OS Giken Differential Realtime Install

[///Mobbin]

After wanting to try a true clutch-type diff for years I've finally ordered one! Planning to self-install and figure I would chronicle the process to help others thinking to do the same. Bare with me as this is going to be a slow process and will likely take weeks for me to complete. Also, not really intending this as a DIY but more of a good source of info. My car is on jackstands already waiting on a new custom suspension setup (more on that later), so figure I may as well do this now while the car is not in use.

I went back and forth on which diff to get and ended up deciding on an OS Giken Spec-S. While I could have gone Spec-X or customized my Spec-S (effectively making it a Spec-X), I decided I'd start with Spec-S and then customize it later if I decide to do that. I'm also sticking with 3.15 gearing for now (DCT transmission) to make the install easier and also maintain street manners. Again here, I may end up swapping the gearing at a later date as my car becomes more of a dedicated track car, we'll see.

Some informative YouTube videos on OS Giken diffs:
MotoIQ on OS Giken Function and Tuning
OS Giken Superlock Spec-S vs TCD Spec-S

Some informative YouTube videos on installing diffs:
Driftworks installing a Florian Diff
RacingDiffs - How to Change a BMW Gear Ratio
RacingDiffs - E46 M3 Complete Differential Rebuild
E36 M3 Diff Rebuild
E46 M3 Differential Oil Leak Fix

While these videos don't cover our exact diffs a lot of the same concepts apply.

I'm also assembling a parts-list and could use some help filling in a few blanks.

Parts List:
2 x E39 M5 Output flanges - part no. 33131214068
2 x E92 M3 Shaft Seal w/ lock ring - part no. 33107510289
Note: This is the seal for the output flanges, be careful not to confuse with the pinion shaft seal
2 x E92 M3 O-rings - part no. 33111214144
2 x E92 M3 Differential Carrier Bearings -
2 x E92 M3 Differential Carrier Bearing Races -
Diff cover sealant -
Sealant for side cover bolts that protrude into diff housing -

OS Giken Differential Fluid - Need 3 Liters, ~1.2L/fill but need to flush and refill after ~500 miles
Reason to just stick with Giken fluid vs. substituting - LINK

Some additional useful links:
E92 M3 Differential Parts Diagram
E39 M5 Differential Parts Diagram

[///Mobbin]

A few tools I'd like to pick up for the installation.

Something to support and lower the diff with, was thinking something like this:
LINK

And a differential backlash gauge, anyone have a recommendation here?

[///Mobbin]

Looks like Loctite 5970 might be the right sealant for both the diff cover and the bolts that go through the side covers into the diff housing.

LINK

[SAMM3Y]

Sub'd. I have an osg diff which isn't currently installed, I switched it out recently to try and shake down a problem. It was a bit of a struggle to change out by myself on quickjacks so your trans jack is a good idea as it'll help get the diff lined up when re-installing which for me was the biggest struggle. I just used a trolley jack and some craftiness. I do miss the diff, it really made the car feel special..

[rhyary]

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[Redd]

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[///Mobbin]

Curious if anyone knows whether the same carrier bearings/races that are used on the e46 m3 are also used on e9x m3's?

If so then the following part numbers should work:
2 x E46 M3 Differential Carrier Bearings - JLM104948
2 x E46 M3 Differential Carrier Bearing Races - JLM104910

The Timken and Koyo brands both seem popular for these.

[///Mobbin]

Haven't ordered any parts/tools quite yet but find myself with some time to do some work this weekend. As a result realized I wanted a backlash gauge to measure current backlash before I took the diff apart. Grabbed what Harbor Freight had available along with a large plastic bin to take the diff apart in and some cheap magnetic parts holders. Job starts today!

[///Mobbin]

First steps, securely jack up the car, remove the middle exhaust section, remove the heat shield covering the driveshaft to differential connection point.

[///Mobbin]

Depending on your brand of rear exhaust you may or may not need to remove the rear exhaust section, going to try lowering the diff w/out removing my Dinan rear section, we'll see. 21mm nuts holding the exhaust to these points need to come off. Of note the heat shield was mostly 8mm/10mm bolts/fasteners. Bungie cord to hold up the half axles.

[///Mobbin]

It's taking some serious torque to remove the Torx E14 bolts that hold the driveshaft and axle shafts to the diff. To the point I'm having to recharge my battery before I complete the job. Will need to get the DCT in neutral to rotate everything as well to get to each bolt. Work in progress.

[///Mobbin]

Planning to put DCT in neutral using this method so I don't need to start the car - YouTube LINK.

[///Mobbin]

Neutral trick worked and was able to get the rest of the E14 bolts out. Next up are the three mounting points for the diff, the front two 18mm bolts loosened with ease, the through-the-subframe rear bolt is going to be a little more difficult, looks like 21mm on both sides, going to need the battery torque wrench again.

[spammysammich]

Originally Posted by ///Mobbin

Planning to put DCT in neutral using this method so I don't need to start the car - YouTube LINK.

You might get a "silent" DTC warning about the car going into neutral when it wasn't expecting. Just FYI. I did.

[///Mobbin]

Originally Posted by spammysammich

You might get a "silent" DTC warning about the car going into neutral when it wasn't expecting. Just FYI. I did.

Appreciate it, will scan and clear just in case.

[///Mobbin]

These are the tools it took to get that last rear 21mm bolt/nut loose, can take the nut out and leave the bolt in for when you are ready to lower, just push up on the diff slightly and can pull the bolt right out, about to lower the diff with a jack bc I didn't order the transmission/bike jack in time.

Diff should arrive today also!

[///Mobbin]

Last diff bolt tools.

[///Mobbin]

And we have a diff! So yeah, diff is insanely heavy, I would never lower on a regular jack again, table or transmission jack only and will still need one to get it back in place. That was unnecessarily dangerous and could have damaged a part doing it, got lucky and didn't.

[///Mobbin]

H14 to drain the diff oil, pulling both drain and fill plugs and will likely add new plugs to my parts list.

[///Mobbin]

In case anyones curious what the factory vLSD looks like. Bunch of 16mm bolts securing the rear diff cover then pried it open with a large screwdriver.

[///Mobbin]

Sneak peak of the new unit — may tear down the old a bit tomorrow but new will have to wait on parts to arrive, stay tuned.

[SAMM3Y]

Here's mine installed