LSD matters

RacerX · Post by **RacerX** » Tue Jan 07, 2003 3:19 am

Correct me if I'm wrong, but I believe that 91 legacy turbos have a Limited Slip Differential. If so I was wondering if there would be a problem if I put in a transmission (with a matching rear differential) from a car that doesn't have a LSD?

entirelyturbo · Post by **entirelyturbo** » Tue Jan 07, 2003 4:14 am

I don't think so...logically, it wouldn't, because I'm pretty sure an LSD is all mechanical, and by removing it entirely will just remove the LSD effect of course and cause no other complications...

However, wait for someone more knowledgeable to post something, I'm really just speculating...

ciper · Post by **ciper** » Tue Jan 07, 2003 4:25 am

Im putting an lsd in my 90 legacy that has a 95 impreza transmission that never had an lsd stock.

Anyone have an idea why an LSD could cause an issue?

I guess the lsd could put more stress on the transmission if previously you were able to spin the tires (releasing pressure).

Aaron's ej22t · Post by **Aaron's ej22t** » Tue Jan 07, 2003 9:16 am

As far as I know, the main purpose of a LSD is to distribute an even amount of power to each wheel connected to the lsd. this should result in better traction and handling.

I hope to find a 91 lsd and swap it into my car in the future.

Post by **DLC** » Tue Jan 07, 2003 4:51 pm

The transmission has absolutely nothing to do with the rear differential past the gear ratio. It has no way of knowing whether there's an LSD in the back or not.

Dave

totech · Post by **totech** » Tue Jan 07, 2003 6:05 pm

Well,

I can imagine situations where the LSD does help, but, my 91 happily spins both rear wheels when I accelerate hard on snow.

I am fully enjoying the snow we are having up here, and although the car technically is 2wd, it really hooks up hard.

entirelyturbo · Post by **entirelyturbo** » Tue Jan 07, 2003 6:11 pm

Is an LSD in a non-turbo 4WD really beneficial? Not enough power to cause excessive wheelspin, and what can te rear wheels do wrong that the front wheels (and quick driver reflexes) can't fix?

ciper · Post by **ciper** » Tue Jan 07, 2003 8:07 pm

subyluvr2212: It in low traction situations that the lsd can help. Many times I have been sitting near a stand still or even dead stop spinning two wheels (one front, one rear).

If you think about it, our current design will let one front wheel spin and one rear wheel.

Adding the lsd will let one front wheel spin but two rear wheels will have to spin (at near equal speed). So its a "2wd" vs "3wd"

IggDawg · Post by **IggDawg** » Tue Jan 07, 2003 9:59 pm

Just make sure you have the proper half-shafts. in the Impreza, the rear half-shafts are different between LSD and non-LSD, so I'm assuming they would be on the Legacies as well.

I could have used one the other day. I beached my car on the "plow barrier" at the end of my driveway. the snow was a little higher than the bottom of my license plate all the way down my long driveway. she plowed right through all that rally style (all 4 spinning

), but I didn't hit the snowplow barrier (packed snow) at the end fast enough and I beached her on the skidplate. both wheels on the left side were spinning, and the right side jsut sat there

. I never have a problem getting all 4 spinning in low traction, but that wouldn't have helped here anyways

. needless to say, I could use some LSDs.

boostjunkie · Post by **boostjunkie** » Tue Jan 07, 2003 10:36 pm

I thought all turbo legacies came standard with lsds? Were they optional or did only the 91's come with them standard?

rallysam · Post by **rallysam** » Tue Jan 07, 2003 11:34 pm

I beached my car on the "plow barrier" at the end of my driveway

Hahaha IggDawg! That sucks.

I almost got stuck once. The keg ran dry at a winter-time college party. I was the only one with AWD, so obviously I was on a mission. I saw that "plow barrier" at the end of the driveway, gritted my teeth, and went for it. Like you said, it's all about inertia!!!!

Sorry to get off topic!

Post by **DLC** » Wed Jan 08, 2003 4:37 pm

Almost no Turbo Legacies have LSDs, the 91s have the highest ratio because, quite frankly, they're the best models the US got.

I'm just glad to have working AWD and snow tires this year, as opposed to a horribly slipping 4EAT and non-working AWD on Kumho Ecsta 712s.

Dave

whitey · Post by **whitey** » Wed Jan 08, 2003 10:33 pm

Iv'e got a LSD on the rear diffs and central diff but it is hard to tell wither you have one unless you jack the car totally off the ground.

To find out put the car on a hoist and turn one of the back wheels (for rear diff LSD), if the other back wheel rotates in the same direction as the one you are turning it is a LSD if it rotates in the opposite direction to the wheel your turning it is an open diff. My rear LSD has a identification plate rivited to the diff apparently LSD was a factory option on RS spec legacys.

With my car if you rotate one back forward wheel all four wheels turn forward if you rotate one front wheel forwards the other front rotates backwards and the two back wheels rotate forward.

With LSD on the back it reduces the chance of spinning one wheel. With an open diff you can stall one wheel and transmit all the power to the other wheel. With LSD it will allways supply some power to both wheels but they do ot have to be turning at the same speed hence the limited slip part (If you had a locked diff both wheel would turn at the same speed allways).

LegacyT · Post by **LegacyT** » Wed Jan 08, 2003 10:58 pm

Also to tell whether some of the 91 Turbo's are LSD equipped, look at the rear end of the differential casing and there should be a gold sticker saying Viscous LSD. If the sticker has fallen off then you can use the method described in the other post's.

Mark,

boostjunkie · Post by **boostjunkie** » Fri Jan 10, 2003 7:25 pm

Got one

Thanks guys!!

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LSD matters

LSD matters