Limited Slip Differential - Revision history

204.101.172.18: /* Mechanism */

2009-02-13T13:58:27Z

Mechanism

← Older revision		Revision as of 13:58, 13 February 2009
Line 37:		Line 37:
	As the input torque of the driveshaft tries to turn the diff centre, internal pressure rings (adjoining the clutch stack) are forced sideways by the spider gear mount trying to climb the ramp, which compresses the clutch stack. The more the clutch stack is compressed, the more coupled the wheels are. The mating of the vertical ramp surfaces in a 1 way LSD on over run produces no cam effect and no corresponding clutch stack compression.		As the input torque of the driveshaft tries to turn the diff centre, internal pressure rings (adjoining the clutch stack) are forced sideways by the spider gear mount trying to climb the ramp, which compresses the clutch stack. The more the clutch stack is compressed, the more coupled the wheels are. The mating of the vertical ramp surfaces in a 1 way LSD on over run produces no cam effect and no corresponding clutch stack compression.

	Another variator is the "cone type", which is ~~prelaoded~~ by a strong spring. These are ~~generaly~~ less effective in high torque situations (drag racing, etc.) but better in low-torque conditions (ice, snow) where there may not be enough torque to apply any clutch pressure in the clutch-pack type, especially if somewhat worn.		Another variator is the "cone type", which is preloaded by a strong spring. These are generally less effective in high torque situations (drag racing, etc.) but better in low-torque conditions (ice, snow) where there may not be enough torque to apply any clutch pressure in the clutch-pack type, especially if somewhat worn.

	=====Servicing=====		=====Servicing=====

99.250.166.66: /* Types */

2008-05-16T11:36:26Z

Types

← Older revision		Revision as of 11:36, 16 May 2008
Line 25:		Line 25:
	If the LSD behaves somewhere inbetween these two extremes, it is a 1.5 way diff, which is a compromise between sportiness and safety.		If the LSD behaves somewhere inbetween these two extremes, it is a 1.5 way diff, which is a compromise between sportiness and safety.

	Clutch LSDs are frequently noisy, clunky, & expensive, which makes them unlikely to be installed on a passenger car these days. However their response speed and coupling strength is the best of the commonly available LSDs. They are also the only commonly available LSD able to stand up to extreme motorsport abuse.		Clutch LSDs are frequently noisy, clunky, & expensive, which makes them unlikely to be installed on a passenger car these days. However their response speed and coupling strength is the best of the commonly available LSDs. They are also the only commonly available LSD able to stand up to extreme motorsport abuse. The Salisbury type ofmultidisc LSD works very well. It does cause some entry understeer - but not a lot - and it is very smooth, progressive and easy to drive.

	The latest version of this basic design, introduced in the late 1990s on the Jeep Grand Cherokee (Spicer sourced) uses a small hydraulic pump, driven by the difference in axle speed, to apply more lockup pressure, similar to the action of an automatic transmission clutch pack. Later Dodge Vipers have also used this system with only moderate success.		The latest version of this basic design, introduced in the late 1990s on the Jeep Grand Cherokee (Spicer sourced) uses a small hydraulic pump, driven by the difference in axle speed, to apply more lockup pressure, similar to the action of an automatic transmission clutch pack. Later Dodge Vipers have also used this system with only moderate success.
Line 44:		Line 44:

	Servicing consists of changing the oil after hard sessions, also to remove metal particles, and eventually replacing the clutches, or the centre. In any case the oil should should be changed regularly (as opposed to the open diff, where the oil could be left unchanged for several hundred thousand kilometres).		Servicing consists of changing the oil after hard sessions, also to remove metal particles, and eventually replacing the clutches, or the centre. In any case the oil should should be changed regularly (as opposed to the open diff, where the oil could be left unchanged for several hundred thousand kilometres).

			=====Spool=====

			Solid spools connect both wheels so that they both turn at the same speed. While this is ideal for straight line acceleration, upon turning the inside wheel drags, causing the car to understeer.

			=====Detroit Locker=====

			The Detroit Locker is not an LSD, but a locking differential. Most often found in off road trucks, the Detroit Locker isn't suitable for racing. "The Detroit Locker is violent and unpredictable in operation and because of this it is simply not possible to place the car precisely where you want it on the racetrack or ot apply the throttle as early as the tires will allow on corner exit. Given any kind of choice at all, no one in their right mind uses a Detroit Locker." - Carroll Smith

	====Torsen Diff====		====Torsen Diff====

99.250.166.66: /* Torsen Diff */

2008-05-16T11:24:43Z

Torsen Diff

← Older revision		Revision as of 11:24, 16 May 2008
Line 49:		Line 49:
	Geared, ''torque-sensing'' mechanical differentials utilize planetary gears to "sense" torque on one shaft. The most famous version is the Torsen differential invented by Vernon Gleasom in 1958, then sold to Gleason Corporation, who started marketing it in 1982. Geared LSDs are less prone to wear than the clutch type, but the high number of parts, and their stress risers, limits their torque handling capability. As such it is not suitable for racing. Technically, these are really torque-biasing diffs, not true LSDs. It requires at least one wheel to grip or else it acts as an open differential (it doesn't work when both tires are slipping).		Geared, ''torque-sensing'' mechanical differentials utilize planetary gears to "sense" torque on one shaft. The most famous version is the Torsen differential invented by Vernon Gleasom in 1958, then sold to Gleason Corporation, who started marketing it in 1982. Geared LSDs are less prone to wear than the clutch type, but the high number of parts, and their stress risers, limits their torque handling capability. As such it is not suitable for racing. Technically, these are really torque-biasing diffs, not true LSDs. It requires at least one wheel to grip or else it acts as an open differential (it doesn't work when both tires are slipping).

	"The worm and wheel is a very inefficient gear configuration at high speeds and it generates a lot of heat - ~~hwich~~ is destructive and wastes power. It has never been very successful , possibly because of a lack of development and possibly because the concepts is just too complex and too inefficient to succeed." - Carroll Smith, Engineer to Win		"The worm and wheel is a very inefficient gear configuration at high speeds and it generates a lot of heat - which is destructive and wastes power. It has never been very successful , possibly because of a lack of development and possibly because the concepts is just too complex and too inefficient to succeed...while they have performed well, have failed early. Gleason engineers certainly have the expertise and the faciities to solve the metallurgy problems." - Carroll Smith, Engineer to Win

	===Speed===		===Speed===

99.250.166.66: /* Torsen Diff */

2008-05-16T11:22:04Z

Torsen Diff

← Older revision		Revision as of 11:22, 16 May 2008
Line 47:		Line 47:
	====Torsen Diff====		====Torsen Diff====

	Geared, ''torque-~~sensitive~~'' mechanical ~~limited slip~~ differentials utilize planetary gears to "sense" torque on one shaft. The most famous version is the Torsen differential invented by Vernon ~~Gleasman~~ in 1958, then sold to Gleason Corporation, who started marketing it in 1982. Geared LSDs are less prone to wear than the clutch type, but ~~some have found~~ their torque ~~distribution characteristics to be less than ideal~~. Technically, these are really torque-biasing diffs, not true LSDs.		Geared, ''torque-sensing'' mechanical differentials utilize planetary gears to "sense" torque on one shaft. The most famous version is the Torsen differential invented by Vernon Gleasom in 1958, then sold to Gleason Corporation, who started marketing it in 1982. Geared LSDs are less prone to wear than the clutch type, but the high number of parts, and their stress risers, limits their torque handling capability. As such it is not suitable for racing. Technically, these are really torque-biasing diffs, not true LSDs. It requires at least one wheel to grip or else it acts as an open differential (it doesn't work when both tires are slipping).

			"The worm and wheel is a very inefficient gear configuration at high speeds and it generates a lot of heat - hwich is destructive and wastes power. It has never been very successful , possibly because of a lack of development and possibly because the concepts is just too complex and too inefficient to succeed." - Carroll Smith, Engineer to Win

	===Speed===		===Speed===

Red marquis: /* Speed */

2007-02-19T01:04:38Z

Speed

← Older revision		Revision as of 01:04, 19 February 2007
Line 50:		Line 50:

	===Speed===		===Speed===
	The ''viscous type'' is generally simpler, and relies on the properties of a dilatant fluid - that is, one which thickens when subject to ~~[[Shear stress\|~~shear]]. [[Silicone]]-based oils are often used. Here, a chamber of fluid rotates with the normal motion of the output shafts, but a differential motion causes paddles or vanes to move through the fluid. The greater the speed of the vanes, the more resistance the fluid will put up to oppose this motion. In contrast to the mechanical type, the limiting action is much softer and more proportional to the slip, so for the average driver is generally much easier to cope with.		The ''viscous type'' is generally simpler, and relies on the properties of a dilatant fluid - that is, one which thickens when subject to shear. Silicone-based oils are often used. Here, a chamber of fluid rotates with the normal motion of the output shafts, but a differential motion causes paddles or vanes to move through the fluid. The greater the speed of the vanes, the more resistance the fluid will put up to oppose this motion. In contrast to the mechanical type, the limiting action is much softer and more proportional to the slip, so for the average driver is generally much easier to cope with.

	The gerotor pump uses the housing to drive the outer side of the pump and one axle shaft to drive the other. When there is differential wheel rotation, the pump pressurizes its working fluid into the clutch pack area to provide a clamp load for frictional resistance to differentiation for a torque transfer to the higher traction wheel. The pump based systems have a lower and upper limits on applied pressure, and internal damping to avoid hysteris.		The gerotor pump uses the housing to drive the outer side of the pump and one axle shaft to drive the other. When there is differential wheel rotation, the pump pressurizes its working fluid into the clutch pack area to provide a clamp load for frictional resistance to differentiation for a torque transfer to the higher traction wheel. The pump based systems have a lower and upper limits on applied pressure, and internal damping to avoid hysteris.

Red marquis: /* Factory Names */

2007-02-19T01:03:31Z

Factory Names

← Older revision		Revision as of 01:03, 19 February 2007
Line 62:		Line 62:
	Other factory names for LSD's include		Other factory names for LSD's include

	[[Pontiac]]: Safe-T-Track		[[Pontiac]]: [[Safe-T-Track]]

	[[Ford]]: Equa-Lock and Trac-Lok		[[Ford]]: [[Equa-Lock]] and [[Trac-Lok]]

	~~[[American Motors Corporation~~]]~~: Twin-Grip~~

	~~[[Ferrari]]: E-Diff~~

			[[American Motors Corporation]]: [[Twin-Grip]]

			[[Ferrari]]: [[E-Diff]]

	==External links==		==External links==

Red marquis: /* References */

2007-02-19T01:03:03Z

References

← Older revision		Revision as of 01:03, 19 February 2007
Line 70:		Line 70:
	[[Ferrari]]: E-Diff		[[Ferrari]]: E-Diff

	~~==References==~~
	~~<references/>~~

24.161.57.157: /* Factory Names */

2006-08-20T23:38:33Z

Factory Names

← Older revision		Revision as of 23:38, 20 August 2006
Line 67:		Line 67:

	[[American Motors Corporation]]: Twin-Grip		[[American Motors Corporation]]: Twin-Grip

	~~[[Mopar]]: Sure Grip~~

	[[Ferrari]]: E-Diff		[[Ferrari]]: E-Diff

24.161.57.157: /* Mechanism */

2006-08-20T22:38:16Z

Mechanism

← Older revision		Revision as of 22:38, 20 August 2006
Line 36:		Line 36:

	As the input torque of the driveshaft tries to turn the diff centre, internal pressure rings (adjoining the clutch stack) are forced sideways by the spider gear mount trying to climb the ramp, which compresses the clutch stack. The more the clutch stack is compressed, the more coupled the wheels are. The mating of the vertical ramp surfaces in a 1 way LSD on over run produces no cam effect and no corresponding clutch stack compression.		As the input torque of the driveshaft tries to turn the diff centre, internal pressure rings (adjoining the clutch stack) are forced sideways by the spider gear mount trying to climb the ramp, which compresses the clutch stack. The more the clutch stack is compressed, the more coupled the wheels are. The mating of the vertical ramp surfaces in a 1 way LSD on over run produces no cam effect and no corresponding clutch stack compression.

			Another variator is the "cone type", which is prelaoded by a strong spring. These are generaly less effective in high torque situations (drag racing, etc.) but better in low-torque conditions (ice, snow) where there may not be enough torque to apply any clutch pressure in the clutch-pack type, especially if somewhat worn.

	=====Servicing=====		=====Servicing=====

24.161.57.157: /* Characteristics */

2006-08-20T22:34:30Z

Characteristics

← Older revision		Revision as of 22:34, 20 August 2006
Line 25:		Line 25:
	If the LSD behaves somewhere inbetween these two extremes, it is a 1.5 way diff, which is a compromise between sportiness and safety.		If the LSD behaves somewhere inbetween these two extremes, it is a 1.5 way diff, which is a compromise between sportiness and safety.

	Clutch LSDs are noisy, clunky, & expensive, which makes them unlikely to be installed on a passenger car these days. However their response speed and coupling strength is the best of the commonly available LSDs. They are also the only commonly available LSD able to stand up to extreme motorsport abuse.		Clutch LSDs are frequently noisy, clunky, & expensive, which makes them unlikely to be installed on a passenger car these days. However their response speed and coupling strength is the best of the commonly available LSDs. They are also the only commonly available LSD able to stand up to extreme motorsport abuse.

			The latest version of this basic design, introduced in the late 1990s on the Jeep Grand Cherokee (Spicer sourced) uses a small hydraulic pump, driven by the difference in axle speed, to apply more lockup pressure, similar to the action of an automatic transmission clutch pack. Later Dodge Vipers have also used this system with only moderate success.

	=====Mechanism=====		=====Mechanism=====