Mark Houlahan
Tech Editor, Mustang Monthly
April 17, 2019

As Mustang owners upgrade the performance of their rides, weak parts are swapped out for stouter pieces. This has been horsepower 101 for decades. When it comes to the Fox Mustang’s T-5 five-speed, once the horsepower goes up and the sticky rear tires are bolted on, the T-5 will often “exit stage right” in some noisy fashion. Often it is a broken Third gear, or some stripped teeth on the input shaft. We’ve seen all manner of carnage over the years. The good news is that the T-5 has been so popular that there are plenty of parts to rebuild and upgrade these transmissions. If you’re lucky, you might even find a T-5 that was swapped out before it broke. These are often sitting in the corner of some shop under a workbench taking up valuable room and can be had for just a few hundred bucks. It takes a little digging and some networking, but there are a lot of T-5 transmissions out there ready for a rebuild and a second life in the tunnel of your classic Mustang (or in your Fox project).

Why rebuild a T-5 versus, say, buying a new transmission like a Tremec TKO-series unit? There’s nothing wrong with the TKO transmissions; they’re built to take the abuse behind high-horsepower engines and are proven winners in many racing circles. However, they have a larger profile than the T-5, which can cause some fitment issues in classic Mustangs (especially the ’65-’66 models), and of course you have that new transmission price tag to go with it. If you’re on a budget, or perhaps already have a T-5 lying around from a barter deal or other project, then rebuilding it is going to be the most economic route, and the smaller size of the T-5 means no fitment issues either. Pretty much the only limiting factor of using the T-5 is its power handling capability. For our typical reader with a “bolt-on” small-block that runs radial street tires and doesn’t drag race with super sticky tires, the T-5 is a great solution.

Rebuilding the T-5 does take a few shop tools, including a press, snap-ring pliers, and pullers, most of which you can find at discount tool stores if you don’t already have them, or hit up a friend with such tools to lend you a hand. Worst case, you can take the parts to a machine shop to be pressed off and on. Other than these few tools, the breakdown and rebuilding of the typical T-5 takes nothing more than some metric handtools and a whole lot of elbow grease getting everything clean to put the transmission back together. We visited our friend David Piercey at his shop, David Piercey’s Mustang Performance, located in Thonotosassa, Florida (just outside of Tampa). David is a wizard with the T-5 five-speed, having built everything from stock rebuilds to all-out race boxes. His selection of T-5 cores meant we could provide some T-5 history/identification in this story as well, which we’ll show in Part 2. While we won’t be using it until reassembly next month, we made a quick call to our friends at Ford Performance Parts for an M-7000-A T-5 Rebuild Kit. The M-7000-A has just about everything you need for the typical rebuild of a 1985-1995 Mustang five-speed.

This sensor on the transmission top cover is the neutral indicator switch and is used by the factory EFI system. It must be removed before attempting to disassemble the transmission further.
With the neutral switch removed the top cover bolts can be removed. There are two shoulder bolts that locate the cover, but otherwise all the bolts are the same length. Just remove the bolts for now.
Remove the four fasteners retaining the shifter assembly to the tailshaft housing and separate it with a small prybar or screw driver and set the shifter aside. If the shifter bushing comes out with the shifter don’t worry about it, the Ford Performance kit comes with a new one.
Using a pin punch, drive the roll pin down through the shift block in the tailshaft housing. It doesn’t need to go all the way through, but it does need to clear the shift shaft so that the shift block can be pulled free with the tailshaft housing itself.
Remove the tailshaft housing fasteners, being extra careful that you haven’t missed any before moving on to separating the housing from the main transmission body.
Separate the tailshaft housing from the main body, but don’t pull back on it. An easy way to handle this is with a rubber mallet or dead-blow plastic hammer. Once separated, pry the tailshaft housing back while simultaneously applying downward pressure to the shift block to remove the shift block and tailshaft housing together.
Now that the tailshaft housing and shift block are free of the main transmission body you can remove the top cover, which includes the shift forks and shifter shaft. Pry at the cover gently to separate the sealer and set the cover aside.
Once we had the cover off this T-5 you could see the shift fork pads were all but destroyed. This is common from over extending the shift forks during hard shifting and from resting your hand on the shifter while driving. A quality aftermarket shifter with adjustable shift stops will prevent this and is highly recommended.
The input shaft bearing retainer is removed from the front of the main case next. This is retained by four bolts and holds the input shaft’s front bearing race, shaft seal, and pre-load shim that sits behind the bearing race. More on that next month during our reassembly.
With the bearing retainer removed the input shaft can be extricated from the main case. As you rotate it you’ll see a crescent shaped cutout on the shaft. This has to be lined up with the cluster gear to allow the input shaft to come forward and out of the case. Some transmissions use roller bearings (that might fall out during this step) and others use a caged bearing. Just keep track of what yours uses and take lots of pictures as you work.
Moving to the rear of the transmission assembly the speedometer drive gear is removed next. It is retained to the output shaft by a spring clip. Simply depress the clip and slide the plastic drive gear off. A new retaining clip is included in the rebuild kit.
Remove this snap ring and the shield behind it on the 5th gear synchro.
Support the fifth gear shift shaft with a block of wood and drive out the retaining pin for the shift fork. Pull the shift fork and 5th gear synchro assembly off the shift shaft.
With the 5th gear synchro out of the way the 5th gear drive gear and blocker ring can be removed next.
Having disassembled everything forward and aft of the main case itself the large mainshaft assembly should lift right out as shown. Give it a little wiggle to unseat the tapered roller bearing at the rear of the case and use your other hand to guide the rear of the shaft up and out of the case.
Now to continue with the remaining pieces within the main case. Disconnect the spring found at the front of the reverse shift rail and pull the shift rail out of the back of the case.
Once the shift rail is out of the way you can carefully rotate the shift rail block and remove it as well.
To remove the cluster-gear shaft the rear retainer must be removed first. This is held in place by a tabbed lock plate. With the main case on end use a hammer and chisel to beat the lock tabs far enough away to allow removal of the four Torx fasteners.
Under the lock plate is this shim, set this aside as well. When setting up the endplay during reassembly this shim (or one of the ones provided in the rebuild kit) will be used to set proper endplay of the cluster-gear shaft.
The cluster-gear shaft rear bearing race is a light press into the main case. You can usually just pry the shaft rearward and the bearing race will pop free as shown.
If you haven’t already removed the oil slinger from the rear of the cluster-gear shaft do so now and set it aside.
Remove the cluster gear shaft from the main case.
Another roll pin retains the reverse idler shaft and gear. Drive it through the shaft until the pin is free.
Pull the idler shaft from the case while keeping a hand on the reverse idler gear so that it can be removed as well once the shaft is free of the gear. This completes the main case disassembly. David sends all the case hard parts out locally to Bullfrog Performance (www.bullfrogperformance.net) where it’s inhouse machine shop hot tanks and cleans all of the aluminum housing components.
All that is left to take apart now is the output shaft. Hopefully your T-5 does not have any gear damage and all you’ll be doing here is pulling everything apart for new synchro blocker rings and bearings. Here the 3-4 synchro and 3rd gear drive gear is pried off the output shaft with two large screwdrivers. These will usually come free as shown, but in some instances a press plate and hydraulic press will need to be used.
Next comes the 2nd gear drive gear snap ring and retaining washer to allow the removal of the drive gear itself.
In later model T-5 transmissions you’ll find this spiral-lock retainer in front of the 1-2 shift synchro/reverse drive gear assembly. Dave unwinds it from the output shaft and tosses it in the scrap pile. For reassembly Dave doesn’t use this and we’ll explain why in Part 2 next month.
From the rear of the output shaft remove the snap ring and 5th gear drive gear, press off the rear bearing, and then remove the thrust washer, 1st gear drive gear, and 2nd gear drive gear snap ring, gear, and blocking ring. Once you have the output shaft completely disassembled you can inspect all the gears and synchros. Thankfully this trans was in good shape with only blocking ring wear and other typical bits that are found in the Ford Performance M-7000-A kit we have on hand.
While the aluminum case bits were sent out Dave used his in-house trusty parts washing station to wash, inspect, and clean all the transmission gears, input shaft, output shaft, counter shaft, and more. Come back next month for Part 2 where we assemble our T-5 with fresh bits and make it ready for installation.

Photography by Mark Houlahan