stock LSD vs aftermarket LSD (on logger)

[maicol76]

I installed aftermarket LSD (OS giken) and tested it on the track.

After test driving, I checked the logger data about rear (RL & RR) wheel speed difference. (red line is accel)

I'm going to show you just objective data, not subjective.

less understeer, much predictable oversteer, much consistent handling and much stable car movement => these are my first feeling

But, my feeling may not be correct yet. I also changed stock front control arm to pillow ball control arm, and tested new LSD & control arm during only 1day trackday.

So, Please refer to the objective data only.

[ThunderMoose]

Thanks for sharing

[dogbone]

It’s clear from the charts that the OS Giken is locking quickly on acceleration—much quicker than the stock diff. Once it’s locked, it stays locked more consistently than the stock diff. It’s also clear that the OSG diff is open on the entry into the corner, which is good.

With the characteristics shown in these charts, you should find the car more predictable on acceleration.

You don’t show much braking activity. The last chart is perhaps the only chart where braking is going on. It’s not clear from that chart if you’re getting any locking on braking. Is this a 1-way diff? Or did you go 1.5-way (to get some locking on braking)?

Did you have the diff custom setup for your specific car? (Spec-X setup)

I have an OS Giken diff as well. I did a long 3-part write up on it that you might find interesting. It starts at post #173, then continues with charts at post #176 and concludes on #177: http://www.m3post.com/forums/showthr...1158445&page=8

[///M Power-Belgium]

Thought it was about dope .

[maicol76]

Originally Posted by dogbone

It’s clear from the charts that the OS Giken is locking quickly on acceleration—much quicker than the stock diff. Once it’s locked, it stays locked more consistently than the stock diff. It’s also clear that the OSG diff is open on the entry into the corner, which is good.

With the characteristics shown in these charts, you should find the car more predictable on acceleration.

You don’t show much braking activity. The last chart is perhaps the only chart where braking is going on. It’s not clear from that chart if you’re getting any locking on braking. Is this a 1-way diff? Or did you go 1.5-way (to get some locking on braking)?

Did you have the diff custom setup for your specific car? (Spec-X setup)

I have an OS Giken diff as well. I did a long 3-part write up on it that you might find interesting. It starts at post #173, then continues with charts at post #176 and concludes on #177: http://www.m3post.com/forums/showthr...1158445&page=8

My diif is 1.5way OS giken TCD, not Superlock (original OS giken factory made TCD, not upgraded from Superlock. initial torque setting is also original, not changed). Because my first installing aftermarket LSD on E92 M3, all settings are original.

The data is from the test and break-in track driving. I had to do soft driving because I changed final drive, too. haha

Thanks for the information and I'll read your thread asap.^^b

[Mvez]

The Giken (1.5 way) in it's stock setting transformed both my Cayman and Miata on track. I fully expect it does the same for the M3.

It's a shame it's such an expensive and PITA modification, or I suspect more people would do it. I've been dragging my feet on it....but thanks for reminding me.

[bigjae1976]

A clutch type diff is a potentially significant upgrade if you commit to throttle. A quicker locking diff will punish you for lifting. Also won't really help those who late apex every turn.

This is the first session with a 3 clutch diff in my E46 330...I think this was my 4th turn under a green flag? I lifted and it was all over from there...

[buddalun]

Originally Posted by maicol76

My diif is 1.5way OS giken TCD, not Superlock (original OS giken factory made TCD, not upgraded from Superlock. initial torque setting is also original, not changed). Because my first installing aftermarket LSD on E92 M3, all settings are original.

The data is from the test and break-in track driving. I had to do soft driving because I changed final drive, too. haha

Thanks for the information and I'll read your thread asap.^^b

You mention changing the final drive. Was this difficult to do with the DCT? Did the require any programming/tuning? What did you change it to? TIA.

[maicol76]

Originally Posted by bigjae1976

A clutch type diff is a potentially significant upgrade if you commit to throttle. A quicker locking diff will punish you for lifting. Also won't really help those who late apex every turn.

This is the first session with a 3 clutch diff in my E46 330...I think this was my 4th turn under a green flag? I lifted and it was all over from there...

Thanks for your advice. I thought I need a change in the way exiting corner.

[maicol76]

Originally Posted by buddalun

You mention changing the final drive. Was this difficult to do with the DCT? Did the require any programming/tuning? What did you change it to? TIA.

Yes, w/ DCT. After upgrading to shorter ratio, shifting shock was much~ greater than stock on the track, Especially, 2nd->3rd gear. So I put the shifting speed level down from 6th to 5th, then shifting shock was decreased slightly.

I think it is necessary to modify the program concerned with shifting (like accurate matching between rpm and speed, or rpm and gear level). If not, shock is about to make a mess, IMO.

[bigjae1976]

Originally Posted by maicol76

Yes, w/ DCT. After upgrading to shorter ratio, shifting shock was much~ greater than stock on the track, Especially, 2nd->3rd gear. So I put the shifting speed level down from 6th to 5th, then shifting shock was decreased slightly.

I think it is necessary to modify the program concerned with shifting (like accurate matching between rpm and speed, or rpm and gear level). If not, shock is about to make a mess, IMO.

What ratio did you go with?

[warp10]

So where you able to change ratio in the computer for DCT?

I am switching to a new diff this season and should like to get a better final drive ratio but am hesitant since if you can't change the computer you risk a mechanics over rev.

[maicol76]

Originally Posted by bigjae1976

What ratio did you go with?

mine is 3.45, not 3.62.

[maicol76]

Originally Posted by warp10

So where you able to change ratio in the computer for DCT?

I am switching to a new diff this season and should like to get a better final drive ratio but am hesitant since if you can't change the computer you risk a mechanics over rev.

I bought F/D from Florian, German guy in this forum. He introduced someone who can modify the program. But all he has done is to say that he was busy, and now he doesn't even answer.

So, my friend contacted his friend, a professional and famous ecu tuner to find the answer, and I was informed by him that it is possible. Now I'm just waiting for him, because he is on vacation until mid-January.

If modifying the program is success, I'll let you know the detail.

[warp10]

Originally Posted by maicol76

I bought F/D from Florian, German guy in this forum. He introduced someone who can modify the program. But all he has done is to say that he was busy, and now he doesn't even answer.

So, my friend contacted his friend, a professional and famous ecu tuner to find the answer, and I was informed by him that it is possible. Now I'm just waiting for him, because he is on vacation until mid-January.

If modifying the program is success, I'll let you know the detail.

Please do

[///Mobbin]

I have the 3.45 diff and the full GTS DCT Tune, no issues at all. The oem DCT tune was fine as well. With the Alpine GTS DCT tune the rev-matching sounded a bit off, no functional issues though. I'm happy with the full oem GTS DCT tune now though so sticking with that, no need for special programming, IMO YMMV.

And thanks to OP for sharing, I am planning to get a new diff this summer and may try to install it myself, good info here.

[Redd]

Where did you get the Full GTS tune? I also have the Alpine GTS tune.

[///Mobbin]

Originally Posted by Redd

Where did you get the Full GTS tune? I also have the Alpine GTS tune.

I just followed these instructions:
LINK

The rev-matching issue could have had something to do with my engine tune as well, I run Dinan Stage II and have the latest version of that tune now, when I had the Alpine DCT Tune I had an older version of the Dinan engine tune.

[///Mobbin]

As another data point I just looked over several rpm graphs and peak engine speed examples from my fastest laps at COTA and found 8300-8391 rpm or so to be the max recorded. The Dinan tune should set an 8600rpm redline (which I may have hit a few times, need to find those examples). I guess the fear is a downshift overrev though, I don't believe I've encountered any of those either.

From my fastest COTA lap, peak rpm on the front straight, S65 bouncing glorious noise off the grand stands:

[bigjae1976]

Anyone run a 3.62 without issues?

[kyrix1st]

I have Superlock on my E36. Rides like a train.