Show Transcript
If your bullnose still has that old four-speed cloer, you’ve probably thought about it. That five-speed swap — five real gears, smoother shifts, maybe even a little better mileage — is the promise of the Mazda M50. Sounds like the perfect upgrade right up until your 351 decides to eat it for lunch. Hi folks, Ed here. Welcome back to Mono’s Garage. Our subject is Ford’s most controversial 5-speed, the Mazda M50: the one that turned a lot of old-school truck guys into believers and just as many into skeptics. When they’re good, they shift clean and make your old truck feel almost civilized. But when they’re bad, you get whining, grinding, and maybe a little puddle under the tailshaft just to remind you who’s boss. I’m covering everything you need to know: the good, the bad, how to take care of one, and when you’re better off with a ZF5, especially if your truck has some muscle behind it. Picture the mid-’80s. Ford was trying to move away from brute-force manuals like the MP435 and the T18. Great boxes if you wanted to pull stumps, but they were heavy, loud, and about as refined as a tractor. The world was changing: fuel economy, emissions, and comfort started to matter. Ford wanted something that felt more like a modern pickup than a farm implement. Ford already had a solid working relationship with Mazda by then — they owned part of the company. Mazda was already supplying transmissions for smaller cars, and Ford knew they could build a gearbox that would shift smoothly. So they went to Mazda and said, ‘We need something that feels like your car boxes but can handle a truck motor.’ That’s how we ended up with the M50: a Mazda 5-speed with overdrive. A transmission born from Mazda’s smooth-shifting DNA but built tough enough, almost tough enough for Ford’s half-tons. It’s not something Mazda ever used in their own trucks. This was a Ford baby, raised in a Mazda factory. You’re going to hear a lot of alphabet soup with these — R1, R2, HD, and a few other oddballs — but really it’s just two families: the R1 for the little trucks and SUVs, and the R2 for full-size rigs like the F-150 and the Bronco. The R1 HD came later when Ford started hanging bigger engines on Rangers and Explorers. The R2 quietly got the same kinds of upgrades over the years: better bearings, stronger forks, little tweaks to make it live longer. There was even a version stuck in a Thunderbird Super Coupe, which is wild because it’s basically a truck transmission behind a blown V6. The first thing you’ll notice is the case. It’s all aluminum — bellhousing and all — cast as one piece. Saves weight, sure, but if you crack it you don’t just swap the bell; you’re shopping for a whole new transmission. Mazda didn’t mess around with separate parts on this thing. They also fully synchronized every forward gear and reverse, which was a big step up. No more double clutching to get into first. No more grinding into reverse because you didn’t let it stop spinning. It was a slick design for its time. The shifter connects straight into the top cover rails, so it’s got a tight, direct feel. None of that long-throw wooden-stick-in-a-bucket action like the MP435. You can tell Mazda tuned it to feel like a car, and when it’s working right it really does — the first time you drive one, you kind of forget it’s a truck transmission. All of that smoothness, though, came with a few compromises. There’s no oil pump inside; it’s all splash lube. That means the…
Gears fling fluid around to keep everything happy. It works fine if you have the right fluid at the right level. We’ll get into that later, but that’s a big one. The clutch setup was another modern touch: hydraulic with a concentric slave bearing inside the bellhousing. Great when it’s working—smooth pedal, no adjustment needed. While Ford never published an official torque rating for the R2, in practice they live fine behind stock 300 and 302 engines. That means roughly 300 to 350 lb·ft of torque. Once you start making more power, like a healthy Windsor build, you run out of headroom pretty fast. It will take it for a while if you baby it, but you can’t dump the clutch at 4,000 rpm and expect it to smile. Dry weight on an R2 is about 115 lb depending on year. The R1s are lighter, more like 85 to 90 lb, but still no featherweight compared to a car transmission. The R2 is roughly 28 inches long overall, give or take, depending on the tailhousing. For comparison, the NP435 tips the scales closer to 130 to 140 lb, and the ZF5 lands in the 160 to 175 lb range, so you’re saving a solid chunk of weight, which was a big part of the design goal. Ratios vary a bit depending on year and application, but most R2 truck boxes fall in a similar range. You can find little differences between early and late units, and the Thunderbird SC version runs a bit shorter at 0.75 overdrive, but those numbers get you in the ballpark. In practice, first gear is a lot taller than the old 6.68 granny in an NP435—you won’t be crawling out of ditches with this thing. It’s built for driving, not digging. The overdrive makes a 3.55 or 3.73 rear gear feel perfect on the highway, the sweet spot for guys dailying their old trucks. Internally, it’s a five-speed, fully synchronized, constant-mesh box. The input shaft runs on tapered roller bearings front and rear with a countershaft that carries the rest of the geartrain. Mazda used brass or carbon-lined synchro rings depending on year: early ones were brass, later ones used the updated friction lining for smoother shifts. The gears are helical cut and quiet, and the countershaft sits in a pair of pressed-in races inside the aluminum case. The clutch splines are 1-1/16 in x 10, standard small-block Ford size, and the input shaft pilot is the same diameter as the NP435, so pilot bushings are easy to match. Output spline count depends on the unit: many 4×4 R2s are 31 spline, while two-wheel-drive versions are often 28 spline, so match the yoke to your specific transmission. Fluid capacity is about 3.8 quarts of automatic transmission fluid. Even though it’s a manual, they were designed for Mercon ATF, not gear oil. These transmissions are picky: gear oil is too thick for the splash action to lube correctly, and it will pool in the bottom while the transmission cooks. If you just bought a truck and don’t know what’s in it, drain and refill it—cheap insurance. When you look at what it replaced, the M50D was a step forward in the ways that mattered for the trucks of the time. It made old trucks feel new, made new trucks easier to live with, and gave Ford a shot at competing with the lighter, smoother rigs from GM and Dodge. It was the beginning of the modern era for Ford manuals, an era where a truck could still work hard, but.
It didn’t have to sound like it was angry about it all the time. And now for the inevitable call to action: if you’re enjoying the video, hit like, subscribe, or better yet, check out patreon.com/bullnosegar. You’ll see some neat behind-the-scenes stuff and even more of me, which is definitely why you’re here, right? So we’ve talked about what the M50 is. Let’s talk about what it does when it decides to remind you it’s not bulletproof. Because for every guy who swears his M50 has been smooth and quiet for 200,000 miles, there’s another guy sitting on the side of the road with a dipstick full of glitter wondering what the hell just happened. The most famous failure, the one that’s practically a rite of passage, is the input bearing. That bearing sits at the front of the transmission right behind the input shaft, and it lives a hard life. Because it’s splash-lubed, the only oil that bearing gets is whatever gets flung up while the gears are spinning. On the highway that’s fine, but around town, especially with thick fluid or a low fill, it starves. It starts to whine, then it howls, then it eventually wipes itself out and takes the input gear with it. If you get a faint 45 to 60 mph whine under light load, that’s an early sign. If the pitch tracks road speed off throttle, start planning a teardown. The next most common issue is synchro wear, especially in third gear. Third is kind of the workhorse of the M50. It’s used a lot in city driving and it takes the brunt of any sloppy shifting or mismatched revs. Over time the synchro cones glaze, the rings lose bite, and you start getting that crunchy, notchy feel when you shift fast. If you have to baby it into third, that’s your sign. Sometimes fresh fluid helps, sometimes it’s just plain worn out. Shift forks are another weak link. They can crack at the base or wear the pads down so far the gear never fully engages. Then there’s the countershaft support bores. Over time the soft aluminum wears where the countershaft bearings sit. Once that happens the gears don’t mesh quite right, and you start hearing that high-pitched whine in second or third gear. Some rebuilders sleeve those bores or use oversized bearings to restore the fit, but if it’s really hogged out, the case is done. Let’s not forget the top cover leaks. These things love to seep around the lid and the shifter tower. The original gaskets were cork, and after a few heat cycles they shrink and weep. Most rebuilders just use RTV now and call it a day. It’s not catastrophic, just annoying. The good news is at least you’ll know when you have this issue because it’ll mark its territory on your driveway. Case cracking is less common, but it’s worth mentioning. The integral bell design means the case is doing double duty: it’s not just holding gears, it’s also part of the mounting structure. Over-torque the bell housing bolts or leave a dowel pin out and the whole thing can flex or crack around the flange. Usually it happens to people who rush a clutch job or bolt it up crooked. That’s a very expensive oops. And then there’s that funky internal slave cylinder. It’s technically part of the clutch system, but it’s inside the transmission. So when it leaks, you’re pulling the whole unit out to replace a $50 part. I don’t know who thought that was a good idea, but they very clearly never had to service one on a gravel driveway. And that’s really the story when it comes to the bad news. When they’re taken care of, they’re fine. But if you run them poorly, they will fail.
The wrong fluid, slammed gears, or putting it behind a hot 351 asks it to do something it wasn’t born to do. If you’ve ever rebuilt a manual transmission before, the M50 isn’t that bad. But if you’ve never been inside one, it can humble you pretty fast. You don’t need a degree in rocket science, but you’ll want some mechanical sense, a clean workspace, and the right tools. Get a rebuild manual, or at least some photos before you start. The parts themselves aren’t hard to find. There are complete bearing and synchro kits on eBay, RockAuto, and some transmission suppliers that specialize in these. A typical rebuild kit runs about $150 to $250. Add seals, a new slave cylinder, and maybe a new shift fork or input bearing upgrade, and you’re still under $400 in parts.
The biggest challenge for a rebuild here isn’t cost, it’s precision. Everything in this box runs on very tight tolerances. The manual calls for specific clearances, and those numbers actually matter. If that sounds intimidating, there’s no shame in taking it to a shop. A professional rebuild usually runs between $800 and $1,200 depending on how deep they go, how bad your core is, and where you live. You’ll get new bearings, synchros, seals, and usually a one-year warranty. That’s not bad for something that will last you years.
If you want to keep one of these alive, keep a few things in mind. People treat them like an old iron four-speed and then wonder why it doesn’t act like one. This unit wants finesse, not violence. First rule: change the automatic transmission fluid every 30,000 to 50,000 miles. Second rule: be gentle when it’s cold. ATF is thick when cold, and these boxes don’t like to be rushed. Synchros need the fluid moving freely to grab cleanly. If it’s stiff or notchy in the first few blocks, that’s okay—don’t force it. Third, learn to shift with some feel. The shifter is short and precise, which is part of its charm. Hammering a two-to-three shift punishes the synchros. You’ll be amazed how much smoother and longer it will last when you stop pretending you’re running a quarter mile.
If you’re towing or running it behind a torquey engine, keep an eye on heat. Long highway pulls on a hot day can cook the oil faster than you’d think. Some people drill a small port and plumb a cooler line, but for most, regular fluid changes are sufficient. And probably the biggest rule: be nice to it. No clutch dumps, no burnouts, no speed shifting at 4,000 rpm. It’s not a top loader or a Tremec. The gears are small, the case is aluminum, and the bearings rely on splash oil. That may sound delicate for a truck part, but that’s the trade-off you made when you left the NP435 behind. You gave up brute strength for drivability. That doesn’t mean it’s weak; it rewards the driver who pays attention. If you do that, it’s not unusual to see these go 200,000 miles or more before needing a full teardown. But if you neglect it, it’ll let you know in the loudest way possible.
After all that, are you thinking about swapping one of these in? I was too until I did the math on how much torque I’ll get out of my old stoked Windsor. But if you’re here to learn whether that math works out for your truck, let’s set you straight, because yeah, the M50 will bolt up
It fits a lot of engines, but that doesn’t mean it’ll survive them all. So let’s start with the easy one, the 3096. The M50 and the 3096 are a perfect marriage: smooth torque curve, low RPM, not a high-rev screamer. That engine and transmission were basically made for each other. Ford ran that combo from the factory for years, and it just works. You’ll wear out the clutch before you hear the transmission. If you’ve got a bullnose 300 and you want overdrive, this swap is a no-brainer.
Next up, the 302. This is where things are still mostly safe, but the gray area starts creeping in. A stock or mild 302—headers, intake, maybe a small cam—the M50 will handle it fine as long as you don’t abuse it. You can even get away with towing light loads or running a little extra timing. But once you start building a serious 302—big cam, heads, high compression, or, God forbid, boost—that’s when the M50D starts sweating a little. In my case, the 351 wins here.
This is where people get themselves in trouble. On paper, it bolts right up and it fits beautifully. In reality, a healthy 351 puts down way more torque than the M50D was ever really rated for. A bone-stock 351, especially a late-’80s smog motor, is probably fine. It’s right on the upper edge of what the transmission’s comfort zone is. But as soon as you wake it up—intake, cam, heads, maybe a stroker kit—you’re flirting with rapid, unscheduled disassembly. The truth is, if you’re running anything beyond a mild Windsor, you’re probably in ZF5 territory.
The ZF was designed to handle torque in the 450 ft-lb range, sometimes more. It’s heavier, but it’s made for that kind of punishment. If your truck has a stock 300 or Windsor and you’re the kind of driver who rolls into the throttle and shifts cleanly, the M50 will make your truck feel like a new machine. But if you’ve got a heavy right foot or you treat every on-ramp like a drag strip, it’s probably the wrong transmission for you.
And when you start talking transmissions to the Ford guys, you find out real quick everyone’s got a favorite. Half the crowd swears by the old MP435 because you just can’t break it. The other half worships the ZF5 like it’s holy scripture. And somewhere in the middle sits the M50—the good-enough five-speed that makes sense on paper and feels great behind the wheel but just can’t shake the shadow of those iron legends.
If you’re trying to decide between them, let’s see what the competition looks like. We’ll start with the MP435 because every bullnose owner either has one or has fought with one. It’s a tank: cast-iron case, granny-low first gear you could practically climb a tree with, and enough mass to anchor a small ship. It’ll take anything you throw at it, but driving one every day is like doing manual labor. You’re rowing a gear stick the length of a pool cue through gates that feel like you’re stirring a bucket of rocks. Fantastic for crawling, horrible for commuting.
The T18 and T19 are the same story. The old Borg-Warners are workhorses. Sure, they’re heavy and clunky and reliable as gravity, but they shift like they’re full of peanut butter. If you’ve ever double-clutched a T18 at a first-and-a-half stoplight, you know what I mean. Then there’s the mighty ZF5, the one everyone brings up when they say, “Yeah, but I want something strong.” They’re not wrong. The ZF5 is the heavyweight champ in this weight class: all aluminum like the M50D, but built like a bridge. Bigger gears, better…
Oiling, a real pump inside, and torque ratings up in the 400s. It will take whatever your 351 or 460 can dish out. The trade-offs are weight, cost, and complexity. It’s a big transmission — about 40 pounds heavier — and it’s longer, so you’ll be dealing with driveshaft and crossmember work all over again. It also shifts a little more like a truck; it’s not bad, but it’s not nearly as slick as the M50. They can also be hard to find in the right configuration for your truck. If you want something modern and bulletproof, there’s always the TMIC route. TKO or TKX five-speeds will handle 600 lb-ft all day, but you’ll pay dearly for that privilege. Expect around three grand before the clutch, and you’ll still be fiddling with shifter replacement and crossmember alignment. Beautiful gearboxes, just not exactly budget-friendly. For most bull-nose guys, the M50 makes sense. It gives you overdrive, keeps the truck quiet, saves weight, and makes it feel ten years newer. It’s not a torque monster, but if you drive it like a grown-up, it will do what you want. If after all that you decide you want one of these middle-of-the-road, nice-shifting transmissions, let’s help you find one. The M50 R2 — that’s the big one from the F-150s and Broncos — uses the standard Ford small-block bell pattern. That’s the same bolt pattern as the 302, 351, and 300 inline-six. It will bolt right up to any of those; no adapter needed. That’s what makes it such a natural fit for bullnose guys, because your truck already runs one of those engines. The 300 and the Windsor family both share that pattern. For once, Ford kept building the R2 long after the bullnose years. In 1997, when the new F-150s came out, they reused the name but changed the bell pattern. The 4.2L V6 version got the S6/3.8L V6 pattern, and the 4.6L modular V8 version got its own modular-family bolt pattern. These won’t bolt to a 300, 302, or 351 without an adapter. And before you go hunting for an adapter, here’s the deal: nobody makes one. You would have to machine a custom adapter plate and deal with input shaft length, pilot engagement, and clutch spacing. The newer transmissions also run electronic sensors and have slightly different mount points. So even if you could get it to bolt up, it would still be a pain to get it to work right. The M50 R1 family is where things start branching out. The R1s came in Rangers and Explorers and used different bell patterns depending on the engine. The 2.3L four-cylinder version has its own pattern shared with nothing else. The 2.9L and 4.0L V6 versions share a Cologne V6 pattern totally different from the small-block Ford bolt circle. The 3.0L Vulcan V6 used another unique pattern shared with some Taurus and Tempo cars. The takeaway for full-size truck guys is that R1s come in every flavor of wrong. If you’re trying to hang one off a 302 or 351, the cases and bell are cast as one piece, so you can’t just swap a bellhousing like you could with an old top-loader or an NP — you have to swap the whole transmission. There is also one oddball version of the R2 that throws people off sometimes: the one used in the Thunderbird Super Coupe and the Cougar XR7 behind the supercharged 3.8L V6. It looks like an R2 on the outside but has a different bell pattern unique to that engine, plus a shorter tailhousing and a different shifter location. It’s a great gearbox for those cars.
Totally useless for a truck unless you plan on doing some serious creative adapter-plate work. For swapping into a bullnose, you’re hunting for an R2 that came out of a 300 or a 302 truck. Even though they’ll bolt to a 351, they almost never came that way from the factory because the torque numbers are right on the line, and that pairing is so rare you’ll likely never see one. The easiest donor is an ’88 to ’96 F-150 or Bronco with a 300 or a 302. Beyond the bolt pattern, there are a few other things you’ll need to consider for this swap. The crossmember will probably need to move a few inches, and your driveshaft length might change depending on whether you’re coming from an MP435 or a T18. It’s nothing major, but it’s worth measuring before you start cutting. You’ll also need to move to hydraulic on the clutch if you’re not already. The M50 uses an internal concentric slave cylinder instead of an external fork. It’s a clean setup, but it means you’ll need a master cylinder, line, and the correct pedal assembly. If you’re handy, you could adapt the later F-150 hardware into your bullnose pretty easily. Some guys even use the whole clutch pedal box from the donor truck. Shifter placement is nearly perfect; in most bullnoses it lands right about where the factory four-speed shifter did. You might need to trim or move your boot just a little, but it’s not a hack job. The transmission mount pattern is a little different, so plan on fabricating a small adapter plate or modifying your crossmember. To summarize: if you’re looking for one in a yard, get the right donor. If it came out of a small-block or 300 truck, it’s basically made to live in your bullnose. If it came out of anything else, it’s probably not worth the trouble. If you find one in the wild, check that the bellhousing pattern matches your block before you buy it. In either case, spin the input shaft and listen—if it sounds like a box full of marbles, walk away. That’s your starting point for a bullnose swap that actually feels like an upgrade instead of a regret. The M50 isn’t a hero or a villain. It’s more like that buddy who will help you move furniture but draws the line at a piano. You have to respect it for what it is, not what you wish it was. It was Ford’s first real step toward trucks being something you could drive every day without feeling like you’d been in a fist fight. It wasn’t perfect, but it delivered something Ford desperately needed: a manual that made a truck feel modern, and one that served Ford well for the next decade. If you’re a bullnose guy seriously thinking about a swap, it’s one of the best ways to make your truck genuinely enjoyable to drive day to day. If you already own one, take care of it. Treat it like the precision piece of machinery it actually is. Do that and it’ll reward you with years of easy, quiet service. If you’re the type who can’t leave anything stock and you’re throwing serious torque around, that’s fine too—just know what the M50 is and what it isn’t. It’s not a race box. It’s not a heavy hauler. It’s a great, honest five-speed that gave old trucks a second life, and for that it deserves a little respect. That’s everything I know (or pretend to know) about the Mazda M50 five-speed. Do you have one you love or hate? Thinking about swapping one in? If so, drop a comment and let me know. If I change your mind, for or against, let me know.
Know that, too. I really enjoy hearing about how this information might influence your decision. As always, if you have any questions, comments, concerns, gripes, or internet ramblings, stick them below. Thanks again so much for watching, and we’ll see you next time. If you want to dig deeper into the builds, the side projects, and the stuff that doesn’t always make it onto YouTube, or just want to get to know me a little better, come hang out on patreon.com/bullnosegar. It helps keep the lights on, keeps the beer fridge full, and funds the builds. I appreciate you being part of the garage. Shine Garage — she’s considered divine. Thanks again for watching; we’ll see you next time.
