To LSD or not?

[Lambobimmer]

I am debating on installing either a Quaife or OS Giken LSD and I am would like to hear some experiences from their owners.

I am running Cobb Stage 2 Agressive with FBO's and I feel like an lsd will do wonders for my car.

[GaryS]

Standard advice is Quaife for street, OS Giken for track and especially for drifting. For track, it's a no-brainer. I have a Wavetrac, which is similar to Quaife. Traction out of tight corners and over bumps and curbings is huge. On the street, you have to drive pretty aggressively on wet or bumpy roads to feel a big difference. In any of those situations, it's not only more fun, it's also safer, and it's nice to see the DSC light stay off.

[int2str]

What driving do you do?

Street: Waste of money
Autocross/Track: Go for it!

[Eyeman]

I agree an LSD is expensive. However, I don't get why everyone thinks it's not worth the money. IMO if you think an LSD is not worth the money then what is worth the money other than a tune? For sure on the street and FMIC is fairly useless, intake and exhaust, same thing. Suspension upgrades are expensive and many including myself somewhat did a suspension upgrade so I could lower the car for cosmetics. Wheels are expensive and the stock wheels look pretty good.

Really it's pretty simple to me, if you spin your tires too much now, you need an LSD if you can afford it.

[int2str]

Originally Posted by Eyeman

I agree an LSD is expensive. However, I don't get why everyone thinks it's not worth the money. IMO if you think an LSD is not worth the money then what is worth the money other than a tune? For sure on the street and FMIC is fairly useless, intake and exhaust, same thing. Suspension upgrades are expensive and many including myself somewhat did a suspension upgrade so I could lower the car for cosmetics. Wheels are expensive and the stock wheels look pretty good.

I'm not sure about "everyone", but I'll answer from my point of view.

"We" (the car community) spend money to "fix" "problems" (lots of quotes here ).
Wheels to generic? That's a "problem". Solution, get new rims. Car looks like an offroad vehicle? No problem, lowering springs to make it look more sporty. Want more excitement, add power. Angel eyes look outdated? Get LEDs. And so on...

But it gets more complicated from there on out. An FMIC, to take your example, doesn't really add any power. But it keeps intake temperatures down and more consistent, which supports higher boost levels. I'd argue that many people who have an FMIC might not actually need it. And it may not do what they think it does.

Which brings me to the LSD....

Really it's pretty simple to me, if you spin your tires too much now, you need an LSD if you can afford it.

The LSD option for our car is a not very well understood option in my mind. I think people thinks it solves the problem that I'd argue they either don't actually have, or probably shouldn't have. As a result, there's some misleading advice out there, undoubtedly fueled by the fact that an LSD is an expensive mod and nobody would want to admit that they'd bought it in error .

I'm all for spending money to fix problems you have with your car, even the purely cosmetic ones. But in the LSD case (and some others out there), I just want to make sure people really identify the problem they have and make sure an LSD is the answer.

My argument is that in most cases (pretty much 100% of street driven cars) an LSD is not the answer.

To put it more simply. If you are not sure whether you need an LSD or not, you don't!

[Zombie1]

If it isn't going to burn a hole in your wallet do it.

[Lambobimmer]

Money is not the issue but I also like to make smart decisions when I decide to spend it on ONE mods. My car is mostly street driven, however I will take it to the drag strip on occassion and I plan on taking some trips to VIR in the future.

At the strip I could never get off of the line very quick becuase of wheel spin. Also, it doesn't feel like you have much control once the wheels break loose. My hope is that an LSD will solve these problems. I would love to find a VAC built used Quaife or OS Giken but that will probably be a more difficult task. If I cannot find an lsd this way I plan on buying a used bolted diff from a salvage yard and ship it to VAC for their build.

When I sell this car I plan on taking it back to stock and parting out all of my mods, including the original diff that is on the car currently. I never understand why people sell their oem parts and then try to buy them back when they are ready to sell. Ever worse, I see a handful of posts selling their cars modded.

When I sold my E46 M3 I got back $.80 on the $1 and I even made money on a 410 rear diff. I don't exprect to get that much back on this car but who knows.

Sorry to ramble and I appreciate all of the feedback.

[135Hoser]

Originally Posted by GaryS

and it's nice to see the DSC light stay off.

I thought BMW just mapped our throttle to the DSC light...

[bootay]

The only downside to an LSD is $$, but the pros are substantial...I have far more traction now, powering through corners and even simple launches...I can press my DTC and launch it hard without triggering traction control at all, even power sliding it a tiny bit. I couldn't control that before the LSD.

If you bought the 335 (and modified it) because you love performance driving, the LSD is great. If you drive it because it's a BMW and never hit twisties FAST, guess it would be less useful .

[Beemw335]

Imo if you plan to go all out on your car and mod for maximum power and enjoy tracking the car, then its a no brainer.
For an everyday car with a few mods, I say no. As much as its needed, uts too expensive if your not gonna take full advantage if it.

[John Dempsey]

My quaife re geared 3.46 is the single best mod I've done on my car

[haitham87]

Originally Posted by John Dempsey

My quaife re geared 3.46 is the single best mod I've done on my car

+1000

[Indo Rider]

More discussion about final drive ratio options for a MT please! Is it really that much better with the shorter gears? I see the lsd vendors saying it is, but i figured there is probably an abundance of auto difs so its easier for them to source those for the rebuilds...

[John Dempsey]

It is unbelievable. It completely changes the car. If youre ever in san diego drive my car. The pull out of corners is much much stronger and the car NEVER feels sluggish. There is nothing i would reccomend more strongly than doing an lsd and if you do an lsd the 3.46 ratio is a must for performance.

[Colt]

Originally Posted by Eyeman

For sure on the street and FMIC is fairly useless

I might be going off topic, but why is a FMIC useless on these cars? Besides buying a tune, a FMIC would be the next thing on my list if I just bought the car. What about various climates from different areas, etc? Someone in Alaska might not need a FMIC as much as someone in Arizona..

As others have said, if you track the car you'll benefit more from the LSD. For a DD I don't think you'll see a huge difference in drive-ability....I don't own one so I couldn't say for sure, just from experience from what I've heard..

[Tterrag]

I'd say go for it. A limited slip differential won't really give you a noticeable difference on the street, but it will allow you to track out of corners a bit more easily with greater confidence. There really are no drawbacks to having a LSD other than some increased weight, but I'd consider a LSD more than worth it.

In snow it may help a bit, too.

[Eyeman]

Angerman, I overstated saying an FMIC is useless for day to day driving. I just doubt for daily driving that you could notice an FMIC as much as you'd notice an LSD, even in Arizona.

It's very hot here in GA and my car heats up very quickly when I really get into the throttle. But my car has never ran hot enough to be an issue with daily driving. I have all the mods as listed below so I'm not against modding our FMIC's. It's just a little funny to me that most say to do that mod but practically just as many say not to get an LSD.

Btw, I might be a little "traction spoiled". Much of my daily driving in the past has been in Porsche's. They have outstanding stock LSD's and substantially less HP than my One. I was sick of traction control interference in my One even before all my HP mods. Modded, these cars seriously need an LSD to me.

[B-Dawg]

Does an LSD alter how the DSC performs? Does anything change with the electronic's control/interference?

I can't tell if I'm asking a dumb question or not, so I apologize if I am.

[Pyrat 2]

I had a Performance Gearing LSD built for my e90 330i and had preliminary discussions with Jim Blanton (owner of PG) for my 135is that is in production in Germany as I draft this. Here are my opinions and plans based upon owning the LSD for 5 years on the e90:

If you get one built strongly consider changing the rear end ratio. Tradeoff is higher RPMs on the highway and associated fuel economy vs. quickness off the line. I had mine build with a 3.38 up from a stock 3.15. This change was noticeable.

If you are in a climate where there is snow regularly, there is a big difference. The LSD plus the snow tires make most Chicago winter conditions a non-event. I regularly pull away from most cars and 4wd trucks at the lights in snowy conditions. In Chicago winters, just getting the car moving can be a problem without the LSD - even with snow tires. DTC frankly just doesn't work that well in the snow. Of course there is no difference in braking and turning capabilities with the LSD in these conditions.

Similar in slippery/rainy conditions. No LSD equals DTC kicking in and applying brakes to the slipping wheel. LSD equals no DTC kick in. Nice!

I track the car several times per year. I can honestly say that I haven't noticed much difference. However, my 330i doesn't have the torque of the 135 or 335. So I don't know if it makes sense in practice vs theory for those cars.

So what are my plans for the 135is on order? Jury is still out as I haven't decided what to do for driving in the winter. If I end up keeping my e90 for the winter then I'll make the call based upon traction in wet conditions and also see what happens at the track next spring. If I decide to part with my e90 I'll order the LSD on day 1 as the winter benefits are that great.

[brusk]

Originally Posted by lamboworld

Money is not the issue but I also like to make smart decisions when I decide to spend it on ONE mods. My car is mostly street driven, however I will take it to the drag strip on occassion and I plan on taking some trips to VIR in the future.

At the strip I could never get off of the line very quick becuase of wheel spin. Also, it doesn't feel like you have much control once the wheels break loose. My hope is that an LSD will solve these problems. I would love to find a VAC built used Quaife or OS Giken but that will probably be a more difficult task. If I cannot find an lsd this way I plan on buying a used bolted diff from a salvage yard and ship it to VAC for their build.

When I sell this car I plan on taking it back to stock and parting out all of my mods, including the original diff that is on the car currently. I never understand why people sell their oem parts and then try to buy them back when they are ready to sell. Ever worse, I see a handful of posts selling their cars modded.

When I sold my E46 M3 I got back $.80 on the $1 and I even made money on a 410 rear diff. I don't exprect to get that much back on this car but who knows.

Sorry to ramble and I appreciate all of the feedback.

From what I've read it would make more sense to invest in better tires than an LSD. I've heard of people adding them and not changing their 60 foot times at all. I did put one in as I as most people like the idea of LSD and it does slightly enhance how the car feels when combined with the rear bushings and arms. Upgrading to Michelin PSS was the most noticeable thing I've done to the car after adding a tune.

[cdde323]

Is there anyone with LSD who bought it mainly so they can drive fast on mountain roads? Depending on what your version of fast is; I would say I lean on the aggressive and unsafe side of speed...

The mountain roads I'm on tend to be pretty damn bumpy... If this helps draw a picture for people in California, GMR/Wilson/Red Road (SoCal) are heavenly smooth compared to some of the conditions we have up here, 236/Black/Bear Creek.

I get the yellow flashing light constantly; not so much because of the turns, but because of the bumps in turns. The car then steals my pedal... I curse loudly and power eventually returns.

Did LSD solve a similar problem?

[John Dempsey]

Originally Posted by cdde323

Is there anyone with LSD who bought it mainly so they can drive fast on mountain roads? Depending on what your version of fast is; I would say I lean on the aggressive and unsafe side of speed...

The mountain roads I'm on tend to be pretty damn bumpy... If this helps draw a picture for people in California, GMR/Wilson/Red Road (SoCal) are heavenly smooth compared to some of the conditions we have up here, 236/Black/Bear Creek.

I get the yellow flashing light constantly; not so much because of the turns, but because of the bumps in turns. The car then steals my pedal... I curse loudly and power eventually returns.

Did LSD solve a similar problem?

I got mine for the track but i do notice a difference when pushing it aggressively through the mountains around here, and it should help a little with the bump issue, but just turn off traction control so your car doesnt cut power