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Rebuilding Your Gearbox - Gearbox Hero
Have No Fear-We Learn How To Save A Tired T5 From The Dreaded Broken Gear.
Depending on driving habits or driving style, your T5-equipped Fox-body or SN-95 probably gets more abuse than the average slushbox. Powershifts at WOT, banging gears in the quarter-mile, and pumping 400-plus horsepower through a 300hp-rated trans is usually a pretty risky combination.
Even with all of the new manual transmissions available for Mustang owners, the T5 is one of those components, like the 5L, that just keeps hanging on-or not. It used to be that the transmission, namely the T5, was the weak link in the Mustang chain, but more modern Mustangs don't suffer from such a weak component. Nevertheless, if you have a 5.0L with a T5 and you plan to keep it that way, upgrades will be in order. So when yours begins grinding into gear or growling at highway speeds, its time for some freshening up. Typically worn components that cause those noises are the blocking rings (grinding) and bearings (growling).
Transmission rebuilds, automatic or manual, are one of the jobs on most shade-tree mechanics' black list. There are many moving components, some which need to be measured with precision tools, that most are afraid they would take one apart and never get it back together correctly.
Well, we felt exactly that way when we tackled this T5. Even though I, your author, rebuilt one T5 a long time ago, I felt a strong sense of anxiety as I broke loose the first of the tailshaft housing bolts. And for good reason: I didn't have diagrams, instructions, or an experienced professional taking the reigns.
Since I had done this before, however, I knew just enough to get me in trouble. If knowledge is power, then I was a measly shoeshine boy in desperate search of a phone booth. Thankfully, a quick search through our archives yielded a Ford service manual for the T5. If you don't have a manual handy, there are some available for free online.
What You Need
Provided you didn't grenade the gears, a simple rebuild kit is atop the list of must-haves. Summit Racing sent us a Ford Racing World Class T5 rebuild kit (PN M-7000-A), which includes bearings and races, blocking rings (sometimes called synchronizers), shims, clips and snap rings, a front bearing retainer, a tube of silicone sealant, and three quarts of ATF. With the exception of tools and instructions, the 94-piece kit has everything you need, and it retails for $249.95 through Summit Racing. If you do have a busted-up T5, some good sources for parts are Astro Performance Warehouse, G-Force Racing Transmissions, and Hanlon Motorsports.
Basic handtools are necessary, like flathead screwdrivers, metric sockets and a ratchet, punches, snap-ring pliers, and a hammer. However, some other less common tools are needed as well. A T40 Torx bit, parts washer, gear puller, dial indicator, press, press plate, and torque wrench are probably not in everyone's garage.
As you take your transmission apart, it's important to inspect every piece for abnormal wear and bent or broken parts. If any other parts are damaged, replace them as well. This is very crucial for the longevity of your transmission. A magnifying glass is nice to have so you can closely inspect parts for cracks.
Also, the job will be much easier if you lay every piece out on a bench in the same order you remove it. This will prevent mixing up parts. Some components look very similar to others, but are slightly different. It's very important that you keep your work area as clean as possible, as dirt can cause premature wear on your new components.
Since the tapered bearings are pressed onto the gear shafts, it is necessary to use a press to remove the old and install the new ones. It is essential that the bearings are pressed on straight and that they do not get damaged during installation. One small nick in a roller could destroy a race very quickly.
Soak the new blocking rings in ATF overnight. This will lubricate them for assembly and prevent premature wear upon initial use. Think of it like priming an oil pump before you start an engine for the first time.
Once all of the components have been cleaned and inspected, assembly can begin. Simply install the parts, piece by piece, in reverse order of disassembly. Once all of the parts are back in the case, but before installing the tailshaft housing or cover, move all of the sleeves one at a time to check for clearance and proper operation. Make sure each gear, including Neutral and Reverse, work properly without binding or grinding.
Now, follow along as we show you the basics of a T5 rebuild. Since we can't show you every step, we hit all of the main points to give you an idea of the process and the level of difficulty.