LSD Question

[ryznsun2000]

With a stock "i" the rule is that power is not always set to both rear wheels... so to remedy this it's advised that "one" would get a LSD to have full time traction to both tires... so under that rule I found out that LSD's aren't made for xi's. Is this because that they just don't make them or is it because xi's have a form of "Limited Slip" with it being AWD? Part two to that question is: With the 67% 33% split, do both wheels in the rear have equal power... and do both wheels in the front have equal power? Assuming that the DSC is off.... (because I'm sure it has an affect)

[M0nK3y]

There is no LSD for any 3 series. Not even a M3

[ryznsun2000]

There is no LSD for any 3 series. Not even a M3

http://www.modbargains.com/product.a...d=TMSBMWE46LSD

Uhh... yea....

[wasp]

call diffsonline ................http://www.diffsonline.com/gallery/index.shtml

[wasp]

There is no LSD for any 3 series. Not even a M3

again monkey puts foot in mouth , how you cant know this info after 3,000 posts leads me to believe you may need help

[ryznsun2000]

call diffsonline ................http://www.diffsonline.com/gallery/index.shtml

I just sent an email...

Thanks...

[Critter7r]

There is no LSD for any 3 series. Not even a M3

Your insistence on remaining uninformed about stuff never ceases to amaze me.

The M-cars come with limited slip diffs.

Ok, whether or not it's an Xi, if both tires (left and right) have the same amount of traction, then yes, power will be sent to both tires equally (whether it's the front or rear axle). Open diffs are like water, the power travels the path of least resistance. So when one tire is on ice, it's the one spinning, the other tire gets nothing. Then, DSC kicks in and brakes the tire that's spinning and lo and behold, the power gets transferred over to the other tire - provided it has traction, you start moving. If both tires are on ice and you mash the gas, the DSC pretty much halts forward progress.

So BMW doesn't use LSD's because all (not just the Xi's) BMW's have a form of limited slip due to DSC.

[ryznsun2000]

Your insistence on remaining uninformed about stuff never ceases to amaze me.

The M-cars come with limited slip diffs.

Ok, whether or not it's an Xi, if both tires (left and right) have the same amount of traction, then yes, power will be sent to both tires equally (whether it's the front or rear axle). Open diffs are like water, the power travels the path of least resistance. So when one tire is on ice, it's the one spinning, the other tire gets nothing. Then, DSC kicks in and brakes the tire that's spinning and lo and behold, the power gets transferred over to the other tire - provided it has traction, you start moving. If both tires are on ice and you mash the gas, the DSC pretty much halts forward progress.

So BMW doesn't use LSD's because all (not just the Xi's) BMW's have a form of limited slip due to DSC.

I appreciate the explanation... really!... it makes a lot more sense...

So getting an LSD for me (assuming that there is one for an xi) would be a good thing or a bad thing?

[ryznsun2000]

Read below...

From: Dan@Diffsonline [mailto:dan@diffsonline.com]
Sent: Thursday, February 07, 2008 4:44 PM
Subject: RE: 2004 330xi



Those are some serious tech questions that I am sure Nick can answer…

That said we have done a bunch of rear limited slips that make the xi’s a blast to drive. They vary from stock ratio with rear limited slip to upgrading front and rear diffs to shorter gears and adding the rear limited slip.

That said going with a rear limited slip runs $2995 for the diff plus a $400 core deposit and $95 for shipping.

Dan Fitzgerald
Diffsonline LLC
Building Performance Differentials and Transmissions for Race and Street BMWs
Bavarian Performance Group LLC
Independent BMW Service, Repair, and Performance
1034 Main St
Winchester MA 01890
781.983.2944
781.279.4435 Fax

Note: NEW ADDRESS

[M0nK3y]

http://www.modbargains.com/product.a...d=TMSBMWE46LSD

Uhh... yea....

i ment to say stock. Aftermarket there is, im not that retarded

[M0nK3y]

again monkey puts foot in mouth , how you cant know this info after 3,000 posts leads me to believe you may need help

someone is out to get me

[ryznsun2000]

So I'd be able to go faster by just changing the diff? Without making any engine mods... is this right?

[M0nK3y]

So I'd be able to go faster by just changing the diff? Without making any engine mods... is this right?

Yes you can, but not really faster, there is no HP gains.

More like faster acceleration.......0-60..........

If your car is manual id go 3.46 diff. That would be a nice set-up. If its automatic, i really don't know a good diff.......

[Smilez]

auto would be a nice 3.91 diff from an x3

[ryznsun2000]

Yes you can, but not really faster, there is no HP gains.

More like faster acceleration.......0-60..........

If your car is manual id go 3.46 diff. That would be a nice set-up. If its automatic, i really don't know a good diff.......

I'm emailing with Dan back and forth... he's doing some further research for me...

[Critter7r]

I appreciate the explanation... really!... it makes a lot more sense...

So getting an LSD for me (assuming that there is one for an xi) would be a good thing or a bad thing?

Depends.... For 95% of the driving population (myself included) that don't need to wring every last percent of power and speed out of their vehicle, an LSD in a vehicle equipped with DSC is redundant. The only thing (that I can think of) you need an LSD for is being able to turn off DSC and steer the vehicle with the throttle on dry pavement. You can't do that with an open diff, and you can't do that with DSC. An open diff won't spin both tires to allow drifting, and DSC won't allow any wheelspin.

[wasp]

exactly, i love doin that in my firebird...........but, lsd will be last, perhaps just as well, dsc will save me on tires

[ryznsun2000]

Depends.... For 95% of the driving population (myself included) that don't need to wring every last percent of power and speed out of their vehicle, an LSD in a vehicle equipped with DSC is redundant. The only thing (that I can think of) you need an LSD for is being able to turn off DSC and steer the vehicle with the throttle on dry pavement. You can't do that with an open diff, and you can't do that with DSC. An open diff won't spin both tires to allow drifting, and DSC won't allow any wheelspin.

Thanks again... so... in essence... this sounds like a long term mod... with regard to what I'm looking to do...

[Daler69]

ok im confused.. im sure my car has a LSD because if i try to a donut or a burnout only one wheel spins and i thought thats what the LSD done.. i want a diff which sends equal power to both wheels all the time to do proper donuts and rolling burn outs..

[Daler69]

Found on the internet:

A limited slip differential (LSD) is a modified or derived type of differential gear arrangement that allows for some difference in rotational velocity of the output shafts, but does not allow the difference in speed to increase beyond a preset amount. In an automobile, such limited slip differentials are sometimes used in place of a standard differential, where they convey certain dynamic advantages, at the expense of greater complexity.
The main advantage of a limited slip differential is found by considering the case of a standard (or "open") differential where one wheel has no contact with the ground at all. In such a case, the contacting wheel will remain stationary, and the non-contacting wheel will rotate freely– the torque transmitted will be equal at both wheels, but will not exceed the threshold of torque needed to move the vehicle, thus the vehicle will remain stationary. In everyday use on typical roads, such a situation is very unlikely, and so a normal differential suffices. For more demanding use however, such as driving off-road, or for high performance vehicles, such a state of affairs is undesirable, and the LSD can be employed to deal with it. By limiting the velocity difference between a pair of driven wheels, useful torque can be transmitted as long as there is some friction available on at least one of the wheels

[rocket66]

Damn, saw this thread and I thought you guys were talkin about acid.I started having flashbacks....

[Erik16]

another point, im not positive, but increasing differental size may decrease your top end speed, or so ive heard.

[ryznsun2000]

another point, im not positive, but increasing differental size may decrease your top end speed, or so ive heard.

More research required... once I'm at that point...

[Daler69]

another point, im not positive, but increasing differental size may decrease your top end speed, or so ive heard.

Yes it does, more accel will give u less top end but like iv said.. acceleration is everything, there is no law on how fast u can get to a speed limit but i lost my licence for 6 months for going over 100mph and to be honest.. going 155mph doesnt feel half as fun as gettin from 0-60 in less than 5 seconds.. lol

[wasp]

i have to agree, the majority of your driving will be in the 0-80 range...............