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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


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Old Thu, Oct-26-2017, 07:50:20 PM   #1
TrixyBang
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Default OS-Giken Superlock e46 m3 ramp and preload

Bought a used OS-Giken Superlock and slapped it to my e46 m3. It is the standard spec. Was wondering what pre-load and ramp angles are beneficial for track use without compromising daily driving too mutch. As from factory (OS GIKEN standard settings) seems to be good in faster corners, it is progressive. Their is too mutch snap oversteer in rainy situations, but too little lock-up in dry situations at lower speed from what I felt. It doesn't lock, doesn't lock, doesn't lock and then it locks and you are into snap oversteer. I spun in the rain while dailying the car, because of the how unprogressive the diff feels on wet surfaces. Was trying to feel the grip in a drift, but it locked too late, while I was waiting for the lockup the car gathered speed, it locked very fast then and wouldn't let go until I spun. Any help is appreciated.

I would like it to lock up a tad sooner, as I need too mutch speed at medium gass for it to lock. I don't want to bully the car into the corners. I would like to use as many clutches as possible, for less wear and being progressive. Progressiveness on dry roads is solid, wet performance catches me off guard.

Last edited by TrixyBang; Thu, Oct-26-2017 at 09:26:59 PM.
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Old Thu, Oct-26-2017, 09:20:13 PM   #2
Bubblegunz
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Default Re: OS-Giken Superlock e46 m3 ramp and preload

We have the unit on our car. I wouldnt touch the preload and ramp angles. Standard preload and ramp are 35/25 ramps from the 90 degree angle, more lock on acceleration over deceleration. And OS Giken does not give a fixed percentage of lock, as any other manufacturer. I think it equates to arround 71% on accel vs 55% on decel. They state up to 100% lock in both directions, possibly not a fixed threshold. It has extremely low preload, so no understeer at all which is a very good thing.

I had similar experience in the begining as it takes time to get used to. Smashed my car actually. The differential is very smooth in lower lock percentages and gradually bites mutch quicker. Drive the car a little, if it still bothers you, contact Hardemann motorsport in NL. They build these for a living.

Last edited by Bubblegunz; Thu, Oct-26-2017 at 09:27:54 PM.
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Old Thu, Oct-26-2017, 11:04:30 PM   #3
STAATS
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Default Re: OS-Giken Superlock e46 m3 ramp and preload

Don't these units have negative pre-load, like they use springs to pull the two main carriers together so they don't apply any pressure to the clutches normally?

Depending on the level of pre-load they use and hence how much force you need to act against in the diff this could be at the very least contributing to the delayed locking effect...

In my limited research, as I couldn't find many people willing to talk about them, I found stories of delayed lock up with the OS-Giken.

Definitely worth speaking to a shop that specialises in them like Turner Motorsport (who I believe in turn use DiffsOnline) or the like.
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Old Sun, Oct-29-2017, 04:10:13 PM   #4
Bubblegunz
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Default Re: OS-Giken Superlock e46 m3 ramp and preload

Quote:
Originally Posted by STAATS View Post
Don't these units have negative pre-load, like they use springs to pull the two main carriers together so they don't apply any pressure to the clutches normally?

Depending on the level of pre-load they use and hence how much force you need to act against in the diff this could be at the very least contributing to the delayed locking effect...

In my limited research, as I couldn't find many people willing to talk about them, I found stories of delayed lock up with the OS-Giken.

Definitely worth speaking to a shop that specialises in them like Turner Motorsport (who I believe in turn use DiffsOnline) or the like.
Yes, the diff has negative preload ~<15% for comparison purposes.

I read such an article as well on this forum - stating on an e92 it has delayed lock. I am not sure how accurate it is. The diff is smooth compared to Drexler for example and it uses a different locking technique.

Drexler uses 7 lsd clutches with friction material. OS-Giken has a hardened metal surface material and 3 times more clutches for smoother locking capabilities, and it can build up to more lock because of the sheer number of clutches. That is the theory...

In reality, I believe there is a perception of delayed lock, because the motorsport diffs are violent on lock-up, as are most clutch type diffs. The OS giken is a *****-cat compared. The lockup is so smooth under little load, but you expect to "feel" it lock up... it locks up, but you don't necessarily feel it as violently. There is no sound, the car doesnt snap.. it just pulls out of corners. I was able to see this when I raced an e36 with s54 engine and drivetrain swap. It was 200 kg lighter, and came out of the last corner before the streight at a mutch higher speed than me, at less than a meter behind me... He wasn't able to catch me up to the next corner, even though he had an 8.7k redline, but had the E46 M3 diff in.

However in extremely slippery conditions, if you mash it, it snaps, and it is violent. Which is what I believe the OP felt. He probably gave it more gass as he didnt feel it locking up, and then it locked up to 70-80% at which point he spun out.

I believe it is a diff you need to get use to and you need to start trusting. I imagined it to be rougher when I purchased it as well. After 2 years of ownership I am still getting used to it. Some may think this is a bad thing... It could be. I think it makes for an interesting drive. You can always go faster arround the track, if you just start to try different things with the diff - it gives you more options. Like changing the line a little, or being more brutal in corner entry... getting on the gas sooner etc. But if you overdo it, you spin out - especially in slippery conditions. Its a balance.

Best regards,
Antony

Last edited by Bubblegunz; Sun, Oct-29-2017 at 04:32:46 PM.
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Discussing The freaking seats in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)