Limited slip, worth it?

ChrisSlicks · 01-13-2010, 01:44 PM

Quote:

Originally Posted by j.arnaldo

How does the LSD actually work? Does it deliver more torque to one of the rear tires (i.e. the one that's not "slipping" so as to compensate for the other one's "fail")? Thanks.

Torque sensing differentials can do that (Torsen for example). The Viscous unit uses perforated discs, rotating in fluid. The discs are stacked such that they alternate for the 2 output shafts, so when one axle is going faster than the other it will generate a hydraulic force against the other to speed up the slower axle. Unfortunately as the fluid heats up it loses it viscosity which makes the whole system ineffective.

Inspector71 · 01-15-2010, 08:10 AM

Thanks, that is good information and gives me something to consider. I am reluctant to make too many mods to my 09 Z I guess.

Junior370z · 12-26-2010, 10:34 PM

Quote:

Originally Posted by ChrisSlicks

Torque sensing differentials can do that (Torsen for example). The Viscous unit uses perforated discs, rotating in fluid. The discs are stacked such that they alternate for the 2 output shafts, so when one axle is going faster than the other it will generate a hydraulic force against the other to speed up the slower axle. Unfortunately as the fluid heats up it loses it viscosity which makes the whole system ineffective.

Just curious. Since viscosity is a major factor for the stock LSD. Would it be safe to say changing the fluids every so often will keep from failing? Like oil changes. Maybe go with a thicker fluid.
Also with the stock sport LSD, does aggressive gear shifts in straight line driving effect it? Or is it only cornering? Some Z's that are FI can wear out te stock LSD with aggressive off the line starts fast right? Thanks.

1slow370 · 12-29-2010, 05:10 AM

the fluid that fails in the stock lsd is the silicone fluid inside the sealed cartridge in the ring gear carrier (a little can in the very nuts-center of the diff) changing the 90w fluid will only keep the gears and bearings feeling happy.

Torsen, positraction, quaife are all the same helical type units with very minor differences, that use inter-meshing worm gears instead of the tradition cone shaped spider gears (the little ones inside the ring gear carrier) that due to torque differences between the two wheels are capable of sending a ratio of of torque from the wheel with the least traction to the wheel with the most traction provided that both wheels have some traction = if you lift a wheel or are in snow it acts like a one wheel wonder.

Clutch and viscous types work on rpm more than torque so if one wheel is spinning faster than the other, it starts locking. If its a really touchy clutch type it means it won't want to turn a corner at slow speed which makes parking lots a pain (properly set there are clutch types that don't do this that much). The reason a viscous doesn't do this is because instead of having friction plates it just has smooth steel plates spaced close together with a bunch of holes in them, and a thick silicone goo that when spun fast enough (one wheel starting slipping crazy) the molecules of silicone work like shoving a stick in between all the holes locking them together. Trouble is the silicone goo is unpredictable and gets crazy hot and either just dies and does nothing, or if you're really lucky blows it's little case up trashing your diff.

to the guy that thrashed the hell out of his car leaving the dealer and it "wouldn't go forward" don't be pointing fingers at the viscous it does virtually nothing in a straight line (unless you were doing a sustained 140mph powerslide) and if it died wouldn't effect the way the car drove really so you either F'ed a bearing right in the A, or something. Was it snubbing wouldn't go forward, or was the motor running and it just wouldn't go forward?

01-15-2010, 08:10 AM	#2 (permalink)
Inspector71 Enthusiast Member Join Date: Sep 2009 Location: Lee's Summit Missouri Posts: 337 Drives: 2015 Pearl White Z Rep Power: 16	ElmZ Thanks, that is good information and gives me something to consider. I am reluctant to make too many mods to my 09 Z I guess.

12-29-2010, 05:10 AM	#4 (permalink)
1slow370 A True Z Fanatic Join Date: Aug 2009 Location: In the D Posts: 3,732 Drives: v8 74 260z ;) Rep Power: 7251	the fluid that fails in the stock lsd is the silicone fluid inside the sealed cartridge in the ring gear carrier (a little can in the very nuts-center of the diff) changing the 90w fluid will only keep the gears and bearings feeling happy. Torsen, positraction, quaife are all the same helical type units with very minor differences, that use inter-meshing worm gears instead of the tradition cone shaped spider gears (the little ones inside the ring gear carrier) that due to torque differences between the two wheels are capable of sending a ratio of of torque from the wheel with the least traction to the wheel with the most traction provided that both wheels have some traction = if you lift a wheel or are in snow it acts like a one wheel wonder. Clutch and viscous types work on rpm more than torque so if one wheel is spinning faster than the other, it starts locking. If its a really touchy clutch type it means it won't want to turn a corner at slow speed which makes parking lots a pain (properly set there are clutch types that don't do this that much). The reason a viscous doesn't do this is because instead of having friction plates it just has smooth steel plates spaced close together with a bunch of holes in them, and a thick silicone goo that when spun fast enough (one wheel starting slipping crazy) the molecules of silicone work like shoving a stick in between all the holes locking them together. Trouble is the silicone goo is unpredictable and gets crazy hot and either just dies and does nothing, or if you're really lucky blows it's little case up trashing your diff. to the guy that thrashed the hell out of his car leaving the dealer and it "wouldn't go forward" don't be pointing fingers at the viscous it does virtually nothing in a straight line (unless you were doing a sustained 140mph powerslide) and if it died wouldn't effect the way the car drove really so you either F'ed a bearing right in the A, or something. Was it snubbing wouldn't go forward, or was the motor running and it just wouldn't go forward? binary0x01, ortiz73ca and WI_Hedgehog like this. __________________ ANSWER PRICE LIST Answers - - - - - - - - - - - - - - - - $0.75 Answers (requiring thought) - - - - $1.25 Answers (correct) - - - - - - - - - - $12.50