What is a T18 Transmission?
The T18 is a top-loading 4-speed manual transmission built by Borg-Warner for trucks, school buses, and heavy-duty commercial truck applications for Ford, Jeep, and International Harvester from 1965 - 1991.
The transmission appeared in many vehicles throughout its history, although it primarily appeared in F-series and Jeep trucks in the late sixties through the mid-eighties. (Ford used the T18 until 1987, when the last F-250 HD was manufactured with the transmission). It was offered in both 2 and 4-wheel drive pickups, (although most owners preferred the automatic transmissions Ford was making).
The best thing about this stick shift transmission was that you couldn’t kill it. It is known to be a durable and steady beast, capable of handling the stresses that larger engines and greater torque demands were produced. Owners were constantly pushing the limits of their trucks, using them for more than just work or farm, but as daily drivers. Many of these transmissions are still on the road today and are a favorite for classic truck restorers.
Even though the T18 enjoyed some success, Ford tweaked the tranny, and relabeled it, the T19, just a couple of years later. (This is likely since the T19 was just a modified version of the T18 rather than a completely new design). The primary difference is the T19 has all four gears synchronized, whereas the T18 does not - only 2nd - 4th). Borg-Warner built both transmissions at their plant in Michigan, making them the perfect partner with Ford pickups.
What Are The Features of a T18 Transmission?
The T18 was made with a cast iron top cover that was sealed to the case with a six-bolt pattern. (It is called a top loader because technicians removed the cover to gain access to the gears, synchro rings, and bearings inside).
For the early production years, the T18 shared the same cover as the T98 (including the same bolt pattern and a few other components). This identical pattern meant technicians had to remove the cover to ensure they were working on a T18, not an older transmission with a newer cover slapped on.
The cast iron case is smaller than you might expect for a manual transmission required to perform a lot of heavy lifting (it is less than a foot long). The transmission height is 17.5 inches, and it’s heavy, weighing over 145 lbs, which makes it tough to manhandle out from under a vehicle. (Be sure you have a stable stand to rest the transmission on as you work on it. The gear ratio is low at 6.32:1, which makes them great vehicles for low-crawlers. The second through fourth gets were fully synchronized, while the first gear was not.
The shift pattern for the T18 was initially a standard H pattern with reverse up on the right near 3rd gear (1966 - ‘78) due to the reverse shifter fork being on the side of the transfer case. Later on, as the T18 was modified, the reverse gear was added to the inside of the top cover, and the reverse gear appeared to the right, only down, near the fourth gear.
Most Ford T18s had ten spline input shafts that stuck out from the front of the tranny a little over six inches. Many technicians used the length to tell the difference between the T18. (The length of the T98 was almost three inches longer).
The front bolt pattern to the engine was typical of Ford’s butterfly seals that they had been using on the T98.
What Were the Gear Ratios for the T18?
(A very rare version of the T18 appeared in diesel applications from 67 - 71 and had higher gear ratios, but the most common ones are listed above.
How Can I Identify a T18 Transmission?
The best way to know that you are working on a T18 is by checking the casting numbers on the side of the case. The numbers are located on the driver’s side. (It more than likely begins with a T18 - 1E for early units. Older units eliminated T18 in favor of beginning with 13-01 to distinguish the Jeep versions).
Another way is to locate the numbers on the top cover. The lettering code of the production number will likely begin with a “C” (the 1960s) or a “D” (70s), or “E” (80s), followed by a number that represents the year it was built. For example, a “D5” would refer to the transmission having been made in 1975.
Look on the passenger side of the transmission, and if you spot a power-take-off (PTO) port, you have a T18. Ford T18s have a bell-housing adapter on the input shaft and a rear adapter on the case, distinguishing them from their Jeep and IH counterparts.
Are The T18s Easy To Rebuild?
Most restorers agree that the T18 and T19s are reasonably easy to rebuild if you’ve had some experience with transmissions. Parts are readily available for most versions (although they are getting more scarce as these transmissions are dwindling).
Rebuild kits are available at most transmission repair shops (or they can order them for you) and online. In addition, plenty of remaining transmissions can be purchased and installed without having to complete a rebuild.