Mustang MonthlyHow To Drivetrain
Deep Inside the Ford Top Loader Four-Speed Transmission
Top Loader Tip-Off: What makes this classic tough-tested brute four-speed transmission the best in Ford history?
When they said necessity was the mother of invention they must have been thinking of Ford Motor Company in the ’60s, with both the cross-bolted 427ci Side Oiler and the Top Loader four-speed transmission. Both were acts of necessity that led to durability and races won. Ford’s raw determination to win is what led to the greatest lineup of high-performance engines, transmissions, and rear axles in Detroit history.
Ford learned through grueling competition that the Borg-Warner T-10 four-speed transmission just wasn’t up to the mean-spirited twist of its big-blocks and super-high output small-blocks on the race track. Born of this quest to win was the top-loading Ford Design four-speed transmission. Obviously, the Top Loader or Toploader gets its name from its top-loading main case that offers unmatched durability. Arguably, a better four-speed doesn’t exist anywhere else. Although, the Top Loader does have a sibling—the 3.03 top-loading three-speed manual transmission.
Ford’s powertrain engineers were asked to develop a family of rugged and dependable three- and four-speed transmissions scheduled to arrive in the 1964 model year, which would ultimately replace the Borg-Warner manual transmissions Ford was currently offering. We include the 3.03 three-speed transmission because it is a top-loading manual transmission, just like the four-speed Top Loader. At a glance, it’s challenging to tell these two transmissions apart.
Few names in the factory performance transmission industry are better known than David Kee of David Kee Toploader Transmissions in San Antonio, Texas. “The Top Loader’s internal parts are assembled through the top of the case, instead of through a side opening as with the T-10 and other vintage Ford manual transmissions,” Kee tells Mustang Monthly. “The Top Loader four-speed transmission is a fully synchronized type in all gears, except the reverse sliding idler gear that is in constant mesh. All forward-speed changes are accomplished with synchronizer sleeves, instead of sliding gears. The synchronizers enable quicker shifts and greatly reduce gear clash, permitting downshifts into any forward gear while the vehicle is in motion. All forward gears in the transmission are the helical-type. However, the reverse sliding gear and the exterior of the first and second-speed synchronizer sleeve are spur-type gears. The Top Loader is stronger than any other four-speed box that has a side-loading cover. Shifter rails are mounted in bosses cast into the case itself, leaving the only function for the top cover to keep lube inside.”
“Ford’s Top Loader was in production from 1964 to 1973 for nearly every type Ford and Mercury vehicle imaginable, along with a number of foreign cars,” Kee adds. “A 1 1/16-inch input shaft was used with 200ci sixes to the 390ci FE Series big-block. The 427, 428, and 429 big-blocks were available only with close ratio gears. The 1 1/16-inch input shaft transmissions are available in both close and wide-gear ratios.”
“The Top Loader transmission was built in three overall lengths during its production life,” Kee says. “The 1964 to 1965 Fairlane, T.V.R., Griffith, and Sunbeam Tiger Top Loader measures 25 1/2-inches long. Shelby’s Cobra with the 427 and 428ci engines, all Mustangs, Falcons, Mavericks, Cougars, and 1966 to 1967 Fairlanes and Comets used 24-inch-long Top Loader transmissions. All full-size cars, as well as the 428, 429 Cyclone, and Torino, used the 27-inch-long box. The 1964 Top Loader that first year used a small four-hole main case with the small O.D. bearing retainer. All 1965 to 1973 cases were wide four-hole cases with the large O.D. bearing retainer.”
“In 1964 and early 1965, a few Top Loader four-speed transmissions used a 25-spline output shaft, which proved to be inadequate,” Kee says. “These 25-spline output shafts were quickly dropped from production. All 200ci to 390 ci engines generally use the 28-spline output shaft. All 427, 428, and 429ci engines use the 31-spline output shaft. There are always a few exceptions, though. Ford’s Top Loader four-speed was produced in 133 different versions.”
01. Here’s the Top Loader’s super rugged main case in raw cast iron. You can get yours and all related parts from David Kee Toploader Transmissions.
02. We’re going to walk you through basic Top Loader assembly protocol to show how this thing goes together. The Reverse sliding, idler gear and shaft assembly is installed first. The reverse idler rolls on a solid shaft with needle bearings doing the grunt work. Thrust washers keep the shaft properly centered.
03. This is the countershaft assembly, which is where gearing through First and Third-speed, plus Reverse, is generated. Power travels from the main shaft to the countershaft gears as you shift through the ranges. This is also known as a “cluster shaft” or “cluster gear” in some circles. Shown here are two countershaft assemblies, the close ratio (top) and wide ratio (bottom). The close ratio is more beneficial for quick acceleration and racing. The countershaft is supported with needle bearings and centered via thrust washers.
Close or Wide Ratio?
Which Top Loader works best, close or wide ratio, and why? Close-ratio is about quick acceleration, which is why you’ll find them in the Boss 302, Shelby Mustang, and other high-performance Ford applications. Wide-ratio makes more sense for open-road driving.
|Fourth Gear:||1.00:1 (Straight Drive)|
|Fourth Gear:||1.00:1 (Straight Drive)|
04. Here’s a Top Loader with both reverse sliding, idler gear and countershaft installed. The reverse idler gear is what provides reverse gear with its square-cut teeth. The reverse shift rail is also installed and forked into the reverse idler.
05. Here’s the Top Loader’s output shaft assembly, which carries the full load of the Top Loader’s internals like synchronizers, gears, and bearings. There are three types of output shafts according to David Kee: The early 25-spline shaft Ford dropped the first year; 28-spline for six, small-block, and light-duty big-block; and 31-spline for high-performance big-blocks.
06. This is the 31-spline output shaft for high-performance big-block power. If you’re going racing with a small-block, it is suggested you opt for the 31-spline shaft while you’re at it.
07. Here is one of two Top Loader input shaft types—1 3/8 inches—the larger of the two. Standard input shaft size is 1 1/16-inches. Both are 10-spline. It is challenging to tell these two shafts apart, but the size difference is significant. The larger 1 3/8-inch shaft is intended primarily for 427 and 428ci big-block applications.
How Does This Thing Work?
Enthusiasts are often mystified by how transmissions work, and Ford’s Top Loader four-speed is no exception. David Kee helps us understand the function. “In first-speed, the first and second-speed synchronizer sleeve is moved rearward by the shift fork. This sleeve engages the first-speed blocking ring, which acts as a cone clutch applied to the freewheeling first-gear. This action speeds up or slows down the first-speed gear to match the speed of the output shaft. Further movement of the sleeve locks the first- and second-speed synchronizer hub to the first-speed gear by means of internal splines.” Kee adds. “Upon engagement of the engine’s clutch, power flows through the input shaft and gear to the meshed countergear, and then to the first-speed gear. This gear transmits the power through the locked synchronizer hub to the output shaft. All other forward-speed gears are in idler motion and are driven by the countershaft gears, but transmit no power because they are not locked to the output shaft. All other forward-speed shifts are manufactured in the same manner as the first-speed shift with to the constant mesh feature. The shift to the fourth-speed locks the third- and fourth-speed synchronizer sleeve to the input shaft. This allows power to flow straight through the input and output shafts.”
The greatest asset the Top Loader has going for it is durability. This is a high-performance four-speed transmission able to take just about anything you can throw at it power wise. It is always suggested you opt for the 1 1/8-inch input shaft and 31-spline output shaft if you’re planning large sums of power.
White Stripe Top Loaders
Kee explains limited production Top Loader transmissions Ford built for factory-backed race cars back in the day. “White stripe Ford Top Loader racing transmissions were used in factory race cars. Gear ratios were custom tailored to the car or track where they were raced. White stripe Top Loaders are extremely rare. The HEH code is hand-stamped into the case, and a white stripe was painted over the casting numbers on the cast-iron units.” Kee shows at least two examples of white stripe Top Loaders with aluminum cases on his website, as used in SCCA Trans Am road race cars. Most, though, were cast iron. “A very small number of these aluminum cases were produced—maybe 10,” Kee adds. Look for XAA-stamped experimental castings in your travels.
08. Here’s the Top Loader’s main case with shift rails. Shift rails are firmly bolstered in this transmission’s main case and not a side cover, which is but one reason this transmission is desired by enthusiasts and racers alike.
09. Casting numbers tell us something about a particular Top Loader main case, extension housing, and the front-bearing retainer. Even though it is labeled C5AR, that doesn’t always mean it is of 1965 vintage. Look for the casting date code. According to Kee, there are two basic Top Loader main cases, narrow four-bolt pattern for the five-bolt bellhousing and the wide eight-bolt pattern for six-bolt bellhousings. However, there’s more. Shift rails and forks should match the main case. Visit the David Kee website for more details davidkeetoploaders.com.
10. A Top Loader’s identification tag provides concrete information about where the main case originated. However, most of these transmissions have been rebuilt, which makes whatever you’ve found dicey at best. It’s a good idea to open the case and examine what’s inside. If anything, you will want to know if it’s close or wide ratio. You wouldn’t want a wide ratio for your Boss 302 or Shelby G.T. 350, for example.
11. The output shaft and all related components were loaded into the main case at Anaheim Gear. All shift rails have been installed. There are six different types of shift rails used in Top Loader transmissions, Kee advises us. Most of it depends on which main case you have. The shift rails, forks, and main case should match.
12. The input shaft has been installed and fitted into the output shaft assembly at the third- and fourth-speed synchronizer, which is already installed. The input shaft rides on needle bearings and the third- and fourth-speed synchronizer at the leading edge of the output shaft.
13. Here’s a close ratio Top Loader in the MCE Engines Raptor Mustang road-race car fitted with a Hurst Competition Plus shifter. All shift rods are adjusted by disconnecting each rod at the transmission’s shift rails. The transmission and shifter must both be in neutral. Once the shifter is centered and in neutral, rods are adjusted until the point at which there’s no load on the rod. This puts everything in neutral.
14. Hurst shifters, as one example, have shift-throw limit stops fore and aft. These stops either lengthen or shorten shifter travel.
15. Factory shifters, which are notoriously sloppy, adjust at the shifter instead of the transmission. Both throw limits and finite calibration happen at the shifter. The example shown is not a Mustang application. However, the adjustment protocol is the same. Stock shifters get sloppy because shifter handle side cups and springs wear and fall out. Then, the shifter handle feels like a broomstick in a barrel.
|Top Loader Main Case Identification|
|Note: A partial VIN (Example: 8F123456) was stamped in the main cases of high-performance applications, such as 289 High-Performance, Boss 302, 390 High-Performance, 428 Cobra Jet, for identification purposes. Courtesy David Kee Toploader Transmissions.|
|Top Loader Bellhousing Identification|
|1965||289 5-bolt block||C3AA-6394-C|
|1965-1967||289 6-bolt block||C5DA-6394-A|
|1965-1967||390/427/428 (11-inch clutch)||C5AA-6394-A|
|1966-1969||390 GT (11 ½-inch clutch)||C6OA-6394-B and D|
|1968-1969||302||C8AA-6394-B (cast iron)|
|1968-1969||390 GT/428 CJ (11½-inch clutch)||C8OA-6394-A|
|1968-1969||428 CJ/SCJ (after 2-15-68)||C8OA-6394-A|
|1969||390-428 (11-inch clutch)||C9AA-6394-C|
|1969||428 CJ-SCJ||C6OA-6394-B and D|
|1970-1971||429 Boss (after 2-2-70)||C9AA-6394-E|
|Top Loader bellhousings must measure 6 1/4-inches deep. If it measures 6 3/4-inches deep, it is a truck bellhousing and should not be used. Courtesy David Kee Toploader Transmissions.|
16. The input shaft should be inspected and dressed to ensure a smooth fit into the clutch disc. Any burrs or imperfections can cause the shaft to hang up during installation. This can also cause clutch engagement and disengagement issues during operation.
17. Always use a clutch pilot bearing for smoother operation. Bushings are cheaper, but you get what you pay for. Pilot bearings are worth every penny.