Dont know much about rear-ends, please help!
02-08-2004, 05:41 PM
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Dont know much about rear-ends, please help! Got a few questions:
What are the differences of these setups: Locker, Spool, Posi etc..? What are they? Can someone explain?
Also, what are channels?
Thanks in advance
What are the differences of these setups: Locker, Spool, Posi etc..? What are they? Can someone explain?
Also, what are channels?
Thanks in advance
02-08-2004, 11:53 PM
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Does this help?
Standard / Open Carrier:
Whenever a vehicle negotiates a turn, the outside wheel must travel farther than the inside wheel. In order for this to happen, the outside wheel must turn faster than the inside wheel. This is accomplished by spider gears that allow the outside wheel to turn faster (this can be either the left or the right, but must be the outside wheel) than the ring gear, while the inside wheel turns slower than the ring gear. The net sum of the speed of the two wheels is twice as fast as the ring gear. That means if the outside wheel is turning 2 rpm faster than the ring gear, the inside wheel is turning 2 rpm slower than the ring gear. This differential action is very straightforward in a standard open differential and works great for more than 95% of vehicles on the road today.
When a vehicle with an open or a standard differential encounter a loose traction surface, it directs power to the wheel with the least resistance. The resulting action is the wheel on the loose surface spins while the opposite wheel on the better traction surface stands still or barely transfers power. The reason a standard open differential works this way is because it is designed to provide equal force to both sides. If the wheel on either side looses traction the other side suffers as well. If for example, the left wheel looses traction and can not provide a resistance force from the left wheel back to the differential side gear, then the right side gear can not transfer a force to the right wheel that is greater than the resistance force of the slipping left wheel. And vice versa. Re-read this a few times and it will make more sense. The main point to remember is that an open differential provides equal power to both sides, NOT equal speed.
An open differential works just fine for 95% of vehicles on the road since most people do not spin their tires often if at all. For those of us who like to burn rubber or go off the dry pavement, there are now too many limited slip and locking differentials to choose from.
Positractions & Limited Slips:
Transmits equal torque to both wheels when driving straight ahead. However when one wheel spins due to loss of traction, a patch of ice, mud, too much throttle, etc., the unit automatically provides more torque to the wheel that has traction. Recommended for daily driving, works well in ice, rain, mud and snow. However, in situations where absolute lockup is needed, a limited slip is not the best choice due to the fact that limited slips do slip in some situations.
Positraction is a type of limited slip and is a term that is used very loosely as another name or description for limited slip differentials. A positraction is not more aggressive than a limited slip or vice versa. The name "positraction" was used by General Motors for their limited slip differential and the name has been associated with limited slips for many years.
Automatic Lockers:
Lockers, mechanical locking differentials that is, provide 100% transfer of power to both drive wheels. This power can be lost if both wheels spin, but a locking differential will never let one wheel spin free by itself while the other one sits still (unless the unit is broken). Automatic locking differentials are engineered to keep both wheels in a constant drive mode, yet have the ability to unlock to permit a difference in wheel speed while negotiating turns. Recommended for serious off-roaders or serious hot-rodders, can be annoying for everyday driving. The main shortcoming of automatic lockers is the noise or banging and clunking inherent in their design. When getting on or off the throttle they tend to bang or clunk. And they sometimes make noise while disengaging when negotiating a turn. These characteristics are due to the design and a few locker manufacturers have come up with designs that make less noise, but no one has developed a perfectly quiet automatic locker yet. One more effect of lockers that hampers every day use, is, they only drive the inside wheel on a turn which can effect vehicle handling. The specific effects of driving the inside wheel is the vehicle tends to yaw from side to side slightly when negotiating a turn under power. When turning sharply while taking off from stop, the inside wheel will tend to spin easily. This is especially more prominent when taking off on a right turn for two reasons. The torque on the rearend housing due to the driveline torque un-weights the right wheel, and right hand turns are tighter because we drive on the right side of the road and we have to cross over the oncoming lane to make a left hand turn which makes it a lot less sharp.
On-Command Lockers:
Many people want the benefits of a locking differential, but do not want the handling characteristics or noise of an automatic locker. There are a few on-command lockers available as an OEM option. These include the 1998 & newer Toyota Tacoma & Land Cruiser. These EOM designs use an electric motor or vacuum diaphragm to engage the locker. When it is not engaged the unit acts like a standard open differential with no ill side effects aside from poor traction. When engaged, these units' lockup 100% and act like a spool with no differential action or difference in speed between the left and right wheels allowed.
Spools & Mini Spools:
For racing, serious off-road, or crazy hot-rodders, a spool is the ultimate traction differential. Actually, it can hardly be called a differential because it does not differentiate. Spools have several purposes in a differential. First, they lock both left and right axles solid together so that there can be no loss of power due to the unit allowing one wheel to spin faster than the other. Second, they usually support the ring gear much better than most other differentials. Last, they can be lighter than a differential, which saves rotating mass as well as un-sprung weight that the suspension has to contain. The main shortcoming of spools is the fact that the outside wheel has to turn faster when negotiating a turn if both wheels are to maintain traction. If the axles are locked together, one or both wheels have to slip in order for the outside wheel to travel farther than the inside wheel. This can cause the rear of the vehicle to spin out, fish-tale, or can cause a lot of noise that sounds like positraction clutch chatter as the axles twist and release. Sometimes these effects are not all that bad, and they are less severe when 35-spline or larger axles are used. For those people on a budget, there are mini-spools available for many rearend designs. A mini-spool fits inside the standard open carrier, replacing the spider gears, and locking the left and right axle shafts together just like a spool does. A mini spool drives exactly like a full spool does, but they are not as strong as a full spool and do not add any extra support to the ring gear like a spool does.
Channels:
In a 3-channel ABS system hydraulic pressure is supplied to the front brakes individually, and is supplied to both rear brakes as if there were only one, although wheel speed is measured at all four wheels individually. This system is less complicated and cheaper to build but is does not provide as much safety and control as a 4-channel ABS.
In a 4-channel ABS system hydraulic pressure is supplied to to all four brakes individually, wheel speed is measured at all four wheels individually. Wheel lockup can be controlled and prevented on all four wheels indiviadually. Improved safety and control over 3-channel ABS.
Standard / Open Carrier:
Whenever a vehicle negotiates a turn, the outside wheel must travel farther than the inside wheel. In order for this to happen, the outside wheel must turn faster than the inside wheel. This is accomplished by spider gears that allow the outside wheel to turn faster (this can be either the left or the right, but must be the outside wheel) than the ring gear, while the inside wheel turns slower than the ring gear. The net sum of the speed of the two wheels is twice as fast as the ring gear. That means if the outside wheel is turning 2 rpm faster than the ring gear, the inside wheel is turning 2 rpm slower than the ring gear. This differential action is very straightforward in a standard open differential and works great for more than 95% of vehicles on the road today.
When a vehicle with an open or a standard differential encounter a loose traction surface, it directs power to the wheel with the least resistance. The resulting action is the wheel on the loose surface spins while the opposite wheel on the better traction surface stands still or barely transfers power. The reason a standard open differential works this way is because it is designed to provide equal force to both sides. If the wheel on either side looses traction the other side suffers as well. If for example, the left wheel looses traction and can not provide a resistance force from the left wheel back to the differential side gear, then the right side gear can not transfer a force to the right wheel that is greater than the resistance force of the slipping left wheel. And vice versa. Re-read this a few times and it will make more sense. The main point to remember is that an open differential provides equal power to both sides, NOT equal speed.
An open differential works just fine for 95% of vehicles on the road since most people do not spin their tires often if at all. For those of us who like to burn rubber or go off the dry pavement, there are now too many limited slip and locking differentials to choose from.
Positractions & Limited Slips:
Transmits equal torque to both wheels when driving straight ahead. However when one wheel spins due to loss of traction, a patch of ice, mud, too much throttle, etc., the unit automatically provides more torque to the wheel that has traction. Recommended for daily driving, works well in ice, rain, mud and snow. However, in situations where absolute lockup is needed, a limited slip is not the best choice due to the fact that limited slips do slip in some situations.
Positraction is a type of limited slip and is a term that is used very loosely as another name or description for limited slip differentials. A positraction is not more aggressive than a limited slip or vice versa. The name "positraction" was used by General Motors for their limited slip differential and the name has been associated with limited slips for many years.
Automatic Lockers:
Lockers, mechanical locking differentials that is, provide 100% transfer of power to both drive wheels. This power can be lost if both wheels spin, but a locking differential will never let one wheel spin free by itself while the other one sits still (unless the unit is broken). Automatic locking differentials are engineered to keep both wheels in a constant drive mode, yet have the ability to unlock to permit a difference in wheel speed while negotiating turns. Recommended for serious off-roaders or serious hot-rodders, can be annoying for everyday driving. The main shortcoming of automatic lockers is the noise or banging and clunking inherent in their design. When getting on or off the throttle they tend to bang or clunk. And they sometimes make noise while disengaging when negotiating a turn. These characteristics are due to the design and a few locker manufacturers have come up with designs that make less noise, but no one has developed a perfectly quiet automatic locker yet. One more effect of lockers that hampers every day use, is, they only drive the inside wheel on a turn which can effect vehicle handling. The specific effects of driving the inside wheel is the vehicle tends to yaw from side to side slightly when negotiating a turn under power. When turning sharply while taking off from stop, the inside wheel will tend to spin easily. This is especially more prominent when taking off on a right turn for two reasons. The torque on the rearend housing due to the driveline torque un-weights the right wheel, and right hand turns are tighter because we drive on the right side of the road and we have to cross over the oncoming lane to make a left hand turn which makes it a lot less sharp.
On-Command Lockers:
Many people want the benefits of a locking differential, but do not want the handling characteristics or noise of an automatic locker. There are a few on-command lockers available as an OEM option. These include the 1998 & newer Toyota Tacoma & Land Cruiser. These EOM designs use an electric motor or vacuum diaphragm to engage the locker. When it is not engaged the unit acts like a standard open differential with no ill side effects aside from poor traction. When engaged, these units' lockup 100% and act like a spool with no differential action or difference in speed between the left and right wheels allowed.
Spools & Mini Spools:
For racing, serious off-road, or crazy hot-rodders, a spool is the ultimate traction differential. Actually, it can hardly be called a differential because it does not differentiate. Spools have several purposes in a differential. First, they lock both left and right axles solid together so that there can be no loss of power due to the unit allowing one wheel to spin faster than the other. Second, they usually support the ring gear much better than most other differentials. Last, they can be lighter than a differential, which saves rotating mass as well as un-sprung weight that the suspension has to contain. The main shortcoming of spools is the fact that the outside wheel has to turn faster when negotiating a turn if both wheels are to maintain traction. If the axles are locked together, one or both wheels have to slip in order for the outside wheel to travel farther than the inside wheel. This can cause the rear of the vehicle to spin out, fish-tale, or can cause a lot of noise that sounds like positraction clutch chatter as the axles twist and release. Sometimes these effects are not all that bad, and they are less severe when 35-spline or larger axles are used. For those people on a budget, there are mini-spools available for many rearend designs. A mini-spool fits inside the standard open carrier, replacing the spider gears, and locking the left and right axle shafts together just like a spool does. A mini spool drives exactly like a full spool does, but they are not as strong as a full spool and do not add any extra support to the ring gear like a spool does.
Channels:
In a 3-channel ABS system hydraulic pressure is supplied to the front brakes individually, and is supplied to both rear brakes as if there were only one, although wheel speed is measured at all four wheels individually. This system is less complicated and cheaper to build but is does not provide as much safety and control as a 4-channel ABS.
In a 4-channel ABS system hydraulic pressure is supplied to to all four brakes individually, wheel speed is measured at all four wheels individually. Wheel lockup can be controlled and prevented on all four wheels indiviadually. Improved safety and control over 3-channel ABS.
