1973 Chevy Camaro - Transmission Swap - 5 Deep
Modern-Day Fun In An Old-School Package
From the October, 2008 issue of Chevy High Performance
By Henry De Los Santos
Photography by Henry De Los Santos
Quick NotesWhat we didSwapped the TH350 for a Classic Motorsports Tremec TKO five-speed
Bottom LineThe commute just got better
Cost (APPROX)$3,600 to $4,800
Automatics work great if you want to check out the view during road trips or if you're trying to lock down those e.t.'s with your 1320 brawler. However, there's something to be said for manually shifting a street machine; fact is, you're in total control.
Last month, we introduced you to our latest second-gen Camaro and even outfitted it with a few personal touches. This month we dive head-first into transforming our '73 into the ultimate street machine, trekking out to Classic Motorsports Group in Carlsbad, California.
If you didn't already know, CMG is known for its incredibly complete five-speed conversions and offers three kits (Basic, Deluxe, and Elite) which allow you to pick and choose based on what fits your application and budget. If you're looking to simply upgrade your factory four-speed Muncie, you'll find the conversion can be made with minimal components. And whether you're going for the full-tilt package or tossing the automatic in favor of a stick, a number of options are available, ranging from clutch upgrades to an all-new bellhousing, a hydraulic throwout bearing system, and a 3-inch-diameter driveshaft, along with your choice of shifter assemblies and handles.
Our conversion from a factory automatic to a five-speed required cutting a hole in the tunnel to allow the stick of the Tremec to come through. Additionally, we needed to purchase the clutch pedal assembly and shifter boot, and we had to cut the carpet for the shifter. If this is something you've been interested in doing for yourself, know that the CMG's Elite package is the most complete system out there. Truth be told, it'll take a little elbow grease to get the job done for a first-timer, but it's definitely doable in a weekend. And should you run into a snag, CMG's tech line has the experience and the know-how to get you through your conversion.
PerspectiveThis was our first major modification to the '73 and one we'll never regret. CMG recommended we take it easy for the first 500 miles, so our first leisurely cruise took us through a series of winding turns in our local canyons, giving us the perfect opportunity to row the gears and just get a better feel of the new setup. While we were told that the first few shifts would feel a little tight and a bit on the notchy side, it certainly wasn't the case-at least not in our minds. It was quite the opposite. Each shift felt smooth and went into every gear on command with little effort, and even better, match-revving the rpm on downshifts proved to be solid. Final verdict: The five-speed swap has given the '73 a whole new attitude and feel, and it's every bit more fun to drive.
Use only GM Synchromesh (PN...
Use only GM Synchromesh (PN 12345349) or Pennzoil Synchromesh. It takes 5.28 pints of synchromesh to fill up the transmissionEvery trans includes the wiring for a neutral safety switchAll kits come with a special pigtail connector that clips directly onto the reverse-light switch connectorAll kits come with a custom-built mechanical speedometer cable with integrated adapter and gearElectronic VSS kits are also available for aftermarket gaugesThe Tremec TKO-600 is rated to handle up to 600 lb-ft
Prior to disassembly, Jim...
Prior to disassembly, Jim Goodlad, known as "GM Jim" throughout the Internet, is responsible for R&D and new product design. He started by checking out the driveshaft angle with the suspension unloaded, which showed 20 degrees. To check the pinion angle, he then rotated the driveshaft 90 degrees and found it at 16.5 degrees, giving a total of 3.5 degrees working angle. While this isn't necessary, it's a good practice to follow because it provides a baseline to ensure that the new setup will drive smoothly with no vibration.
Using a trans jack for support,...
Using a trans jack for support, we disconnected the exhaust and removed the starter. Since our transmission lines were pretty beat up, rather than trying to salvage them, we went ahead and cut them. Just make sure to have a pan handy underneath or else you're in for a mess. From there, it was only a matter of removing the bellhousing bolts from the motor (three on each side) and the tranny was out. The passenger side can be a little more challenging due to header and cooler line clearance. The scary part-every bolt was only finger-tight.
With the flywheel removed,...
With the flywheel removed, Goodlad used an abrasive wheel to clean up the back of the block. Then, using a file, he checked the block for any imperfections that could prevent the new bellhousing from sitting flush. Once everything checked out, he installed the needle roller pilot bearing with a flat drift. He emphasized the importance of using a flush tool rather than the end of a socket; any bearing distortion could make it hard to install the transmission and even cause premature bearing failure.
The Elite kit comes with a...
The Elite kit comes with a nodular iron flywheel and hardware, but we opted for the SFI-approved billet steel upgrade for an additional $150. If you're using the supplied ARP moly lube, you'll want to torque the flywheel bolts to 70 ft-lb; otherwise it's 90 ft-lb with conventional oil.
The Elite kit also comes with...
The Elite kit also comes with a heavy-duty clutch kit rated at 425 hp and includes a disc, a pressure plate, a throwout bearing, an alignment tool, and hardware. Since we upgraded to the billet flywheel and have a motor making a significant amount of power waiting to be dropped in, we went with the Strip Comp rated at 700 hp for $345 more. Once it was secured in place, Goodlad torqued the 3/8-inch bolts to 35 ft-lb.
You can skip this step if...
You can skip this step if you're using the mechanical linkage. Because we were using a hydraulic throwout bearing setup, prior to placing the hydraulic bearing the antirotation stud was installed onto the input shaft retainer collar.
Included in the kit is an...
Included in the kit is an aluminum reproduction version of GM's 621 bellhousing. It is precision-built for a perfect fit, machined within 0.005 runout, and comes with the ball stud, a factory inspection cover, and hardware.
The self-adjusting hydraulic...
The self-adjusting hydraulic throwout bearing assembly comes complete as one unit with custom braided lines and slides right over the input shaft. The two braided lines that attach to the bearing are a bleeder line up top and a lower line that connects to the compact master cylinder.
If you don't have a factory...
If you don't have a factory console (or are converting a factory automatic to stick), the stock Tremec shifter mechanism centered in your floorboard is more than adequate. If you're looking for a true bolt-on shifter from a four-speed conversion that'll position the shifter stub in the factory location without cutting or modifying the trans tunnel, then the optional offset shifter is the way to go. It'll cost an additional $295, but that's a bargain if you don't want to cut or are planning to eventually install the factory console.
Because we were starting with...
Because we were starting with an automatic car, the tranny had to be mocked up from underneath to see where the shifter hole needed to be cut. Once it was positioned, it was only a matter of hitting it with a punch, then using a jigsaw.
The CMG crossmember is mandrel-bent,...
The CMG crossmember is mandrel-bent, 0.120-inch-wall, 1020 carbon-steel tubing with CNC-cut flanges, and features precision TIG welding. Translation: It offers a perfect fit with serious rigidity. All kits come with an Energy Suspension polyurethane mount for longevity. If your body mounts are crushed or if you have floor sag, you will have to play with it a little to get the crossmember to fit properly. We had both issues, but it still went together with minimal effort.
Hydraulic Vs. Mechanical
If you're debating which route to go, then pay attention: If it's simply a desire for easier pedal effort, the hydraulic throwout bearing will not be the end-all cure. We had the opportunity to feel both, and when matched to the proper pressure plate with the correct pedal geometry, you can expect both to operate similarly. The only difference we noticed is that the hydraulic had a "peak" feel, then depressed fairly quickly, while the mechanical seemed to allow you to feel a wider range of motion.
Something else to consider is the price. CMG offers a trick hydraulic setup with the lines, bearing, master cylinder, and firewall mounting bracket as a $745 upgrade. If you want it solely for the sake of having it, then at least you're being honest with yourself. Where that system comes in handy is if you have limited space and can take advantage of its rather compact package. Another consideration is the headers. Do you have a custom set? Do you have money invested in the coating? Also, automatic-only tubes can potentially cause clearance issues with the mechanical linkage.
What can you expect in the CMG conversion? Everything you see here, and as we mentioned earlier, you also get your choice of upgrades, such as the beefier driveshaft anytime your powerplant gets in the 500hp range, and choices of clutch and pressure plate assembly, scattershield, flywheels, and pedal assemblies. Should you want the hydraulic throwout bearing over the conventional one, expect to add an extra $745.
If you're simply swapping over your four-speed to a five, you can opt for the Deluxe kit, which comes with your choice of the TKO-500 or the stronger TKO-600, driveshaft, custom crossmember, shift knob, speedo cable, reverse light connector, tranny mount, pilot bearing, hardware kit, and the one-year extended warranty, for $2,695 ($2,755 for the TKO-600). Ultimately, it's a one-stop shop; it's only a matter of choosing the package that fits your needs.
This was our first major modification to the '73 and one we'll never regret. CMG recommended we take it easy for the first 500 miles, so our first leisurely cruise took us through a series of winding turns in our local canyons, giving us the perfect opportunity to row the gears and just get a better feel of the new setup. While we were told that the first few shifts would feel a little tight and a bit on the notchy side, it certainly wasn't the case-at least not in our minds. It was quite the opposite. Each shift felt smooth and went into every gear on command with little effort, and even better, match-revving the rpm on downshifts proved to be solid. Final verdict: The five-speed swap has given the '73 a whole new attitude and feel, and it's every bit more fun to drive.
Each Deluxe and Elite package...
Each Deluxe and Elite package comes with a driveshaft. For first- and second-gen Camaros, CMG offers complete bolt-in pieces with Spicer U-joints and a C6 slip-yoke, rated up to 500 hp. If you're generating more power (or whenever the application requires a driveshaft that's 50 inches or longer), CMG recommends stepping up to the 3.5-inch-diameter steel or an aluminum driveshaft. Larger 1350 U-joints are also available for higher horsepower applications.
Shown here is the hydraulic...
Shown here is the hydraulic throwout bearing's master cylinder and linkage, which slides through the CMG billet aluminum firewall mount bracket (arrow). The bracket alone is a vital custom-made CMG piece that provides support for the thin firewall as well as proper geometry for the pushrod and the way it's angled; it is designed to clear boosters.
For the remote mount reservoir...
For the remote mount reservoir kit, CMG provides an ample amount of line for placement wherever it works best for your particular application. During our installation, we made a custom mount from a 31/4-inch strip of 1/8-inch-thick metal to place it next to the brake master cylinder.
Whether you need a clutch...
Whether you need a clutch pedal for the hydraulic bearing or the complete linkage for a mechanical setup with the Z-bar, CMG offers a total package deal as an upgrade.
Our carpet is pretty ragged,...
Our carpet is pretty ragged, and until we replace it, we're waiting to mount the shifter boot and trim. Nevertheless, the shifter has that classic appeal, and the ball on top of the retro handle says it all.
There you have it, from start...
There you have it, from start to finish. The CMG Elite kit is a complete, turnkey package that's constucted from a serious amount of R&D. Then again, when you have a bunch of gearheads who wrench on their own cars as test vehicles, it really shouldn't come as a surprise when their system delivers what they promise.