Hello all, I'm fairly new to the forum here. Bought an '82 a little over a year ago. Eventually I want to do a body off, but want to enjoy driving it for a while first. For now, I'm doing little things here and there. I'd like to know if and what anyone has done to reinforce the frame with out pulling the body off. I'll be changing the engine's top end and I figure I can squeeze a few more pony's out of it, but I'm a little worried about torquing the frame if I play too hard. Also, I plan on swapping the vacuum brake assist for an Hydroboost.

 

I wouldn't worry about the stock frame if your using the stock bottom end. If anything weld up the lower a-arm u channels. They are prone to breaking off.

 

I'm pretty sure I can hit 300hp, but eventually I'd like to hit 400HP. I've heard that the frame rails can torque and stress the fiberglass among other things... So am I paranoid or do you think it'll be fine?

 

That's no big deal with a stock frame.

 

400 hp Will not hurt your frame. I run 425hp and the only thing I hurt is my back tires.

 

My question is why do people think that the C3 frames are weak? Some of the most powerful engines ever produced were in the mid 60's and 1970. What car did they go in?

Your worry should be the aluminum differential that GM put in to reduce the weight and supposedly increase mileage. Once you go with a cast iron unit the next thing to worry about is the 700R4...

 

Thanks for the responses all! FRSTR90 - your right about the differential, I plan on beefing that up and as for the 700R4 -I figure it should last a while as long as I'm not rodding on it all the time. I know I'll need a beeffier R4, but those are easy to come by. Thanks again!

 

i have the engine out of my 79 the lower control amr brackets at one time have been rewelded in dont know why.
now with a closer look the frame has small cracke next to where the welds are
if see pic's of other people welding webbins at the lower controle arm mounts and nthe engine mounts and the ft frame horns for the bumper support
my ? #1 is why do u think these had to be rewelded
and #2 is can all the webbing welds be done with the body on the frame
fyi i have a 383 crate engine going in spec. are 475hp 525 ft
700r4 behind it
3:73 cast iron rear end from duntov
and i seen pic's of some cars having a adjustable strut bar in the front
what came out of the car was a 350 hp th350 trans with a 2400 stall and the o.e. rear end with 3:73 gears

 

425 hp ZZ383, 700R4... Just get in and drive !! If you want to worry about something think about all the other drivers not having as much fun as you !!

 

If you want frame reinforcement, do what this guy did.

Damned fine craftsmanship.

 

And Chevy's own performance manual detailed how to strengthen the frame for racing...

 

For when you do decide to pull the body here is a link to some things I did; seam welded the frame, boxed in the horns, gusseted around the motor mounts and steering mount points...

http://islandtimeinvestor.com/iti/vette/frame/

 

I've not worried about strengthening my frame, but I'd be interested in reading that manual. What is it in?

 

Paranoid? No. You're falling victim to unsubstatiated Corvette Myths.

Ditto for the Hydroboost. You don't need it.

 

i've seen many posts on these brakes and i have a a question. are the brakes are powered by a pump (p/s pump?) ? what happens if the drive belt fails? is there a back-up?

 

http://corvette.wikia.com/wiki/Misc_Overall

About 1/3 of the way down the page you'll find "Chevy Power Book on Corvette" in .pdf format.

 

Promoted by the race engineers at Chevrolet.

The information on the torsional strength of the C2/3, C4 and C5 chassis setups in Dave McLellan's book Corvette From the Inside is quite interesting. He should know what he's talking about, having spent quite a while as chief engineer of the Corvette division.

On top of that, I just cut some parts off of a low-mileage, stock, very rust-free California '75 that my parts guy had in his shop. The car was declared to be unrepairable when it was discovered that the upper control arm mounts had torn almost completely free of the frame.

Don't need 400+ HP, either. I prefer the Hydroboost over the stock vacuum booster for several reasons:
1) you can remove it from the engine bay, rather than having to strip the dash apart.
2) it's a lot smaller, and a whole lot easier to work around.
3) it provides better braking power.

There's a reservoir in the system that gives you a few safety stops if the system loses pressure, along with it being a "fail-on" setup. If you lose pressure, eventually the brakes will just lock up and you won't go anywhere. If the system is still pressurized but the pump isn't turning, the only likely result would be an increase in braking force, I don't think it would completely fail.

 

Various versions are available for download, or you can get copies at swap meets or eBay. Run a Google search for "Chevrolet Power Manual," you should find some sources. The only one I can find on my computer right now is the Corvette section of the 5th edition, put out sometime after the C4 introduction. It talks about frame strengthening, roll cages, suspension upgrades, etc. The full thing has stuff for all sorts of Chevy vehicles.

 

Stock frame is pretty tough. The flexible area is that long expanse between the front crossmember and the trans crossmember. The rear kickup area can be a little flexible..but the C-3's already have braces the C-2's don't have.

Years ago when I had the body off mine I added some 3/16" plating around the rear kickup area. Spent a lot of time on it blending it in. Once body is on you can't see any of it. It did stiffen things up a lot. I also welded the seams along the main rails...probably not needed..but did it anyway.

I raced the car for quite a while with no issues, but during a good 2nd gear powershift it would flex enough that the interior floor lights would come on no matter how much I adjusted the switches. My buddies and I always laughed at that. Once all the stiffening was done that never happened again.

But even with that going on...and through today....the car literally doesn't have one stress crack in the body anywhere...and this is how I drive it a lot! The rubber body mounts on a C-2 and later C-3's I think is a good thing!



JIM

 

Refering to #3) Once you get to the point of locking up the brakes, it doesn't matter how much power the system has. While auto-crossing, I can regularly lock up Hoosier A6, Kumho V710, and Grand-Am Continental slicks (read very sticky) tires on a stock system. I run a good semi metallic pad like Hawk HPS or HP+ on stock replacement rotors. It doesn't take much to lock up the brakes. Anything more just locks up the brakes quicker, and will not stop you any quicker. In fact it will lengthen your stopping distance. The stock system is perfectly capable of taking anything you can throw at it. With some cooling ducts, it will take even more abuse. The next thing to do if you want better braking performance is install ABS!