1981 Camaro - C-Prepared Build

Awww. You like me!

https://grassrootsmotorsports.com/news/readers-ride-cone-killing-camaro/

Yeah progress!

a high rise IM and dual carbs would look BA in that car.

TurboFocus wrote: a high rise IM and dual carbs would look BA in that car.

I agree it would look bad ass, but it might cause an issue seeing the course.

Just put a pair of fiberglass driveway markers on the front bumper. It'll make it easier.

In reply to Gimp:

Who needs to see where they are going anyways?

Gotta look good first :D

I haven't gotten to the exhaust yet, but I have been knocking out a few things because new toys (tools) arrived.

I picked up a 1.5" punch and flare tool and had some fun making roll cage gussets.

I know these add a little strength, but if I'm being honest, it's all about style this time for me.

I also did some work to mount a passenger seat and lower the driver's seat. In this picture, you can see the lowered driver's seat vs the unmodified passenger seat (both are at the same "recline").

I did this mostly for helmet clearance, as I have a stupidly long torso. The seats are on sliders, and the seat moves up as it moves forward, so most drivers will have no problem seeing over the 40 feet of hood.

Next, all the "interior" comes back out, the trans tunnel gets raised, and the exhaust gets mapped out.

Got a little bit more done over the weekend. Not pictured was swapping a good door from another Miata onto my mom's Miata. Not an awful job, but took a few hours.

On Saturday I worked on lowering the passenger seat. You can see what it looked like before here:

Of course, as with most things, what I thought would take an hour took the better part of the day. I had to remake the front legs of the seat brackets entirely to clear the hump in the floor from the catalytic converter, but I got the two seats to sit pretty close to each other in height and layback.

Sunday I took a ride up to PA to grab the afore mentioned Miata door, as well as the front clip of the car (it's almost as if the pieces of this car were scattered to the four corners of the Earth). Storage, even in a slightly larger two car garage is at a premium, so this was my solution.

My buddy Mikey said it reminded him of the Star Wars scene where they were lowering Darth Vader's helmet onto his head.

The clip is so light there is no issue in stressing the garage door hangers at the back (the fronts are into hooks in the studs), and if I lower the clip down a little the door opens and closes fine.

I also did some work to the trans tunnel. At full compression in the rear, the driveshaft was getting into the tunnel. So cut cut, snip snip, weld weld.

It needed to be raised about two inches.:

And mostly done (still need to tack it to floor pan):

Next step is finally start on the exhaust and driveshaft loop. I've been doing a good bit of parts collecting so I should be able to hit the ground running.

Dammit, I don't know why your images never show up on my computer.

In reply to Sky_Render:

They are running off of my own site, http://teamziptie.com.

I had an issue with Chrome and Privacy Badger, I think, where the images wouldn't show up. Possible you have some sort of filtering on?

I love those dimpled holes. If I could figure out a good place to put them on my car, I would get myself a dimple kit. I look forward to seeing this beast at Nationals

loosecannon wrote: I love those dimpled holes. If I could figure out a good place to put them on my car, I would get myself a dimple kit. I look forward to seeing this beast at Nationals

If I had worked harder on cage fitment they wouldn't be needed, but at least they look cool!

I'm looking forward to seeing this car at Lincoln myself.

Just a small little update. Tunnel mods are done. I removed the brackets for the center console since I kept bumping into them, and of course the spot welds tore the metal out. Welding on this old metal sucks. I took the lazy way out since the metal was so thin. I mean, it's not a show car.

I also made a few patches for the remaining open spots in the floor. Nothing too exciting, but progress is progress.

Gimp wrote:

TurboFocus wrote: a high rise IM and dual carbs would look BA in that car.

I agree it would look bad ass, but it might cause an issue seeing the course.

If you drive it like a proper CP car, you'll be sideways enough that it won't matter.

Gimp already has experience with how a tunnel ram with dual carbs performs, it was just a "low-profile" version.

Done is never "done."

I was hoping to show you some exhaust work this time around, but I ran into some snags. I had to make some parts changes along the way to make things work a little better, starting with the transmission crossmember.

The goal here is a dual 3" exhaust system. The trick is keeping that system entirely above the subframe. The rules allow me to cut the floor for clearance, so that's not a problem, but things were just too tight at the transmission crossmember. Luckily a solution was just a call and credit card away.

This particular crossmember is for an '81 with a TH350. Since I'm running a Jerico, I had to spin the crossmember 180 degrees to get the mount to line up, but everything looks good. Once I got things bolted in to place, I measured my driveline angle.

Engine angle sitting on top of the intake where the carb mounts:

Tail shaft angle:

CORRECT ME IF I'M WRONG, but I believe the engine isn't angled back enough. Right now the trans is using a standard height poly mount. I have ordered a "short" mount which is about a third of an inch shorter. I think that should get things at a better angle. Thoughts? What should I be shooting for here?

Once I got that bit sorted, it was time to swap out another piece. Some of you may remember my cool blade sway bar from a previous page.

The problem was, no matter how much I messed with it, it just wasn't going to work. The sway bar at ride height couldn't be level, and was pointed so far down that at full droop it would bind. So I called my friend Brian over at Karcepts and ordered up a Speedway Engineering splined sway bar from him. Brian uses these in his S2000 kits and knows a ton about them.

I haven't calculated the rate of PVC yet, but I think I might need something stiffer (I have since ordered the actual splined bar after making sure everything will work).

Mounting it meant spending a good few hours cutting off my old brackets, but the new mounting setup is far simpler. I just drilled straight through the uprights in the suspension "box." I will run large washers to make sure the tube doesn't get crushed.

One cool thing this mounting setup will allow me to do is move the rotational axis from the front to the back and allow for two different arm lengths. This means I can take the same bar, and dramatically stiffen or soften it.

I will be running it in the "forward" position to start.

I also took some time and further cut the rear fenders to accommodate full suspension travel. The car is built for a total of about four inches bump travel before parts start conflicting with each other. This will all for 3" of operational bump travel, which is plenty.

Here is the car at bump and at around ride height (may be an inch too high) with the flares.

New trans mount should show up tomorrow. That finishes my list of excuses to start on the exhaust, so that should hopefully be the next thing I show you.

Well, the new transmission mount didn't work. Wasn't a height issue, but the GForce crossmember has two slots that line up perfectly with the outside two holes on a traditional poly mount. The problem? Those holes are from the manufacturing process and are not to be used. $100 proprietary mount ordered. Ugh.

Since I was in a spending money kind of mood, I started to determine the offset for the new rear wheels. I'm going from 16x12 to 16x14 to better support the radial slicks. My current wheels have a 7" backspace, and are a little too inboard. This is likely from me ordering too narrow of an axle. Oh well.

The fun part about Wide 5s is if you want to try another offset, just flip the wheel.

You'd never run like that, but it's useful for trying things. Flipping like this simulates a wheel with "about" 5" of backspace.

While that looks very cool, it's far too outboard. I'm thinking a 6" backspace may be in order (so I've order some 1" spacers to test). It may be possible too that even with a 6" backspace wheel, the flares may not work on the back. That's okay - it's only fiberglass and I'm not afraid to cut anything anymore.

Looking great. Is there any "ideal" track width calculation that builders use?

JGRAHAM wrote: Looking great. Is there any "ideal" track width calculation that builders use?

For autocross, it's as narrow as you can get it. I'm limited by not being able to clearance the stock frame for tire clearance (there are some tricks you can pull, however).

Aside from that, if you can, I like to have the rear slightly more narrow than the front. The logic behind this is if you miss it (a cone) with the front, you'll more than likely miss it with the rear. If your rear track is wider, you stand a much better chance of hitting that same cone.

Thanks Gimp. Good reasoning!

Over on the Mod Yahoo group, there was a discussion of ideal overall width, wheelbase and track width for autocross and I noticed a trend among the guys listing their measurements. If I took their wheelbase and divided by the Golden Ratio (1.61), it would get their front track width. Dunno if it's a rule or a coincidence but it works on my car. Here is more info on the Golden Ratio: https://en.wikipedia.org/wiki/Golden_ratio

loosecannon wrote: Over on the Mod Yahoo group, there was a discussion of ideal overall width, wheelbase and track width for autocross and I noticed a trend among the guys listing their measurements. If I took their wheelbase and divided by the Golden Ratio (1.61), it would get their front track width. Dunno if it's a rule or a coincidence but it works on my car. Here is more info on the Golden Ratio: https://en.wikipedia.org/wiki/Golden_ratio

I'll have to see how that maths out for me. Really, in the world of CP cars, narrow is probably going to have the biggest impact. That's my main concern with the newer Mustangs in the class.

EDIT - using that ratio gives me 67" front track width. I'm probably well over (stock "width" of the car is around 74"). I'll measure next time I'm assembled.

DOUBLE EDIT - I just remembered that "track width" is measured from tire centerline to centerline. Time to check my measurements.

I'll have to check my ranger and see if the golden ratio follows suit!

Something important that I just realized:

TRACK WIDTH is tire CENTERLINE to CENTERLINE. 67" if feasible with my car. I was thinking overall width.

Yeh, that Golden Ratio shows up all over the place and these guys were listing off their track widths and wheelbases and I did some math and realized they were all pretty close to that 1.61 ratio. So weird

In reply to loosecannon:

I just checked the Vette & it's 1.606. Funny, I had no idea this was a legitimate thing.