Rear differential...LSD or not?
 

I was joyriding in a sandy area the other night with my friend in his jeep behind me. I stopped to smoke a cig with him and take a break and such. When we went off, I let the clutch out at about 4000 rpm and had no problem.

The problem came later when my friend commented on how one of my rear wheels was shooting out way more sand than the other.

I was under the impression that the LSD should make them somewhat even even though it is only viscous. Does it need to really warm up before it starts sharing the power or does it only distribute a very small percentage? I have mobil 1 synthetic fluid in there, does that make a difference?

LMK

Thanks

it will take some of the power off of the wheel that is spinning but, there still can be cases like in sand that one wheel will spin more than the other depending on condition.

(next time say u have a wrx. not all subarus have lsds)
sand is not a great way to judge a viscous LSD... the stock rear is slow to react its not like a clutch type.

oops, sorry, I did forget to mention that I have a WRX.

[quote][size=1][color=gray][i]Origami posted by rustokman[/i][/color]
[font=Arial][color=royalblue]I was under the impression that the LSD should make them somewhat even even though it is only viscous. Does it need to really warm up before it starts sharing the power or does it only distribute a very small percentage? I have mobil 1 synthetic fluid in there, does that make a difference?
[/color][/font][/size][/quote]I have no idea about using synthetic in the rear LSD.

The viscous LSD doesn't need to be 'warmed up' before it's effective. It works from the shearing forces generating heat and increasing viscosity of the fluid to help limit the speed differential between the left and right axles, if one of them is on a surface that gives less traction than the other. It doesn't channel 100% of the power to the side with the best traction, however - it [i]limits[/i] slip, like the name implies. Still much improvement over an open diff.

It's probably best not to test it out by putting one wheel on a really slick surface and the other on dry pavement, while dropping the hammer at high RPM. It might be enough to cause damage to the LSD (high heat generated within the LSD).

[size=1][color=skyblue]--
0==[color=blue]WW[/color]==0
"…axles of evil…" - george w. bush[/color][/size]

doesnt AWD transfer power to whatever wheels have the most traction?

Appearently not, the differentials in our AWD cars only transfer some of the power to the wheels with grip while the wheel slipping continues to slip. In a locked differential both wheels will spin at the same speed. Some differentials can lock and unlock but there are none that I know of for AWD cars, only RWD and 4X4.

I may be wrong though

[QUOTE][i]Originally posted by SnoHumper[/i]
[B] doesnt AWD transfer power to whatever wheels have the most traction? [/B][/QUOTE]

[QUOTE][i]Originally posted by rustokman[/i]
[B] Appearently not, the differentials in our AWD cars only transfer some of the power to the wheels with grip while the wheel slipping continues to slip. In a locked differential both wheels will spin at the same speed. Some differentials can lock and unlock but there are none that I know of for AWD cars, only RWD and 4X4.

I may be wrong though [/B][/QUOTE]

Viscous limited slips will transfer [i]some[/i] power to the non-slipping wheels, but usually not all of it. With non-limited slips, once a wheel starts spinning, all of the torque goes to that wheel. this is why FWD cars do one-wheel burnouts, unless equipped with an LSD. RWD cars do it to, but they are much more likely to have a limited slip, or 'posi' in V8 circles.