OS Giken Differential Realtime Install

[///Mobbin]

Practice tip, need a metal disc of correct size to fully seat the race. Second picture shows gap if just flat seated and not fully seated with the disc.

[///Mobbin]

Getting lucky here as the shop happened to have the perfect metal disc sizes.

[///Mobbin]

So same thing with the bearings, there was a slight gap beneath the bearing when pressing with the flat disc, need a circular piece of pipe that is just right for that middle ring of the bearing. One of the photos below shows the gap.

[///Mobbin]

Ready for the ring gear but a few stuck bolts, about to try a fresh battery on them, backup plan is to use this as an excuse to order more tools! Thinking Milwaukee for my next impact wrench, have some M12 stuff already.

[bigjae1976]

I use their large impact and it will spin the ring gear bolts off easily. I also have an analog dial indicator, much easier to use.

Great work!

[Redd]

Old ring gear doesn't want to come off cos it wants you to get that 3.45 gearset. And you'd be saving money from not having to buy the Milwaukee.

[///Mobbin]

So I ended up buying the 250 ft lb Milwaukee M12 stubby and still couldn't loosen the bolts, thought a fresh tool would do it but nope. A buddy ended up coming over with his M18 high torque impact that does 1400 ft lbs, got most of the rest off easy but one bolt took a little work with that even, surprising. Got the ring off with a hammer and large screwdriver hitting the top of the screwdriver around the edges, tried a rubber mallet first but it wasn't enough.

Next questions, what should I torque the ring bolts too and should I red loctite them?

[bigjae1976]

I just leave 4 bolts in and bang on the bolts to get the crown gear off. Probably wouldn't want to reuse them.

There's an angle torque spec. I can't get it done since I have no way to hold the carrier. I use a big M18 Milwaukee Impact and go with a couple of ugga-dugga's. No loctite.

[Mog-10]

Subscribed. I'm interested in your results with the OS Giken. I have heard mixed results. I want one/not sure and not sure on what spec to get especially since I'm not running a conventional diff that other M3 enthusiasts do. I don't track the car it's an e93 but I am hard on it.

[dogbone]

Originally Posted by Mog-10

Subscribed. I'm interested in your results with the OS Giken. I have heard mixed results. I want one/not sure and not sure on what spec to get especially since I'm not running a conventional diff that other M3 enthusiasts do. I don't track the car it's an e93 but I am hard on it.

Mixed results? Curious what you mean by that.

I’ve run the OS Giken pretty darn hard since the end of 2015 with no issues. I check in the AIM Solo data to monitor how my wheel speed spins look and they still look good after 6+ years.

As far as what one to get: Do not get Soec-S. Spec-S is simply a generic setup diff that someone came up with so that vendors could have diffs sitting in stock ready to go. You don’t want that. You want the diff setup to your specific car—-your weight, power, aero, driving style, tires, etc. Then the people at OSG take that info and set the diff up based on the thousands of cars they have setup and stored in their database. THAT’S the diff you want. It’s like an extra $150 for the custom setup. An E93 M3 that is not tracked is definitely going to need a setup quite different than a stripped out E92 race car with aero and slicks.

If you haven’t seen it, I did a lonnnnnnnng write up on the OS Giken diff vs the stock M3 diff in my build thread. If you have not seen it, and you really are interested in this topic, I highly recommend you check it out. It’s a 3-part write up that starts on page 8 and continues on page 9: Diff write up

[Mog-10]

https://www.e90post.com/forums/showthread.php?t=1044864


At this moment I am running a super 8.8 from a s550 mustang with a tr2 diff.

Originally Posted by dogbone

Mixed results? Curious what you mean by that.

I’ve run the OS Giken pretty darn hard since the end of 2015 with no issues. I check in the AIM Solo data to monitor how my wheel speed spins look and they still look good after 6+ years.

As far as what one to get: Do not get Soec-S. Spec-S is simply a generic setup diff that someone came up with so that vendors could have diffs sitting in stock ready to go. You don’t want that. You want the diff setup to your specific car—-your weight, power, aero, driving style, tires, etc. Then the people at OSG take that info and set the diff up based on the thousands of cars they have setup and stored in their database. THAT’S the diff you want. It’s like an extra $150 for the custom setup. An E93 M3 that is not tracked is definitely going to need a setup quite different than a stripped out E92 race car with aero and slicks.

If you haven’t seen it, I did a lonnnnnnnng write up on the OS Giken diff vs the stock M3 diff in my build thread. If you have not seen it, and you really are interested in this topic, I highly recommend you check it out. It’s a 3-part write up that starts on page 8 and continues on page 9: Diff write up

[Redd]

Originally Posted by dogbone

Mixed results? Curious what you mean by that.

I’ve run the OS Giken pretty darn hard since the end of 2015 with no issues. I check in the AIM Solo data to monitor how my wheel speed spins look and they still look good after 6+ years.

As far as what one to get: Do not get Soec-S. Spec-S is simply a generic setup diff that someone came up with so that vendors could have diffs sitting in stock ready to go. You don’t want that. You want the diff setup to your specific car—-your weight, power, aero, driving style, tires, etc. Then the people at OSG take that info and set the diff up based on the thousands of cars they have setup and stored in their database. THAT’S the diff you want. It’s like an extra $150 for the custom setup. An E93 M3 that is not tracked is definitely going to need a setup quite different than a stripped out E92 race car with aero and slicks.

If you haven’t seen it, I did a lonnnnnnnng write up on the OS Giken diff vs the stock M3 diff in my build thread. If you have not seen it, and you really are interested in this topic, I highly recommend you check it out. It’s a 3-part write up that starts on page 8 and continues on page 9: Diff write up

Very happy with my Spec-S for triple duty street, hill, track but I'm not as advanced a driver as you are. Even with Spec-S you will feel a big diff in how the car behaves. Spec-X is even better I'm sure.

[///Mobbin]

dogbone and Redd, appreciate the feedback from you both! I've chatted with a number of folks that have Spec-S units on multiple different platforms and they've all really enjoyed the cars behavior both on/off track (varying skill levels). I also spoke with the seller I purchased from, Jonathan at Shaftworks USA (who also used to work at OS Giken), and his indication was that for a street/track car on mostly 200tw tires and r-comps the Spec-S should work well. What he or Giken would change (and what would make the diff Spec-X) is to make the diff lock up quicker and be optimized for stickier tires like Hoosiers and/or slicks. They can also optimize the diff for increased power levels (such as supercharged cars). FWIW, I realize Giken has multiple behaviors they can revise (see the MotoIQ video in the first post for examples), so this is likely an over simplification. His indication was that if I ran a more aggressive Spec-X set up on the street I may hear some clunking noises and the diff would also be less optimized for that use. All that said, for a pure track car I'd absolutely go Spec-X (and I may still go that route long term) but for me, my car still sees the street for now and I also just wanted to try Spec-S to have that data point. I also may or may not add a supercharger, may or may not add bigger aero, so want to wait for those decisions before I customize. Granted it's a good amount of work to swap the diff so straight to Spec-X may be logical here if you know where your car is headed (I hear you Gabe!), just want to try Spec-S first and also keep changing my mind on where my car is headed so there's that also. Good advice all around and good to think through this at purchase.

Of note, these are the parameters for an e9x m3 Spec-S diff:
Ramps - 25/35
Lock Timing - 336
Total Plates - 20
Preload - 10S

[RickyBobby]

In regards to the impact gun, I found that air tools often outperform the battery powdered counterparts.

Years ago, I tackled a nismo diff and found that an air gun was the only way to remove the ring gear bolts. I also drove the diff down to my local shop to use their heavy duty vice. The spec on my particular bolts were torque xxx plus 90 degrees (with red loctite) so I'm curious to know what the specs are for the M3.

This is a great thread! It's reminding me why I will pay someone to do mine when the time comes 😂

[///Mobbin]

Checkout the bolt ridge impressions on the original diff, telling about how much torque was used! I haven't been able to locate our exact torque specs for the ring bolts but also i don't think I'd be able to implement without a proper vice setup. That said I am going to red loctite as a safety precaution, did some research on the various red loctite options and ended up getting loctite 263. I believe the temp spec on it is ~360F (though the packaging says 300) and my research tells me diff fluid on track maxes out around 260-280. Also though, these bolts are constantly exposed to diff fluid and temp cycling so I do wonder if the loctite can even withstand that, figure why not though. Loctite 263 does also indicate some oil resistant properties. One other note, if you red loctite (and it's actually effective) and you go to swap the ring/pinion later it's likely you'd have to apply some heat to each bolt to get it loose. Maybe I should have done this for the factory bolts as well, easy enough with a butane torch, assuming the leftover oil doesn't ignite*!

[///Mobbin]

Loctite 263 website indicated operating temperature range of -65.0 - 360.0 °F (-55.0 - 180.0 °C ) and "oil tolerant" characteristic - LINK

YouTube video showing a preferred loctite application method for an enclosed bolt - https://youtu.be/TLfNjcijk-k?t=52

[///Mobbin]

De-oiling so I can apply loctite to a clean dry surface, will do the same for the bolts themselves.

[///Mobbin]

Ring gear on. 10 minute set, 24-hour cure, may install in diff housing but then wait to add diff fluid until tomorrow.

[///Mobbin]

About to swap the o-rings and install new flange seals in the side bearing carriers. One thing to note here, the side carrier parts each have oiling ports, from some of the install videos I've watched there is a certain orientation these ports should face when installed to ensure they receive oil, will see if I can point to that in a subsequent post.

[///Mobbin]

This video explains the intended orientation of the oiling ports at around the 1:58 mark. Thanks to Theodore for linking to this video in his DIY thread on how to fix your leaking diff - LINK

[///Mobbin]

Scraping off the old gasket and setting the new diff in place, exciting moment!

[///Mobbin]

Don't forget to match the shims and ideally same cups to the proper sides and hand insert the side carriers, just enough to get a few bolts started. Just going to tighten a few bolts on each side for now to then measure backlash and check the ring/pinion gear pattern. Purple arrows are noting that two side carrier bolts from each side go through into the diff housing, will apply some black sealant to these when I install them, not torquing these to spec either, just good and tight! Note I haven't put in the flange seals yet, actually going to use the flanges to push them in as they seal against the flanges anyway.