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Limited Slip Differential


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14 replies to this topic

#1 Jack in Norfolk

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Posted 02 October 2003 - 08:39 PM

ok,
now that I have thoroughly confused several about the center locking diff, what's up with the LSD?
I thought that these were common on sports cars.
How does it work?
What is the advantage off road?
Is it the same thing as posi traction?
If you havent got an LSD, what have you got?

#2 Caboobaroo

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Posted 02 October 2003 - 08:47 PM

1. an LSD works when one wheel slips, one wheel grips
2. the advantage of using off road is so you still have power to one wheel when the other is off the ground
3. ok just for the records, a positrac rear end is an LSD with a different name.
4. If you don't have an LSD or a positrac rear end, you've got whats known as an open diff. basically when one wheel is off the ground, that wheel will get all of the power and the other wheel won't.

I hope this answers some questions:D

#3 TheSubaruJunkie

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Posted 02 October 2003 - 08:49 PM

If you look at an open diff... it will turn the wheel with the LEAST ammount of traction. If you look at a locked diff. it will turn BOTH tires with EQUAL amount of traction. No matter what. But when one tire spins faster than the other, the slower tire will be forced to turn the same speed which makes it chirp or drag.

A LSD will send equal amount of traction to both wheels, but when one tire rotates faster than the other, the diff allows it to slip (limited amount of slip) so that the diff doesnt bind and break.

Not as good as a locker, but alot better than an open diff.

-Brian

#4 TheSubaruJunkie

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Posted 02 October 2003 - 08:51 PM

To correct Cabooob.... If you have a LSD, and one tire is completly off the ground, chances are all the power will goto that wheel off the ground. Only a true locker will transfer equal power to both axle's at all times.

-Brian

#5 Mike W

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Posted 02 October 2003 - 08:52 PM

This should help: http://members.rennl...S84Gleason.html (good cutaway diagrams)
http://www.houseofth...fferentials.htm
http://auto.howstuff...fferential6.htm
http://auto.howstuff...ifferential.htm
http://kmhafer.datsu....com/Subaru.htm
http://kmhafer.datsu....com/Subaru.htm (how to rebuild our LSDs)

Most of us are using clutchpack type LSD found most often in RX and turbo cars from the mid 80's. In the 90's viscous LSDs started showing up on Legacy turbos etc.

#6 TheSubaruJunkie

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Posted 02 October 2003 - 08:58 PM

I heard if you install 2 clutch packs into a LSD, it locks it up REAL tight like a locker.

not sure if it can be done on a sube.

-Brian

#7 cole098

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Posted 02 October 2003 - 08:59 PM

Then what year cars came with this???? Cars with ea81 or cars with ea82

#8 TheSubaruJunkie

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Posted 02 October 2003 - 09:05 PM

EA82 Cars will only have them. The LSD's came stock on RX's from 1987+ but were available as an option for all EA82 cars i believe from 1985 on.

-Brian

#9 Jack in Norfolk

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Posted 02 October 2003 - 09:15 PM

but you can swap in an LSD into an EA81 car, is that correct?

#10 bushbasher

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Posted 02 October 2003 - 09:18 PM

all lsd's are 3.7 I think, so to put an lsd in any manual dual range car you must swap out the 3.7s and put in the 3.9s from your old open diff. There is a tutorial in the USRM.

#11 LUVMYBRAT

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Posted 02 October 2003 - 09:19 PM

okay so an lsd is a nice thing to have, a locker would be ideal. Did subes come with lockers? who and where has aftermarket fo subes???:-\

#12 TheSubaruJunkie

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Posted 02 October 2003 - 09:23 PM

All LSD's are 3.9. Most EA81's are 3.7 The LSD would need to be converted (directions can be found in the USRM)

There are no lockers for subaru's. You can weld your spider gears and create a locker out of an open diff. But you cannot use it for street use.

-Brian

#13 calebz

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Posted 02 October 2003 - 09:36 PM

Sorry brian.. the LSD's are 3.7 for 80's ea82 soobs.. I believe( not sure on this one ) that the FT4WD 5 speed XT6 had an option of a 3.9 LSD.. but I could be wrong.. I do know that the RX's and GL-10's and such that came with an LSD were 3.7 though

#14 TheSubaruJunkie

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Posted 02 October 2003 - 09:37 PM

Yeah, your right. I keep getting them mixed up. 3.7.... 3.9.... yeah, one of those two.

-Brian

#15 bushbasher

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Posted 02 October 2003 - 09:56 PM

I repeat... NO LOCKERS. You can weld it or search the boneyards for an lsd. That's it. There so far is not enough of a market for things like lockers or lower range gear sets, r&p's etc.




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