VLSD and LSD
06-12-2007, 10:11 PM
#3
This is the best description for the in's and out's of VLSD and how it fuction's that I've ever run across, it's a cut and paste of course.
Hitachi/Tochigi Fuji Sangyo
"Viscous LSD units are popular OEM LSD solutions, as they are relatively simple and cheap to produce. They come in many performance Subarus, Nissans, Mazdas, Toyotas, etc. The LSD unit consists of stacks of thin plates with holes or slots, all suspended in a special silicone fluid. They have no clutches to wear out, and locking characteristics can theoretically be changed by varying fluid viscosity. Generally, however, these units are non-serviceable, and require no special maintenance. As the differential spins, the plates shear the fluid up to a point, after which the fluid provides some resistance to shear, allowing 15-25% torque transfer to the other wheel. The downside is that these units don't act like a limited slip until one wheel actually starts slipping (i.e., they don't prevent slippage), which means the VLSD action often kicks in after you've already exited the corner. Compared to the proactive nature of the Torsen LSDs, the VLSDs are reactive units. They do not prevent slippage, they merely sense differences in rotation, not torque. They also don't allow for very much torque transfer, compared to mechanical or clutch-pack LSDs. They do still work well for starting from a dead stop in slippery conditions. It is important to note that VLSDs locking characteristics occur both during acceleration AND braking, as it can't tell the difference between the two, but merely reacts to the rotational speed differences between the two drive wheels. "
Hitachi/Tochigi Fuji Sangyo
"Viscous LSD units are popular OEM LSD solutions, as they are relatively simple and cheap to produce. They come in many performance Subarus, Nissans, Mazdas, Toyotas, etc. The LSD unit consists of stacks of thin plates with holes or slots, all suspended in a special silicone fluid. They have no clutches to wear out, and locking characteristics can theoretically be changed by varying fluid viscosity. Generally, however, these units are non-serviceable, and require no special maintenance. As the differential spins, the plates shear the fluid up to a point, after which the fluid provides some resistance to shear, allowing 15-25% torque transfer to the other wheel. The downside is that these units don't act like a limited slip until one wheel actually starts slipping (i.e., they don't prevent slippage), which means the VLSD action often kicks in after you've already exited the corner. Compared to the proactive nature of the Torsen LSDs, the VLSDs are reactive units. They do not prevent slippage, they merely sense differences in rotation, not torque. They also don't allow for very much torque transfer, compared to mechanical or clutch-pack LSDs. They do still work well for starting from a dead stop in slippery conditions. It is important to note that VLSDs locking characteristics occur both during acceleration AND braking, as it can't tell the difference between the two, but merely reacts to the rotational speed differences between the two drive wheels. "
06-13-2007, 10:45 AM
#4
Originally Posted by Gsedan35
This is the best description for the in's and out's of VLSD and how it fuction's that I've ever run across, it's a cut and paste of course.
Hitachi/Tochigi Fuji Sangyo
"Viscous LSD units are popular OEM LSD solutions, as they are relatively simple and cheap to produce. They come in many performance Subarus, Nissans, Mazdas, Toyotas, etc. The LSD unit consists of stacks of thin plates with holes or slots, all suspended in a special silicone fluid. They have no clutches to wear out, and locking characteristics can theoretically be changed by varying fluid viscosity. Generally, however, these units are non-serviceable, and require no special maintenance. As the differential spins, the plates shear the fluid up to a point, after which the fluid provides some resistance to shear, allowing 15-25% torque transfer to the other wheel. The downside is that these units don't act like a limited slip until one wheel actually starts slipping (i.e., they don't prevent slippage), which means the VLSD action often kicks in after you've already exited the corner. Compared to the proactive nature of the Torsen LSDs, the VLSDs are reactive units. They do not prevent slippage, they merely sense differences in rotation, not torque. They also don't allow for very much torque transfer, compared to mechanical or clutch-pack LSDs. They do still work well for starting from a dead stop in slippery conditions. It is important to note that VLSDs locking characteristics occur both during acceleration AND braking, as it can't tell the difference between the two, but merely reacts to the rotational speed differences between the two drive wheels. "
Hitachi/Tochigi Fuji Sangyo
"Viscous LSD units are popular OEM LSD solutions, as they are relatively simple and cheap to produce. They come in many performance Subarus, Nissans, Mazdas, Toyotas, etc. The LSD unit consists of stacks of thin plates with holes or slots, all suspended in a special silicone fluid. They have no clutches to wear out, and locking characteristics can theoretically be changed by varying fluid viscosity. Generally, however, these units are non-serviceable, and require no special maintenance. As the differential spins, the plates shear the fluid up to a point, after which the fluid provides some resistance to shear, allowing 15-25% torque transfer to the other wheel. The downside is that these units don't act like a limited slip until one wheel actually starts slipping (i.e., they don't prevent slippage), which means the VLSD action often kicks in after you've already exited the corner. Compared to the proactive nature of the Torsen LSDs, the VLSDs are reactive units. They do not prevent slippage, they merely sense differences in rotation, not torque. They also don't allow for very much torque transfer, compared to mechanical or clutch-pack LSDs. They do still work well for starting from a dead stop in slippery conditions. It is important to note that VLSDs locking characteristics occur both during acceleration AND braking, as it can't tell the difference between the two, but merely reacts to the rotational speed differences between the two drive wheels. "
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