OS Giken differential
Thread Starter
Joined: Feb 2017
Posts: 123
Likes: 6
OS Giken differential
I have been researching the OS Giken 1.5 differential for quite a while. I've already read the threads here but no one really goes in depth on what it really does. How does it change the feel of the car? I autocross on the semi-competitive level and I think the stock differential might be causing me problems in my current classing (STR). What kind of feedback do you guys have that have used it in this regard?
Thanks in advance!
-Maniac
Thanks in advance!
-Maniac
Joined: Sep 2014
Posts: 470
Likes: 34
From: west michigan
the stock diff is good, the OSG is great. ATS is another really good option, from the research ive done they are both great choices and from what ive seen they say search around for the best deal, you cannot go wrong with either. the major advantage to my understanding from the guys ive talked to is the ability to get on power way sooner without the car wanting to swing out. from the few folks i have talked to i race with they said it was easily worth well over a second maybe 2 seconds on a 1:40-ish track.
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Joined: May 2014
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I have driven my AP1 with stock diff on a practice Autox course back to back with a friends AP1 with a nearly identical suspension setup with an OSG diff. I felt there was more you could do under decell into corners as well as power delivery coming out (was able to let the car rotate a bit more and then make it stick with power delivery more reliably with the OSG). The OSG I believe is going to manage power delivery better as you start unloading the inside wheel more as well.
Joined: Mar 2016
Posts: 315
Likes: 56
its magic 
would recommend Lugod at OSG did a great job on the str tune.
i found it made the car way more stable in part lift / full lift /brake situations due to the decel lock.
If you're at all sideways in an offset or slalom or brake zone it just helps the car hang on, sorta almost feels like its dragging the inside rear around and keeping it planted.
Of course it also delivers power better as expected as well, just makes the car overall easier to push and drive hard.
Also found it free'd up car setup a bit alllowing more freedom to dial in rear bar and give the car more front end while still having that really forgiving rear.
locally of the 5 str s2000's there's 3 of us that have the osg.
would recommend Lugod at OSG did a great job on the str tune. i found it made the car way more stable in part lift / full lift /brake situations due to the decel lock.
If you're at all sideways in an offset or slalom or brake zone it just helps the car hang on, sorta almost feels like its dragging the inside rear around and keeping it planted.
Of course it also delivers power better as expected as well, just makes the car overall easier to push and drive hard.
Also found it free'd up car setup a bit alllowing more freedom to dial in rear bar and give the car more front end while still having that really forgiving rear.
locally of the 5 str s2000's there's 3 of us that have the osg.
Thread Starter
Joined: Feb 2017
Posts: 123
Likes: 6
I have driven my AP1 with stock diff on a practice Autox course back to back with a friends AP1 with a nearly identical suspension setup with an OSG diff. I felt there was more you could do under decell into corners as well as power delivery coming out (was able to let the car rotate a bit more and then make it stick with power delivery more reliably with the OSG). The OSG I believe is going to manage power delivery better as you start unloading the inside wheel more as well.
its magic would recommend Lugod at OSG did a great job on the str tune.
i found it made the car way more stable in part lift / full lift /brake situations due to the decel lock.
If you're at all sideways in an offset or slalom or brake zone it just helps the car hang on, sorta almost feels like its dragging the inside rear around and keeping it planted.
Of course it also delivers power better as expected as well, just makes the car overall easier to push and drive hard.
Also found it free'd up car setup a bit alllowing more freedom to dial in rear bar and give the car more front end while still having that really forgiving rear.
locally of the 5 str s2000's there's 3 of us that have the osg.
would recommend Lugod at OSG did a great job on the str tune.i found it made the car way more stable in part lift / full lift /brake situations due to the decel lock.
If you're at all sideways in an offset or slalom or brake zone it just helps the car hang on, sorta almost feels like its dragging the inside rear around and keeping it planted.
Of course it also delivers power better as expected as well, just makes the car overall easier to push and drive hard.
Also found it free'd up car setup a bit alllowing more freedom to dial in rear bar and give the car more front end while still having that really forgiving rear.
locally of the 5 str s2000's there's 3 of us that have the osg.
Thanks all that have replied so far!
Joined: Apr 2005
Posts: 1,318
Likes: 125
From: Scottsdale, Az
I bought a used Blackwatch Racing tuned OS Giken (1.1 way 3/38 ramps) but haven't had the time to put it in yet, I am hoping it makes a large difference coming out of corners since my car spins the inside pretty heavily at this point.
I can maybe believe a second or two per two minute track if it is one where you're killing the drive out of corners early with inner rear spin, but it still sounds a bit high. We will see next month as I am going back to a ~1m track that has three corners that I had consistent wheel spin at this past weekend.
I can maybe believe a second or two per two minute track if it is one where you're killing the drive out of corners early with inner rear spin, but it still sounds a bit high. We will see next month as I am going back to a ~1m track that has three corners that I had consistent wheel spin at this past weekend.
Thread Starter
Joined: Feb 2017
Posts: 123
Likes: 6
I bought a used Blackwatch Racing tuned OS Giken (1.1 way 3/38 ramps) but haven't had the time to put it in yet, I am hoping it makes a large difference coming out of corners since my car spins the inside pretty heavily at this point.
I can maybe believe a second or two per two minute track if it is one where you're killing the drive out of corners early with inner rear spin, but it still sounds a bit high. We will see next month as I am going back to a ~1m track that has three corners that I had consistent wheel spin at this past weekend.
I can maybe believe a second or two per two minute track if it is one where you're killing the drive out of corners early with inner rear spin, but it still sounds a bit high. We will see next month as I am going back to a ~1m track that has three corners that I had consistent wheel spin at this past weekend.
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Joined: Sep 2004
Posts: 111
Likes: 10
From: SoCal
what kind of tuning are you guys doing to the OSG diff to optimize it more?
is there anyone in OSGiken USA that's very familiar with setting up this diff for S2000?
wondering how much difference it would make a tuned OSG vs off the shelf OSG
is there anyone in OSGiken USA that's very familiar with setting up this diff for S2000?
wondering how much difference it would make a tuned OSG vs off the shelf OSG
Joined: Apr 2005
Posts: 1,318
Likes: 125
From: Scottsdale, Az
Breakdown of specs:
-first pair of numbers (i.e. 25/38), refers to the cam angle, 25 degrees decel, 38 degrees accel. The higher the number the more aggressive (reaches full lock earlier with less torque)
-second number (i.e. 224), refers to total amount of spring tension on LSD internal pressure ring â 224kg. A high number means slower lock timing, and a low number means quicker lock timing. For comparison most of our LSDâs come standard with 336kg.
-third number (i.e. 12)), refers to number of clutch plate PAIRS, so for the S2000 LSD, there is actually 24 clutch disks. The most plates that we have ever fitted to any LSD is 14 pairs, which is normally found on bigger vehicles like Nissan 350Z or BMW M3âs.
-last number, (i.e. 10s), refers to initial preload. This number is an arbitrary number that is assigned by the engineers, and its hard to pinpoint what the actual preload would be since it is also dependent on the number and size of the clutch disk.
The HPD S2000 LSD settings are actually more conservative than our normal setting (I presume that quote from the website is actually referring to the K-series LSD which has a rather aggressive setting). In actuality, the HPD LSD was originally set for road-racing, so it has a lock timing more suited to long sweepers and high speed chicanes. For autocross, we generally recommend a quick locking LSD, so our normal settings should be suitable for what you are doing.
-first pair of numbers (i.e. 25/38), refers to the cam angle, 25 degrees decel, 38 degrees accel. The higher the number the more aggressive (reaches full lock earlier with less torque)
-second number (i.e. 224), refers to total amount of spring tension on LSD internal pressure ring â 224kg. A high number means slower lock timing, and a low number means quicker lock timing. For comparison most of our LSDâs come standard with 336kg.
-third number (i.e. 12)), refers to number of clutch plate PAIRS, so for the S2000 LSD, there is actually 24 clutch disks. The most plates that we have ever fitted to any LSD is 14 pairs, which is normally found on bigger vehicles like Nissan 350Z or BMW M3âs.
-last number, (i.e. 10s), refers to initial preload. This number is an arbitrary number that is assigned by the engineers, and its hard to pinpoint what the actual preload would be since it is also dependent on the number and size of the clutch disk.
The HPD S2000 LSD settings are actually more conservative than our normal setting (I presume that quote from the website is actually referring to the K-series LSD which has a rather aggressive setting). In actuality, the HPD LSD was originally set for road-racing, so it has a lock timing more suited to long sweepers and high speed chicanes. For autocross, we generally recommend a quick locking LSD, so our normal settings should be suitable for what you are doing.
OSGiken 25/38-336-12-12S
PuddyMod 25/38-376-12-12S
Honda Performance Development 25/38-224-12-10S
I also have the numbers that were etched into the casing on my BWR one, but I won't be sharing them for the obvious reason.
Joined: Nov 2010
Posts: 420
Likes: 50
From: 'burbs of Chicago
Talk with Jon Lugod from OSG, he's had(has?) an S2000 and has setup/won many scca solo national championships. He can make it more gooder.