In our minds, the joy of owning a classic muscle car is 50 percent style and 50 percent experience. There is nothing quite like the visual presence of a late-’60s or early-’70s GM muscle car—whether that be Chevelle, Nova, Camaro, or the like. There’s also nothing quite like driving one of these cars. It’s something about that raw power of a pushrod V-8 and questionable handling characteristics that pushes the engagement well beyond most other driving experiences. If there is one thing that can take that driving experience to the next level, it’s shifting your own gears.
If haste was our upmost priority, we might have just removed the hood, pulled the old engine and trans, then stabbed in our new 383 and five-speed. But dropping in a shiny new drivetrain into the midst of a grimy, 50-year-old engine bay just didn’t seem right. We decided to take the time to pull the front clip and clean everything thoroughly. We also performed a partial firewall smoothing by removing the original heater core and welding in a flat fill panel. Then we coated everything using satin black POR-15 Top Coat to ensure a long-lasting finish.
There’s been a lot of “save the stick” talk over the past decade or so in regards to new vehicles. If you’ve driven modern cars lately, you can understand why. For an automotive enthusiast, you need that added driver engagement because the smooth, quite ride and brisk acceleration of modern cars gets boring quick. A recent Internet meme contends that comparing Tesla 0-to-60 times to other “real” performance cars is akin to comparing a microwave to a barbecue grill—yeah it might cook faster but when was the last time someone asked for a microwave burger? So, if throwing a manual transmission into a modern appliance on four wheels can actually make it fun to drive, just think how a stick would feel in a ’60s muscle car!
TREMEC currently offers seven different variations of the five-speed TKX consisting of Ford and GM styles with different gear ratios. We reached out to TREMEC and they sent us part number TCET18083, which is the GM version with a shorter First gear of 3.27:1 instead of 2.87:1. While it’s not a deal breaker either way, it’ll make it easier to get moving from a stop without needing excessive revs or riding the clutch.
Obviously, we’re not the first ones to figure this out. There’s a reason factory four-speed cars tend to be so dang expensive. Rather than try to find a reasonably priced Nova SS with a stick (do those even exist?), we’ll just make our own. While we’re at it, we might as well add an overdrive gear, too.
Pictured is everything SST sent us for the automatic to manual conversion in our ’69 Nova. They even took inventory, with photos, of each individual component during packaging so we could make sure everything they sent is accounted for.
Remember when we topped our fresh 383ci stroker build with a Holley 650 Double-Pumper? That is because we hoped to back our small-block with a manual transmission. The “on or off” nature of a manual pairs best with mechanical secondaries when you want to put your foot in it. Well, thanks to some fantastic companies in the industry, we were able to turn that dream into a reality. What’s even better is we were able to do it in our home garage with relative ease.
Since we sourced our transmission directly from TREMEC, we had to convert the shifter location and input shaft retainer using the parts supplied by SST. The detailed instructions they sent made this process a breeze.
When TREMEC first announced the TKX a few years back, we knew it was the perfect transmission for our ’69 Nova. A compact five-speed that can handle 600 lb-ft of torque and high-rpm shifts? Yes, please! Up until that point, a five-speed transmission that could handle the torque of even a mildly built 383ci small-block was a big ask. The only other option was the larger, six-speed T56 Magnum, which was overkill for us. Not only would it require extensive floor and tunnel modifications, but we just didn’t see the need for two overdrive gears. As long as we have at least one gear that drops us below 1.00:1 for highway cruising that will be just fine.
If you order your TKX and conversion parts from SST, the correct shifter and input shaft retainer will come pre-installed.
So TREMEC had the transmission we wanted, but how do we actually go about installing it? After being in production for a few years, various companies have developed swap kits for specific applications to help take some of the guesswork out of it. One such company that stepped up to the plate was Silver Sport Transmissions (SST).
Then we bolted the McLeod flywheel to the crankshaft of our small-block Chevy, torqueing the bolts to spec and using thread locker.
As it turned out, SST went well beyond taking “some” of the guesswork out of it, providing everything from the correct bellhousing to the shifter and shift location adapter, clutch master cylinder, concentric slave cylinder, manual brake and clutch pedals, transmission yoke, and fluids. They even send the little things like hardware, transmission isolator, pedal pads, and mechanical speedometer cable. SST also partners with McLeod Racing to provide a complete clutch kit and flywheels for each specific engine and horsepower needs. The only missing piece of the puzzle was adapting our already-beefy Inland Empire Driveline (IED) driveshaft to the new transmission. For that, we reached back out to IED and they were able to help make the necessary modifications.
Using a properly sized socket, we carefully tapped in the pilot bearing supplied by SST.
The entire conversion took around two weeks; working a couple hours each night plus a few half-days on weekends. The only aspects of the conversion we haven’t addressed are installing the new speedometer cable and reverse light/safety neutral wiring. We’ll get to those when we replace our factory steering column.
Next we measured the runout on our bellhousing. SST supplied great instructions on this, but we’ll describe it in short. Using a magnetic base and dial indicator we checked how centered the bellhousing is to the crankshaft. It takes some trial and error to get the orientation just right, but a great trick SST mentioned is removing a couple bolts on the flywheel to provide a flat mounting surface for the magnetic base. In our case, we were just outside the 0.005-inch maximum runout and needed to get a set of offset dowel pins to correct it.We then removed the bellhousing to install our McLeod clutch and pressure plate. We opted for their Super Street Pro line of single-disc clutch, which is designed to handle up to 550 hp. Even though our 383 in current form will only make 400-450 hp, we wanted some headroom in case we install a burlier top end in the future.Our next measurement to verify was the air cushion of the concentric slave cylinder (CSC) or throwout bearing. To do this, we bolted the bellhousing back up to the engine. Using an adjustable square we measured the distance between the fingers of the clutch and the transmission mounting face on the bellhousing.On the transmission, we placed the CSC on the input shaft and compressed it until it bottomed out. Using the same adjustable square, we measured the distance between the face of the CSC to the bellhousing mounting surface on the transmission. SST specified at least 1/8 inch and no more than 3/8 inch of clearance. We were right on the money with 1/8-inch cushion. Without enough space, you’ll be constantly “riding” your clutch and causing premature wear, even with the pedal out. Too much cushion and you’ll have problems getting the clutch to fully disengage.With the bellhousing back on the transmission for the last time, we proceeded to install the hydraulic line to the slave cylinder.Next, it was time for the fun stuff: cutting up our factory automatic transmission tunnel. To get in the ballpark, we measured from the mounting face of the bellhousing back to the centerline of the shifter. Then, with the engine sitting on the motor mounts, we transferred those measurements to the underside of the trans tunnel.From under the car, we drilled a single hole in the center of our measured shifter location. Then, from inside the car, we measured and marked what we wanted to cut. We drilled pilot holes followed by a uni-bit to give a starting point for our reciprocating saw. We only cut a small rectangle out; just enough to get in the ballpark and start test-fitting with the engine and transmission in place.With our runout and CSC cushion measurements taken and hydraulic line hooked up, we were ready to bolt the TKX to our small-block.Next we loaded our new drivetrain into the Nova to see how much more material needed to be removed. We left a fender cover against the firewall to protect from scratches and used a floor jack under the end of the five-speed to control the angle.We cut little by little until we were able to bolt the TKX to the crossmember supplied by SST without the transmission case hitting the tunnel. We aren’t too familiar with the differences in floorpans of the ’68-72 Novas, but ours being an original Powerglide car probably meant we had one of the smallest transmission tunnels. Cars fitted with factory TH350s would surely need less modification.To avoid taking more out of the floor than was necessary, we used our grinder with a 4-inch flap disc to take down a couple ears on the top of the five-speed and give that extra ½ inch of clearance we needed.SST called for the use of a factory four-speed tunnel hump, so we decided we’d modify ours to cover the larger hole in the tunnel. Then, to make it removable, we picked up a rivet nut installation tool for $75 on Amazon and installed a few rivet nuts.This tech story isn’t about how to do primitive at-home fabrication with basic tools and a 120V flux-core welder. As such, we’ll breeze over the modifications done to our factory four-speed hump and just say it does a good job sealing the hole in our trans tunnel. Luckily, it will hide under the carpet, so we’re good with it.To cut out the carpet for the new shifter, we pulled the transmission down out of the way and fitted the carpet where we wanted it. The heavy insulation under our carpet made it tough to mark clearly, so we used some black spray paint to fill the section we needed to remove.As mentioned, SST supplied new factory-style clutch and brake pedals. As always, it’s a little tough working under the dash but replacing our original brake pedal with the new assembly was actually easier than anticipated.Next we moved onto installing the clutch master cylinder. We unbolted the brake master cylinder to give us more working room, then removed the factory cover underneath. Using the backing plate for the clutch master as a template, we drilled the three pilot holes needed.Getting the top two bolts and nuts started can be tough by yourself, so SST recommended using a piece of painter’s tape to hold the bolts in place while going under the dash to thread on the nuts.Here’s a look at the backside of the clutch master cylinder and pushrod installed. It’s important to get the pushrod adjusted correctly to allow for complete travel of the hydraulic master cylinder. When trying to bleed the system, if the pedal can’t come all the way to the top or be pushed until it bottoms out, you’ll end up with air in the lines.SST provides a bracket to mount the reservoir on the same firewall studs as the brake master cylinder. In our case, we also had our proportioning valve bracket mounted in the same place and didn’t have long enough studs to accommodate both. Our quick and clean solution was to tack weld the supplied bracket to the backside of the proportioning valve bracket. Another option would have been to drill two new holes and mount it directly to the firewall.Once the reservoir was mounted with the high- and low-pressure lines hooked up, we grabbed a friend and proceeded to bleed the hydraulic clutch system. To make life a little easier, we used bailing wire to hang our bottle during the process. To make our life more difficult, we neglected to check the fluid level often enough while bleeding, which meant we had to run through a lot more fluid than we otherwise would have.A few years back, after installing a new rearend and suspension, we’d picked up a custom driveshaft from Inland Empire Driveline (IED) in Ontario, California. The shaft and U-joints were still in good shape so we dropped it off with the guys at IED with new measurements. They were able to cut it down to the right length, install the new yoke, balance it, give it a fresh coat of paint, and send us on our way.It was onto the final touches: reinstalling the shifter boot and trim ring. To fit the boot to the trim ring, we flipped the fabric inside out and folded the edges in half up against the underside of the trim ring. Then we used a pick to poke holes for the screws and made marks to trim away the excess fabric.With the TKX install complete and our seat bolted back in the car, we could finally sit behind the wheel and get a feel for what the new and improved driving experience would be like. Now we just have to get rid of that factory automatic steering column and button up all the other odds and ends to get our 383ci small-block fired up for the first time.
