1970 Camaro/Corvette/Dirt Latemodel Build

Hey,

My name is Cody and this is my 1970 Camaro build.

The car has currently been competing the last year and a half, but I will start from the beginning of the build.

The build started in late 2019 from a rusted out '70 Camaro I bought from my dad. There was a local Optima USCA race in June of 2020 and that was the goal for the first event. It took about 8 months to go from the rusted out car to its first race.

I'll go through and explain everything as I post pictures. Essentially when I started building the car, the rules for USCA stated no tube chassis unless it was store bought (Detriot Speed, Speedtech, etc). So I based the front suspension off the factory subframe, but used a C5 Corvette cradle, spindles, and arms. Since these are Uni-body cars, I fab'ed up "Subframe  connectors" for the rear and built a 3 link with a Winters Quickchange. My background is circle track racing so I knew these worked extremely well.

Here is car when I got it;

And here is the car today;

First, I built a jig to set the car on the pinch welds and started cutting. I cut for days it seemed. I retained the factory rockers and laid 2x3 square tubing on their insides and started building the center chassis.

Once the center frame was squared up, the roll cage started. For whatever reason, the headliner in this car was in excellent condition. So basically the entire build is around this headliner I didn't want to remove.

Easily welded all the top joints

Main cage done. The remaining bars will be added later to make working inside the car easier.​​​​​

Looks great, I'll be following this! Are the rockers attached to the box section? If so, did you have to notch the rockers or just butt the box alongside?

Badass

In reply to Racingsnake :

Thanks. I laid the 2x3 tubing against the rocker and stitch welded it. Once the floor plans are gone the inside of the rocker is nice and flat. I want to say both side taper inward towards the front a bit. 

Next, i started on the rear frame section and lower links. I designed a center pulled style 3 link. It gives tons of drive off the corner, but sacrifices braking with brake hop.

The lower links are as long as I could get them. They come inside the car and almost touch the front seats.

Track bar mount mock up. Factory frame rail still fits.

I debated how I wanted to build the tunnel and ultimately went with square tubing. I figured this would make the tin work easier with less contour.

Also, this is the point where I decided it was time to learn to TIG weld. So I ordered the cheapest eBay welder ($100) and got to work.

Mid Valley Dog Box to build the tunnel around.

I got lots of TIG practice on those pie cuts.

Started to figure it out on the transmission mount.

Sheet metal mock up. This was NOT fun. Top piece is aluminum. 

In reply to OutrunNAScaR14 :

Cody, are those lower links rigidly attached to the axle tubes, or do they allow the tubes to rotate under acceleration and deceleration and the pull-bar third link allows some "cushioning"?

In reply to DeadSkunk (Warren) : 

They are rigidly attached via a 3/4"spherical bearing. The top third is solid too, but I have a decoupled link to test eventually.

Are you familiar with the third link variation where there is one link nosed down for accel and a second third link nosed up for decel? I forget what it's called.

In reply to DeadSkunk (Warren) :

I am familiar with it however I have no experience with it. I've seen videos on dirt modifieds and some road race stuff. And of course the Ron Sutton stuff, if I dare say his name in here. I don't make a ton of power right now, but whenever I do I will be sure to experiment with it. The car puts the power down so well with the center pull, forward drive isn't much of a problem at the moment.

Cool....I'll be watching this build thread for any ideas I can steal and use on mine. Welcome to the GRM family.

Up next, front suspension. I'm working off the stock subframe but with a lot of modifications. I cut the factory spring pockets out ot make room for the coilovers. I cut out the center crossmember to make room for the Corvette cradle. The factory Camaro crossmemeber weighed the same as the C5 cradle, upper and lower A arms, and spindles.

The frame was notched so the C5 cradle bolts into place like on the Corvette. 4 bolts total. This cradle also made the LS easier to install, since that is what it's made for. It moved the engine back about 7" from stock.

Notch mock up.

More mocking

Front bars into place.

Tubular core support and bumper support done.

Engine set into place, firewall cut out, and CAD firewall in.

Spring pocket removal/TIG practice.

I took a lot of time in designing the upper A arm mounts. I wanted a ton of adjustability and easy adjustability. So I came up with this. The back side of the mount is serrated and uses a serrated block to adjust roll centers up and down. Then I machined some square stock with a slot that the A arm bolts to to adjust caster without affecting camber. 

OutrunNAScaR14 said:

 

In reply to DeadSkunk (Warren) : 

They are rigidly attached via a 3/4"spherical bearing. The top third is solid too, but I have a decoupled link to test eventually.

 

I'm curious about the reasoning behind your design here with the lower rear control arm. I understand the longest arm possible side of it. The location of the mount so close to axle centerline and behind the axle besides is a bit confusing to me about why vs the mount being below the axle (like most others) or even below and rearward for the length. The forward push of the car moving is there regardless but I can't convince myself one way or the other what the rotational forces are doing with the mount in that location. I'd guess its minimal either way with such a short lever arm length or was that the goal (then tune mostly with upper link)? Just to be clear I'm not knocking it....just wanting to understand the reasoning for it.

In reply to asphalt_gundam :

This style three link is common on asphalt late models these days. It helps promote forward drive by keeping the pinion pointed down and not climbing, transferring bite into the rear tires. I don't know the exact science but from my research and talking to the circle track guys I decided to try it for road racing and autocross. It does in fact work great with drive off the corner, but limits how much rear brake you can put into the car. It also helps reduce rear steer.

Next season I will be moving the rear springs to in front of the axle tube to hopefully get even more forward bite with hurting braking. 

In reply to OutrunNAScaR14 :

Thanks. I can see how it for sure would help reduce actual axle rotation and keep the pinion down. Seems like loading the rear tires then relies on the upper link alone (mechanically any way) as the lowers are pretty much only pushing the car forward. Its always interesting to see different setups and how they work.

DeadSkunk (Warren) said:

Are you familiar with the third link variation where there is one link nosed down for accel and a second third link nosed up for decel? I forget what it's called.

It's called a "decoupled" link.  I'm going to head that direction once I get the rest of my car working a little better.

More tin work. The firewall doghouse was a real PITA. The tunnel was pretty straight forward and turned out nice.

Aluminum floor pan ready to get a million holes drilled.

Floor installed

Back to the rear suspension.

Here is the upper third link mount mocked in, and the lower mounts in place.

Mock up third link

Splined sway bar from a NASCAR road course car.

And these last few pictures are the rear suspension pretty much wrapped up.

Really nice work, following along!

OutrunNAScaR14 said:

In reply to Racingsnake :

Thanks. I laid the 2x3 tubing against the rocker and stitch welded it. Once the floor plans are gone the inside of the rocker is nice and flat. I want to say both side taper inward towards the front a bit. 

Thanks. Loving this build. Did you machine the serrations on the upper a arm mounts or did you take something off the shelf and modify it?

Reminds me a lot of what I am doing. We need more updates for sure!

Although I haven't posted lately due to another stealth project I have on the go.

Well do your best, OK?