The World in 5

A complete buyer’s guide to street manual five-speed gearboxes

Word: Jeff Smith; Photos Courtesy of the companies, Jeff Smith

Not all that long ago, if you wanted a performance manual transmission you could have any trans you wanted, as long as it was a four-speed. That was it — four forward gears with a limited number of ratios.

It was a simpler time, for sure. The problem was that fourth gear was always 1:1. What that meant for a street car was if you were sporting a set of 4.56:1 rear end gears, highway cruising wasn’t something you looked forward to since even at a pedestrian 60 mph you were probably spinning the engine close to 3,500 rpm.

Thankfully, the world is now full of manual gearboxes that not only offer overdrive ratios, but can also transmit copious amounts of torque and horsepower without fear of sawing themselves in half. In fact, there are so many choices in the overdrive market we decided to concentrate just on the five-speeds.

There are several veteran gearboxes worthy of note, as well as a couple of newcomers you may not have heard about. We’re going to cover all of their important aspects from gear ratios, to torque capacity, weight, and even whether these boxes have reverse synchronizers.

The five-speed boxes under our review are the Richmond Street 5 speed (originally the Doug Nash 4+1), Richmond’s newer Street 5 Speed OD, the new Legend LGT-700, the latest addition Muscle 5 trans from McLeod, the Tremec TKO 500 and 600 versions, and a selection of T-5-based transmissions from Modern Driveline and G-Force, among others. We even discovered a Mopar-specific five-speed from Passon Performance that looks very strong. We won’t include the Mustang-specific T-45 five-speed that came in 1996-’02 Mustangs as it does not appear to be a suitable performance candidate.

The Breakdown

If we had to narrow down transmission selection into just two major categories, it would have to be the combination of gear ratio selection (emphasizing First gear) and torque capacity. This is interesting because for a street car, these two factors can go hand-in-hand.

We’ll start with torque capacity, although for a typical street car, most if not all of these transmissions will be capable of handling the power created by typical street small-block engines. As an example, a properly built, normally-aspirated street engine with good flowing heads and a decent cam can make 1.25 lb-ft of torque per cubic inch. So a 400c.i. small block would be capable of making around 500 lb-ft of torque (400 x 1.25 = 500).

With big blocks, the numbers grow pretty quickly, with a 468c.i. Rat motor for example capable of close to 600 lb-ft of torque. It’s this twisting effort that a manual transmission must endure. Smaller displacement engines that spin much higher have a different requirement since these engines will stress shift quality above 7,000 rpm. Here, the extra weight and mass of larger gears makes that a more challenging situation and places emphasis on reduced gear deflection under load and synchro design.

With all this in mind, 21st Century manual transmissions must be capable of handling more torque than a ’60s era four-speed. One way to evaluate any manual transmission’s torque capacity is to look at the transmission’s center-to-center distance. This is the distance between the centerline of the input shaft and the centerline of the cluster gear.

As this distance increases, it allows larger gears to be used, which increases the tooth size and overlap between the input and the cluster. This is not the only criterion for estimating transmission strength since gear material, tooth design, heat treatment, and a dozen other factors play a critical role in power capacity, but this is one simple way to help establish a transmission’s capacity to transfer power from the engine to the rearend.

Another important factor in power capacity is the actual First gear ratio. The power path through a manual transmission starts at the input shaft and, except when the input and output shafts are tied together in 1:1, the power then extends down to the cluster where it is routed back up through the mainshaft. This means the tooth engagement between the input shaft gear and the cluster must transfer and withstand the torque input in First, Second, and Third gears.

This means the First gear ratio has a direct effect on torque capacity, much like the relationship between the pinion gear and the ring gear in a rearend. As the ratio becomes deeper (numerically higher), the pinion gear becomes smaller in diameter with fewer teeth, while the ring gear tooth count increases.

The same is true with a manual transmission. For example, as the First gear ratio gets deeper (again, numerically larger numbers) the capacity of these gears to support torque is reduced. This is evident in technical data from Richmond in rating its Super T-10 four-speeds. They rate their 2.43:1 First gear transmission at 375 lb-ft of torque capacity, but that same transmission with a 2.88:1 First gear ratio is only rated at 300 lb-ft. That doesn’t mean the transmission won’t survive behind a strong engine; we have first-hand knowledge using the 2.88:1 trans in a 3,500-pound street car raced in numerous track days, drag races, and autocross using a 420c.i. small block that consistently makes 550 hp and 560 lb-ft of torque.

So you can see there’s probably quite a bit of room in torque ratings since there does not appear to be a standardized test employed in establishing these ratings.

Another aspect worth noting with regard to First gear ratio is the deeper the First gear ratio, the farther away it is from Fourth gear’s 1:1. This means there must be a greater rpm drop between each gear ratio in between First and Fourth to accommodate this deeper ratio. The greater the rpm drop between gears, the slower the maximum potential acceleration rate.

Stated another way, close ratio transmissions usually offer a taller First gear ratio but minimize the rpm drop for each gear change. The compromise is to find a First gear ratio deep enough yet still minimizing the rpm drop for each gear change. We plugged the ratios of a TKO 600 transmission into the Quarter Pro drag strip simulation program and shifting at 6,500 from Third (1.34:1) to Fourth gear (1:1) drops the rpm a touch more than 1,300 rpm.

We will evaluate each transmission separately, offering their specs for comparison. Beyond strength and price, it is our opinion the transmission’s First gear and overdrive ratios are the most important (but not the only) considerations for choosing a five-speed manual trans.

Each vehicle will have different requirements affecting which First gear and overdrive ratio that might be ideal. But for many muscle car and street performance applications, it would appear First gear ratios between 2.40:1 and 3.00:1 will be the most popular, based on the street rear axle ratios spanning 3.00:1 to 4:00:1.

Rather than waste any more space, let’s dive into the details for each of these transmissions. See if one in particular jumps out as the one best for your car or truck.

Ford and GM T-5

We thought we’d start with the smallest and lightest of the five-speeds. This transmission actually started life as a mild-mannered gearbox for the 1980 AMC Spirit/Accord and made its performance debut in 1983 in 5.0 Mustangs.

The only T-5 worthy of discussion are the World Class (WC) boxes introduced in 1985 in 5.0 Mustangs and later in V8 Camaros and Firebirds, behind the 5.0L engines only. Since then, companies like D&D Performance, Modern Driveline, and G-Force have upgraded components and gear sets to produce a transmission that is durable enough to hold up behind 400 lb-ft of torque small-block engines.

The advantage of this transmission is it is the lightest of the performance five-speeds at around 70 pounds. One reason is be-cause this transmission also has the smallest center-to-center distance at 3.03 inches.

The V8 version boxes spin a 2.95:1 First gear although G-Force also sells a 2.42:1 gear set that can be considered the closest to what we might call a close-ratio set. G-Force claims its stronger drag racing gear set can handle as much as 500 lb-ft or 600 hp in a 3,300-pound car with a drag radial tire.

Modern Driveline says its modified T-5’s are often used behind 450 hp engines, but they and G-Force prefer to deal one-on-one with specific customer applications. Stock WC T-5 transmissions are typically rated at 375 lb-ft.

The T-5 is an internal rail shifter transmission, which places the shifter inline with the transmission with internal linkage. When transplanting this transmission into an earlier car, you should know that sheet metal modifications will inevitably need to be made to the floor pan to accommodate the shifter because older, external shifter transmissions offset the linkage to the driver’s side of the tunnel.

Red Roberts’ Driveline Components builds offset shifters for the T-5 and other single rail transmission like the T-56 that allows you to reposition the shifter closer to its original location. His contact information is listed in the source guide.

McLeod Muscle 5

This is the latest addition to the aftermarket five-speed lineup from McLeod. This transmission is loosely based on the T-5 mainly because the center distance is the same as a T-5 and the gear ratios — at least the First offering — are also the same as the V8 GM T-5. Improvements include 8620 steel gears and a 32-spline output shaft, which is significantly larger than the production T-5’s 28-spline.

Most of the other transmissions in this range use the 32-spline output, which is most commonly used with the TH-400 automatic and higher output four-speeds. The input shaft is also slightly larger with a 1 1/8-inch diameter, 26-spline that is larger and stronger than the T-5.

McLeod chose to base this transmission around the T-5 primarily to save space. The transmission is among the smallest case transmissions and will fit under tight early muscle car floor pans with clearance compared to larger transmissions like the T-56.

The Muscle 5 is also a single-rail transmission so the shifter is positioned roughly equal with the transmission centerline. This will offer challenges and require some sheet metal changes to certain body styles. Currently, McLeod is offering this transmission only in the GM configuration, but future plans include Ford and perhaps Mopar applications.

One of the Muscle 5’s selling points is this transmission utilizes a strengthening plate located where the input shaft ties to the output shaft. In production T-5 transmissions, deflection in this area is often the cause of Third gear failures.

The Muscle 5 increases its strength by placing a bulkhead to stiffen this area and prevent the main shaft from migrating from the cluster gear. So, if you are looking for a lightweight five-speed that can take some abuse, this might be a good choice. The transmission is new enough we have not had a chance to experience it first-hand. But by all appearances, it would make a great street five-speed, especially with its 37 percent overdrive.

Legend 700

This is also a relatively new five-speed produced by the Legend Gear and Transmission Company.

The transmission gets its name from its torque rating of 700 lb-ft that was tested at this level in each of the forward gears, including overdrive. This is a robust transmission with a center distance of 3.35 inches, which places it in the same category as the T-56 six-speed at 85mm.

The trans is currently offered in two different 2.66:1 and 2.97:1 First gear ratios with either a 0.80:1 or 0.69: 1 overdrive.

As we mentioned in the intro, strength is created by building upon several different layers, and the Legend trans offers not only steel gears but 4140 steel shift forks with bronze shift pads and forged steel blocker rings.

The synchros use current technology carbon-Kevlar friction liners and Legend specifies using a Monolec ATF trans fluid for lube. Speaking of synchros, this is the only trans in our collection with a synchronized reverse gear. So no more crunching gears into reverse.

The company’s technical specs reveal as many as 10 different shifter locations designed to make this transmission a direct fit for most popular applications. In fact, the trans face has provisions for nearly all performance GM, Ford, and Mopar transmission bolt patterns.

Like many of the newer transmission designs, this is a single-rail shifter transmission with the shifter inline, but shifting at high rpm should be easier since it only moves one rail, while many of the other transmissions move two rails during critical gear changes like from Second to Third.

The Legend also offers multiple tail shaft configurations that reposition the shifter to a driver-side bias to fit older muscle car floor pans without modification. You can also spec an optional REM finish for the gears that should be beneficial for reducing trans operating temperature.

The multiple shifter and other options also push the price between $3,495 to $5,000, making it one of the most expensive transmissions in this review. But if it will take 700 lb-ft of continuous torque even in overdrive, it might be worth it!

Richmond Street Five-Speed O.D.

Until now, we’ve been dealing with internal rail transmissions. The Richmond places the shifter on the outside, like the older four-speeds from the ’60s and ’70s.

Because of its unique design, the price reflects the fact the trans comes with a Long-style shifter. This transmission was designed to directly replace Richmond’s line of Super T-10 four-speeds, so the case is the same length as the Super T-10 and employs a TH-400 style 32-spline output shaft.

This means other than having to modify the floor to accommodate the shifter, this transmission is literally a bolt-in, at least for some GM cars.

The trans also sports the widest center distance of any of the transmissions listed in this review with a 3.50-inch distance, and with its 600 lb-ft of torque rating, it appears it can back that up.
Weight is a bit of an issue as it nearly equals the Legend at 106 pounds, but this is a direct result of gear size. Our suggestion would be the 2.89:1 gear ratio as the other two First gear ratios are deeper but retain the same Second through Fifth ratios.

This makes the rpm drop between First and Second more precipitous. Richmond offers these transmissions for most popular engines including Ford and Mopar applications although early Fords and Mopars may need floor pan massaging in order to accommodate the larger case.

The case design is also reminiscent of the older Richmond five-speed with its vertically split case to make servicing the transmission easier. It sports a large, engine-specific input shaft and the TH-400 style 32-spline output shaft that equals the largest of all the five-speeds. Like all these aftermarket transmissions, the Richmond comes with a back-up light switch as well as a mechanical speedometer drive.

Richmond Five-Speed

Before the Richmond Street Five-Speed Overdrive transmission hit the market, Richmond offered an earlier five-speed that is the only box to not employ an overdrive.

The concept is actually quite interesting and worth closer scrutiny as it offers several benefits not found with its competitors. It’s possible that many enthusiasts might shy away from this transmission because it lacks an overdrive, but that is not necessarily a detriment. The concept dates back to the early 1980s when Doug Nash built the 4+1.

Richmond purchased the tooling for this transmission and continues to build this transmission complete with its vertically split case.

The idea was to stick a deep First gear ratio in front of a close-ratio box that would minimize the rpm drop between gears and then use Fifth gear as 1:1. This means instead of a deep 3.73:1 or 4.10:1 rear gear, you would maintain a stock 2.73:1 or 3.08:1 rear gear. Let’s do some quick math to illustrate the idea.

The most common Richmond version uses the 3.28:1 First gear ratio. Multiply that times a 2.73:1 rear gear and the result is 8.95:1. To put this in perspective, that’s the equivalent of a Muncie close ratio four-speed (2.20:1 First gear) with a 4.07:1 rear gear. Plus, the Richmond 5 maintains a close gear spread.
The largest drop is between First and Second, which is what you want, while the drop from Third to Fourth is a mere 19 percent, which is desirous to minimize the rpm drop. For example, shifting into Fourth from 6,500 only drops the rpm to 5,265 rpm as opposed to other transmissions that have as much as a 28-percent drop (6,500 to 4,680 rpm).

Another advantage to the 1:1 Fifth gear is this is obviously a straight connection between the input and output shafts so no friction or power is lost in the transfer as it would be with an overdrive gear.
The accepted percentage of loss through an overdrive is roughly 2–3 percent. Another minor advantage is when you use the taller rear gear like a 3.08:1 for example, the pinion gear diameter is very large, offering increased tooth contact with the ring gear. Take a look at the difference in pinion diameters between a 4.56:1 and 3.08:1 pinion gears, and you will understand.

The Richmond five-speed is still hefty at 95 pounds but that’s still 11 pounds lighter than its overdrive brother. Its price is around $2,700 without the shifter. The dedicated Long shifter (PN HN-1000) is available separately and runs about $550. It’s important to note this shifter sits very high on the transmission and will require significant floor pan surgery to fit most cars.

Tremec TKO 500/600 Five-Speeds

Perhaps the best known of the aftermarket five-speeds is the TKO 500/600 transmissions. These two transmissions are essentially the same with differences centering on gear ratio selection and torque capacity.

The numbers reflect the torque ratings of the two transmissions with the difference attributable to the deeper First gear ratio of 3.27:1 for the 500 versus 2.87:1 for the 600. These transmissions offer completely different gear spreads, including the overdrive ratios with the 500 at 0.68:1 and the 600 with an even taller 0.64:1 ratio.

These are important considerations since a 36-percent overdrive will turn a 3.73:1 gear ratio into the equivalent of a 2.39:1 rear cog. This might sound good on the surface, but an engine with a carburetor and a big cam may not be very happy at a cruise rpm of 2,160 rpm at 70 mph with a 26-inch tall tire.
Like most modern transmissions, the Tremecs are internal rail shifters, which positions the shifter at the centerline of the driveline.

For older muscle car conversions, there are several companies that specialize in altering the Tremec to fit within the shifter opening of many popular older body styles like the First generation Camaro and early Mustangs. Companies such as American Powertrain, Modern Driveline, Silver Sports Transmissions (SST) and several others offer either converted transmissions or swap kits for a specific application, complete with shifters, crossmembers, driveshafts, and hardware to make the conversion easier. SST even offers a synchro upgrade with bronze shaft arm pads that makes 7,000 rpm shifts a little easier.

Our personal choice between the two would be the 600 as much for its conservative First gear ratio, although its 0.64 overdrive at 36 percent is almost too much, especially for cars with a tall rear gear. Other pluses are its 31-spline output shaft that accepts a Ford C-6 style yoke and a dry weight of only 99 pounds. All of that combines to create a great street transmission.

Passon Five-Speed

This transmission is specifically designed as a Mopar five-speed overdrive replacement for the original Mopar A-833 four-speed.

The trans was designed and built by Passon Performance in Sugarloaf, Pennsylvania, and owner Dave Passon says that unlike generic five-speeds, this trans is a direct replacement for any A, B, or E-body Mopar that originally came with a four-speed.

The trans is rated for 700 lb-ft of continuous torque application, which makes it incredibly strong and capable of living behind a monster stroke RB or Hemi engine.

The trans is compact in outside dimensions yet it is equal to the strongest center distance of 3.50-inches, and the gears are all 9310 alloy steel, offering an exceptionally high tensile strength.

There are three different versions based on the intended body style and extension housing, and the shifter minus handle is included. The case is cast from 356 T6 aluminum, and all the transmissions employ a 30-spline output shaft. Passon also recommends using a 75W-140 synthetic for the gear lube, comparable with the lube generally used with the older manual transmissions.

There is only one gear ratio package available, but it is comparable to the fine-spline pre-’71 A-833 four-speed ratios, with the addition of a great 30-percent overdrive in Fifth gear. If you think about it, it’s just like bolting in an overdrive with no other modifications. Because this is a Mopar-specific transmission, you can expect its limited reach to be reflected in the price at $4,995, but this does include the shifter. This would be a kick-ass trans for a big-inch Max Wedge ’64 Savoy for someone with a penchant for banging gears in the best Ronnie Sox tradition.

Center distances, torque ratings, and weight

As a point of reference, a Richmond Super T-10 four-speed center distance
is 3.25 inches and with a 2.43:1 First gear ratio. The trans weighs 70 pounds
and is rated at 375 lb-ft of torque.

GEAR RATIO MATH
Determining Final Drive Ratio in Overdrive:
Effective Rear Gear Ratio = Overdrive Ratio x Rear Gear Ratio
Example: 0.77 x 3.55:1 = 2.73:1

Final Drive Ratio: (rpm x Tire Dia.) / (MPH x 336)
Example: 2,800 rpm, 26″ Dire Dia., 70 mph
Final Drive Ratio: (2,800 x 26) /
(70 x 336) = 2,800 / 23,520 = 3.09
Final Drive Ratio: 3.09:1

Rpm at a Given Speed: (mph x rear gear ratio x 336) / tire dia.
Example: 70 MPH, 3.55 x 0.64 = 2.27:1 rear gear ratio, tire dia. 26″
rpm: (70 x 2.27 x 336) / 26 = 53,390 / 26 = 2,053
rpm = 2,053

mph = (rpm x Dire Dia.) /
(Gear Ratio x 336)
Example: 2,300 rpm, 26″ Tire Dia., 2.31:1 Gear Ratio
mph: (2,300 x 26) / (2.31 x 336) = 59,800 / 776 = 77 mph
mph = 77

First gear ratios

On the surface, it may appear the ideal First gear ratio for a street performance car would be the deepest (highest numerical) ratio. For most performance applications, that turns out to be not true. Much of this depends on what you plan to do with the car. Let’s start with the transmissions in this story. First gear ratios extend from as deep as 4.41:1 to as tall as 2.66:1. That gives us quite a spread to work with.
It’s essential you know that the Overall First Gear Ratio (OFGR) is the product of multiplying First gear times by the rear gear ratio. The rear tire size will also have an effect on acceleration, but we’ll leave that for a later story. Let’s take that deepest ratio as an example.

Start with a typical street car like a ’71 Camaro with a small block. Let’s say the car weighs 3,600 pounds with a mild 355c.i. small block with a 3.42:1 rear gear and a 26-inch tall rear tire. If we bolted in that Richmond 5-speed with a 4.41:1 First gear ratio, this would produce an overall First gear ratio of 4.41 x 3.42 = 15.1:1.

This probably doesn’t mean much on the surface, but the standard OFGR for a street car is anywhere from 8:1 to 11:1, so right away we can see that this 15:1 ratio is way too deep. To put this in perspective, let’s look at the ratio a different way. That 15.1:1 is the same OFGR as a close ratio Muncie four-speed (2.20:1 First gear) with a 6.86:1 rear end gear. Yikes!

So if your car is equipped with a rear gear anywhere between 3.08:1 and 3.55:1 ratios, one simple way to look for a First gear ratio is to divide the nominal 10:1 by the rear gear ratio to determine a decent First gear ratio. As an example, 10 / 3.55 = 2.81:1. In that case, the Tremec TKO 600’s 2.87:1 is nearly identical. The T-5’s 2.95:1 is also very close. This assumes a 10:1 ratio.

But to change that around a bit, let’s use a different application where the car is now a ’69 Caprice with a small displacement, fuel-injected 5.3L LS engine. In this case, the engine is small, making perhaps 375 to 390 lb-ft of torque, and the car is heavy — around 3,900 pounds. In this instance, the owner probably desires both spirited performance and decent highway fuel mileage.

Plus, the car is currently equipped with a 3.08:1 rear gear. In this case, a deeper ratio First gear would help to get the car moving. Let’s place the overall First gear ratio at 11:1 and dividing by 3.08:1 gives us a First gear ratio of 3.57:1. The closest to that would be either the TKO-500 at 3.27:1 or perhaps the Richmond 5-speed Overdrive with its optional 3.33:1. The performance T-5 variants might also work here with their 2.95:1 ratios, but that would drop the overall First gear ratio to only 9.1:1.

Another consideration should also be the overdrive ratio. In this last case, the Tremec TKO-500 offers a 0.68:1 overdrive, which would reduce the 3.08:1 rear gear to a tall 2.09:1 effective rear gear ratio. In a car with a 26-inch tall tire, that would put the engine at 1,890 rpm at 70 mph. With EFI, that might work well. The overdrive ratios for our five-speeds are between 0.64:1 and 0.89:1 for the road race version of the TKO-600. The 0.64 is pretty steep, while the 0.89 is only an 11-percent overdrive, which for the highway isn’t enough.

One way to quickly evaluate an overdrive ratio is to simply multiply the cruising rpm of your current non-overdrive 1:1 high gear transmission. So, if at 70 mph your current combination spins the engine at 3,200 rpm, then an overdrive ratio of 0.68 would drop to a nice cruising 2,176 rpm at the same 70 mph.
Hopefully these examples have helped you see you can use some simple math to help figure out which transmission ratios would work best for your combination. Often, being conservative will produce the best overall package that you will enjoy driving for years to come.

Sources

American Powertrain
americanpowertrain.com

Bowler Transmissions
bowlertransmissions.com

D&D Performance
ddperformance.com

G-Force Transmissions
gforcetransmissions.com

Jody’s Transmissions
jodystransmissions.com

Legend Gear & Transmission
legendgt.com

McLeod Racing
mcleodracing.com

Modern Driveline
moderndriveline.com

Passon Performance
passonperformance.com

Richmond Gear
richmondgear.com

Rockland Standard Gear
rsgear.com