The Definitive e39 LSD Thread.

[Ahheck01]

It's probably the biggest complaint about the non-M e39 - no LSD. Seeing as it's such a desireable thing, I figure we should dedicate a single thread to discussing all the options, costs, etc. for upgrading to an LSD.

Share you experiences, ideas, opinions, etc.!

-Evan

[Ahheck01]

What are the different ways to get an LSD on a 540? I hear the M5 LSD swap is hella-expensive.

[xatlas0]

What are the different ways to get an LSD on a 540? I hear the M5 LSD swap is hella-expensive.

I am afraid that is the only way that I am aware of, other than possibly having Metric Mechanic essentially build you one. I do not know if they do E39 diffs. I would imagine they could, since they can do E46 diffs.

[Ahheck01]

DiffsOnline will build one, but for over $5k for a limited slip. :confused

[joey93turbo]

Could a gear man take our stock diff and make it LSD with another set of gears?

BTW very good thread idea.

[Ahheck01]

BTW very good thread idea.
Thanks! I think I'll put in the original post a list of all questions asked in the thread, as long as their answers if provided. I'll update regularly as people post - at least daily.

Does anyone have a writeup for the M5 swap?

-Evan

[xatlas0]

Could a gear man take our stock diff and make it LSD with another set of gears?

BTW very good thread idea.

That is what is meant when they "make" you a diff. Costs an arm+leg. Another question is what would be required to use a different style diff, like an E46 diff?

[Ahheck01]

Found this: http://forums.bimmerforums.com/forum/showthread.php?t=371042&highlight=e39+LSD

Some guy did the M5 diff swap. Good read!

-Evan

[joey93turbo]

So where would they get these gears they use to "make" you a diff using the old housing? Why's it so expensive?

[xatlas0]

So where would they get these gears they use to "make" you a diff using the old housing? Why's it so expensive?

I could be wrong, but I think ZF, the transmission and power steering manufacturer, makes them. That's how it is for the older units, anyway.

[Ken21]

guys....a bit OT but what's the best upgrade for a 540ia ??

i think a open diff will be good for me since a LSD cost is........

thanks

[joey93turbo]

I could be wrong, but I think ZF, the transmission and power steering manufacturer, makes them. That's how it is for the older units, anyway.

Any idea how I'd go about finding a price for these? is most of the $5k cost just labor and the fact that not many other companies offer this service?

[xatlas0]

Any idea how I'd go about finding a price for these? is most of the $5k cost just labor and the fact that not many other companies offer this service?

I think part of it is, you can't just "buy" ZF parts anymore. If you look on Realoem, with the older models, you can buy individual components of virtually everything, rather than single units of many things, like transmissions, alternators, diffs, etc. Now, you cannot do that. I think only a certified ZF rebuilder has the ability to buy specific internal components, like Metric Mechanic. Thusly, since parts only come from one source, they can charge whatever they feel like for them.

The 5k is mostly for parts; changing a diff isn't all that difficult.

[mnchvgs79]

Weld the spider gears and have posi ;)

[joey93turbo]

WOW $5k in parts, that's crazy.

[Johnny 5]

What we need to know is the carrier type. The carrier is the open or locked portion of the diff that the ring gear bolts to. The carrier in a BMW should be the same for all ratios. Now, what carrier does the 540i have? Is it the same as an M5? Does have more or less splines? Are there differences in ABS controls?

If the carrier in the M5 unit is the same as the 540i, then the ring gear will bolt up and you can put that hydraulic variable LSD in a 540i case.

In the past, BMW has changed cases from one body style to the next, but has retained the ring and pinion size and/or the carrier. So there could be a carrier from another BMW that will fit. For instance, an E32 carrier may be the same as an E39. Then you could use the 750iL clutch-type LSD in the E39 case. This is an example and may not be true.



So the next question is the ratio. What other ratios came in a large case E39 or E38 or whatever else has this diff type?

Standard 540i 6 speed: 2.81:1 open
Standard 540i Auto:
Standard 540iT Auto: 3.15:1 open (I think)
M5 3.15:1 locker

The whole custom diff. thing has had me laughing for years. BMW differentials are almost exactly the same as US made truck or Spicer style differential. Any competant shop could change the carrier and/or gear set for you. They may only charge you more because they know you have a BMW.

Also, BMW diffs are very stout. So you wont need to buy a brand new gearset. Most used sets will do fine. Also, rebuilding a stock clutch-type LSD is no different that building an American Trac-loc or whatever. So, you could also have that rebuilt for cheap. (if the parts are not too high) Where you will be set back is the factory or Timken bearings and the precision tools to set backlash and pinion depth. Also, if you don't know how to work on this stuff, you will have to pay the increasingly high shop labor charges.

[m5james]

What we need to know is the carrier type. The carrier is the open or locked portion of the diff that the ring gear bolts to. The carrier in a BMW should be the same for all ratios. Now, what carrier does the 540i have? Is it the same as an M5? Does have more or less splines? Are there differences in ABS controls?

If the carrier in the M5 unit is the same as the 540i, then the ring gear will bolt up and you can put that hydraulic variable LSD in a 540i case.

In the past, BMW has changed cases from one body style to the next, but has retained the ring and pinion size and/or the carrier. So there could be a carrier from another BMW that will fit. For instance, an E32 carrier may be the same as an E39. Then you could use the 750iL clutch-type LSD in the E39 case. This is an example and may not be true.



So the next question is the ratio. What other ratios came in a large case E39 or E38 or whatever else has this diff type?

Standard 540i 6 speed: 2.81:1 open
Standard 540i Auto:
Standard 540iT Auto: 3.15:1 open (I think)
M5 3.15:1 locker

The whole custom diff. thing has had me laughing for years. BMW differentials are almost exactly the same as US made truck or Spicer style differential. Any competant shop could change the carrier and/or gear set for you. They may only charge you more because they know you have a BMW.

Also, BMW diffs are very stout. So you wont need to buy a brand new gearset. Most used sets will do fine. Also, rebuilding a stock clutch-type LSD is no different that building an American Trac-loc or whatever. So, you could also have that rebuilt for cheap. (if the parts are not too high) Where you will be set back is the factory or Timken bearings and the precision tools to set backlash and pinion depth. Also, if you don't know how to work on this stuff, you will have to pay the increasingly high shop labor charges.

Can you elaborate more....are you saying that some local american builder can order the parts we need to convert ratios or to even LSD?

[eurotunerwerks]

i would LOVE to hear more.

[Johnny 5]

I love it, your father loves it, and your aunt Eunice loves it too.

Sure any quality shop can do it. That may be the problem though.

You need an expirienced tech that has built enough rearends to know how to set the backlash (the mesh between the ring and pinion gears) and pinion depth with shims. They also have to crush a sleeve that holds the driveshaft yoke to the pinion. As for the rearend bearings, as long as you have the parts, those are not hard to install.

You should be able to get a shim kit and crush sleeve for the pinion. You'll need gear marking compound(to set backlash), new bearings, new ring gear bolts, Lock-tite for the bolts and cover, shims for the carrier(if you change carriers), and whatever other bolts you need that are under stress.

Now if you just want a deeper ratio, then just swap a 740i/L or 540iT rearend with the 3.15:1 ratio. If you want an LSD, that is the carrier piece, then you will need to go ahead and rebuild the rearend. Where you get the LSD is up to you.

And if you want it to be just like the $5000 diff, then paint it and have the bolts replated. You may also want to polish the diff cover to match your polished rear control arms;)

[m5james]

740i/L and 540iT only come with 3.15 ratios if you have the Sport option, otherwise it is still a 2.81 ratio. I've had mine replaced with another stock unit after toasting mine, long story, would have 3.64...another long story, but point is not ALL of the 740i/L and 540iT come with 3.15 - I don't think the 740i Sport package started till 01 either, and they don't make an iL sSport package.