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Old 04-02-2012, 06:07 PM   #21
TX78666
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Those who just don't get it will never appreciate what a LSD can do.
But, being able to appreciate it, and getting a couple thousand dollars worth of benefit, are two different matters.

Here's a riddle for everyone. All of the talk is always about power loss with an open diff, and inside wheel spin (other than the 1/4 mile stuff). If the inside wheel maintains traction, then (with an open diff) the outside wheel will spin faster than the inside wheel, as it needs to travel further. The outside wheel also should have more traction, since that's where the weight is.

An LSD does not know if one wheel is spinning faster because of lost traction, or because it is on the outside. It acts to keep them both spinning closer to the same speed as one another.

The riddle is, when both wheels have traction in a corner, does the LSD create a tendency for the rear of the car to want to go in a straight line? Does this affect handling?

I know the stock answer is that the LSD is better for handling, and overall, I don't question that it is. I just wonder about the physics of it, in the scenario described.

Anyone awake for that class?
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Old 04-02-2012, 06:15 PM   #22
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You got me excited with the "Go LSD"
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Old 04-02-2012, 06:15 PM   #23
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I guess I am particularly wondering, relative to the different setup options for LSD. Is it possible to set one up with not enough slip? All of my experience is with factory limited slip diffs. Part of me was sighing with relief, when my wife turned down the offer for a new diff. One less thing for me to figure out.
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Old 04-02-2012, 06:44 PM   #24
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Da Fvck do you need a LSD for ? I dont even have one
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Old 04-02-2012, 06:58 PM   #25
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my main reason if i were to get an lsd if there was a ton of snow and rain annually
in my case there is a ton of sh!tty weather so i do need a lsd some times but i live through it without the fun
OP if you can afford it go for it i personally think you wont but ill just say you should
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Old 04-02-2012, 07:16 PM   #26
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Originally Posted by TX78666 View Post
But, being able to appreciate it, and getting a couple thousand dollars worth of benefit, are two different matters.

Here's a riddle for everyone. All of the talk is always about power loss with an open diff, and inside wheel spin (other than the 1/4 mile stuff). If the inside wheel maintains traction, then (with an open diff) the outside wheel will spin faster than the inside wheel, as it needs to travel further. The outside wheel also should have more traction, since that's where the weight is.

An LSD does not know if one wheel is spinning faster because of lost traction, or because it is on the outside. It acts to keep them both spinning closer to the same speed as one another.

The riddle is, when both wheels have traction in a corner, does the LSD create a tendency for the rear of the car to want to go in a straight line? Does this affect handling?

I know the stock answer is that the LSD is better for handling, and overall, I don't question that it is. I just wonder about the physics of it, in the scenario described.

Anyone awake for that class?
Do some searching for 1.5 and 2 way limited slip diff, the short answer is yes it can make the rear tend to go straight. (Of course you are at full throttle when you get to going straight on a track any way if you have enough traction )

Some interesting limited slip diff reading for your enjoyment !!
http://www.taylor-race.com/pdf/under...ferentials.pdf
http://www.performancegearing.com/specifications.php
http://www.wavetrac.net/
http://www.quaife.co.uk/shop/products/qdf14n
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Last edited by shanneba; 04-02-2012 at 07:52 PM.
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Old 04-02-2012, 07:23 PM   #27
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Unless your putting down over 100 hp more than stock and a manual tranny you dont need an LSD even for the track < i track mine often and do just fine, You dont need to get one for wet road or snow either , I drove mine for nearly 3 years in the snow without problems
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Old 04-02-2012, 07:26 PM   #28
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also, are you sure your pinion bearing is going out? have you checked your fluid and or replaced recently?
Was hoping a post like this would be here.

OP, diff whine is a very common thing. Have you looked to see if you have any signs of leaks around the seal in back, to the drive axles or from the drive shaft. Very easy to check the level...and to drain and fill.

Please start there. I understand the guys like their lsds, but you don't need it at all...and you don't need another diff.

My crappy stock pos 2.93 diff has 230K miles on it, doesn't whine, and brings me to 39 in first, 69 in second. I can't wait to show a 330 what a 328 can do on the dragstrip...coming up end of May!

Change the fluid first. Then, consider other things too before changing the diff. I can't say I've heard of one diff failure here at all. Because of that, you might also want to search your regional forum for a well-recommended Indy. Just saying!
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Old 04-02-2012, 07:28 PM   #29
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BMW Diffs are really strong, Im going with the low on fluid diagonis
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Was hoping a post like this would be here.

OP, diff whine is a very common thing. Have you looked to see if you have any signs of leaks around the seal in back, to the drive axles or from the drive shaft. Very easy to check the level...and to drain and fill.

Please start there. I understand the guys like their lsds, but you don't need it at all...and you don't need another diff.

My crappy stock pos 2.93 diff has 230K miles on it, doesn't whine, and brings me to 39 in first, 69 in second. I can't wait to show a 330 what a 328 can do on the dragstrip...coming up end of May!

Change the fluid first. Then, consider other things too before changing the diff. I can't say I've heard of one diff failure here at all. Because of that, you might also want to search your regional forum for a well-recommended Indy. Just saying!
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Old 04-02-2012, 07:32 PM   #30
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The indy I had do it (I don't have access to a lift and jackstands scare me) said he didn't drop the driveshaft which means the tape wasn't touched.. which means my diff truly whines.

Or I could put back my silent 2.93...
Hopefully mines doesn't wine, I picked up a 3.38 also... but what's this about "dropping the driveshaft"? I've never heard of anything like that with swapping the diff?
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Old 04-02-2012, 07:32 PM   #31
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da fvck do we need fluids for?
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Old 04-02-2012, 07:41 PM   #32
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Hopefully mines doesn't wine, I picked up a 3.38 also... but what's this about "dropping the driveshaft"? I've never heard of anything like that with swapping the diff?
His Indy dosent know what hes doing if he said thats the reason why it whines, By tape i think hes reffering to a sort of clayish substance that goes between the steady bearing and the car to dampen noise
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Old 04-02-2012, 07:42 PM   #33
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da fvck do we need fluids for?
Intoxication
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Old 04-02-2012, 07:43 PM   #34
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His Indy dosent know what hes doing if he said thats the reason why it whines, By tape i think hes reffering to a sort of clayish substance that goes between the steady bearing and the car to dampen noise
Yeah I'm getting ready to swap mines in over the weekend 'cause I should finally have time and this tape and drive-shaft dropping stuff threw me off.... I was like
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Old 04-02-2012, 07:47 PM   #35
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Do some searching for 1.5 and 2 way limited slip diff, the short answer is yes it can make the rear tend to go straight. (Of course you are at full throttle when you get to going straight on a track any way if you have enough traction )

Some interesting limited slip diff reading for your enjoyment !!
http://www.taylor-race.com/pdf/under...ferentials.pdf
Thanks.

I'll check that out. I was really just looking for the short answer (which you provided), but I will read the link, too.
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Old 04-02-2012, 07:54 PM   #36
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Unless your putting down over 100 hp more than stock and a manual tranny you dont need an LSD even for the track < i track mine often and do just fine, You dont need to get one for wet road or snow either , I drove mine for nearly 3 years in the snow without problems
Did you ever drive a BMW with a LSD in the wet, ice or snow?
If you did you would know the benefits.
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Old 04-02-2012, 07:56 PM   #37
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Unless your putting down over 100 hp more than stock and a manual tranny you dont need an LSD even for the track < i track mine often and do just fine, You dont need to get one for wet road or snow either , I drove mine for nearly 3 years in the snow without problems
i give up!!!!!!!!!

way too many people posting about something they don't fully understand

i wish i had Moderator options so i could just delete the nonesense
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Old 04-02-2012, 07:58 PM   #38
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Old 04-02-2012, 08:01 PM   #39
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LSD > No LSD. There's a reason it's almost always offered at an additional cost.

Don't believe me? Take two identical Jeeps, one with LSD's in both axles and one without, out on a mud-filled trail. Which one is probably getting winched out?
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Old 04-02-2012, 10:27 PM   #40
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LSD > No LSD. There's a reason it's almost always offered at an additional cost.

Don't believe me? Take two identical Jeeps, one with LSD's in both axles and one without, out on a mud-filled trail. Which one is probably getting winched out?
LSD > non LSD yes.

Jeep analogy - no.

Take a Jeep with 44" mudders and a Jeep with Pilot Sports and throw them in the mud. I should then put 44" mudders on my e46?

Take a Jeep with 4WD and a Jeep with 2WD and throw them in the mud. So, I should have 4WD for the track?

The "higher price must mean better" idea is also dangerous.

LSD is better, but not for the reasons you cited, particularly in this application.
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