Upgraded Differential Options?

[Advorsor]

Was wondering if a diff upgrade makes sense for a car that only sees a few track days per/year (mostly street driven)?

Specifically, looking at the Os Giken unit:

https://www.ecstuning.com/b-os-giken...unit/bm237-ha/

[Obioban]

For a street car that sees track use, I think wavetrac is the best option.

Been running one for ~20,000 miles, including 10-15 events, and have no complaints.

No clutches, so should last ~forever without rebuilds. Totally silent. Can deal with zero traction on one wheel (ice). Not as good on track as a multiclutch, but better than stock on track and better than multiclutch on the street.

[Advorsor]

Thank you sir! Will look into Wavetrac

[bmwfnatic]

Also keep in mind that just purchasing an (aftermaket) LSD core is not the only thing required.
You really can't just put it in, reassemble, and call it a day, nor take it to your local mechanic that normally changes oil and brake pads, he probably won't have a clue either.

Proper installation (if we only focus on the carrier side, the pinion side adds more complexity and measurements).
will require disassembling and reassembling the unit a few times to firstly get the carrier bearing preload within spec (total shim thickness)
and afterwards set the proper backlash and gear pattern (left vs. right shim thickness).

Doing all this will require special tools, shim kits that are expensive and on the edge of being NLA from BMW, and a lot of time.

I DIY literally everything, but rebuilding the diff is something I left to someone that has done it hundreds of times and has all the tools and aforementioned shims, as there is no cost saving to be had if you want it done right and are not planning on opening your own little diff rebuilding business.

Just something to keep in mind.

[gaiakai]

Also keep in mind that just purchasing an (aftermaket) LSD core is not the only thing required.
You really can't just put it in, reassemble, and call it a day, nor take it to your local mechanic that normally changes oil and brake pads, he probably won't have a clue either.

Proper installation (if we only focus on the carrier side, the pinion side adds more complexity and measurements).
will require disassembling and reassembling the unit a few times to firstly get the carrier bearing preload within spec (total shim thickness)
and afterwards set the proper backlash and gear pattern (left vs. right shim thickness).

Doing all this will require special tools, shim kits that are expensive and on the edge of being NLA from BMW, and a lot of time.

I DIY literally everything, but rebuilding the diff is something I left to someone that has done it hundreds of times and has all the tools and aforementioned shims, as there is no cost saving to be had if you want it done right and are not planning on opening your own little diff rebuilding business.

Just something to keep in mind.

Is this why diffsonline can easily total 5k even with no options, because they give you a complete diff and do all that hard work for you? Or am I just misunderstanding it and we'd still have to take the whole thing apart regardless

[oceansize]

Is this why diffsonline can easily total 5k even with no options, because they give you a complete diff and do all that hard work for you? Or am I just misunderstanding it and we'd still have to take the whole thing apart regardless

Diffsonline sells you the whole pumpkin, you swap in and out. I bought mine (not a wave trac) from them for that reason. There is a core charge as well.

[bigjae46]

Do you need to upgrade the diff? No but a diff can be a significant performance upgrade.

[bigjae46]

Also keep in mind that just purchasing an (aftermaket) LSD core is not the only thing required.
You really can't just put it in, reassemble, and call it a day, nor take it to your local mechanic that normally changes oil and brake pads, he probably won't have a clue either.

Proper installation (if we only focus on the carrier side, the pinion side adds more complexity and measurements).
will require disassembling and reassembling the unit a few times to firstly get the carrier bearing preload within spec (total shim thickness)
and afterwards set the proper backlash and gear pattern (left vs. right shim thickness).

Doing all this will require special tools, shim kits that are expensive and on the edge of being NLA from BMW, and a lot of time.

I DIY literally everything, but rebuilding the diff is something I left to someone that has done it hundreds of times and has all the tools and aforementioned shims, as there is no cost saving to be had if you want it done right and are not planning on opening your own little diff rebuilding business.

Just something to keep in mind.

An LSD unit can just be straight swapped in. Remove, swap the ring gear and reinstall. You will need the carrier bearings/races, o-rings, output shaft seals, and either a gasket or sealant for the diff cover. Technically the ring gear bolts should be changed.

The ring gear to pinion gear relationship is not being changed unless the LSD unit is a different dimension. There might be some very minor difference but not enough to change the how the gears mesh. If you're worried about preload then you can install the LSD unit without the ring gear on it and take a preload measurement. BUT...you'll need to measure backlash and check the gear pattern if you make any adjustments.

All you really need to check is backlash and gear pattern which will very likely be good to go unless the specs were off before the LSD swap. Every diff I've done has had 1.6 to 1.8mm carrier shims. If you have the shims that originally came with the diff then it should be spot on unless you're making a massive gearing change like going from a 3.15 to a 4.44.

[EthanolTurbo]

Get a Drexler. OS Giken is overhyped and meh.

[jet_dogg]

Thinking about selling my drexler 🤔