The Manual Gear Box Mazda 323

The manual transaxle i disassembled (pulled apart) was from a Mazda 323. It consisted of these parts, a mainshaft that houses the gears, selector fork(interlock mechanism) that are used to prevent the engagement of more than one gear at a time, an input shaft that houses the driver gears and next to this on the mainshaft are gear selectors which are the driven gears, reverse shaft also known as reverse shift rod and reverse shift sleeve and another reverse shaft but smaller, all used together to select the reverse gear, and at the bottom of the gear box is the crown wheel which is known as the final drive inside the gear box.This is a step by step of how i did the task i was given.
1) Remove all 12 bolts holding on the transmission case.
2) Remove the bolts securing the reverse gear idler shaft.
3) Remove bolt securing the interlock sleeve.
4) Remove the case.
5) Remove the reverse idler shaft and gear.
6) Remove the bolt from the reverse gear shift rod sleeve.
7) Remove the roll pin, using a pair of pliers and also remove magnet if fitted.
8) Remove the aluminun plug from the side of the transmission housing,by levering the reverse lever shaft with a flat blade screwdriver from inner end this will push the plug out.
9) Remove the reverse shift rod.
10) Remove roll pin from crank lever shaft using a hammer and a dot punch.
11) Remove crank lever shaft and lever.
12) Remove gear selectors and gears as one assembly.
13) Remove seletor forks from gear assembly.
14) Remove final drive.eg crown wheel.
Once all in pieces i counted how many teeth were on each component such as
1st gear on input shaft has 12 teeth.(driver gears)
2nd gear on input shaft has 18 teeth.
3rd gear on input shaft has 31 teeth.
4th gear on input shaft has 37 teeth.
1st gear on mainshaft has 41 teeth.(driven gears)
2nd gear on mainshaft has 37 teeth.
3rd gear on mainshaft has 40 teeth.
4th gear on mainshaft has 34 teeth.
The pinion has 29 teeth and the crown wheel has 77.
Then i had to calculate the gear ratio. Definition= the number of turns of the input to produce 1 turn of the output.Its easy and il show you.
Ratio calculation:
Formula: the number of teeth on the driven gear divided by the number of teeth on the driving gear.
Lets say the driven gear is 44 and the driver gear is 11 the driving gear must rotate 4 time to rotate the driven gear once. This ratio is said to be 4 to 1.
The torque of the larger gear is 4 times that of the smaller gear.
So after i done that i put it all back together which is basically the reverse of the disassembly.
The purpose of a manual gearbox is: To allow drive to operate the engine in its most efficient speed range.To allow driver to select a suitable gear ratio to increase engine torque(torque multiplication) to match an increased load requirement.Change down to a lower gear, a higher numerical gear ratio. Allows driver to select a suitable gear to reduce engine torque multiplication, in favor of increasing vehicle speed, as load reduces.(change up to a higher gear- a lower numerical gear ratio. Allows driver to select neutral and disconnect drive. Allows driver to select reverse gear and drive vehicle backwards.
Note:Spur toothed gears are usually used for reverse gears as it not used frequently or for long periods and it also provide a less costly sliding gear engagement.
Helical toothed gears are used in most gear boxes due to there increased strength, durability, quietness and moderate cost.
Herringbone toothed gears are seldom used in automotive application due to their high cost and complexity.

Auto transmission

The automatic I disassembled and reassembled was a Ravigneaux Borg Warmer 35.
Auotmatic transmission: A set of gear ratio's that will auotmatically shift to a higher or lower ratio,depending on vehicle speed.
It consisted of the following parts:
Drum assembly,an input shaft, rear clutch,rear band,planetary gearset,ring gear,output shaft,govener,forward sun and shaft,reverse sun and front band.
Govener: The govener valve which monitor vehicle speed.
Gearsets: Usually planetary(epicyclic) used to create the various speed ratio's required.
Servos: Is used to apply brake bands to clutch packs.
Rear band: Used to engage clutch packs.
Front band: Also used to hold gearset components stationary.
Output shaft: Is used to change gear ratio.
Rear clutch: Used to select gears(lower or higher).
Planetary gearset: Used to connect gearbox to driveshaft.
A input shaft: Used to connect torque converter to the gearbox.
Torque converter: Is used to convert torque between engine and transmission.
Two advantages of using a ''lock up'' torque converter are:
1)It improves fuel efficiency.
2)It increases vehicle top speed.
A simple planetary gearset consists of :
1)Sun gear: In the centre of the gearset which other components(gears) rotate.
2)Ring gear or Annulus: Arond the outside of the gear set.
3)Planetary Carrier: On which are mounted the planetary pinions, which are located between the inner sun gear, and outer ring gear and connect both to these gears.
Automatic transmissions comprise of three major sections:
1)Torque converter or fluid coupling.
2)Mechanical gear ratio and operating system.
3)Hydraulic control system.
Heres a lil law I threw in on fluids.
Pascals Law: ''When any part of fluid is subjected to a pressure, the pressure is transmitted equally and undiminished to every portion of the surface of the containing vessel.''
The next bit is on torque converter I cut and pasted it from the internet.
The front section is called the torque converter. In replacing the traditional clutch, it performs three functions:
* It acts as a hydraulic clutch (fluid coupling), allowing the engine to idle even with the transmission in gear.
* It allows the transmission to shift from gear to gear smoothly, without requiring that the driver close the throttle during the shift.
* It multiplies engine torque making the transmission more responsive and reducing the amount of shifting required.
The torque converter is a metal case that is shaped like a sphere that has been flattened on opposite sides and is bolted to the rear of the engine's crankshaft. Generally, the entire metal case rotates at engine speed and serves as the engine's flywheel.
The case contains three sets of blades. One set is attached directly to the case forming the impeller or pump. Another set is directly connected to the output shaft, and forms the turbine. The third set (stator) is mounted on a hub which, in turn, is mounted on a stationary shaft through a one-way clutch. Rollers are wedged into slots, preventing backward rotation. When the rollers are not in the slots, the stator turns in the same direction as the impeller. The pump, which is driven by the converter hub at engine speed, keeps the torque converter full of transmission fluid at all times. Fluid flows continuously through the unit to provide cooling.
A fluid coupling will only transmit the torque the engine develops; it cannot increase the torque. This is one job of the torque converter. The impeller drive member is driven at engine speed by the engine's crankshaft and pumps fluid, to its center, which is flung outward by centrifugal force as it turns. Since the outer edge of the converter spins faster than the center, the fluid gains speed. Fluid is directed toward the turbine driven member by curved impeller blades, causing the turbine to rotate in the same direction as the impeller. The turbine blades are curved in the opposite direction of the impeller blades.
In flowing through the pump and turbine, the fluid flows in two separate directions. It flows through the turbine blades, and it spins with the engine. The stator, whose blades are stationary when the vehicle is being accelerated at low speeds, converts one type of flow into another. Instead of allowing the fluid to flow straight back into the pump, the stator's curved blades turn the fluid almost 90° toward the direction of rotation of the engine. Thus the fluid does not flow as fast toward the pump, but is already spinning when the pump picks it up. This has the effect of allowing the pump to turn much faster than the turbine. This difference in speed may be compared to the difference in speed between the smaller and larger gears in any gear train. The result is that engine power output is higher, and engine torque is multiplied.
As the speed of the turbine increases, the fluid spins faster and faster in the direction of engine rotation. Therefore, the ability of the stator to redirect the fluid flow is reduced. Under cruising conditions, the stator is eventually forced to rotate on its one-way clutch and the torque converter begins to behave almost like a solid shaft, with the pump and turbine speeds being almost equal.
In the late 70's, Chrysler Corporation introduced an automatic transmission, featuring what is called a "lock-up" clutch in the transmission's torque converter. The lock-up is a fully automatic clutch that engages only when the transmission shifts into top gear or when needed based on a predetermined demand factor.
The lock-up clutch is activated by a piston. When engaged, the lock-up clutch gives the benefits of a manual transmission, eliminating torque converter slippage. In the engaged position, engine torque is delivered mechanically, rather than hydrodynamically (through fluid). This gives improved fuel economy and cooler transmission operating temperatures.
In the early 80's, Ford introduced what is known as the Automatic Overdrive Transmission (AOT). Essentially, this transmission uses a lock-up torque converter, by offering an additional refinement. The transmission is a four-speed unit, with fourth gear as an overdrive (0.67:1). Torque is transmitted via a full mechanical lock-up from the engine, completely bypassing the torque converter and eliminating hydraulic slippage.
In third gear (1:1 ratio), engine power follows a "split-torque" path, in which there is a 60% lock-up. Sixty percent of the power is transmitted through solid connections and 40% of the engine power is delivered through the torque converter.
Throughout the 90's, Subaru introduced an Electronic Continuously Variable Transmission (ECVT) and Honda introduced their version (CVT). This transmission uses a metal belt and two variable-diameter pulleys to keep smooth, uninterrupted range of gearing. Size of the pulleys is controlled through the use of hydraulics. This unit produces a miles per gallon closer to a manual transmission, while attaining a smoother shift than an automatic transmission.