Final wheel drive

Note: If you are likely to change your back diff liquid yourself, (or you plan on opening the diff up for support) before you allow fluid out, make sure the fill port can be opened. Absolutely nothing worse than letting fluid out and then having no way to getting new fluid back.
FWD last drives are extremely simple in comparison to RWD set-ups. Virtually all FWD engines are transverse mounted, which means that rotational torque is created parallel to the direction that the wheels must rotate. There is no need to modify/pivot the path of rotation in the ultimate drive. The ultimate drive pinion gear will sit on the end of the output shaft. (multiple result shafts and pinion gears are feasible) The pinion equipment(s) will mesh with the ultimate drive ring equipment. In almost all instances the pinion and band gear will have helical cut tooth just like the remaining tranny/transaxle. The pinion gear will be smaller sized and have a much lower tooth count than the ring equipment. This produces the final drive ratio. The band gear will drive the differential. (Differential operation will be described in the differential section of this content) Rotational torque is sent to the front tires through CV shafts. (CV shafts are generally referred to as axles)
An open up differential is the most common type of differential found in passenger vehicles today. It is usually a simple (cheap) style that uses 4 gears (sometimes 6), that are known as spider gears, to drive the axle shafts but also permit them to rotate at different speeds if required. “Spider gears” is a slang term that is commonly used to spell it out all of the differential gears. There are two different types of spider gears, the differential pinion gears and the axle part gears. The differential case (not housing) gets rotational torque through the band gear and uses it to operate a vehicle the differential pin. The differential pinion gears ride upon this pin and so are driven because of it. Rotational torpue is usually then used in the axle part gears and out through the CV shafts/axle shafts to the tires. If the automobile is travelling in a directly line, there is no differential actions and the differential pinion gears only will drive the axle side gears. If the automobile enters a convert, the outer wheel must rotate quicker compared to the inside wheel. The differential pinion gears will start to rotate as they drive the axle aspect gears, allowing the outer wheel to increase and the within wheel to slow down. This design works well so long as both of the driven wheels possess traction. If one wheel doesn’t have enough traction, rotational torque will follow the road of least resistance and the wheel with small traction will spin while the wheel with traction won’t rotate at all. Since the wheel with traction isn’t rotating, the vehicle cannot move.
Limited-slip differentials limit the amount of differential action allowed. If one wheel starts spinning excessively faster compared to the other (way more than durring normal cornering), an LSD will limit the velocity difference. This is an advantage over a normal open differential style. If one drive wheel looses traction, the LSD action will allow the wheel with traction to get rotational torque and allow the vehicle to go. There are many different designs currently used today. Some work better than others depending on the application.
Clutch style LSDs are based on a open differential design. They have another clutch pack on each one of the axle side gears or axle shafts within the final drive casing. Clutch discs sit down between the axle shafts’ splines and the differential case. Half of the discs are splined to the axle shaft and the others are splined to the differential case. Friction material is used to split up the clutch discs. Springs put strain on the axle part gears which put strain on the clutch. If an axle shaft wants to spin quicker or slower than the differential case, it must overcome the clutch to take action. If one axle shaft tries to rotate faster than the differential case then the other will attempt to rotate slower. Both clutches will withstand this action. As the acceleration difference increases, it turns into harder to overcome the clutches. When the automobile is making a tight turn at low swiftness (parking), the clutches provide little resistance. When one drive wheel looses traction and all the torque goes to that wheel, the clutches level of resistance becomes much more apparent and the wheel with traction will rotate at (near) the rate of the differential case. This kind of differential will likely need a special type of liquid or some form of additive. If the fluid isn’t changed at the correct intervals, the clutches may become less effective. Resulting in small to no LSD action. Fluid change intervals differ between applications. There is usually nothing incorrect with this style, but keep in mind that they are just as strong as a plain open differential.
Solid/spool differentials are mostly used in drag racing. Solid differentials, like the name implies, are completely solid and will not allow any difference in drive wheel speed. The drive wheels always rotate at the same swiftness, even in a turn. This is not a concern on a drag race vehicle as drag vehicles are traveling in a straight line 99% of that time period. This can also be an edge for vehicles that are becoming set-up for drifting. A welded differential is a regular open differential which has experienced the spider gears welded to create a solid differential. Solid differentials certainly are a great modification for vehicles created for track use. As for street use, a LSD option will be advisable over a solid differential. Every convert a vehicle takes will cause the axles to wind-up and tire slippage. This is most noticeable when traveling through a slow turn (parking). The result is accelerated tire use and also premature axle Final wheel drive failure. One big advantage of the solid differential over the other styles is its power. Since torque is applied directly to each axle, there is absolutely no spider gears, which are the weak spot of open differentials.