Here is the cool part: the shifter location is the same as a Muncie 4-speed, and one will only need to move their crossmember back a couple inches to convert. ... i have a 1970 gto that has a m-21 close ratio muncie 4 speed tranny with 3.90 axle gears. i love how the car takes off from a dead stop, but the engine is screaming on the highway.
I replaced the Saginaw three speed in my 1968 C-10 with a Muncie M-13 three speed. I was out of a 1974 Chevy van and I do beleive that it was a six cylinder van. Trans had a cast iron case, used regular Muncie four speed sychros and small parts (hubs sliders bearings, seals, dog rings, etc.). Service parts will not be a problem for ya.
So best application for your car would be the M-20 unless you simply want a close ratio M-21. I had a factory M-21 in my '67 GTO which had the factory 3.90 rear. The close ratio keeps the RPM's higher up in the power band with each shift and there is little spread between the gears - thus the "close ratio" designation.
close ratio Muncie's were used on higher hp engines that had lower rear gears (3.55,3.73,4.10&4.56), the main purpose of them was to keep the engine in the upper rpm …
Close ratio trannies were generally ran with 3.73 and lower r.e.g.'s whereas the wide ratio was generally ran with the 3.55's and higher due to the 2.54 first gear vs the 2.20 of the close ratio. I love my 3.31's and my wide ratio M-20 tranny but a 26.5" tall, wide L-60 tire does strain my 11" clutch.. They measured a modern 298/53-14 on 9" rims..
Since the original M-22 was ONLY available in the close ratio version, there is NOW an M-22W. This M-22W version is simply a wide ratio version (thus the W) of the M-22. Since the M-22 was only a close ratio tranny, it was usually only available, and more compatable, with the lower ratio rearend gears such as 3.70, 4.10, etc.
Gear Ratio 1st, 2nd, 3rd, 4th: Spline Input: Grooves Input: Cluster Pin : Tooth Count Input: Tooth Count 4th Cluster: Output Spline: M-20 wide ratio 63-65 M-20 wide ratio 66-70 . M-20 wide ratio 71-74 . M-21 close ratio 63-65 . M-21 close ratio 66-70 . M-21 close ratio 71-74 . M-22 close ratio 65-69 . M-22 close ratio 70-74. 2.56, 1.91, 1.48, 1.00
I went from a M21 to a Tremec Magnum 6 speed close ratio matched up to a 396 3.73 rear and 27.1" rear tires. I was considering the TKO 600 but went with the 6 speed because of the overdrive ratios. 5th gear 0.80 and 6th gear 0.63 Cruising down the highway at 55 mph In 5th gear 2036 rpm and at 75 mph in 6th gear 2186 rpm.
Muncie also had a second close-ratio transmission called an M22, which enthusiasts christened Rockcrusher; this was used in performance big-block engines and Corvettes and is a highly sought-after performance transmission today, and is the heavy-duty version of the 2.20 ratio M21 4-speed. The later-model 1971-74 units are more popular with …
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The Muncie 4 speed,was first designed in 1963,and lasted until 1974. There are 2 basic ratios,close and wide. The close ratio gear box,gives you a fairly high first gear,with the rest of the gears fairly close together,for less …
The 4-speed was the product of careful engineering intended to modernize GM's transmission offerings. skip to content. ... (2.56:1 first gear) and the M21 close-ratio (2.20:1 first gear). 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 ...
The T-10 is based on the earlier three-speed transmission called the T-85. A close look at the layout inside reveals the T-10 is just the three speed with the reverse gear tucked into the extension housing to make room for the fourth gear. ... The close ratio gearboxs generally came with 3.73+ gear ratio'ed cars. 3.55 geared and higher ...
For example P7C05 will read: Muncie four speed aluminum for passenger car 1976, March, 5th. 1969-1974 codes include a suffix letter at the end to aid in identification of transmission ratios. A = 2.52 1st gear wide ratio M20, B=2.20 1st gear close …
57 3 Speed Stick w/Overdrive Chevy Tri Five Forum ·My car was a factory 3 speed car with a close ratio Muncie in it That is a 1 first gear and a 1 I believe in second gear and 1 in third gear It has a 1 rear axle and generally is a good around town driver But get it on the freeway and at 75 MPH it s running close to 4 000RPM
At 75 MPH, with a 3.31:1 gear ratio and a 27.1" tall tire, your engine will be turning 3078 RPM. The same combination with a 3.42:1 gear ratio will put you at 3180 RPM. The same combination with a 3.55:1 gear ratio will put you at 3301 RPM. The same combination with a 3.73:1 gear ratio will put you at 3468 RPM.
The gear ratio is the proportion of the number of rotations the output shaft produces to one rotation of the input shaft. This ratio describes the difference in rotational speed between the transmission output and the car engine. Gear ratios may also be used to explain the relationship between tires, differentials, rear end…
GM's goal with the Muncie four-speed was to produce a better shift employing larger synchro cones. He tells us both the M20 wide-ratio and M21 close-ratio transmissions were first offered in 1963. The M22 Rock Crusher would come later to accommodate the heavy twist of Chevrolet's big-blocks in the mid-1960s.
Depending on engine/rear gear ratio, the car was delivered with either a wide ratio or close ratio Muncie. The option was still M20 for the 4sp. In 1966, the two ratios were broken …
Both the wide-ratio M20 and close-ratio M21 debuted in 1963 in the Corvette. The M22 "Rock Crusher" followed four years later. It uses stronger components to handle big-block power. ... Gear ratios are the same as the close-ratio M21. The Muncie four-speed was used in a wide range of GM products through the 60s and 70s. However, the Rock ...
GM Manual Transmissions Muncie M21/M22 (Also M20 and BW T-10) Gear Vendors owes a lot to the Muncie close ratio trans. These words are very similar for the M20 and T10 but with some slight ratio differences depending on model.All M21/22 have the same 22% upshift and 28% downshift spread as the Gear Vendors. Overdrive … Continue reading GM 4-Speed Manual →
The Muncie M21 is a close-ratio unit originally designed to be matched with 4.11:1 or 4.56:1 GM 4 Series differentials. The M21 was for higher performance cars. A close-ratio …
The close ratio transmission makes the car's reponse to gear changes very much the same be it 1-2 or 3-4, and likewise in the reverse. It's preferred and/or more associated with road racing and touring open country side. There is a noticable difference between starting off with the close ratio and the wide ratio trannies.
Restored 68-70 Muncie M22 Rock Crusher 4 Speed Close Ratio With Unstamped Case (For: Chevrolet) Opens in a new window or tab. Remanufactured. ... 1973 Pontiac Firebird M20 Wide Ratio Muncie 4 Speed Transmission Core 3925661 (For: Chevrolet) Opens in a new window or tab. Pre-Owned. $1,050.00. or Best Offer +$224.55 shipping. 15 watchers.
However, the wide ratio intermediate shaft turns at 1.1 times the rate of the close ratio intermediate shaft, so the drop in revs between 1st, 2nd, and 3rd gears is the same in both transmissions.....BUT, the drop to 4th gear (1:1 in both transmissions) is (about) 500rpm in the close ratio transmission, and (about) 1500rpm in the wide ratio ...
Had a '69 Mach 1 with 290 HP 351W and wide ratio 4-speed (2.78 low). Didn't know any better and thought I had the "bad" transmission as a "close ratio" sounded like it …
Yes but 4th gear for both are 1:1…so identical. So to support the tighter lock on the power band (closer spaced gears) the close ratios start with a steeper first gear. That's why the close ratio appears in cars with 3.89, 3.91 and 4.30 gears. Occasionally they pop up in Boss 302s with 3.50 gears.
Just three types of Muncie 4-speeds are available based on the RPO (regular production option) code used when a car was ordered: the M20 (standard wide-ratio), M21 (close-ratio), and M22 (heavy-duty close-ratio). (The M does not stand for "Muncie.") Typically, when you ordered a GM car you had standard options and accessories installed.
The wide ratio (M20) transmission has a lower first gear with a wider spread between gears, so it will be easier to get the car rolling with something like 3.08 gears. The …
Wide ratios are good for heavier vehicles or vehicles with a broader HP and TQ curve. All 4-speed muncie ratios end at 1:1, so close ratio means your first gear won't be as …
I recently removed my close ratio 3 speed and installed a wide ratio 3 speed with overdrive. I need to tell you that I have a 4.56:1 rear axel and even with these low gears there is a big difference in the first gear launch. The numbers are; with the close ratio at 2.2:1 and 4.56 gears I had about a 10:1 overall first gear total ratio.
However, if you are looking for a Muncie transmission with a higher top speed, then the M20 is the better choice. 3. Gear Ratios. Muncie M21-The Muncie M21 is a close-ratio transmission with a gear set having a 3.36:1 ratio first gear and 0.68:1 ratio fourth gear suitable for high-performance cars.
Meanwhile, the Muncie M21 close-ratio transmission has a gear set with a 1st gear ratio of 3.36:1 and a 4th gear ratio of 0.68:1, making it ideal for high-performance automobiles. Weight Since the M21's gear set is more robust than the M20's, there is a weight difference between the two.
The M22's are both close ratio and the M21 is a wide ratio...again from what I was told years ago. I know that the M22 was supposedly stronger than the M21 and that the close ratio rock crusher was supposed to the the beefiest, but not sure why or if this is even true.
BUT, the ratio split/RPM drop between gears is the same for 1st/2nd and 2nd/3rd... The "wide"/"close" difference is the 3rd/4th gear... Take anyoriginal GM M20/M21/M22 to 6000 RPM in 1st, shift to second, and your RPMs will be around 4470 RPM... But the M20 has lower ratios which help offset higher "highway" rear-end gear ratios...
The Muncie M21 is a close-ratio unit originally designed to be matched with 4.11:1 or 4.56:1 GM 4 Series differentials. High performance cars now had a transmission that could handle its high power. A close-ratio gearbox keeps shift points closer together, which keeps rpms up.
