OS Giken Differential in Viper

[Torquemonster]

I wasn't comparing lap times, as they would be likely close in good hands. I was talking about control and safety with big power on public roads... the ability to steer when traction was gone.

 

[Canyon707]

I know there was a delay but, it's time to put them to the test. I haven't spoke with Devin so I don't know the status of the axle parts that were over heat treated but, I think they should be back on track soon. If anyone is currently running one or knows HOLLAAR UP.......

 

[Cop Magnet]

Any update on you guys who've been waiting for this diff?

 

[Canyon707]

Have yet to ear anything.

 

[Canyon707]

UPDATE 7/16/09
Thank you for the inquiry. Last week, OS Giken, told us that we are still probably 4 weeks out. The stub axles are being manufactured. This has been very frustrating, and we have expressed this to O.S. Giken. On the positive side, the oil issues are now gone, we have U.S. access to the BP 250wt lubricant.

 

[Tom F&L GoR]

Seems unusual to me that this more modern hardware still requires the thickest oil. I don't know anything about these diffs, except they must run really hot to need SAE 250 oil.

 

[Viper X]

The Quaife has been very bullet proof in 3 of my Vipers so far.

It really helps keep my 925 rwhp Paxton car going straight under power.

Sounds like the Giken would be good for the drags or drifting - not so sure how good it would be on a road course or set up aggressively then street driven.

I'll stick with the Quaife for now but would like to hear any road racer's comments on the Giken.

Good luck,

Dan

 

[treesnake]

The Quaife has been very bullet proof in 3 of my Vipers so far.

It really helps keep my 925 rwhp Paxton car going straight under power.

Sounds like the Giken would be good for the drags or drifting - not so sure how good it would be on a road course or set up aggressively then street driven.

I'll stick with the Quaife for now but would like to hear any road racer's comments on the Giken.

Good luck,

Dan

I agree with VIPERX. I love the way my quaiffe diff works.
All these little gliches in the manufacture and release of the OSG diff. Makes me a little nervous. Maybe next year after they have been out for a while....

 

[ILLSMOQ]

ditto on the quaiffe...rock solid

 

[j-rho]

For a car that seems a decent % of street use in addition to performance driving, I'd recommend the Quaife.

For a pure autocross car (in a class where you can change the diff), I would recommend the OS Giken.

For a pure track car, I would recommend the driver test both rear ends to see which one they like better. Keep in mind the clutch-types have some adjustability the Quaife doesn't, allowing you to tweak it for different tracks and situations.

 

[dave6666]

Just talked to Unitrax and the OS Gen 3 unit they are expecting some stock by the end of this week. With all of the delays so far don't shoot me if there turns out to be further delays.

 

[Canyon707]

My diff has been there for a couple months. 2nd in line.

 

[Canyon707]

Parts are in and ready to ship. I am looking forward to this new diff. 3.55 gears

 

[Canyon707]

My OS Giken shipped today. Exciting for me. It's interesting to hear all the comments pros and cons on this diff but, there is a better unit on the market today. After a long discussion with Devin at Unitrax he says there is not a better unit available. He welcomes your inquires. This is not a diff for drifting it is set up for street and racing. its center balanced no carbon fiber parts inside all ssteel. This guy knows all about diffs so I listened to what he had to say.

quote: Hello Chris:


The SuperLock that drift drivers run is set up differently than the unit that you would get. The lockup on the 1.5 Spec-S SuperLock is smooth and gradual. If you were in a a situation under full throttle and the unit ramped up to full lock and you need to gain more control through the wheel, come out of the throttle. There are no more safety concerns with the O.S. Giken SuperLock Spec-S 1.5 way unit than with any other LSD.


The SRT 10 SuperLock is centered weighted and equipped with new stub axles. The unit installs like the stock LSD; no machining, drilling, or shortening of the stub axles.

 

[gb66gth]

In reading the devolpment info, provided earlier in the thread, something was mentioned about how the OS Giken dif. would reduce understeer on entry into slow corners on a road course (not a direct quote). Can someone explain to me how this works, that is the dif having an efffect on the front end of the car? I'm no mechanical engineer so a little help here, please....

 

[j-rho]

In reading the devolpment info, provided earlier in the thread, something was mentioned about how the OS Giken dif. would reduce understeer on entry into slow corners on a road course (not a direct quote). Can someone explain to me how this works, that is the dif having an efffect on the front end of the car? I'm no mechanical engineer so a little help here, please....

Reduced corner entry understeer is not a characteristic of clutch-type limited slip differentials vs. the stock Viper units or a Quaife/torsen. It'll make it worse. A 1.5-way won't be as bad as a 2-way or spool though - the "original torque setting" (quote from below) is still greater than zero.

Here's why- when a car is going straight, all 4 wheels are turning at the same speed. In a corner, the inside wheels are turning slower than the outside wheels. In order to initiate a turn, the outside wheels have to speed up vs. the inside. A mechanical clutch-type LSD resists the creation of this speed delta between inside and outside wheels - EVEN WITH THE THROTTLE CLOSED. An open diff doesn't do this, nor do the stock viscous units or a helical diff like the Quaife. This resistance makes it more work for the front tires to rotate the car, hence more entry understeer.

All this isn't necessarily the end of the world, some people like the extra "stability" while trail-braking into a corner. If I were to buy a diff for my car (which is used primarily for autocross), the OS Giken is what I'd choose.

 

[Canyon707]

It arrived today from Unitrax.

 

[Cop Magnet]

Reduced corner entry understeer is not a characteristic of clutch-type limited slip differentials vs. the stock Viper units or a Quaife/torsen. It'll make it worse. A 1.5-way won't be as bad as a 2-way or spool though - the "original torque setting" (quote from below) is still greater than zero.

Here's why- when a car is going straight, all 4 wheels are turning at the same speed. In a corner, the inside wheels are turning slower than the outside wheels. In order to initiate a turn, the outside wheels have to speed up vs. the inside. A mechanical clutch-type LSD resists the creation of this speed delta between inside and outside wheels - EVEN WITH THE THROTTLE CLOSED. An open diff doesn't do this, nor do the stock viscous units or a helical diff like the Quaife. This resistance makes it more work for the front tires to rotate the car, hence more entry understeer.

All this isn't necessarily the end of the world, some people like the extra "stability" while trail-braking into a corner. If I were to buy a diff for my car (which is used primarily for autocross), the OS Giken is what I'd choose.

Concisely stated. Thank you.

 

[Nader]

Any updates on the Giken? You have it installed?

It arrived today from Unitrax.

 

[Canyon707]

I might be installing it tomorrow or wed. depends on available lift. I had a couple of things to do last week so I didn't get to it but, for sure this week.

 

[gb66gth]

Thanks j-rho!

 

[Nader]

j-rho you obviously know what you are talking about and know a few things about race cars and driving a car on the track.

The one comment i have is regarding this comment, "A mechanical clutch-type LSD resists the creation of this speed delta between inside and outside wheels - EVEN WITH THE THROTTLE CLOSED."

I was told that Giken will only lock under power and it is a gradual lock not immediate. I have also been told when unlocked it reacts similar to an open differential. That came directly from Unitrax.

I do have another question about this comment "If I were to buy a diff for my car (which is used primarily for autocross), the OS Giken is what I'd choose." can you describe why you would prefer the Giken? Your initial points made it seem as if you would prefer and open style diff.

I am trying to educate myself so I am just asking questions...

Thanks.

Reduced corner entry understeer is not a characteristic of clutch-type limited slip differentials vs. the stock Viper units or a Quaife/torsen. It'll make it worse. A 1.5-way won't be as bad as a 2-way or spool though - the "original torque setting" (quote from below) is still greater than zero.

Here's why- when a car is going straight, all 4 wheels are turning at the same speed. In a corner, the inside wheels are turning slower than the outside wheels. In order to initiate a turn, the outside wheels have to speed up vs. the inside. A mechanical clutch-type LSD resists the creation of this speed delta between inside and outside wheels - EVEN WITH THE THROTTLE CLOSED. An open diff doesn't do this, nor do the stock viscous units or a helical diff like the Quaife. This resistance makes it more work for the front tires to rotate the car, hence more entry understeer.

All this isn't necessarily the end of the world, some people like the extra "stability" while trail-braking into a corner. If I were to buy a diff for my car (which is used primarily for autocross), the OS Giken is what I'd choose.

 

[JonB]

Re: OS Giken REPLIES:

OS Giken has sent a reply that I have been asked to post......suffice to say, they do NOT agree with much of what is posted above. Here is their verbatim response:


The OS Super Lock LSD Spec-S settings allow for a smooth and progressive ramp up in lock all the way to 100% lock. The OS Super Lock is unlike other traditional clutch type differentials in that the unique design allows for almost twice the number of clutch plates. More clutch disks provide more surface area to create more friction, necessary to provide the limited slip effect as well as full lock. Having more clutch plates also means that we can achieve up to 100% lock while using minimal preload on the clutch disks. This preload is what provides the “lock” people refer to when one wheel is off the ground. The preload for the OS Spec-S units is set more to supply added stability, rather than full “one-wheel performance”. The preload is mild enough that it will feel very similar to a stock open differential to the daily driver, until the torque is applied. From that point, the unit will provide a smooth and progressive lock up (in direct relation to amount of torque applied, of course) and keep the vehicle moving forward. The Spec-S units utilize a 1.5way cam angle, meaning that the ramp-up to lock will be bias to providing a more positive lock up on acceleration and far less on deceleration, where the ramp to lock-up will serve more to stabilize the vehicle during braking/deceleration. In essence, the Spec-S will feel like an open differential that doesn’t allow for unwanted wheel spin when exiting corners or “tail wagging” during heavy straight line accelerating (as the unit will provide progressive locking at equal rates to both wheels due to the centered design of our unit). For drag users, this will translate to greater straight line acceleration and keep the rear where it is supposed to be. For track/autocross users this translates to faster corner exit speeds (progressive lock allows for earlier application of throttle) and more stability during heavy braking. In addition, due to the minimum amount of preload utilized, corner entry is essentially unaffected. Faster times will be achieved.

 

[mjorgensen Woodhouse]

OK so this differential has no way to torque bias back and forth left to right as the Quaife does then right? I feel the shifting of the Quaife's torque is a huge advantage to keeping the rear end "behind" you, be it straight line or cornering... I will reserve the right to remain un bias for now, but that said my Quaife is staying for now.

 

[j-rho]

j-rho you obviously know what you are talking about and know a few things about race cars and driving a car on the track.

The one comment i have is regarding this comment, "A mechanical clutch-type LSD resists the creation of this speed delta between inside and outside wheels - EVEN WITH THE THROTTLE CLOSED."

I was told that Giken will only lock under power and it is a gradual lock not immediate. I have also been told when unlocked it reacts similar to an open differential. That came directly from Unitrax.

I do have another question about this comment "If I were to buy a diff for my car (which is used primarily for autocross), the OS Giken is what I'd choose." can you describe why you would prefer the Giken? Your initial points made it seem as if you would prefer and open style diff.

I am trying to educate myself so I am just asking questions...

Thanks.

Hello,
This bit describes what I was saying, quoted from above:

The preload for the OS Spec-S units is set more to supply added stability, rather than full “one-wheel performance”. The preload is mild enough that it will feel very similar to a stock open differential to the daily driver, until the torque is applied. From that point, the unit will provide a smooth and progressive lock up (in direct relation to amount of torque applied, of course) and keep the vehicle moving forward. The Spec-S units utilize a 1.5way cam angle, meaning that the ramp-up to lock will be bias to providing a more positive lock up on acceleration and far less on deceleration, where the ramp to lock-up will serve more to stabilize the vehicle during braking/deceleration.

That preload is always there in the clutches, even with the throttle closed. Stabilize = understeer. Again, this isn't necessarily a negative thing so don't take it as such.

More clutches (or specifically, more clutch area) is great, and more progressive engagement is great too (are the clutches carbon? that would be good), but there is nothing magical happening here, it's still a 1.5-way clutch type diff, and as such is subject to all a clutch type's pros and cons. The extent to which cons have been minimized and pros maximized through refinements in technology, I would rather we leave to the end users than the company's marketing department.

Then there's this:

For track/autocross users this translates to faster corner exit speeds (progressive lock allows for earlier application of throttle) and more stability during heavy braking. In addition, due to the minimum amount of preload utilized, corner entry is essentially unaffected. Faster times will be achieved.

I don't know about you, but I usually am braking at corner entry, so I don't see how I can get more stability and have entry not be affected. It's one or the other. The neat thing about clutch-types with adjustable preload is you actually get to tune that parameter yourself, but instead of them touting that virtue, we're instead subjected to some "win-win" marketing-speak.

Nader, the extent to which the diff behaves like an open diff on entry is determined by the preload and the ramp angle on the ".5-way" part of things. In a good diff these are user-adjustable, so you can set it anywhere you want between the extremes of "just like an open diff" and "adding lots of stability".

You have to remember with a diff like this, there's basically a clutch between your two rear wheels, and it works just like the clutch between your engine and trans. With the clutch fully disengaged, it acts just like an open diff; fully engaged, it becomes fully locked.
There's nothing for the clutch(es) to do when the rear wheels are turning the same speed, but as they turn different speeds (like when entering a corner), the preload "grab" of the clutch will resist this. The pressure holding the clutch together is also affected by torque from the engine. When you press the gas pedal, it's like lifting your foot off the clutch pedal - the input torque form the engine works to press the clutch engaged, more tightly maintaining relative rear wheel speeds. The same thing happens (although to a smaller extent on a 1.5-way), when you lift off the throttle - the force of engine braking back through the driveshaft will also push the clutch together, providing "stability" aka an understeer effect if you also happen to be turning the wheel.

The reason I'd prefer the clutch-type Giken to a Quaife for autocross is that in our cone-dodging endeavors, we put the car in some really tortuous stuff - like expecting the car to put power down in first gear on the way out of a really tight corner. The problem is a helical diff like the Quaife depends on there being *some* counter-torque from the inside drive wheel. If the car is leaned over hard enough to sufficiently unload the inside drive wheel, it won't have enough load to counter the torque being sent its way, and it will start to spin, just like an open diff. Once it starts spinning, its counter-torque actually decreases, making the problem worse (more power goes its way) until you either back out of the throttle, or enough load has fallen back on the inside drive tire because you're already coming out of the corner but still aren't accelerating.

I get that people who sell this stuff for a living sometimes get anxious when people like me start posting. I'm not trying to dissuade anybody from buying anything, just suggesting people educate themselves about what they're getting and if/why/how it will benefit them, without having to rely on the pretty words on the side of the box. (Can you tell I don't like marketing and sales people yet?)

If anything, a serious track or performance ****** should probably buy BOTH a Quaife and an OS Giken (from Jon B at Partsrack or Mark J at Woodhouse of course! ) so they can test and compare themselves to find out what works best for them in different situations.

 

[Canyon707]

I just got OS Giken installed today. That took about 5 hours to yank out the old diff and put in the new one. Also spoke with Devin and he sent Joh the post above to put on the board here. Putting a lot of unknowns to rest. After breakin I will get back and let you know my thoughts on driving with it.

 

[Vic]

Great thread! Lots of technical info here.


(gawd, I'm so confused!)




j/k!






.

 

[Nader]

Have one on the way already installed in the case. Should be a simple bolt in swap. Went with 3.33s.

 

[treesnake]

OK so this differential has no way to torque bias back and forth left to right as the Quaife does then right? I feel the shifting of the Quaife's torque is a huge advantage to keeping the rear end "behind" you, be it straight line or cornering... I will reserve the right to remain un bias for now, but that said my Quaife is staying for now.

I'm with Mark. Lot of questions here. No questions with the Quaiffe, works GREAT...

I am anxious to see if/how well it works...

 

[Canyon707]

Mine also came all done in the case. A few things to know on changing out the diff.
Here is how I did it. Start to finish.
Fortunately I had a lift to use. it does make it easier.
Removed pan.
Removed drive shaft. I used new bolts and new straps (Recommended)
Removed driver side tire.
Removed brake caliper. use a bungee cord to hang it off to the side.
Removed E brake cable from both sides
removed E brake assembly from the side worked on. I think this work can be done from either side I did it from the driver side.
Removed rotor
Removed Upper a frame from spindle. This was tough as it's such a tight fit and not to break the rubber grease assembly. A fork may damage it but you may have to use one I hammered on the arm to pop it out. Do not remove the upper arm from the frame as this will throw out the alingment of the rear wheel,
next disconnect the tie rod from the spindle and the spindle will fold out.
Now that the spindle is out you can tap the axle on this side out of the diff spline. You really don't need and axle puller.
once the axle is out of the diff tie it up to the top of the frame.
unbolt the diff, You will need something to hold it up I used a jack to keep it stable slowly lowering down a few inches so I could push the diff to the side to remove the other axle.
Once free I lowered out the dirr which took some finaggling but it was pretty easy.
one thing to remember is to make sure your E brake cables are out from between the diffs frame.
Assembly is reverse.
Need to break it in per instructions.
All in all not that hard to do took about 5 hours the first time. Typical Viper both metric and SAE threads mostly box wrenches 3/4", 18, 17, 13/16", 15/16" and a few other smallar wrenches and a set of metric and SAE allen wrenches for the brake caliper. also loctite.

Have one on the way already installed in the case. Should be a simple bolt in swap. Went with 3.33s.