Ciro Racing C3-R - 1968 Corvette for Street/Autocross

[rjsolo]

Ciro Racing's goal is to build this C3 corvette into a regionally competitive ProTouring autocross car, while remaining streetable. This will be a budget build, mostly done in a home garage. The plan is to build it in several stages while being able to use the car in between phases. We also want try out, and share our findings of some products that we have had success with on other cars. That said, we're happy to have partner's like Bilstein, Vansteel and Dunlop tires helping with this project. We will also be working with PCHrods later on, when we're ready to do a motor swap. Yawsport is providing custom coil-over hardware and springs, as well as roll bar fabrication.

These are renderings of the direction for the C3-R:





Here's a pic of the car purchase about a year ago. It'a a solid rust free SoCal car. Auto, manual brakes, power steering, replacement 350 smogger engine that probably puts down 150 hp to the wheels. Previous owner went through the interior and dash. Looks better in the pic, paint is faded


As mentioned the car will be built in phases. I'll try not to over burden with too much corvette specific detail (I may do that in the corvette forums), but focus on improvements that make it a better autocross car.

Phase I - Suspension, steering and get it working well enough to test at some events. (In progress)

Phase 2 - Wheels, flares, brakes, safety, interior.

Phase 3 - Power! LS / T56 swap and all involved parts.

Phase 4 - Exterior, paint, graphics, chassis stiffening, Vintage AC and Aero.

[FLYNAVY53]

Awesome! Love the C3 builds! Not a fan of the wing, but everything else looks like its going to be sweet....looking forward to the progress!

[rjsolo]

Awesome! Love the C3 builds! Not a fan of the wing, but everything else looks like its going to be sweet....looking forward to the progress!

Thanks! Yes the wing would be removable. On these older cars the wing really helps reduce unsafe lift, even at moderate speeds. Plus Ciro Racing provides custom wing fitments to a lot of racers. We had 3 customer cars with our carbon fiber wings at the OUSCI in Vegas, taking a close 2nd overall! Unfortunately the USCA and SCCA banned big wings this year for muscle cars.

See our facebook page for OUSCI pics: https://www.facebook.com/CiroDesignRacing

Rick

[rjsolo]

Phase I

I tore down the rear end, had new U-joints pressed in, cleaned and painted everything, and ordered the camber strut parts back in Oct '14. At this point I was planning to go with a composite leaf and rebuild the stock trailing arms with solid Johnny joints.

After talking with Vansteel, I decided to bit the bullet and go with coil-overs. Started wrenching on the car again in Feb, but have been really thrashing on it everyday for the last 3 weeks. Trying to get it ready for some of the events coming up in SoCal, the first being this weekend. There are events going on for the next 5 weeks, including GoodGuys next month.


Rear suspension almost completed:

What was originally was going to be a just replace the rear spring and bad half shaft u-joint, became a total rear suspension rebuild and coil-over conversion.


- Relocated new camber links, heim-jointed steel.
- Raised diff, so I can lower the car without incurring excessive toe change.
- Vansteel coil-over conversion trailing arms, double offset for more tire clearance. New top frame shock mounts.
- New braided brake lines.
- Solid u-joints for axles and drive shaft.
- New hardware, cleaned and painted the parts and frame

Removed the crusty rear suspension and diff:


Trailing arms and hubs. Was really lucky, as the arm pivot bolts and toe shims came out easily. Most are rusted solid and take many hours with the sawsall to remove.

[rjsolo]

Rear Suspension:

New Parts!

- Cleaned and painted the diff and crossmember.

- Can also see the cut-down stock rubber diff crossmember mounting cups. This allowed the crossmenber to be raised up to the chassis, also made some 1/8" reinforced rubber pads to isolate noise from the diff. Went with steel and poly for the pinion mount, also elongated the mounting holes for proper driveshaft angel.
To finish it off, Vansteel makes nice anodized alum disks to secure the cross member.

- Solid U-joints for the half shafts and driveshaft.

- Made spacers to relocate the strut pivot lower, as the stock rear camber curve is actually too great.



- Went up a size on the rod- ends, along with steel tubes for the camber links instead of alum. Didn't think this was a good place to save weight. Always glad to get away from eccentrics for adjustment.

[lvrpool32]

good luck with the build. I will be interested to see how it turns out.
Nick

[Mr.VENGEANCE]

[rjsolo]

good luck with the build. I will be interested to see how it turns out.
Nick

Thanks Nick, your serious car was part of the inspiration for the build. I'll probably pick your brain as the car progresses, if you don't mind.

Rick

[gardnerme]

What was originally going to be a just replace the rear spring and bad half shaft u-joint, became a total rear suspension rebuild and coil-over conversion.

Nope. That does not sound familiar at all. :-)

Love this project. Good luck!

[rjsolo]

Nope. That does not sound familiar at all. :-)

Love this project. Good luck!

I think it's called mission creep, or " while I'm in there...".

[rjsolo]

Here's the trick Vansteel trailing arms w/rear coil-over mounts, one of the few splurges beyond a beater build:
- Notched for tire clearance front and rear
- The TA pivot bolt takes 3 hands to install.
- Poly bushings
- Relocates the parking cable on top of the arm for tire clearance.





Rear Suspension installed:
- Wire brushed and painted frame.
- New braided SS brake lines " while I was in there".
- Hubs rebuilt.
- New parking brake cable and springs.
- Trailing arms in and reassembled.







Power bled the rear brakes with Vac bleeder, using hi-temp ATE blue fluid



Car set on ground with wood block bumpstops, waiting for coil-overs.:



See proper half shaft angle, slightly lower at the wheels.

[rjsolo]

Installed the Quicker Ratio Power Steering last week:

The stock power steering gear box is 4 turns lock-lock, with ~45 deg of play. So that needed to be improved to be able to precisely steer the car at the limit, and hit the apexes!

I went with the Borgeson box, they make a complete kit for most muscle cars. Includes hoses, pitman arm mount and all hardware. Also called the Jeep box, as users were adapting those to fit, but now Borgeson sells it complete. Vansteel offers the corvette versions. Reduces lock -lock to about 2.75-3 turns, with a stiffer detent on center.

Get's rid of the leaky complex stock hydraulic ram. Easy install, my 14yr old son and I did it in one day



Stock gear coming out:



New box installed. Need to shorten the steering shaft for the longer gearbox. Tap with hammer to collapse the shaft ~2.75"

[rjsolo]

Went with a smaller steering wheel to replace the large thin-rimmed stocker. Almost got a direct bolt-on Grant wheel that I put on my first car in the late '70s. But instead found this nice suede race wheel, that has some needed dish, and a yellow indicator line for when you get sideways.



Stock



Corvette bolt pattern actually matches modern aftermarket wheels, although the holes are clocked at the wrong angle. So didn't even need to pull the hub. Drilled 3 horn holes.



I cleaned, painted and adapted the stock horn button. The horn did need to be modded to allow it to be rotated correctly.



Finished install feels much better. Also was able to line it up from being 1/2 hole angle off, when we installed the Borgeseon box.

[lvrpool32]

Looking good!

[rjsolo]

Looking good!

Thanks Nick, been jammin' on the front suspension to try to make 2 events this weekend, but the shock parts were delayed at the builder.

[rjsolo]

This is a good time to post about the shocks, since they will be arriving in a days.

I went with aluminum bodied ASN Bilsteins, they have external threads for direct coil-over use. It uses the same valving found on their high-end $10K LeMans race shocks. The ASNs are probably one of the best values out there for a proven performance shock,. at a reasonable ~$235 each. Bilstein also makes a steel body SN model for less $. The SNs have a snap-ring groove, so coil-over sleeves can be added.

The ASNs have large digressive pistons. Large pistons are a good thing on our older muscle car suspension geometry. Since the shocks are set inboard from the wheels, the pistons have a short range of travel, and is under more force. The large pistons have more control with the car's poor motion ratios.

The digressive valve allows the shock force to blow off at high shaft speeds, like seen when hitting bumps. This supple valving has a couple of advantages. One, for racing it allows the tires to follow the surface for more traction. The other is it allows the use of stiff spring rates, and have a good ride on the street. Many mistake ride harshness due to springs, but it's usually from too much high-speed valving. A few years ago I drove my car 5 hrs with my family in it, to drop it off for SEMA, at that was with 1000lb springs.

Available in a variety of sizes, include the short 4" versions I needed.



Very light weight, under 2 pounds each (w/o fluid). Precision solid rod end mounts.

[vstol]

Looking fwd to the build!!

https://www.pro-touring.com/threads/...-replica-build

[rjsolo]

Looking fwd to the build!!

https://www.pro-touring.com/threads/...-replica-build

Thanks. Of course mine is nothing compared to your build!

[Neil B]

Yup. Nothing like a silver/gray shark-bodied Corvette with flares.

[ChevelleNV]

Yup. Nothing like a silver/gray shark-bodied Corvette with flares.

Ya, this vette is evil looking I like it....