Limited slip and locking differentials
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Rearend housings will often have codes stamped into the axle tube or center section (depending on make and type of rearend) that can be decoded to give the gear ratio, manufacturer, date of manufacture, LSD or open, etc. Some rearends can be identified as to type by the casting numbers (raised numbers cast into the metal, not stamped), because some rearends use different housings for open and LSD differentials. | Rearend housings will often have codes stamped into the axle tube or center section (depending on make and type of rearend) that can be decoded to give the gear ratio, manufacturer, date of manufacture, LSD or open, etc. Some rearends can be identified as to type by the casting numbers (raised numbers cast into the metal, not stamped), because some rearends use different housings for open and LSD differentials. | ||
| − | Many LSD rearends carried tags | + | Many LSD rearends carried tags saying to use limited slip lube only- a good indicator that the rearend was a LSD originally, but of course the entire rearend or the diff could have been replaced during the life of the vehicle. |
{| | {| | ||
| − | |[[File:Lsdlube tag.jpg|thumb|center|300px| | + | |[[File:Lsdlube tag.jpg|thumb|center|300px|LSD lube tag]] |
|} | |} | ||
| − | ==Different ways | + | ==Different ways to get limited slip== |
| − | Limited slip is accomplished by different means, depending on the manufacturer, application and vehicle. There is the cone type LSD, there is the clutch type LSD, there are viscous type, there are locking type differentials (mechanical, pneumatic and electric operated) and all accomplish the same basic thing- applying power to the wheel having traction or basically both wheels simultaneously. | + | Limited slip is accomplished by different means, depending on the manufacturer, application and vehicle use. There is the cone type LSD, there is the clutch type LSD, there are viscous type, there are locking type differentials (mechanical, pneumatic and electric operated) and all accomplish the same basic thing- applying power to the wheel having traction or basically both wheels simultaneously. |
Depending on the type and application, there may be some slip allowed, i.e. the two wheels are not connected to one another directly, like in the case of the viscous, clutch, and cone types. In other cases (like the locking-type differentials), the wheels are directly linked while in the locked position. | Depending on the type and application, there may be some slip allowed, i.e. the two wheels are not connected to one another directly, like in the case of the viscous, clutch, and cone types. In other cases (like the locking-type differentials), the wheels are directly linked while in the locked position. | ||
==="Lunchbox" locker=== | ==="Lunchbox" locker=== | ||
| − | The lunchbox locker, or "drop-in" locker is a type of automatic locker that replaces the side (axle) gears and spider (pinion) gears (in some/most types) of a diff. The pinion gears referred to | + | [[File:Auto locker.jpg|thumb|160px|left|Lunchbox locker]] |
| + | The lunchbox locker, or "drop-in" locker is a type of automatic locker that replaces the side (axle) gears and spider (pinion) gears (in some/most types) of a diff. The pinion gears referred to here are NOT the same as the pinion gear that meshes with the ring gear. Instead, they're the smaller gears in the center of the diff that allows the two wheels to rotate at different speeds when turning, etc. | ||
| − | A lunchbox locker is relatively easy to install, mainly because the original backlash and preload settings are not disturbed during the installation. | + | A lunchbox locker is relatively easy to install, mainly because the original backlash and preload settings are not disturbed during the installation. The lunchbox locker will only be as strong as the original carrier and rearend housing it's installed in, so using one in a weak design will ''still'' be a weak design. One thing that makes it better than some of the less expensive alternatives to a proper LSD is the lunchbox does act as a differential. Not particularly well, though, and because of its idiosyncrasies its generally not recommended for street use because of things like how it can lock while cornering, depending on how the power is applied. |
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| − | ==Spools== | + | <br style="clear:both"/> |
| + | ===Spools=== | ||
A spool is not a differential, and isn't considered to be limited slip, either. A spool connects both wheels the same as if there were a live axle (think of a go kart from the '60s). In the case of a spool or mini spool (or welded spider gears), both wheels are turning the same speed all the time- even when going around a corner or doing parking lot maneuvers. This causes the inside wheel to rotate faster than it needs to when cornering or maneuvering. The result is reduced tread life, squealing of the tires even at slow speeds when turning, and a lot of stress on the rear end components. Not to mention a potential loss of control in low-traction conditions like ice, snow or rain. | A spool is not a differential, and isn't considered to be limited slip, either. A spool connects both wheels the same as if there were a live axle (think of a go kart from the '60s). In the case of a spool or mini spool (or welded spider gears), both wheels are turning the same speed all the time- even when going around a corner or doing parking lot maneuvers. This causes the inside wheel to rotate faster than it needs to when cornering or maneuvering. The result is reduced tread life, squealing of the tires even at slow speeds when turning, and a lot of stress on the rear end components. Not to mention a potential loss of control in low-traction conditions like ice, snow or rain. | ||
| − | + | A mini spool is much like a spool, but without the strength of a spool because like the lunchbox locker, it only replaces the spider and axle gears; the rest of the rear end is all reused, so there's no net gain in strength. | |
{| | {| | ||
|[[File:Spool.jpg|thumb|250px|center|Spool]] | |[[File:Spool.jpg|thumb|250px|center|Spool]] | ||
| + | |[[File:Mini spool.jpg|thumb|245px|center|Mini spool]] | ||
|} | |} | ||
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| + | ===Welded spider gears=== | ||
| + | [[File:Welded spiders.jpg|thumb|250px|left|This abomination is what an open diff with welded spider gears looks like]] | ||
| + | A welded diff has the dubious distinction of not only having all the drawbacks of a spool on the street, but also adds the danger of loss of control should the welds break and jam between the ring gear and pinion- which will lock the rear wheels. Not what you want to happen at ANY speed, let alone at the top end of a run, or while carving the canyons. | ||
| + | <br style="clear:both"/> | ||
| + | |||
| + | {{warning|The only reason the spools and welded diff are shown here is so they can be identified if they're found inside a rearend, and to stress that there is no place for a spool or welded spiders on the street. Period. It matters very little to anyone who finds themselves upside down in a ditch that someone ''else'' claimed they drove on the street for 20 years with either one of these (or a mini spool) without any problems. What '''should''' matter is that using either one on the street is a very unsafe practice that should be avoided altogether. A spool is a racing modification only. A welded diff is not safe on the street OR track. Just don't do it.}} | ||
==Resources== | ==Resources== | ||
*[http://www.crankshaftcoalition.com/wiki/Gear_ratio_check Gear ratio check] | *[http://www.crankshaftcoalition.com/wiki/Gear_ratio_check Gear ratio check] | ||
*[http://chevellestuff.net/qd/generic_rear_axle_info.htm Generic rearend info] from Chevellestuff.net | *[http://chevellestuff.net/qd/generic_rear_axle_info.htm Generic rearend info] from Chevellestuff.net | ||
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[[Category:Rearend]] | [[Category:Rearend]] | ||
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