Selecting the right clutch and manual transmission is as important as building a big-power engine. If you are smoking the clutch or breaking transmissions, then all that power you are making might as well be thrown out the window. We had that same problem with our project Riced Rat Rod, with the Dart 400ci small block. We needed a kickass overdrive manual transmission and a good clutch so we turned to the experts at Tremec and SPEC clutch for a TKO and a SPEC Stage 3! Here’s the scoop…

So what does it take to install a Tremec TKO 600 into a Nissan 240SX?

Surprisingly, it was rather easy. Since clearances on the trans tunnel were going to be tight, we opted for an internal hydraulic release bearing supplied by Quartermaster that was made for a 10.5″ push-style clutch. With the bearing shimmed, the transmission mated up with ease to the small block, interjected by a standard Tremec steel bell housing.

We know you’ll love our “tire trick” that long-time hotrodders have used to steady their engine going into their muscle car. Works just as well with a rice machine!

We installed the engine over at the local Nissan performance shop, McKinney Motorsports

We knew that the larger bell housing of the small block was going to require some ‘massaging’ of the firewall to clear. After some light smacks with a dead blow around the tunnel, it was time to shove the 400ci Dart-bred Chevy down into the engine bay. Installation went faster than expected and it was secured with a simple engine mount that was designed by McKinney Motorsports.

For the shifter location, the Tremec TKO 600 shifter sits further forward like a Muncie, which is about four inches shorter than a typical 5-speed based transmission. This means that we had to cut a small recess in the tunnel to allow the Tremec short shifter to sit through.

By the end, we had added a simple extension that bolted between the shifter handle and transmission that put it back in the OEM location. For the drive shaft, we went with a custom piece that used a combination Muncie slip yoke and 240SX rear end bolt pattern. The transmission mount was easy. We actually found out that one of their other transmission mount applications fit perfectly onto the small block, via an Energy Suspension bushing.

Installing the SPEC Flywheel and Clutch on a Small Block Chevy

We are going to go over plenty of details about our Tremec and the choice of SPEC Clutch, but first we’re going to tell you how we did it. As you know, installing a clutch on a vehicle requires removing the transmission out of the vehicle first. Being that our engine was on a hoist, it made our lives a lot easier.

First start by placing the flywheel flush against the crankshaft surface. Try to line up the holes the best you can and make sure you push the flywheel on straight. Pushing at an angle can damage the flywheel. Also, select a quality flywheel bolt. We used ARP’s torqued 95 ft/lbs. Here you can see the SPEC flywheel with the removable friction surface! Trick!

With the pilot bearing installed in the crank, insert the SPEC clutch disc onto the alignment tool and then slide the alignment tool into the crank. Push the end of the alignment tool in firmly because if the disc sags, it won’t line up correctly.

Finally, we installed the SPEC pressure plate with the clutch alignment tool still in place. Use the SPEC-supplied allen head bolts with some thread locker to hold the bolts in place. Tighten the pressure plate as you would a wheel, installing the bolts cross-wise from each other and tighten each bolt slightly at a time until they are all mounted. Remove the pilot bearing tool and you’re done!

If you want to check out this video, check out how fast the Riced Rat Rod revs with our SPEC setup!

Understanding Clutches

The two main parts of a clutch are the pressure plate and the clutch disc. When it comes to choosing a clutch, you’re looking for a clutch that will work with your power level, and be light for a minimum of reciprocating weight. We needed an expert to help us pick a clutch, and those experts were at SPEC Clutch in Alabama.

“Outside power level and driving style, we always suggest going as light as you can go on your budget,” explained David Norton of SPEC Clutch. “Also, you need to make sure that the parts are SFI certified to make sure they hold up to high speed and integrity. The diameter of the clamp, pressure of the pressure plate, and friction coefficient of the material is what determines torque capacity.”

Let’s get educated about clutches – and you’ll have a better understanding of what we chose for the Riced Rat Rod and why.

Clutch Disc: Sprung vs Unsprung

Sideways facing springs in the clutch disc face help absorb vibrations transmitted through the engine – it’s basically a harmonic balancer for the clutch, but also helps street engagement. “The springs in the clutch are going to increase off the line drivability,” Norton explained. “When the clutch is engaged, the springs make for a soft transmit of power. The unsprung is a little lighter and is one piece over the sprung hub.”

The common misconception is that these springs help decrease chatter, which is directly related to the clutch material used. On the flip side, a sprung clutch is typically multi-piece while unsprung clutches are single, where durability can play an issue.

Clutch 101: Clutch Material

Clutch discs are made from different materials at their engagement points. This material can vary from organic, metallic or kevlar. These points are related to the grabbing force of the clutch to hook the flywheel and pressure plate together on shifts.

“Different materials work better in different applications and each material has its place,” said Norton. “The organic is a great material because it is a good value. We add some features like a steel backing which reduces the possibility of fraying that is a problem in OEM applications. Organic is an all purpose material for all forms of racing on a moderate level of pressure.” While a slipping clutch can be related to weak clamping by the pressure plate, it is mostly caused by the inability of the clutch to sufficiently lock the transmission and engine together.

Clutch 101: Full Face vs Puck

Clutch faces work in reverse of how you think they would. A full face clutch is used in street applications, while puck clutches are typically used in racing. The decrease in surface area of the clutch increases the harshness of engagement, but also requires less friction to grab (though a better stronger clutch material). It also weighs less.

“When you decrease the surface area, as long as you have material that can handle the extra pressure, you are raising the pressure per square inch ratio on the material, thus raising torque capacity,” Norton explained. “You have to have a material that can handle the pinpointing of that pressure, as the pressures are extremely high. We find that organic can’t handle that extra pressure, as they will compress. This is why we use a carbon graphite semi-metallic that will handle the pressures and not decrease wear.”

Pressure Plates: Not Just Force

The pressure plate’s job is to apply force, or clamp load, to the clutch disc to hold it firmly to the flywheel. The clutch fingers work as a lever to remove pressure off the disc to disengage it as the release bearing is depressed onto them. The issue is, how much force or pressure is right, and how much is too much?

As you can probably guess, making sure that the pressure plate is providing an adequate clamping force to the disc plays a big role in keeping the clutch from slipping under high load situations. On the turn side, having a clutch with unneeded clamping force may cause unneeded pedal force to disengage the clutch. That is why you need to choose the right level of SPEC Clutch, because even the wrong SPEC clutch is the wrong clutch, period!

SPEC: Picking the Right Stage…

SPEC offers Stage 1, 2, 2-plus, and 3 clutches that we all considered. They also offer more serious Stage 4 and 5, but those were a little too aggressive for our Riced Rat Rod. Let’s take a look at what we considered…

For Stage 1, SPEC molds carbon kevlar with a high performance organic lining for the disc, which helps increase life and soften engagement. This lining comes with a bonded steel backing for strength under high clamp loads and temperatures. The hub is double sprung with spring cover relieves for flexibility, and heat treated components for strength and durability.

Best for: Street and many track / off-road applications. However, we didn’t choose this because our engine was a little too serious for Stage 1.

The Stage 2 clutches come in a full Kevlar disc with a steel backing for additional safety. Kevlar is not a harsh compound and is still OEM-like in engagement, but with a higher torque capacity. The hub is double sprung and heat treated to further help engagement.

“The Kevlar material is great for drivability,” SPEC explained. “It has the nicest drivability of any of the performance materials. It is also really easy on the surfaces of the flywheel and pressure plate. The only downside is that it is not as tolerant to high temperatures from slipping the clutch. For applications where you are slipping for extended periods of time, it isn’t recommended, but for an application like drag racing it is perfect. Our NMRA Factory Stock / Pure Street guys love it.

Best for: Drag racing, Street / Strip. We didn’t choose it because we are going to be slipping our clutch in some motorsport activities (drifting, autocross, etc.).

The Stage 2-plus is a hybrid creation between the Stage 2 and Stage 3, featuring a multi-friction disc in a full faced configuration. One side of the disc is a carbon semi-metallic and the other is Kevlar. This step allows for the same stock pedal engagement, but with 15-20% higher torque capacity. Again, the hub is sprung to help soften engagement. Great for street, drag, autocross, road racing, pulling, rallying and drifting.

“It is a combination of Stage 2 and 3,” according to Norton. “It has some semi-metallic and Kevlar fiber in it. This allows for a little more aggressive hit over the Stage 2 and still has great drivability for the street with a higher torque capacity.”

Best for: Street, drag, autocross, road racing, drift (think all-around). WE REALLY considered the Stage 2+. However, we want a puck-style clutch for possible nitrous use.

The Stage 3 moves from a full face clutch to a puck-type disc. Now on the stage 3, the pads are full carbon semi-metallic. The Stage 3 is the clutch we went with, and it is surprisingly easy to engage for a puck. Virtually no chatter whatsoever. SPEC designed the Stage 3 for dual purpose cars – street cars that also see a fair amount of track time. Great for street, drag, road racing, pulling, rallying and drifting.

“Our metallic pads are different than most, using a lot of carbon and graphite in the pad. So our puck clutches are something we really worked on to make it as drivable as possible. Semi-metallics and pucks are when you need extreme torque capacities.”

Best for: Track cars that see street use. This was our clutch!

Now that we’ve shown you the clutch, let’s check out the transmission.

Tremec’s Trusty TKO-600 5-Speed Transmission

Those familiar with 5-speeds will notice that the TKO-600 is about the same size as a conventional 5-speed. Those familiar with classic Chevy muscle cars will further notice that the TKO-600 looks similar to a Muncie 4-speed.

The TKO-600 is Tremec’s top-of-the-line 5-speed transmission for vehicle applications. It has many features that make this transmission work in everything from a classic Nova to a Nissan 240SX, as showcased in our “Riced Rat Rod.”

From the TKO 500 came the upgrade, the TKO 600. “The 100 foot pounds of torque difference is made from the 10 spline input shaft that is used from Ford applications,” explained Nate Tovey, Marketing Director of Tremec Transmissions. “The GM style 26 spline input shaft is what gives you the additional surface area. As well, the 600 uses a 2.87:1 first while the TKO 500 uses the 3.27:1. The 3.27 is much more aggressive. The smaller gear of the 3.27 will not allow as much torque of the larger 2.87.”

The TKO is really popular for retrofit applications, meaning guys that are converting from Muncies to Chrysler 4-speeds. It is stronger, smoother shifting, and has overdrive. Also, the multi-shifter configuration works well for custom work. “It’s the Swiss Army knife of transmissions, it’s so versatile,” said Tovey.

In addition to being light, the higher center distance from main shaft to counter shaft allows for larger gear sizes and higher torque carrying capacity. They also offer close gear ratio (2.87 and 3.27) models, available for high-performance racing applications

Internally, the robust transmission design comes with a 3-rail shift system with cast iron shift forks. All gears and shafts are made from special grade steel (ASTM 4615) that permits increased torque carrying capacity

The TKO-600 even comes equipped with a short-throw billet aluminum shifter that isolates road noise, while providing clean crisp shifts. Tremec includes the standard, furthest back location shifter but with the two other removable top plates on the transmission, you can move the shifter to a total of eight other locations.

As for electronics, the transmission comes equipped with a neutral safety switch and back-up light circuit. There are also dual electronic and mechanical speedometer pick-ups and it comes with an electronic speed sensor installed.

Other features include three unique crossmember mounting configurations, three different input shafts, and three available overdrive ratios.

Rice Rat Rod… An ‘Ode For The Future’

Planning for the installation of the SPEC clutch, Quartermaster release bearing, and Tremec transmission took a little preparation work to make sure that all of the components worked together.

In the end, the installation couldn’t have gone more smoothly. The SPEC Stage 3 clutch engages like an OEM clutch with extremely light pedal pressure, but it’s still able to hold all the power we can throw at it. The Tremec transmission shifts smoothly and has great gearing for all sorts of driving we have used it for.

Next up for the Riced Rat Rod? FAST wide-band O2 sensor installation!