Also manufactured and used by as the Trimatic transmission. This is a page from an old factory 1967 Nova assembly manual showing three different part numbers for the M20 and one number for the M21. Many people want to know exactly what year the transmission came from, and what vehicle it was in. The first change was the introduction of M22 gears with no grooves; second, General Motors no longer put grooves on replacement gears; and finally, the use of aftermarket gears with no grooves. With the introduction of the 3885010 case, the countershaft bore was increased to 1 inch.
Coincidentally, March 1965 seems to be a time when the 396 engine started to migrate into more vehicles, such as Z16 Chevelles, Corvettes, and full-size Impalas. The M-21 has a higher pitch angle on its gear teeth. This is for a 1968 production car. To contribute to our operating budget,. They are the exact same transmission. Corvette production determined how Muncie design evolved.
The evolution of case design also helps pinpoint the year a case was released. Ford led the design of the 10-speed transmission, as well as filing the design patents for said transmission. Feel free to upload pictures and ask questions. Automatic Transmissions Some transmissions may have a code stamped into their case or a tag riveted to them. A very small number of 396 engines also found their way into the 1965 Impala.
In-exchange for Ford's 10-speed transmission, General Motors will let Ford use its 9-speed transmission for front-wheel drive applications; Ford ultimately declined use of the 9T. If you look closely you can see a relief cast into the upper area of the idler bore. In most cases if someone has told you that you are looking at a 700R4 and you count 16 bolts you can be reasonably sure that you have found what you were looking for. It was used primarily with the 26-spline input shaft and larger 32-spline output-shaft models, so it appears that they were looking to optimize strength everywhere possible since the 454 engine was introduced in 1970. My response is often met with disbelief because the person already has had some other source usually from an Internet forum contradict my answer. Generally able to handle up to 400 foot pounds of torque.
By late 1963 the rare 3839606 case started to show up in cars with a larger bearing bore. Tooling up for a die casting is very expensive. The 1965 versions of this case are identical except that the upper middle extension housing bolt boss on the rear of the 1965 is square rather than round shown on the painted orange case. The same sources indicate that 1352-251 is the same transmission as a 1352-249, except assembled by Tremec after Borg-Warner stopped production. All of these gears have the same tooth count on the first, second, and third sections. Some of the best Muncie builders participate on that page.
In 2012, he helped establish OnAllCylinders, where he enjoys covering all facets of hot rodding and racing. By 1963, wider gears improved the T10; this meant that the front bearing had to get narrow to compensate for the size difference of the front portion of the countergear. These transmissions probably were assembled with special alloy gears, because the case casting is identical to the 3851325 as well. Serial Numbers Serial numbers are stamped into the case. Casting number revisions are always chronological, which means that a higher number corresponds to a later part. It is unique to the Muncie and was used until the very end of production in all main cases with the exception of the 3831704 case. While we have made every effort in making the information presented here as factual as possible, but there still could be some discrepancies or errors.
By the start of 1969 these cases and all future cases had the drain plug boss drilled and threaded. Many rebuilders have bins full of tags. These two milled 3864 cases have March 1965 assembly dates. Ratio Identification As mentioned previously, we know that the Muncie came with several ratios. The first units were for the 1982 model year.
The staff has been amazing to work with and takes care of their customers better than any other company I have ever dealt with. This is a 1970 M20 case. Most transmissions are missing these tags, but if you want to do a complete restoration they are generally necessary. The smaller 6207-type bearing replaced the larger 6307 bearing in 1963. In fact all of the upper-speed gears have the same tooth count regardless of ratios. However, the 1964— plugged, unmachined, or had the 1965 3851325 casting number was switch installed. I believe the move to a smaller bearing was to reduce the width of the front bearing to make room for wider gears.