Best type of LSD for track use

[Sleepless]

Originally Posted by CSG Mike

You don't have to lift the wheel to turn the Torsen into an open diff, only apply enough torque to lose traction (spin) with one wheel.

I actually teach a variation of a controlled single rear wheel traction loss to induce faster yaw rates under specific circumstances on track.

Agreed, but at corner exit it seems improbable he is unweighting the inside to make it an open diff or even close. or am I missing something?

[Sleepless]

Originally Posted by mhiscott

Bear in mind this was on 215 width RE11a. I will be running 245 width RE71r this summer on a 17x9 tc105n. Last year I was on the stock wheels.

That will make a HUGE difference; even between same sizes!

[CSG Mike]

Originally Posted by Sleepless

Agreed, but at corner exit it seems improbable he is unweighting the inside to make it an open diff or even close. or am I missing something?

It's a lot easier than you would think, even with a stock car, particularly 2nd gear corners.

[CSG Mike]

Originally Posted by mhiscott

The rear was definitely loose. Bear in mind this was on 215 width RE11a. I will be running 245 width RE71r this summer on a 17x9 tc105n. Last year I was on the stock wheels.

Shoot me a PM on the pricing of those units if you don't mind. I'm struggling on the Canadian dollar exchange atm. Still trying to decide whether to commit now and take the 45 percent currency hit, or hope things improve and the price of oil stabilizes and ride it out til the CAD comes out of the toilet lol.

Mike - Can you give any insight into what benefits I would see with the 1.5 way on braking stability vs 1 way? How are the OS Gikens setup from the factory? I know you can custom order them for different configs, as they can't be changed between 1/1.5/2 like the Cusco. Have you tried both diffs back to back?

Zero effect on braking stability in a straight line. Under trail braking, the balance you set on turn-in will be exaggerated. If you like to trail brake for rotation, thatll be promoted. If you're plowing into a corner, then that'll be promoted.

Configuration of the diff will matter more than the brand of diff you get; comparing them "back to back" is essentially meaningless. It's like comparing two different brands of fuel back to back, when the tune to take advantage of the fuel is more important; without the tune, the fuel either "works" or "doesn't work", without optimizing at all.

[mhiscott]

Originally Posted by CSG Mike

It's a lot easier than you would think, even with a stock car, particularly 2nd gear corners.

The one 2nd gear corner on the track is the one causing me the most headache with the lsd acting up.

[mrk1]

Originally Posted by mhiscott

The one 2nd gear corner on the track is the one causing me the most headache with the lsd acting up.

Makes sense, extra power from the turbo doesn't help.

Then again spinning both tires with a nice LSD doesn't help acceleration either but it sure is fun haha.

[mhiscott]

Yea no matter what I'll have to modulate the throttle coming out of that corner. It just felt that every time you feel like it'd be safe to get back on the power, it'd spin up a tire. To get around it you had to almost walk on eggshells in that turn and your exit speed would be terrible.

[simpleisbest]

Hate to see misinformation out run wild on the net.

I would advise to talk to the manufactures and get their take on how their diffs compare when shopping for a part that takes significant labor to install. Tuning diffs is not like swapping suspension for most users, as many will not be able to do it as a DIY and will need the paid labor hours from a shop.

The OS Giken units and Cusco units provide their locking performance in very different ways.

The OS Giken unit is a negative preload biased unit with an internal design that allows for more plates than other brands (30-50% more). The OSG units use preload to handle road surface variants and have a typically lower level of preload to than other brands. The lower the preload the more "open" the diff will feel on "turn-in". OSG units can function at low levels of preload because of the large size and number of disks. If similar preload was to be tried in other brands, the diff may not lock enough to exit the corner without wheelspin. The negative preload is used with the selected cam angle to control the rate of lock. The OSG pressure ring cam lobes (part that pushes the apart the pressure ring to get lock) are precision cut to mate with the cam angle of the pressure ring (different types of angles are offered based on customer needs). This provides the ability to have a very linear locking feel and incremental lock control with the throttle/torque input. OSG always tunes their diffs to lock to 100%, yet with different rates of locking ramp up depending on power and grip level. The LSD cases and internal gears are forged and chemically heat treated. Clutch disks do not require any break-in, as they are precision machined for perpendicularity. The units are not 100% user tune-able, as they do not sell tuning parts to the public. Tuning/inspection is $150 and covers consultation and return freight. You can order a unit in 1way, 1.5, 2way configurations.

The Cusco units have a traditional clutch type internal gear design, thus it would be typically more limited on the number and size of plates than the OSG. The RS design has eliminated the cone spring (the part that sets preload in a clutch type LSD). This elimination has freed up more internal space for clutch disks. To provide preload, Cusco uses internal springs that can be swapped to adjust preload. Their cam lobe is generic, however the pressure ring is machined with different configurations to provide adjust-ability. The LSD case is billet and chemically heat treated, internal gears are forged, plates will need break in.

While the forums can be a good place to start your research, I would suggest calling the manufacturers to get some first hand knowledge. While they all can be bias as to why theirs is the best, you will gain some insight on what makes them different (because they are) and where to invest your hard earned cash to weigh the costs vs performance

[TylerLieberman]

Everybody in this thread is wrong.


Welded diff.


You're welcome.

[mhiscott]

Originally Posted by simpleisbest

Hate to see misinformation out run wild on the net.

I would advise to talk to the manufactures and get their take on how their diffs compare when shopping for a part that takes significant labor to install. Tuning diffs is not like swapping suspension for most users, as many will not be able to do it as a DIY and will need the paid labor hours from a shop.

The OS Giken units and Cusco units provide their locking performance in very different ways.

The OS Giken unit is a negative preload biased unit with an internal design that allows for more plates than other brands (30-50% more). The OSG units use preload to handle road surface variants and have a typically lower level of preload to than other brands. The lower the preload the more "open" the diff will feel on "turn-in". OSG units can function at low levels of preload because of the large size and number of disks. If similar preload was to be tried in other brands, the diff may not lock enough to exit the corner without wheelspin. The negative preload is used with the selected cam angle to control the rate of lock. The OSG pressure ring cam lobes (part that pushes the apart the pressure ring to get lock) are precision cut to mate with the cam angle of the pressure ring (different types of angles are offered based on customer needs). This provides the ability to have a very linear locking feel and incremental lock control with the throttle/torque input. OSG always tunes their diffs to lock to 100%, yet with different rates of locking ramp up depending on power and grip level. The LSD cases and internal gears are forged and chemically heat treated. Clutch disks do not require any break-in, as they are precision machined for perpendicularity. The units are not 100% user tune-able, as they do not sell tuning parts to the public. Tuning/inspection is $150 and covers consultation and return freight. You can order a unit in 1way, 1.5, 2way configurations.

The Cusco units have a traditional clutch type internal gear design, thus it would be typically more limited on the number and size of plates than the OSG. The RS design has eliminated the cone spring (the part that sets preload in a clutch type LSD). This elimination has freed up more internal space for clutch disks. To provide preload, Cusco uses internal springs that can be swapped to adjust preload. Their cam lobe is generic, however the pressure ring is machined with different configurations to provide adjust-ability. The LSD case is billet and chemically heat treated, internal gears are forged, plates will need break in.

While the forums can be a good place to start your research, I would suggest calling the manufacturers to get some first hand knowledge. While they all can be bias as to why theirs is the best, you will gain some insight on what makes them different (because they are) and where to invest your hard earned cash to weigh the costs vs performance

Thanks for the insight. Very detailed reply.

I do my won wrenching and have a spare pumpkin so I can reconfigure with little downtime. The characteristics of the OS giken sound very favorable. What you stated suggests there would be less sudden push on corner entry with this diff due to the lessened preload. Am I right?

[renfield90]

Originally Posted by TylerLieberman

Everybody in this thread is wrong.


Welded diff.


You're welcome.

Better yet, just use a spool.

[CSG Mike]

Originally Posted by simpleisbest

Hate to see misinformation out run wild on the net.

I would advise to talk to the manufactures and get their take on how their diffs compare when shopping for a part that takes significant labor to install. Tuning diffs is not like swapping suspension for most users, as many will not be able to do it as a DIY and will need the paid labor hours from a shop.

The OS Giken units and Cusco units provide their locking performance in very different ways.

The OS Giken unit is a negative preload biased unit with an internal design that allows for more plates than other brands (30-50% more). The OSG units use preload to handle road surface variants and have a typically lower level of preload to than other brands. The lower the preload the more "open" the diff will feel on "turn-in". OSG units can function at low levels of preload because of the large size and number of disks. If similar preload was to be tried in other brands, the diff may not lock enough to exit the corner without wheelspin. The negative preload is used with the selected cam angle to control the rate of lock. The OSG pressure ring cam lobes (part that pushes the apart the pressure ring to get lock) are precision cut to mate with the cam angle of the pressure ring (different types of angles are offered based on customer needs). This provides the ability to have a very linear locking feel and incremental lock control with the throttle/torque input. OSG always tunes their diffs to lock to 100%, yet with different rates of locking ramp up depending on power and grip level. The LSD cases and internal gears are forged and chemically heat treated. Clutch disks do not require any break-in, as they are precision machined for perpendicularity. The units are not 100% user tune-able, as they do not sell tuning parts to the public. Tuning/inspection is $150 and covers consultation and return freight. You can order a unit in 1way, 1.5, 2way configurations.

The Cusco units have a traditional clutch type internal gear design, thus it would be typically more limited on the number and size of plates than the OSG. The RS design has eliminated the cone spring (the part that sets preload in a clutch type LSD). This elimination has freed up more internal space for clutch disks. To provide preload, Cusco uses internal springs that can be swapped to adjust preload. Their cam lobe is generic, however the pressure ring is machined with different configurations to provide adjust-ability. The LSD case is billet and chemically heat treated, internal gears are forged, plates will need break in.

While the forums can be a good place to start your research, I would suggest calling the manufacturers to get some first hand knowledge. While they all can be bias as to why theirs is the best, you will gain some insight on what makes them different (because they are) and where to invest your hard earned cash to weigh the costs vs performance

This almost seems like marketing for the OSG, but if you actually had a OSG and Cusco diff side to side, you'd know the number of friction surfaces on this platform is the same. Understandably, I know you auso AutoX, and OSG has a huge presence there; it helps that they employ nationally competitive drivers, who can also help end users configure their LSDs. The OSG info, is, almost word-for-word, exactly how the OSG guys present their product, and in many cases, quite accurate. The FRS is one of those exceptions, due to having a shared LSD core with so many other cars (thank you Toyota!)

The Cusco Hybrid and the OSG work virtually identically, in terms of function, behavior, and lockup engagement. For all intents and purposes, the Cusco and OSG are functionally identical in terms of configuration and tunability.

Disclaimer: CSG currently has an ATS and OSG LSD in rotation for testing.

[simpleisbest]

It is misinformation to lead people to believe that fiction surface area is totally dependent on the sheer number of disks. You need to look at size and surface type. If you look at the disks face, you will see that the Cusco unit heavy use of oil grooves decrease usable surface area. Similar to tread blocks for tires. Less contact patch.

If you disbelieve, then do the math.

To say they the two are functionally identical is also incorrect. You can tune the two to units to "drive" similar to a point. If your units you are testing are tuned as such, they could be similar for you. The mechanics of how each works and the tuning craft are polar opposites....

It's not marketing speak, it's call an layman explanation of mechanical engineering....

[mrk1]

Originally Posted by simpleisbest

Hate to see misinformation out run wild on the net.

Where is the misinformation? Your simply going to into much farther detail then it seems like the OP is looking for.