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      08-20-2013, 10:37 PM   #45
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I'm not familiar with the Spec-S OSG but the OSG units i've run in 700whp+ Turbo NSX's and Nissan 350Zs (amongst others in stock powered NSXs, S2000, 350Zs, E46 M3s) were phenomenal.

I actually felt the there was too much preload in the off-the-shelf units (non-S) and deactivated plates and increased the spring rates of the negative internal springs and softened the preload washers, even in a 700whp Turbo NSX application. Here's the article on the OSG and how I tuned it:

http://www.motoiq.com/MagazineArticl...ferential.aspx


Sorry to hear you're having so much difficulties with them.
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      08-21-2013, 02:45 AM   #46
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hey billy,

thanks for your input.
i already knew the nsx osg article, great writeup!

spec-s setup means standard setup in osg terms! if you want anything else, they call it spec-x.

obviously the spec-s standard osg units vary from application to application concerning their capability and performance.
my standard setup had too much neg. preload and too much clutchpacks deactivated. in yours it seems to be the other way around.

in my opinion it seems they dont test each application in the certain car it is meant for?! so the customer has to do the work :-(
soon, i will install the third setup of the osg and i hope this one will finally work like i want and expect it to. if not, i wont try any longer as i already have some proper working units from zf and drexler. maybe my expectation on the osg is too high as zf and drexler are known to be high performing, very competitive units.
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      08-21-2013, 10:23 AM   #47
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Thank you.

I take it yours was an off the shelf e92 application? Fwiw, I've never personally seen an osg lsd that didn't come off the shelf with all the plates active, and I disliked that I had to deactivate plates myself and take further measures to free it up (especially to prevent low speed chattering). For the power and grip (330 slicks) in my use, the clutch still locked even with some plates deactivated.

I hope you figure out how to make it work for you, I've been nothing but happy with them. So what is the diff doing that you don't like?
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      08-21-2013, 02:01 PM   #48
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the off the shelf one had only 5 out of 7 clutchpacks activated on each side:
furthermore it had 336kg neg. preload.


it didnt lock at all... no noise, no problems in normal driving... but massive single wheelspin when driven hard.

then i changed pressure plates to more shallow ramps, reduced neg. preload to 224kg and activated all clutchpacks what lead to an massive lockup even in normal driving.


next up i'll change the pressure plates back to the spec-s version and leave all clutchpacks engaged and the neg. preload at 224kg.
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      08-21-2013, 07:56 PM   #49
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Sounds like a good plan. Surprised you got a ton of inside wheelspin. I forget the neg preload of my setup, but I deactivated the same amount on the turbo NSX with no inside wheel spin.

How much power are you making and what tires? What are the ramp angles of both center sections on accel/decel?
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      09-05-2013, 02:13 PM   #50
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engine is stock, tires were michelin ps2 and ps cup.
the steeper ones are 55 degrees on power and 65 on coast (or 35/25 depending on which way you measure it). the shallow ones are 35/35 (or 55/55).
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      11-03-2013, 11:11 AM   #51
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a little update here:
currently i am driving the titan traction master with sintered clutches and 30/30 ramps.



drives and feels like the modified zf one. only relevant difference is the huge assembly clearance compared to drexler/zf units. you can feel that sometimes when lifting/hitting the gas (you feel the moment when the spring is totally compressed)... clearance and feel is just like in the gkn multiplate units of the gt2/3 porsches in stock oe setup.
i personally prefer smaller clearance for a more direct reaction.

so far i did not abuse the car since i installed the titan. only street driving. so track & drift testing will follow asap.
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      04-28-2014, 01:13 PM   #52
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Quote:
Originally Posted by driftflo View Post




and last but not least i have an old friend of mine here as well. an "old" zf lsd unit from a M5 E39 which also fits into the E92 rear axle. but as this unit locks quite weak in stock configuration, i am massively modifying this unit to fit more clutchpacks and/or use different ramp angles. this unit is performing well if modified correctly (i did this kind of mods in other m-cars quite often yet) and is still a lot cheaper than all other mentioned units.



...
Hello my friend .
I have send you also mail .

I have an M5 e39.
1) is it a direct bolt on swap the M3 OEM LSD to e39 M5 ;
2) how easy is to change the OEM 25% LSD to more lockup percentage as you mention you will do ?

Thank you
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      04-29-2014, 06:48 AM   #53
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got your email but i am pretty busy at the moment. i will reply to you asap!
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      06-26-2014, 05:31 PM   #54
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Hi, I've read all of your posts and it seems your the authority on the e92 M3 lsd. I'm told mine is toast now and has been dying for some time. The car is at the shop now and am contemplating options of new replacement unit (factory) or going to an OS Giken as it seems the most loved. Thoughts? The car has 50k miles on it and the lsd is toast, if that gives you an idea of how hard I drive it. I grew up racing cars so I drive it hard for about 2h pretty flat out in the canyons around here every weekend. I absolutely hate how the diff is currently being all wasted it is so bad I thought the right rear suspension was broken!

Any input is appreciated. Thanks!

Quote:
Originally Posted by driftflo View Post
the stock diff is a speed-sensing unit. it has no accel/decel values as it has no ramps where the diffaxles run up and down generating pressure depending on the torque applied, as in a torque-sensing clutch-type lsd design.
with the stock unit you necesserily need different wheel speeds over a certain amount of time (meaning: one spinning wheel) to activate the sheerpump which generates the pressure on the clutches. the engagement is smooth... as is the disengagement.
so one wheel spins for a short while, diff starts locking smoothly (and can lock up to 100% which means no matter how big the torque difference left/right will get, it remains locked), then after locking a while there is of course no more difference in wheel speeds and the sheer pump will disengage and releasing the pressure on the piston. so the diff opens up smoothly. if there is still a huge difference in traction l/r it will again start from the beginning... on and on...

so with this unit you will have no corner entry and mid understeer at all (except the amount of preload it is set to.... this is what you feel when turning in low speeds and a lot of customers are complaining about... also here in this forum).
but on corner exit, when hitting the gas quite hard, this unit will not lock immediately but let the inner wheel spin for a while. this is when your opponent with a clutch-type lsd will gain several feet... and you have no "direct connection" (via the gas pedal and the currently applied torque) to your lsd as everything happens timeshifted in a speedsensing unit.


shimming the preload spring is pretty silly in my opinion. i know this is done often but for street and track driving it definitely is the wrong direction of modification. for a drifting only car you can drive high preloads.
and keep in mind that this will always lead to higher wear.

concerning nitriding i am no expert. but for the clutches i would not change them out of manufacturer hardness spec. as the inner clutches are molybdenum sprayed i am not sure if you can simply nitride them?! some guys apply some surface finishing (rem polishing) on it. this has no disadvantage and i could imagine it will extend life and reduce oil pollution (a very important point if you drive a porsche with a gearbox-integrated diff).
i only nitride diff-items that were machined and then have no sufficient surface hardness any more.

anyway, i wouldnt waste time and money in optimising a non-optimum stock lsd-unit. if you have no complains about the stock unit leave it like it is. if you want a higher performing, quicker reacting unit, change to one of the above mentioned.


the drexler gt4 has two rampsets on the pressure plates: 40/50 and 50/65 degree ramps (dont mix this with locking rates given in %!!!)
drexler calculates the angles like zf did (based on the vertical zeroline) and this is the opposite way as os giken does (they take the horizontal line... so you need to subtract from 90 to get the "other" values). so in osg language this would be 50/40 and 40/25.

drexler doesnt give lockup rates (as any other aftermarket lsd manufacturer does not either). i calculated the following:
40/50 degree ramps: ~85/70%
50/65 degree ramps: ~70/40%

in standard it is setup for more decel lockup and i think the lower, higher locking values.

i am currently driving 40% accel, 70% decel. this provides to few lockup on accel for me. so i am thinking whether to rotate the pressure rings so i will have 70 an accel and 40 on decel or go with the 70/85 that the other rampset would provide?!
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      06-28-2014, 05:19 PM   #55
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Quote:
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Hi, I've read all of your posts and it seems your the authority on the e92 M3 lsd. I'm told mine is toast now and has been dying for some time. The car is at the shop now and am contemplating options of new replacement unit (factory) or going to an OS Giken as it seems the most loved. Thoughts? The car has 50k miles on it and the lsd is toast, if that gives you an idea of how hard I drive it. I grew up racing cars so I drive it hard for about 2h pretty flat out in the canyons around here every weekend. I absolutely hate how the diff is currently being all wasted it is so bad I thought the right rear suspension was broken!

Any input is appreciated. Thanks!
I have run DiffsOnline diffs in the past and they have a mountain of experience with Race / Street diffs for e92 M3.

Might want to give them a holler than trying to figure it out on your own.

http://diffsonline.com/
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      06-29-2014, 01:45 PM   #56
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Quote:
Originally Posted by spr View Post
Hi, I've read all of your posts and it seems your the authority on the e92 M3 lsd. I'm told mine is toast now and has been dying for some time. The car is at the shop now and am contemplating options of new replacement unit (factory) or going to an OS Giken as it seems the most loved. Thoughts? The car has 50k miles on it and the lsd is toast, if that gives you an idea of how hard I drive it. I grew up racing cars so I drive it hard for about 2h pretty flat out in the canyons around here every weekend. I absolutely hate how the diff is currently being all wasted it is so bad I thought the right rear suspension was broken!

Any input is appreciated. Thanks!
dear spr,

the stock unit is not intended for hard driving. so a worn out unit after 50k miles of hard driving is quite normal.

i would not buy a os giken unit anymore. at least the standard setup for the M3 is senseless. if you want to do a lot of research and development it possibly makes sense. if i have some leisure time i will try a 3rd setup and will post my findings here.

i drove a different/custom osg setup that i suggested to the owner in a M3 E46. it worked quite ok on a drift event but i did not have the chance to check all things and driving situations to really judge about it.

if anybody suggests a osg to you ask him if he can exactly tell you what setup (clutchpacks, ramps, preload springs) he is driving. and check if he is really into performance driving or just cruising around on the racetrack.

i tried to get infos on the unit and the certain setups of other guys and shops/sellers here in the forums. so far i got nothing useful at all... so i have my doubts if anybody really did any real testing with this unit.


the titan traction master out of the box setup is useless too. but you can fix it easily. so this unit would be more interesting in my opinion.

the best out of the box unit is the drexler gt4 unit. but massively expensive and it need to be rebuilt regularly!

the "normal" drexler (non-gt4) is also quite good, although you can optimise it depending on your preferences as well.


currently i am building some own lsd units based on the zf/drexler design. but with own clutches (thicker molybdenum surface, harder steel, more durable...), optimized oil flow, reduced weight, various custom preload springs, quick and smooth reaction... in short, i tried to sort out all things that i didn't like on the units i tested so far.

i will build each unit to the specific customer needs. so i need to know what someone wants to do with his car, how the setup of the car is and then i will suggest and build the unit with the according setup.

these units and custom setups are already installed in some E92 and E46 street, track and driftcars and feedback is great so far.

i will post some pictures and further details asap.
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      06-29-2014, 01:57 PM   #57
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Quote:
Originally Posted by Wizegi///M3 View Post
I have run DiffsOnline diffs in the past and they have a mountain of experience with Race / Street diffs for e92 M3.

Might want to give them a holler than trying to figure it out on your own.

http://diffsonline.com/
i just checked their website...

these guys offer a kaaz unit for the E92 M3?!
well... kaaz doesn't ;-)

furthermore they write about their "2 clutch option" in the technical information: "This unit is set to 40% static lock".
but a static lock cannot be defined by a percentage value as it would be depending on the current input torque and thus be dynamic... and not static. the static lock (or "preload") is a certain torque value that has nothing to do with the input torque.
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      06-29-2014, 03:11 PM   #58
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I dont think Kaaz for E9x is not out in the market yet right?
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      06-29-2014, 03:29 PM   #59
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right, unfortunately there is no kaaz for e92 m3 out there.
i would love to try a kaaz in my m3. i installed and drove a lot of kaaz units in other cars and really like them. rough but great performance.
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      07-14-2014, 03:26 PM   #60
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today i built a new prototype lsd for my E46 M3 racer:
http://www.m3racing.de/e46umbau.html#20

nearly all parts are custom made or modified to my specs.

would also fit in a E92 of course... and i possibly will build another one for it, if it will handle like i expect it to! ;-)







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      07-14-2014, 03:33 PM   #61
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very nice! let us know how it performs
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      07-14-2014, 04:03 PM   #62
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I just got the OS Gikken fitted to my e92. They also installed the turner solid subframe bushes and derlin diff bushes. However, there is CONSIDERABLE whine from 40mph up with the windows up. It is unreasonable at 80mph freeway driving. I dropped the car back to them to diagnose/fix it. Also they used just regular diff oil where Gikken stuff is 80w-250. Would this make a difference?

Is the diff not setup right or is it the derlin diff bushes or both? Do you have the spec for the differential backlash et al? Any help is appreciated. The sounds sounds like a poorly setup diff from my friends old mustang. Thoughts? Thanks!

Here is what I found for the specs. Can you confirm this is right so they can confirm setup? Also, they setup the backlash by feel, e.g. rotating the input shaft and flanges to feel the play. Sound screwy?

http://www.m3forum.net/m3forum/showthread.php?t=340871
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      07-14-2014, 04:41 PM   #63
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Thanks for the info. I had the warranty replace the diff so ended up doing the OS. I didn't see your thread until now. Please let me know re issues I'm having. Thanks.

Quote:
Originally Posted by driftflo View Post
dear spr,

the stock unit is not intended for hard driving. so a worn out unit after 50k miles of hard driving is quite normal.

i would not buy a os giken unit anymore. at least the standard setup for the M3 is senseless. if you want to do a lot of research and development it possibly makes sense. if i have some leisure time i will try a 3rd setup and will post my findings here.

i drove a different/custom osg setup that i suggested to the owner in a M3 E46. it worked quite ok on a drift event but i did not have the chance to check all things and driving situations to really judge about it.

if anybody suggests a osg to you ask him if he can exactly tell you what setup (clutchpacks, ramps, preload springs) he is driving. and check if he is really into performance driving or just cruising around on the racetrack.

i tried to get infos on the unit and the certain setups of other guys and shops/sellers here in the forums. so far i got nothing useful at all... so i have my doubts if anybody really did any real testing with this unit.


the titan traction master out of the box setup is useless too. but you can fix it easily. so this unit would be more interesting in my opinion.

the best out of the box unit is the drexler gt4 unit. but massively expensive and it need to be rebuilt regularly!

the "normal" drexler (non-gt4) is also quite good, although you can optimise it depending on your preferences as well.


currently i am building some own lsd units based on the zf/drexler design. but with own clutches (thicker molybdenum surface, harder steel, more durable...), optimized oil flow, reduced weight, various custom preload springs, quick and smooth reaction... in short, i tried to sort out all things that i didn't like on the units i tested so far.

i will build each unit to the specific customer needs. so i need to know what someone wants to do with his car, how the setup of the car is and then i will suggest and build the unit with the according setup.

these units and custom setups are already installed in some E92 and E46 street, track and driftcars and feedback is great so far.

i will post some pictures and further details asap.
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      07-14-2014, 05:18 PM   #64
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Quote:
Originally Posted by spr View Post
I just got the OS Gikken fitted to my e92. They also installed the turner solid subframe bushes and derlin diff bushes. However, there is CONSIDERABLE whine from 40mph up with the windows up. It is unreasonable at 80mph freeway driving. I dropped the car back to them to diagnose/fix it. Also they used just regular diff oil where Gikken stuff is 80w-250. Would this make a difference?

Is the diff not setup right or is it the derlin diff bushes or both? Do you have the spec for the differential backlash et al? Any help is appreciated. The sounds sounds like a poorly setup diff from my friends old mustang. Thoughts? Thanks!

Here is what I found for the specs. Can you confirm this is right so they can confirm setup? Also, they setup the backlash by feel, e.g. rotating the input shaft and flanges to feel the play. Sound screwy?

http://www.m3forum.net/m3forum/showthread.php?t=340871


In theory, yes, a thinner fluid might be noisier. If OS Gikken recommends 85w250, that's what I would run. I wasn't even aware something that thick was sold. You may also need even more friction modifier to quiet it down, but I would start with the proper gear lube first.
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      07-14-2014, 11:25 PM   #65
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spr, the values in the link seem not wrong, but the "right" values depend on your driving style. racecar, streetcar, drag... not a diy job... you should have the job done by a specialised shop.
more on that in your other thread.
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      07-14-2014, 11:42 PM   #66
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It was done by a high end shop.
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