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Old 09-04-2007, 02:10 PM   #1
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A couple of differential questions

Do any know if LSD, limited slip differentials give better fuel economy, or would it have no affect on economy unless running a lot of ice and snow roads, icy hills, etc?

Other than looking in the owners manual for the information, is the check for LSD's to jack up both tires and check for direction of spin by turning one wheel, ie: both tires spin in the same direction = LSD, or if one tire spins forward and one backward = not LSD.

Do Prius and other hybrid vehicles normally come with LSD or open differentials and when ordering a new hybrid vehicle is an option to have LSD differentials given?

More than a couple of questions I guess, Thanks.
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Old 09-04-2007, 03:54 PM   #2
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lsd's usually only come on performance models of cars and like you said, they will only give better fuel economy if you are spinning your wheel :P
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Old 09-04-2007, 04:13 PM   #3
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I'd think a LSD would reduce FE since it would resist the difference in axle speed anytime the car goes around a corner.

Viscous lsd's rely on the difference in rotating speeds of L and R wheels for their lsd action. They tend to have very low resistance between L and R wheels when the speed difference between the wheels is low, and higher resistance when the wheels are turning at vastly different speeds.

Clutch type lsd's have low resistance under low power, and high resistance with high power.

Here's a curious fact: the power distribution of an open diff when both wheels have good traction is 50/50, even when cornering.
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Old 09-04-2007, 04:53 PM   #4
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Thanks fellows,

I decided to do a tire rotation this afternoon and during the course was able to confirm by doing the 'wheel turn test' that both front and rear diffs on this 07 Nissan Pathfinder are open (non-LSD) which allows me to install a lower friction and hopefully a fuel saving gear oil that is still within OEM spec. Redline 75W-90NS GL-5 is about the best I've found so far for the application. Cheers.
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Old 09-04-2007, 06:26 PM   #5
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I'm gonna go in a corner now.... I read the title too fast and was expecting some differential equations...
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Old 09-04-2007, 07:12 PM   #6
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Quote:
Originally Posted by trebuchet03 View Post
I'm gonna go in a corner now.... I read the title too fast and was expecting some differential equations...
hahhahahaha ha
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Old 09-04-2007, 09:14 PM   #7
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Quote:
Originally Posted by thisisntjared View Post
lsd's usually only come on performance models of cars and like you said, they will only give better fuel economy if you are spinning your wheel :P
Not trying to be contentious, but many vehicles sold in cold northern climes come standard with LSD's. In Canada it's difficult to find a vehicle without.
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Old 09-04-2007, 09:28 PM   #8
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LSDs help with snow traction is probably why

As for your Pathfinder acting like an open diff, some LSDs require a bit of preload before kicking in. My TJ is moody like that and a friends STi with a torson LSD was similar.
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Old 09-06-2007, 05:12 PM   #9
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Quote:
Originally Posted by Greybrick View Post
Not trying to be contentious, but many vehicles sold in cold northern climes come standard with LSD's. In Canada it's difficult to find a vehicle without.
i am not surprized because of the snow, but out of curiosity, do any sohc hondas come with an lsd? or are there any fwd toyotas that come with an lsd?

i dont live in canada so please humor me. i am asking about japanese cars because that is really what i know. i never knew if the ford taurus or anything like that came with an lsd in the states let alone canada.

i mean i know almost all awd cars that are worth something have lsd's, but what about all the fwd ones? in particular, the entire economy car genre.

i am thinking that if integras and civics in canada all came with lsds, then i should start importing canadian transmissions.
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