Upgraded LSD options for Z4 M

[dekaliber]

Aside from the 3.91 and 4.10 LSDs offered by Dinan, what alternatives are out there for a shorter final gear (short of swapping gears yourself)?

[The__J__Factor]

Most people buy from http://diffsonline.com/

But the gear ratios you mentioned are the main stream, and a bunch of different companies offer them.

[RussRamz]

I'm installing a Drexler motorsport diff with 4.1 gearing in my car next month. Total cost is 3450 Euro.

[inTgr8r]

running smaller tires will reduce the effective final drive.

[trsbmw]

The title of the post mentions upgraded LSD options, but the text of the post only references gearing. Am I missing something?

Gearing is one thing, but upgrades to the M variable lockup diff itself is another.

I dont have much experience in this area, but what are the typical complaints about the M LSD, which necessitate an upgrade? (Especially something that justfies a 3400 Euro cost!!!)

[gnx]

Originally Posted by RussRamz

I'm installing a Drexler motorsport diff with 4.1 gearing in my car next month. Total cost is 3450 Euro.

Your feedback on this will be eagerly awaited.

[dekaliber]

Originally Posted by trsbmw

The title of the post mentions upgraded LSD options, but the text of the post only references gearing. Am I missing something?

Gearing is one thing, but upgrades to the M variable lockup diff itself is another.

I dont have much experience in this area, but what are the typical complaints about the M LSD, which necessitate an upgrade? (Especially something that justfies a 3400 Euro cost!!!)

Sorry, should have been more clear. I was just referring the gearing portion of the LSD. The stock final drive ratio is 3.62 which many have indicated is inadequate to really bring out the full potential of the high-revving S54. Changing to a shorter ratio like 3.91 or 4.1 effectively increases torque to the wheels by running the engine at slightly higher RPMs relative to the speed of the car.

With a 3.62 final drive ratio you hit 60 MPH at around 7000 RPM. Increasing it to 4.1 means you hit 60 right around 8000. 3.91 is in between. All of this means better acceleration at a slight compromise to fuel economy.

Originally Posted by inTgr8r

running smaller tires will reduce the effective final drive.

But this also increases your odometer readings and reduce your speedometer readings proportionally. (I think you're pulling my leg, in any case.)

[epbrown]

Originally Posted by dekaliber

But this also increases your odometer readings and reduce your speedometer readings proportionally. (I think you're pulling my leg, in any case.)

He's right, but there aren't really a lot of options in that regard for the Z4MC. Eighteen inch wheels are the limit for most styles because of our brakes, smaller aspect ratio tires would be a bit smaller but ride even more harshly. We can't do like the kids in Humboldt Park who put 10" wheels on old Hondas to spin out all the time.

As far as gearing - the 3.91 and 4.10 are the Motorsport gearsets from BMW, which everyone resells - its why everyone has the same upgrade options. As far as I know, no one else made gears at all, much less in other ratios. You could go custom, but that'd be pricey. I wouldn't even know where to begin with that.

[Z4-VILLA]

as is the z4m is needs nothing but a full exhaust, intake and a tune.
LSD is just not worth it in most cases....

[epbrown]

Originally Posted by Z4-Villalona

as is the z4m is needs nothing but a full exhaust, intake and a tune.
LSD is just not worth it in most cases....

I'm the opposite - I think gears are all it needs to put performance where it should be; those mods have a low bang-for-the-buck, imo. I do love the sound of the Supersprint, though.

[RussRamz]

Originally Posted by Z4-Villalona

as is the z4m is needs nothing but a full exhaust, intake and a tune.
LSD is just not worth it in most cases....

A motorsport LSD isn't about power and 1/4 mile drag races. It's about putting the power down minimizing wheel spin and getting on the throttle earlier coming out of corners on a road circuit. A proper LSD will greatly enhance controllability of the car. The Z4M ///M differential is less than optimal and rather crude when it comes to modern LSDs.

[Diokaef]

Originally Posted by RussRamz

A motorsport LSD isn't about power and 1/4 mile drag races. It's about putting the power down minimizing wheel spin and getting on the throttle earlier coming out of corners on a road circuit. A proper LSD will greatly enhance controllability of the car. The Z4M ///M differential is less than optimal and rather crude when it comes to modern LSDs.

+1

[F360C]

Originally Posted by Z4-Villalona

as is the z4m is needs nothing but a full exhaust, intake and a tune.
LSD is just not worth it in most cases....

And all that is worthless unless you can put the power to the ground.... so you def need tires and better suspenions in addition to all the power bits. Then when you get to that point you need better brakes because you are carrying more corner speed and because of the addional power hitting much higher terminal speeds down the straights. Then you come to the conclusion that the car is too heavy and you need to feel more connected to it so you buy race seats to drop some weight while keeping you more stable inside the car. Then when you have gotten to the point that RussRamz is at you see that you are losing time coming out of corners because the stock M diff is not putting down the power as well as motorsport diff can. It sure is a slippery slope this modding thing. Once you up grade one area for better performance you realize that the other areas of the car are now lacking too.
In terms of the diff I feel that it could lock sooner. Some times when I am coming out of corners you can feel it not locking soon enough but on my prioity list of mods it is not one of the most critical

[Z4Murder]

Originally Posted by F360C

And all that is worthless unless you can put the power to the ground.... so you def need tires and better suspenions in addition to all the power bits. Then when you get to that point you need better brakes because you are carrying more corner speed and because of the addional power hitting much higher terminal speeds down the straights. Then you come to the conclusion that the car is too heavy and you need to feel more connected to it so you buy race seats to drop some weight while keeping you more stable inside the car. Then when you have gotten to the point that RussRamz is at you see that you are losing time coming out of corners because the stock M diff is not putting down the power as well as motorsport diff can. It sure is a slippery slope this modding thing. Once you up grade one area for better performance you realize that the other areas of the car are now lacking too.
In terms of the diff I feel that it could lock sooner. Some times when I am coming out of corners you can feel it not locking soon enough but on my prioity list of mods it is not one of the most critical

very well put