pologreen1

C4 vettes have :

1. Convertible X brace / R&D X brace
2. Targa brace
3. Camber brace
4. Harness brace/ cross frame brace

What are some thoughts on this brace?

Tom400CFI

My first thought is that you should post this in the FRAME TECH TALK thread.

My second thought, is that someone stole my idea!
I think something like this would help the front of car a lot...but it still won't help the mid car torsion issues, IMO.

Churchkey

Would like to see another down tube @ each of the kick out bends but IMHO a clever & good looking method to stiffen the front stub + add cowl support.

Luv the ZR-1's.

93Rubie

I personally think C4's have a lot of weight added to them with all this bracing for little to no actual benefit.

Until someone with the braces ponies up and shows me ACTUAL numerical differences in handling capabilities I'm not sold. I don't care how it "feels" its how it actually performs.

They did handling tests years ago targa on and targa off. No difference was found. I don't think adding a bunch of weight to the car is going to benefit the handling.

Then again this is from my performance perspective, if I was just into cruising around and concerned about feel then if it makes it feel better...what the heck.

That brace might work but again is it worth the weight and cost penalty. I think the mid section of the car needs it worse.

pologreen1

That photo is from like '08, and it was done before that. The car was in Japan.

I would like to try it someday. I'm pretty fat now anyway, but I'd like to know what it weighed, I bet the radio and junk are just as much or more.

pologreen1

The reason I'm sold on bracing is it ties the car together period. For example my car was ragged out as far joints, bearings etc. It felt like crap, I added the camber brace and crossbar brace and one or the other helped, I'd say the camber brace did it because it really helped tighten up the nose of the car. Also stopped a lot of the shake where you could see the hood moving when on it.

The ones that were so beefy are probably not worth the weight, but I want to reproduce my own parts in CF and put them on the car.

Now I have new parts in it, but I'll still keep the braces.
I also think about sway bars and how different sizes act, there is something to torsional energy imo (PROBABLY A FAKE PHRASE).

OTOH there is a guy here that DIZ that says his roll bar/ cage did not help strengthen the car. IDK.

383tpimachine

I think it wont fit my driverside due to supercharger so no comment.

cardo0

I'd have to agree. That looks like it would add more weight than stiffness.

blackozvet

thanks for posting those pics polo, its an interesting brace !

Rubie makes a good point, how much does any particular brace work ? the only way to truly know is for someone to put them on a car that is tracked and compare back to back times.

Dont forget that the spring rates and swaybar rates are determined by the engineers when they test the cars, and that includes how much they twist and turn in the chassis.
If you change the stiffness of the chassis, then the spring and swaybar rates may have to change too (albeit only slightly in some cases)
I know this happened in my car when I put the rear harness bar in (that connects the rear chassis bars to the halo seat belt points) the car went quicker (as proven by the times) but I had to go from 24 mm to 19 mm rear sway bar to get the car to work properly. With the harness bar and 24 mm bar in, it wanted to power over steer out of every corner whereas before the harness bar went in the car was much more compliant, due no doubt to chassis flex.

Could you tell the difference in a street car ? Maybe, but could you tell it accurately ?
The only way would be to track the car without any chassis stiffeners, then add them one by one, make your necessary suspension adjustments, and check against the timesheet. If you do 6 meetings a year, thats probably how long it will take to work it out.

Tom400CFI

But some tests like the one Rubie mentioned, show that frame stiffness is not neccessarily corrilated w/track performance. Stiffer frame doesn't equal faster times.

The proper way to verify frame stiffness is to put the thing on some device where you can twist the frame and measure the force/degree, with and without the devices. I've tried this to do this, but can't find a frame to but for. Called Corvette Recycling several times...Apparently they're not really interested in selling Corvette parts.

blackozvet

what I was trying to say is that a stiffer chassis will only get you so much on the track, eventually your combination of springs, swaybars, shocks, wheels and tyres will limit your gains.
The more you stiffen the car, the more things you will need to change (i.e. upgrade/adjust) to gain the benefit.
This isnt my theory, this is how it was explained to me in simple terms by someone that knows chassis stuff.

Aardwolf

It looks like a lot of extra weight for no benefit. Did you talk to the owner or just found the picture somewhere?

pologreen1

Only found the picture after remembering it. I wish there were better photos of where it all attaches.

Someone on here used to talk with the owner.

helphos

I'm interested in this thread because I want a more 'coupe-like' experience in my vert. The cowl shake is terrible, and the rattles are more than irritating. I autocross this thing, but I don't care if a stiffer frame would improve my autocross times, I just want a better driving experience, and stiffening the frame would do it for me.
I'd like to know which solutions offer the greatest bang for the buck in terms of overall driving experience.
To tie this back to PoloGreen's initial post, I'd be interested in knowing what that pictured brace provides in terms of stiffness and what it might cost (if it's even commercially available).
Thanks to all the posters on this thread for the input. I noticed nobody mentioned the Killebrew-designed No-Flex bars, but I've seen it praised on other threads.

blackozvet

the brace in the original photo's looks well made, it would have been nice to see where it ties down lower on the chassis.
how well does it work ? no one knows for sure, but something is probably better than nothing.
as tom400 said, it would need before and after tests done on a chassis measuring jig to know for sure. My bet is a well made camber brace would work just as well.

If you want to brace up a c4 (and your not going to put in a 6 point cage) then you will need at least 3 braces to do it right.
Front camber brace (and probably done a bit better than some of the commerically available ones)
Chassis X brace (under the car)
Rear harness bar (connecting rear chassis rails to halo seatbelt points)