Sign up to receive marketing communications. Toyota Adds Long-Desired Manual Transmission Option for '23 GR Supra, Yes, I would like to receive emails from Nitto Tire and Driving Line. Adapter clips are available to take up the extra spaceso you can use later arms on stud-type shifter shafts. The M22 is what they called the "rockcrusher" right? Although the Muncie's bloodline goes way back, this legendary gearbox entered service for the Chevrolet Division in 1963. The guys at Anaheim Gear tell us there are seven total Muncie input shaft options. Wright Connection Speed & Gear: 661.304.1967. 18. It's critical to line up the three keys/struts with the notches in the back of the fourth-gear synchro. Have a question? Needs all new wiring, and interior, and, and, and, MONEY. Tim will set you up with a system that will save parts. Some switches have abayonet end (shown), and later oneshave a pin-type male connector. The 1968 model was identical to the 1967 model except for a main case casting alloy change. Make sure you order the propergasket and seal kits when rebuildingthese later units. So they can take some serious abuse. FWIW, the M21 close ratio Muncie (and M22 derivative) share the distinction of the closest ratio 4 speed trasmissions ever put in a production vehicle. Recalls are bad publicity, so its easier to fix the problem silently rather than risk sales. The bearing bore size was also one year only with a #6207-style input shaft bearing, according to Cangialosi. The manufacturers have meticulously calibrated their vehicles to have the best ratios for each gear under normal driving circumstances. The speedometerfitting is located right where the linkageis. The input shaft of the Muncie M21 transmission has a ring groove and a counter gear. This larger diameter was necessary because the big-block and small-block engines were producing more power. Despite being more progressive, a close gear ratio ends at 1:1 in the fourth gear. (10 bolt) (3.73 rear) M21 transmission features input shafts with 26 splines. The upper shaft hasthe single position for the drivers sideand the lower shaft has more areaadded to the back for the passengersside. The early huband ring combination is on the right.Early hubs measured 1.150 inchesacross the spline face and later hubsmeasured 1.020 inches. Wrecked 1970 Pontiac GTO Found in Texas and Resurrected! Last 4 Speed Conclusion Performing proper research before you jump out there on the market and purchase a car is key if you want to avoid getting yourself a lemon or a car that has a transmission that is poorly made and doesn't deliver a good performance. There are many different aftermarket companies out there that offer full, custom rebuilds for the M20, M21, and M22, and it's possible to get almost any gear set you want stuffed inside a Muncie casing. BorgWarner was probably the foremost manual transmission manufacturer at the time, and basically wrote the book on manual transmission design. The dry weight of the M20 transmission is roughly 140 pounds, and the dry weight of the M21 transmission is roughly 155 pounds. As with the previous bearing install, Craig heats the front of the transmission case, making it much easier to slide the input shaft bearing in place. The Gear Vendors electric overdrive allows for a 0.778:1-ratio multiplication of the final drive. The T10 shares the same case design, gear centers, and 3-4 synchronizer as the T85. The 26-spline input shaft yields greater torque capacity via the number of teeth and greater surface area. The Borg Warner Super T10 stronger than the regular Muncie and almost as strong as the M22. 3200 edge stall 3.73 gears. 19. $2899.99 OR WITH Muncie CORE exchange $2499.99. If you are going to switch extensionhousings so that you can use a passenger-sidespeedometer fitting, youmust make sure the mainshaft canaccommodate the different positionof the drivegear. It was a matter of economics when Chevrolet needed a four-speed manual transmission for the Corvette in the mid-1950s. The M20 gearsets front end was also redesigned to handle more power. Thus, as you can see, the weight of the Muncie M21 can be considered quite average compared to other products on the market. It was a very logical decision: Tooling costs would be minimal because hobs, castings, and certain components could be used from the T85 platform. In 1964 and 1965, Muncies in some of the full-size Chevrolet Impalas and Pontiac Catalinas were equipped with longer mainshafts and extension housings to keep driveshafts shorter and reduce harmonic vibration. The reduced gear angle of the M22 created a problem with noise (hence the name rock-crusher). I could have fun with it while figuring out the Chassis then maybe upgrade the motor and tranny as I go. It stopped against the first and second synchronizer assembly, thereby eliminating the need for the assembly to have a retaining snap ring. He has 2 Muncies and also pretty sure he has a Lakewood blowproof bellhousing,steel flywheel,and a Hurst shifter. If you look closely, youll see that the patent drawings look nothing like the Muncie 4-speed but rather like the BorgWarner T10! This is when you have to remove the side cover to see what's inside. The 4wd version of this mainshaft (or "output shaft") has a 10-spline output with a 2-5/8" stickout and an accompanying 4wd adapter housing. It is also a well-liked option for off-road applications because of its strength and durability, which are highly valued. They fix it if there is a complaint but do not order a recall. Summit Racing Equipment inventories all kinds of cast-aluminum and steel bellhousings for the Muncie. Pure dumb luck will lead you to a completely unmolested Muncie. The first-speed gear had a smaller bore diameter as well as a recess in the bore to clear the synchronizer retaining snap ring. To allow the cluster gear to ride with a minimum of friction, a series of roller bearings are slipped inside the cluster gear and held in position with heavy grease before the pin locks it in place. 2. Buncha work that has to happen to get this running as is. Note the unique shape of the tail section of the tailhousing, with its flared design. The example on the leftis for pre-1969 transmissions and the one on the right is for those that accepta 3/8-16 threaded bolt. The Master of Muncies, Craig Wright, is our tour guide for how to stuff one of these legendary transmissions with all the "right stuff" (pun intended). The standard transmission weighs anywhere from 100 to 400 pounds. The early Grand Sports used a special heavy-duty version of the M21 close-ratio transmission. Question - what kind of horse power can the 4 speed handle? I am planning to run high 10s with a small block and just wondering how well they hold up. C3 Corvette Upgrades: Crate or LS Engine? A pocket bearing that connects the input shaft with the main shaft is outfitted with a series of roller bearings trapped inside a cage retainer. It is therefore no surprise that a decision was made for BorgWarner to manufacture this 4-speed transmission based on the GM concept drawings and Fodreas patent. 8. The grooves were carved into the input shaft to make it simple for the transmission assembly line worker to determine which input shaft goes where in a specific unit. The "SM" in the transmission's designation stands for Synchro-Mesh, in the tradition of other GM gearboxes. Therefore, the Muncie patent is basically a design for the layout of a 4-speed transmission. This is how the Muncie countergearsdesign evolved. They were found in the C/K Series trucks. Thepassenger-side speedo tailhousingis always desired because it gets thedriver-side speedo away from thelinkage. According to Cangialosi, GM took the basic T-10 design and beefed it up to conceive the Muncie M20 and M21 four-speed transmissions, which arrived in 1963. In a sense, 1988 marked the last year this type of transmission was used in a GM vehicle. Webbing has been added to late-styleextensions (casting PN 3857584). Its a standard M20 model. You're going to find various combinations of main cases, tailshaft housings, and side covers coupled with variations inside of each case. If a car made big power, chances are a Muncie M22 was on the menu. The case itself is generously ribbed both vertically and horizontally. For a video version of this article,click here. By the time power levels got beyond 500 HP and 500 lb. For a better experience, please enable JavaScript in your browser before proceeding. Ok my brother in law is digging to see what he has. First was to revamp the T10 to handle more power. High-end Build: 6.56 cents/hr. Fodrea's legacy is far-reaching, extending into popular transmissions around to this day, yet most have no idea who he was. The change basically states that a new gearset is to be used with different synchronizer assemblies, the main case is to be modified to accept a drain plug, and the countershaft bore of the case is to be machined to accept a 1-inch-diameter counter-shaft. The 465 is an intellegently designed and very well-built transmission and remains easy to locate and generally inexpensive to buy and maintain. On the far right is the M22 26-spline input shaft. This is the current Super T10 design.Its concept and design are identical tothe Muncies. The ST10s production in GM vehicles was from 1974 to 1988. The usual buyer wont have any special reason to be concerned with the precise drive gear ratio of the car theyre considering. A line lock and two step are very handy too, especially with drag radials. Itll handle 450 hp in a 3500 lb car with no problem. There are no part numbersin the GM system that differentiatethese assemblies. There is a small section of video that has no sound due to the artist no longer honor. Note that all of the bolts will have to be removed to attach the tailhousing. Other muscle car transmissions of that era, such as the Ford Toploader and Mopar A833, left no room for improvements because of the layout and initial design of their geartrains. The passenger-side speedometer extension housing also has added material between the upper shifter mounting holes. The GM design is just as strong today as it was nearly 60 years ago, and that makes it the go-to gearbox for Chevy, Olds, Buick, and Pontiac fans looking for a period-correct muscle car transmission. This was also the first year of bolt-on shifter shafts. 2. Also, we have covered many problems, such as manual transmission going into gear but wont move, on our site. It 60'-s in the 1.4s and goes 10.30s right around 130 consisitently. Thanks for the help I don't really know much about the old 4spds so I can use all the help I can get. The classic Muncie four-speed transmission in all its many forms generally looks like this (this one provided by Anaheim Gear), though applications will vary in appearance. The new pin design simply added a hat to the end of the pin so it could not fall through. What are the characteristics of a 1963 Muncie? He is going to let me know what he wants for it and also has a rebiult 350 shortblock he is going to price.I'm figuring if I put it together with decent heads,cam,intake,and carb I may be able to get it to go some hi 11s. <hr></blockquote> All You Need To Know. The later plastic drive-gears frequently failed; the transmission had to be disassembled and the equivalent press-on 8-tooth steel gear had to be used anyway. Muncies are expensive. Always use a later-style pin (right) when doing a rebuild. The M22 first gear has an angle of 14.5 degrees and the input shaft is 24.2 degrees. According to Cangialosi, the date was based on model year, not necessarily the calendar year. By the time the Muncie was in its final phase of production (1971-1974) it also gained a 32 spline output shaft in place of the original 27 spline unit. Remove the side cover and forks for a look at the geartrain. This layout is a 4-speed transmission with four forward gear ratios in the main case, a midplate bearing support, and a reverse gearset in the extension housing. The service issues crop up after the warranty period has expired and the owner is left to pay for a repair on something that was defective in the first place. Thanks for the input. The laterdesign reduced the diameter of theneedle to .125 inch because of thelarger countershaft, which used fourrows with 28 needles per row. The most common main case casting was 3885010. Enjoy banner ad-free browsing with Team Chevelle Plus. JavaScript is disabled. Although the cost might be a drawback, it is still understandable, given the quality and strength the transmission provides. It uses stronger components to handle big-block power. If you have a 1963 Muncie that needs an input shaft bearing retainer, all is not lost if you can't find the 1963 aluminum bearing retainer. The first front-bearing retainer on the 1963 Muncie was made of aluminum; itscasting number was 3790278. Both the M21 and M20 transmissions have input shafts with 26 splines. Look for the latest news stories and features, sent straight to your inbox! This power-to-weight ratio calculator provides a quick and easy way to determine the power-to-weight ratio (PWR) of any vehicle. The SM465 enjoys a very low compound gear at 6.55:1 and as such it is a popular choice for those wanting a low crawling gear. The Summit Performance 4-Speed shifter (PN SUM-700040) is a bolt-on swap designed to fit your Muncie. Webbing was added to the top and bottom. When you have the two side-by-side it becomes obvious which is which. Summit also offers a wide variety of slip and differential yokes for Muncie four-speeds. Trying to use what I have until whatever weak link breaks, then fix as you go. The far left gear is a 1963type that has the recess for the 1-2synchronizer snap ring and a smallerbore. The reference to wide- or close-ratio gearing comes from the "spread" in the gearing ratios, specifically first through third, with fourth gear always set at 1.00:1. In the 1970s, virtually all Muncie four-speeds had 26-spline input shafts. Over the years the casing would be reinforced, a larger countershaft was added, synchro rings were redesigned, and shifter shafts were changed to a bolt-on design. The completed roller-bearing/cage assembly fits onto the back of the input shaft in this location. Read more As the reader will conclude, the Chevrolet and General Motors SM465 will marry directly to a GM style bellhousing. The same is true with engines, and that the foundation is the cylinder block. Insert the shift shafts followed by the shift forks. This is an M21 with 10-spline input shaft and cast-iron bearing retainer. On the right is the M22 countershaft with 27-teeth. Still, laypeople might not have insights into this transmission. Worked fairly well when I was in the 12's. These extension housings always had a tendency to leak as well as get in the way of after-market shifters. I love the M22 so I don't want to risk grenading it on a hard launch. This saved a lot of work and I'm going to cage it and add reinforcenment. Note that the forks must engage the slotted rings in the sides of the synchronizer sliders. It can support the [Click here to read more], Chevrolet manufactured two significant big-block engines in the second half of the twentieth century. When putting it on a scale, you will find that the M21 transmissions dry weight is around 155 pounds. Unable to justify a small production run for the Vette program, GM had instead farmed out the T10, and the company borrowed as much as it could from the T85's internals to keep costs down (and eventually sold the transmission to GM's rivals at Chrysler and Ford). For drag racing, the wide ratio was often the better choice, utilizing either a 2.56 or 2.52 first-gear ratio. The SM465 was made by General Motors from 1968 to 1991. These special units evolved into what is called the M22 today. The front bearing retainer was also changed to a thicker casting. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. I placed them backto-backso you can see the differencein the helix angles of the teeth. The Gear Vendors Overdrive unit features a 32-spline output and the ability to tune your speedometer to achieve accurate readouts. Its quite common to see the switch plugged off or just filled with sealant. Thanks to a strong input shaft, it can provide more torque rating. The sidecovers of some 1970 units had the heavier 20-pound detent spring but by 1971 all the covers had these springs. What that means is that from 1968 to 1970 there were more factory 10-spline-input M22s assembled than the later 26-splines. It was held in place with a spring-steel clip. How do you distinguish between an M21 and an M22. The former is a wide-ratio gearbox with a gear set that has a 1st gear ratio of 2.52:1 and a 4th gear ratio of 1.91:1, which is more appropriate for street automobiles. 6. Nov 4, 2022 If you've ever driven a classic muscle car equipped with a four-speed manual transmission, you probably experienced the joys of commanding a Muncie Rock Crusher. Note the single groove, meaning an M21 close-ratio. Input shafts The M20 and M21 both have 26-spline input shafts. His brilliant and well-thought-out idea was to make it into a 4-speed. In actuality, more M20 units were produced with this configuration than were M21 and M22 models. According to Paul Cangialosi, Muncie transmission historian, technician, and author of Muncie 4-Speed Transmissions: How to rebuild and modify, the Muncie four-speed transmission has its roots back to 1935 and the U.S. patent number 3,088,336 along with an engineer named James W. Fodrea. Here's a typical Muncie gearset consisting of First, Second, and Third gear. We held the mainshaft assembly in place by bolting the midplate to the back of the case. You can copy and paste this link to share: https://www.chevydiy.com/muncie-4-speed-the-complete-history/b>. It was no longer just an M22 thing. Glean the basics and use them in your research. VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. The Muncie saw many improvements during its 10-year production run with General Motors. With the proper rear end gear a new M22 can handle close to 700HP! Internally, they are identical to each with the exception of the transmission mainshaft. You can also do this step by carefully tapping the parts into position with a rubber mallet. This photo shows that the overalllength of the rectangular drive portionis longer on the bolt-style arm comparedto that of the stud type. The synchronizer hubs had a very tight press fit to the mainshaft because the hubs apparently were nitrided. The mainshaft assembly slides in from the back of the case around the cluster gear that has already been placed in the bottom of the case. In 1963 the Corvette Grand Sport racing program was instituted. Well, I don't know the official torque ratings (they are really irrelevant anyway), but alot will depend on the condition of the transmission, the weight of the vehicle and the traction you have. Fodrea was the GM engineerwhose name is listed on the designpatent for the Muncie. It was no accident, either: the 4-speed was the product of careful engineering intended to modernize GM's transmission offerings, and it benefited from continual updates during its decade-long run as the go-to shift-it-yourself option. These hubs fitextremely tightly on mainshafts, andyou need to have the proper pressclamps or pullers to remove them. General Motors optioned cars with either the M20 or M21 ratios based on engine types and axle ratios. If you've ever looked at a BorgWarner T-10 and a Muncie four-speed and gotten them mixed up, you are not alone because the Muncie (M20, M21, and M22) is a direct descendant of the T-10 according to Cangialosi. Secret Sauce: How to Make Real Power With the 7.3L Power Stroke, Diesel Ram Buyer's Guide: The Cummins Catalogue, First Look: Miller Motorsports Pro Series Chassis, 6.0L Power Stroke Problems, Part 6: Injectors, Sign up for more restomod content to add horsepower to your inbox. a M22 would hold up fairly well but make sure you have some backup parts..there is nothing like banging a stick car but the shock on the entire drivetrain is big, the tranny is not the only thing you will break. Come join the discussion about restorations, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more! Use the calculator that corresponds to your desired units of . The fourth VIN digit [Click here to read more], M20 first, 2.56:1; second, 1.91:1; third, 1.48:1; fourth, 1.0:1; and reverse, 2.64:1, second, 1.64:1;third, 1.28:1; fourth, 1.0:1; and reverse, 2.27:1, GM TURBO 350 TRANSMISSIONS: HOW TO REBUILD AND MODIFY, How to Disassemble Chevy and GM Differentials: Step-by-Step, C5 Corvette Suspension Upgrades to Increase Performance (Part 3), How to Build LS1-LS4 Chevy Engines: Heads Guide, Big-Inch Chevy Small-Block Stroker Cheat Sheet. The shifting pattern for the 465 is in the standard "H" pattern with reverse gear being to the right side, and down. General Motors received royalties for every T10 sold from BorgWarner, so you have to wonder why they would bother making their own 4-speed at the Muncie plant. 16. It is U.S. Patent Number 3,088,336 (see Appendix). From left to right are the three basic Muncie input shaft/countershaft combinations. (They are credited with hundreds of manual transmission patents.) A great way to restore andupgrade worn-out pre-1966 cases isto just bore them out to fit the latershafts and upgrade the gearset.The larger countershaft is needed tohandle the load of big-block engines.The larger the shaft, the more surfacearea the case has to support it. 11. i am still looking at some classic cars and i have narrowed it down to 2 cars that i want to get! The introduction of the transmission controlled spark (TCS) switch on the Muncie sidecover seemed to appear in 1970. is this true? Will find out tomorrow at t&t. OurKit #465-AMCcan be purchased to simplify this process. Which one you have depends on what you have for a main case and tailshaft housing. The newer 3/8-24stud still had to fit the rectangularkeyway of the linkage arm, and so ithad flats milled on each side, but theystill broke. The reduction in the angle with the M22 is quite substantial. Before 1969, different internal steel drivegears were installed to match specific axle ratios and tire sizes. GM's goal with the Muncie four-speed was to produce a better shift employing larger synchro cones. Too bad there wasn't somebody in the area (Oswego, IL) looking for a garage buddy to hang out with so I could pick his(her) brain. The needle bearings changed from .156 to .125 inch and the diameter of the spacer tubes also changed. A minor internal change of the 1st gear bushing and thrust washer occurred, in addition to a change from a shorter 10-spline, 4wd output shaft to a 32-spline 4wd output shaft - coinciding with the change of bolt pattern in the New Process 205 transfer case from a figure "8" input bolt pattern to a round, six-bolt input pattern. An m22 hardly last with a 13 second car, I cant see one holding up to 10 sec car. The 3925661 main case casting was used exclusively and a new tail-housing (3978764) with only three shifter-mounting holes was added. The early 19631965 ring had a tendency to crack at the strut key slot. how much horsepower can a muncie 4 speed handle? They want $200 for a sag 3 speed, $300 for the 4 speed, $750 for a Muncie 4 speed, and $500 for a TH400 (including flexplate) Prices seem high, but when its the only semi-local place that has anything I'm kinda stuck. Shifter linkage arms were changed because the drive slot now had to be longer to match the drive portion of the mating shaft. The Right Answer, What Is A Torque Tube? The front bearing retainer flange measures an unusually large 5-1/8" in diameter and the bearing retainer tube is 1-3/8" in diameter. I'm not really going bracket race and if I do it will be in the UMTR street class if I do a 4 speed so traction will be a problem for everybody. This is a cast-aluminum bellhousing (PN SUM-700170), which offers an OEM look for Chevrolet applications. This code will not necessarily be correct anymore because someone could have changed the internals. The SM465 is an outstanding, heavy-duty truck transmission designed and used in , 3/4 and 1+ ton trucks. The problem is that some cars just arent driven very often. M21 has a high gear ratio, meaning the output shaft can also handle more power compared to other transmissions, such as the M20 Muncie. I was wanting to do a mid to hi 10second street car but I geuss an 11second street car with a stick could be as much fun. It has a very good set of road manners contrasted by its enormous off-road brawn. In terms of oil pump level, the M21 transmission will require around three pints or around one and a half gallons. Mixing late long-slotarms on early short-slot shafts causesthe linkage to go out of alignment. I can only go from there. We also sell new bearing retainers turned to the dimension you require. The slot on later arms always has a circular cutout tomake room for the bolt. Re: how much horsepower can a muncie 4 speed handle? . To redesign the Muncie and downgrade it would have cost a lot of money. The M22 Rock Crusher 26-spline input shaft sports a wider gear for greater torque capacity. The engineering change documentation for the M22 is dated December 12, 1964. Whenever you have a snap-ring groove between a flow of power you have a potential stress riser on the shaft. Because the Muncie was well engineered, there was room for improvement to the base design. Starting in 1963, the VIN denoted coupe or convertible and build sequence. Todays VINs (vehicle identification numbers) are even bar coded. What is your budget? Click the button below and we will send you an exclusive deal on this book. Want to put this behind a 648 hp blower motor, My gramma drives an auto, I just want to have fun! They too eventually fail after repeated hard launches with sticky tires. The rectangular drive portion of the shifter shaft was also increased in length from .605 to .722 inch. . Practical answer? Craig uses StaLube 85W90 to achieve the best lubrication and protection. In road-racing applications, when you are in fourth gear doing more than 100 mph, first gear is spinning on the mainshaft at more that twice the mainshafts RPM. One of the most common swaps involves a Muncie 4-speed. Shift points are kept close together in this M21 close-ratio gearbox, which maintains cruise RPMs (revolutions per minute) high. The M21 will have a faster peak speed than the M20 since the M21 comes with a higher center gear ratio. If you have a 2800 lb car with some moderate power, an M22 will likely hold up and run some fast times. These dimples reduce stress risers on the areas gear teeth that can develop cracks because of fatigue. Putting the slider into a forward position will help you connect the two shafts. How can you tell if you have a rock crush M22? Note the slot in the inner ring of the reverse gearthis is where the reverse fork will locate. Second was the direct benefit of the increased sales volume of the 4-speed GM muscle car market. . The 4.10 gearing can be swapped in, but this isn't a great idea - you'd be much happier with the 3.65 gearing in a Fiero. Apr 23, 2011. How much HP will a Muncie 4 speed hold. The Muncie was originally a stronger alternative to the T-10 and Super T-10 because it could take the torque. the nice thing about the sag. Both 2wd and 4wd versions of the SM465 can be used equally well, and there are no inherent advantages to either one once you have installed our adapter assembly. That the Muncie has much in common with the T-10 is no accident. The standard first-gear sleeve is on the top and the sleeve for the M22 is on the bottom (GM PN 3932228). one car is an auto as we speak and i don't want a fun car to be an auto bad enough my daily is and auto i don't want to have fun in an auto just my thing. From the 1960s until the late 1980s General Motors issued Technical Service Bulletins by mail or fax to alert dealerships of potential service issues. By 1966 it was relocatedto the upper passenger side. Typically, the M20/M21 gearsets have a first-gear helix angle of 26.4 degrees and an input shaft angle of 39 degrees. The same prep holds true for the second-gear, synchro and slider assembly. The latter also offered a 1.64 second, 1.28 third, and direct-drive 1.00 fourth gear, making it the most popular choice for street racers (as a close-ratio design allowed drivers to run through the gears much more quickly while taking maximum advantage of a vehicle's power band). This is what the assembly looks like with the front bearing installed, prior to inserting the input shaft into the front of the case. Shifter shafts damaged because of broken studs or stripped threads were now a problem of the past. The hole in the shaft was actuallyused on 19691970 models thathad a clip-on plastic gear. manual transmission going into gear but wont move, Clutch Safety Switch Bypass An Ultimate Guide, Does Corvette Have Back Seat? One of our friends/customers has a '65 GTO he drag races. The M20 and M21 cluster gears are cut at a 45-degree angle. That's asking a LOT from a "stock" transmission. T1 denotes the first gears tooth count, and T2 is the second gear teeth count. Here are a few significant differences between the two. Looking for info on another classic muscle car gearbox? With the ability to handle higher torque and horsepower, the new Super Muncie shown here can take up to 600 lb-ft of vicious torque. We invite you to get behind the wheel with us, it's certain to be an interesting drive. The 2wd version has a 35-spline threaded mainshaft compatible with a driveshaft yoke, and accompanying 2wd style tailhousing. Both the wide-ratio M20 and close-ratio M21 debuted in 1963 in the Corvette. Want to put this behind a 648 hp blower motor, My gramma drives an auto, I just want to have fun! This has never been together before. By 1965 the shifter-shaft designs changed because they had been snapping. You are using the information and automotive parts portrayed in this video solely at your own risk. The late-style synchro hub andblocking rings (left) were used on19661974 transmissions. Author and technician Paul Cangialosi tells us the original U.S. patent for the Muncie four-speed was filed on November 29, 1957, and approved May 7, 1963. It's just that simple to switch from standard 1:1 final-drive gearing to 0.778:1. Another factor that differs between Muncie M21 and M20 is the gears and output shafts. (Nitriding is a heat-treating process that adds surface hardness to the hub splines without distortion.) In the early 1960s, GM was looking to move away from the four-speed manual transmissions it had been purchasing from BorgWarner and bring production in-house. This bearing is placed into the front of the input shaft/fourth-gear assembly. Contact Us. Driving Line Accelerating Automotive Passion by providing a fresh angle of what fuels us. The Muncie design has roots going back to 1935. I've heard that it wont last long. However, the M21 has a higher torque capacity due to a stronger input shaft. For a 10 year period starting in the golden age of 1960s performance, General Motors' Muncie, Indiana transmission factory churned out several different flavors of this manual gearbox. The 1969 design changes were subtle, and now all models had drain plugs as a standard issue. The Muncie M21 was officially introduced in 1963. To show the approximate gains [Click here to read more], General Motors, like all the other car manufacturers of the time, did not put much valuable information on the vehicle identification number (VIN) plate. Looking for the webbing isan easy way to recognize the castingwhen looking for parts. By checking this box, you agree to Nitto Tires, Patina Perfect: A Coyote-Powered 71 F-100 Thats Just Right. The main case will sport a seven-digit casting number (found above the US Patent No), which is not a GM part number. On episode 11 of HOT ROD Garage, Mike Finnegan rounds out a bunch of El Camino upgrades with a big heart transplant. Is that the better trans. The M21 is superior for performance vehicles, while the M20 is superior for everyday transportation. The left shifter shaft has a 3/8-24threaded stud with machined flats onboth sides. If you liked this article you will LOVE the full book. See Chapter 2 for more information on serial numbers. GM learned early on the Muncie four-speed needed a larger input shaft bearing for improved durability. JavaScript is disabled. 21. This is just a temporary positioning while we install the countershaft bolt, locking it to the midplate. Filed Under: Chevy Tech Tips, Transmissions, If you were building a house, youd want to ensure that the foundation is a solid as possible before you built the rest of that multistory dream home. The cluster gear fits into the bottom of the case and is held there with a pin that runs through its center. For a better experience, please enable JavaScript in your browser before proceeding. The original M20 was only offered for one year. Check whether there are any rings around the shaft splines. The cast-iron three-speed retainer, #604932, can be used in place of the aluminum retainer and will be stronger. This is not a Muncie 4-speed retainer. A snap ring retained the first and second synchronizer assembly on the mainshaft. This layout is a 4-speed transmission with four forward gear ratios in the main case, a midplate bearing support, and a reverse gearset in the extension housing. Several NASCAR transmissions, such as the G-Force T101, are also T10-based. There are six known Muncie side covers. It will fit into the front of the transmission case opening. The upside to the racket was the ability to hold even big block torque without worrying about grenading on the starting line. A bushing was used with a v notch to promote better oil flow under the gear. if a sag would handle 500 ft-lbs with any abuse at alldo you think there'd be any market for a muncie? The transmissions oil-fill ports are on the side of the device, making it challenging to change and fill the oil. The early production Muncie four-speed case is the small-bore unit and can be identified by the GM casting number 3831704 (see Muncie M20/M21/M22 Main Case Identification chart). The T-85 three-speed transmission was one result of that merger. Most of the laterGM overhaul shop manuals showfour spacers in the exploded-viewdiagrams when, in fact, the transmissionsused six. Owners of most of these cars eliminated this system because they felt it hurt performance. The Muncie 4-speed transmission is a legend among fans of GM muscle cars. The Muncie 4-speed transmission is a legend among fans of GM muscle cars. Looking for a Muncie shifter engineered to fit within your budget? The later model Muncie 4-speeds (used with the V6 in 85 and early 86) have a beefed-up case and 3.65 gearing. Small changes in countergear needle bearing spacer tubes surfaced. Paul Cangialosi shares some of his Muncie 4 speed rebuild upgrade tips. A forum community dedicated to Chevrolet Chevelle owners and enthusiasts. In case you encounter these issues, you can check them out and get the answers you need. This is listed as PN-SL24229 from Wright Connection Speed & Gear. Before 1966 the speedometer gear bullet fitting on the extension housing was located on the drivers side in the middle of the shift linkage and below the oil level. The diameter of the main case countershaft bore was officially increased to 1 inch. This motor kinda fell in my lap, looks like it could be fun, BUT I'm on Uncle Sams dime and not a lot of extra coin. Therectangular slot of the linkage armmust fit properly. In a wide-ratio gearbox, the gear ratios between the first and second gear, the third and 1:1 fourth change more abruptly. Hurst Competition Plus shifters designed for earlier transmissions usually do not fit on these gearboxes. Saginaw 3-speed, Saginaw 4-speed, Muncie 4-speed, and TH350 (with 6 tailshaft) are all the same length within 1/8 or so. The transmission was also 3/4 inch longer than older models. 3. Tailshaft housings will vary based on original application. The Fora platform includes forum software by XenForo. For Synchro-Mesh, in fact, the transmissionsused six vertically and horizontally the is... Retained the first front-bearing retainer on the areas gear teeth that can develop cracks because of thelarger countershaft which. Pretty sure he has information on serial numbers they called the M22 created a with. Two shafts M22 created a problem with noise ( hence the name rock-crusher ) M20 M21... 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