there any such thing as subframe connectors for a stingray? ive put them on some of my other muscle cars and it made a big difference. Im thinking with a convertible big block, a stingray could get a lot of good out of some sort of frame stiffening. what do you guys do to beef up the frame?

 

The Corvette frame has fully-boxed side members and is full-length already, with the full acceleration load taken horizontally at the front of the rear trailing arms, into the strongest part of the frame; can't imagine any benefit from stiffening it any further.

Subframe connectors are made to tie together and stiffen the underbody and front subframe on unit-body cars like Mustangs and Camaros that take acceleration loading through the front eye of the rear springs, into the underbody sheet metal; that's why they benefit from subframe connectors. :thumbs:

 

ok very cool. what spooked me was the handling thread going on and one member said

"Combine this stiff spring with a relatively flexible chassis (especially if it's a convert.) and you have a formula for poor ride and lots of flex on poor surfaces."

so that kinda got to me a little. dont want to bend anything down there.


[Modified by C2Vert, 6:25 PM 4/18/2003]

 

I think that was my comment. By modern standards the C2 is rather flexible, but it was good for it's day. The F-40/41 suspension components were developed back in the day when "spring it like a go-kart" was the prevailing theory for racing, and it was focused at racing on high speed tracks.

Though many of us think of these suspensions as "neat" because they are relatively rare and meant for racing, they are very ill-suited for normal street and highway driving. The base suspension with a modern set of adjustable shock absorbers is the the best combination.

Another issue that enters into the equation is frame corrosion. Corvette frames have been known to rust in half, and the kickup where the rear trailing arms mount is a problem area, so if you think your car has excess flex a thorough frame inspection is in order including a borescope inspection through the available access holes as corrosion can start on the INSIDE and work it's way through.

In a 1963 SAE paper by Duntov et al. it is stated that the '63 coupe is 90 percent stiffer than the '62 convertible. The '63 body is solidly bolted to the chassis, so the (coupe) structure becomes a three dimensional space frame with both the bird cage and fiberglass acting as stiffeners. That's one reason why I like the '63 coupe. In the interest of reducing NVH Chevrolet began refining the design as soon as the '63 completed engineering release, which resulted in the rubber body cushions that decoupled the body from the chassis beginning in '64, and though this reduced NVH, it made for a more flexible structure.

Duke





[Modified by SWCDuke, 10:59 AM 4/18/2003]

 

ok thats all very good info and your the second person to mention the kickup to me in just a few days so ill definitely have to pay attention to that. but so whats your solution to the problem? if i have a 5-600 horse big block should i just put on a good set of springs and shocks and leave the frame be? or is there some failsafe mod i can do for peace of mind?

 

Unlike typical muscle cars with longitudinal leaf springs, the Corvette IRS design separates spring and shock issues from acceleration loads; the springs and shocks are not affected by those loads. The biggest issue with a big-horsepower big-block will be half-shafts and U-joints, especially if you move away from the "safety valve" provided by relatively stock tire sizes. If you intend to drag-race it and use slicks, be prepared to spend some big bucks on specialized aftermarket yokes, U-joints, and half-shafts that will take those loads, or the stock parts will wind up looking like this:



:steering:

 

i will never drag race or put slicks on my car. but i do occasionally like to do some heavy accelerations. my problem is i have the phobia "stock isnt good enough" kind of thing and Im always wanting to upgrade just in case. even if i dont need to, i feel that i do. ive heard about the halfshafts, ujoints and what not so id do that. hopefully then, based on what you tell me, that would be good enough.

 

The chassis can be stiffended by welding in the box section and adding gussets. GM did make mods to the frame over time until around 70 or so. When I used to autocross, the hot drivers knew that the Stingrays had stiffer frames than the Sting Rays. Still, being of the "right stuff" the Sting Rays can be made as rigid as the Stingrays. The Chevy Power Manual provides an entire section of the setting up the Corvette chassis. Quoting from the manual:

"Use a new 1969 or later Corvette frame or a good solid 1969 or later used frame. The 1969 and later frames incorporate corner braces (Figure 1) between the differential carrier front crossmember and frame kickup over the axle shafts which provide increased lateral stiffness at the rear suspension attachments."

Also in manual "All welds should be full length arc welds, since the production frame has skip welding on it (Figure 2). Manual also shows where to reinforce at steering box, where to add gussets, etc.

The Chevy Power Manual (5th edition, 1984) could answer a lot of your questions.


[Modified by toddalin, 1:27 PM 4/18/2003]

 

All excellent advice. This forum is a great place to get any Corvette question answered, but the members above are definately the most knowledgeable members on the forum. I would heed their advice.

 

The only problem is when you add the additional bracing the corner brace doesn't have enough clearance. The storage areas behind the seats intefere with the corner braces. You have to alter the storage box, one corner at least, to give enough room for the brace to fit.

 

My C-2 convertible might be a little on the xtreme side, considering HP and I do use slicks etc and go to the track. My experience was that it does flex a pretty good bit.

I could always tell when I was on a good run because the interior floor lights would stay on all the way through second gear and flash on the 2-3/3-4 shifts. No matter how tight you put switches. It seems to flex right at the kickup area and on the left side in the long expanse area behind sterring box.

During the new Dana IRS install, I completely welded the frame, completely boxed/plated the kickup/crossmember areas, gusseted inside the kickups,and built internal "boxes" inside the frame end rails at the kickup areas. Lots of finishing have rendered nearly invisible to the casual observer. With the body back in place, you really have to look and know what you're looking for to notice. I hope it makes things lots better in that area.

I feel the forward/midsection of the frame is still vulnerable to lots of flex. I've thought about mid motor plates, but that is pretty visible. The best way is a roll bar with side bars, but there goes that stealth factor. Therewas some talk here a while back about foam stiffening agents sprayed into the frame that sounded pretty neat, but I don't know of anyone that has done it yet.

Primarily, for most cars, just make sure the frame is solid in the kickup area and use normal tires, and you'll be fine.

JIM