the rough road or course, but you have to balance downward force for tire plant with being able to maintain contact.

I am out of phone battery- need to charge later.!

jb78L-82

Who said anything about aluminum heads or modified engines and suspension?

Please provide support for your statements:

1970 BB C3: 53% front/47% rear....documentation below:

http://www.roadandtrack.com/new-cars...-454-corvette/

I was actually generous with my BB weight distribution numbers...turns out to be more nose heavy^..I have seen also 54% Front:46 % rear cited in the literature

BB C3's have a cut out in the front cross member to accommodate the engine protruding forward slightly (it is not totally behind the mid line like the SBC C3's) and the BB engine sits MUCH higher contributing to a much higher center of gravity in addition to the weight.

There is no free ride with the BB engine, a fact that I find many BB owners are unaware of and the effect that big engine has on chassis dynamics and handling. Duntov stated many times he preferred the better handling SBC C3's over the BB cars...Now power is another thing.....

1978 weight distribution(SBC, no BB in 78):

48% Front: 52% Rear...I did say that in my post, didn't I?

http://www.thevettenet.com/corvette_specs.php?year=1978

TheSkunkWorks

There's nothing within my fact based apples-to-apples rebuttal to your contrived blanket statements about BBC C3s which requires my mounting a defense. So rather than take part in even further derailing the OPs worthwhile thread, I'm satisfied with leaving it to stand on its own for by-standing viewers to discern for themselves whether I've made my case.

jb78L-82

Me as well....but the facts as stated in my post #30 are correct and verified...sorry!

I would love to hear others views on what we discussed???? and how they feel about random statements versus posts supported by documentation?

Contrived????

I spend a considerable amount of time backing up what I say with documentation. You sir...do not.

ignatz

I don't care to step in between you gentlemen. I would like to point out that there are more slides by this author with extensive calculations performed on anti-roll bars using a generic C3 as an example. I've edited my original post to include a link to this second series of slides. I kind of halfway noticed it when I posted originally but hadn't yet followed up on it.

Despite the subjective measure of tuning the suspension, which you've both discussed, the engineer in me (a EE, so not all the apropos, but still...) wants to get a handle on some numbers. So when I get a little time, I'm going to plow through these equations to try to get some idea of suspension travel AND maybe the shock requirements. Feel free yourselves. And after that I'll have a look at quark spin. I have to remark that the increased effect of anti roll bars on roll stiffness seems pretty remarkable.

Also with regard to that, I've found a couple of other discussions on the subject, the Herb Adams Corvette Handling paper where he mentions critical damping as being desirable (a short not too informative plot showing oscillation behavior) , and a Carroll Smith Cause and Effect Guide, which is a simplified tuning cookbook like: if this happens, fix it like this.

TCracingCA

I have four wheel scales, we can put your small and big block on them and see where the weight is and calculate center of gravity. I actually have Corvette articles showing all of that!

The Corvette engine placement and position was done for this production based chassis with some emphasis to improve all that and give a performance advantage!