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Anyone fitted a clutch type diff OS Giken etc?

spiller

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Looking into a diff upgrade and possible change of gearing at the same time. The factory torsen is compromised ina number of areas especially in a road course environment. Wavetrac seems to have the helical issue of unloaded wheel causing open diff characteristics sorted out. However I still prefer a traditional clutch type differential for outright performance. Yes, they can be noisy and difficult to live with but the tech these days with “progesssive loading” makes them very usable on the road (plus who doesn’t mind a bit of chatter!).

So has anyone upgraded their diff with a clutch type such as OS Giken?
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JohnD

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If one wheel gets airborne it acts like an open diff, the unloaded wheel will just spin freely. So I am told, I have never experienced that but I try to not jump curbs so that could be why. However, changing clutch packs gets old quickly and I don't miss that.
 

SteveW

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I have an OS Giken on order to go inside the new diff carrier w/3.55s I will have built. As an autocrosser I see many of the top runners in ST, CAM, etc running these diffs and raving about them. Online the best descriptions I could find of what it must drive like were from a Viper forum:

I have had the Quaife foe 5500 miles and the Giken for 400 now. The Quaife is still my choice for most drivers with less experience because it does a great job of keeping the rear in the rear. In hard driving though if you get an inside wheel light the handling and power application is inconsistent.

The Giken on the other hand since it will lock and you get the 100% to the outside tire just plain takes off out of the corner and it will react the exact same each time, so you feel the tire at the edge better. When the unit starts to engage and lock the car straightens out a bit and gives you great confidence to get into the gas early. For autocross and the track I have been really shocked at the difference it makes it the speed you are capable of. Off throttle the thing just turns in with no drama and you will be able to control rotation with the throttle.

Have to admit I was skeptical at first because I loved the Quaife so much over the stock diffs. I only endorse things that I believe in though so until I had the chance to try it myself That was the case. Now that I have I'm very proud to be able to say that I love it and will be glad to offer it to my customers!
See also: https://grassrootsmotorsports.com/articles/whats-the-diff/

Torsen LSD (stock gear-type)

list price: comes stock
fast lap: 36.79 sec.
mean time: 36.97 sec.
The Honda S2000 uses a fantastic Torsen gear-type differential that has served many autocross and track drivers well. This piece of equipment has many things going for it, including the fact that it comes with the car at no charge. It also has no real bad habits, as it works well and will never wear out. It does, however, leave something on the table. It promotes understeer in tighter corners that eventually leads to wheelspin as the inside tire becomes unloaded. The Torsen also doesn’t lock up the rear axle to the point where a driver can use power oversteer to bring around the tail. Unfortunately, the Torsen’s behavior cannot be changed—it is what it is. Ian liked the Torsen’s high-speed manners. He also found that he could maintain a good arc through the track’s decreasing-radius, high-speed sweeper.

The Torsen-equipped S2000 turned consistent laps in the low-37-second range, with one flyer at 36.79. The average was 36.97 seconds. Now we could move on to the aftermarket units.

OS Giken Super Lock LSD

The OS Giken differential is a hybrid-type unit that makes use of both locking- and clutch-type technologies.

list price: $1390
fast lap: 36.45 sec.
mean time: 36.61 sec.
The OS Giken Super Lock LSD is a newcomer to the U.S. market, but that hasn’t stopped this unit from establishing a rabid following. Like the Kaaz, the OS Giken is a 1.5-way differential that locks fully under acceleration and only partially while braking. However, the OS Giken uses more clutch plates than the Kaaz; OS Giken says that reduced wear and even more progressive locking action are the benefits.

On track, Ian loved how the OS Giken allowed for part-throttle understeer, then progressively led to oversteer as more throttle was added. The car was easy to modulate and remained consistent from lap to lap.

Essentially, the OS Giken provided the best of the two other differentials: Like the Torsen, the OS Giken was quiet and composed during the high-speed sections; like the Kaaz, the OS Giken allowed Ian to hang out the tail in the slower stuff.

Ian’s times backed up his impressions, as he posted the fastest lap of the day when running the OS Giken: 36.45 seconds. He also clocked very consistent laps that yielded our fastest average of 36.61 seconds. Like the Kaaz, the OS Giken is also tunable for a variety of speeds and degrees of locking. However, we were very happy with the unit as delivered. Its very progressive lockup was just what our duo desired.

Kaaz 1.5-way LSD

list price: $895.50
fast lap: 36.73 sec.
mean time: 36.93 sec.
The Kaaz limited-slip differential is a variation on the clutch-type theme. When the vehicle is coasting, the internal clutch plates rotate freely without any preload, allowing the differential to act like an open unit. However, applying torque to the differential through either acceleration or braking causes a cone-shaped pressure ring to gradually lock the plates together.

The Kaaz is considered a 1.5-way limited-slip differential because it exhibits more lockup under acceleration than braking. A 1-way differential, by comparison, only locks under acceleration, while a 2-way unit exhibits the same amount of lock under both braking and acceleration. Generally speaking, a 1.5-way differential is easier to drive than a 2-way, as braking and turn-in are both smoother.

As expected, Ian found that the Kaaz offered very good exit speeds through the slower corners. “It’s very effective for rotation,” he noted. He also added that it responded almost immediately to throttle application.

The abrupt transition between understeer and oversteer did make for some exciting laps, as he found the Kaaz to be a little dicey during higher-speed maneuvers. For example, a turn that was stable and controlled with the Torsen became an exercise in knife-edge cornering with this unit; the car wanted to quickly transition to oversteer whenever Ian lifted off the throttle.

Despite the sketchiness at higher speeds, the predictable and welcome oversteer in the slower spots helped Ian really lay down some fast sessions. He initially scared himself a bit in that first, fast corner, landing a slow lap time of 37.44 seconds. After that, however, a string of high-36s flashed on the timer. His 36.93-second average was probably a tenth higher than it should have been thanks to that first-lap bobble.

A final word on this unit: While it’s possible to tune the Kaaz, doing so requires tearing down the differential and reconfiguring the clutch discs.This job can be accomplished in a home shop, but it’s probably not feasible trackside.

Two-Wheel Peel
The variety of available performance differentials is immense, each with its own positives and negatives. In this case, our on-track winner was the OS Giken, as it was both the fastest and easiest to drive. The OS Giken did come away with one strike against it, however, as it costs nearly $500 more than the runner-up, Kaaz.

Despite the higher price tag, Ian and Peter ran the OS Giken differential during the season-ending SCCA Runoffs. While Ian finished where he started—ninth out of 18 cars—the results don’t show one important fact: During the race’s opening moments, an overzealous overtaker spun Ian off course and to the back of the pack.

That spin put Ian into catch-up mode for the bulk of the race, and he discovered something else while making up those lost positions: His tire wear was significantly better than expected. “I caught several Kaaz-equipped S2000s that had simply run out of tire on the rear,” Ian noted. “We are very pleased with this differential.”
 
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spiller

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^^^ excellent info. Am I right to assume the OSG unit for our cars is a 1.5 way? I gather that it’s tunable but you can get away with 100% locking due to the progressive locking characteristics meaning slow speed turns on the street should not be much of an issue.
[MENTION=16275]SteveW[/MENTION] where did you order your diff from? Are any additional parts required for the install? I would like to change to a shorter final drive at the same time. Maybe 3.73 or 4.09
 

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spiller

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If one wheel gets airborne it acts like an open diff, the unloaded wheel will just spin freely. So I am told, I have never experienced that but I try to not jump curbs so that could be why. However, changing clutch packs gets old quickly and I don't miss that.
That’s one point, the other is that it doesn’t lock like a traditional diff under deceleration meaning less stability under threshold braking. Also the ability of a torsen to put down power to the wheels on corner exit is not in the same hemisphere as a good clutch type LSD. Torsens are good because they don’t wear and they allow manufacturers to achieve good turn in on their cars with a compromised street wheel alignment.
 

SteveW

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^^^ excellent info. Am I right to assume the OSG unit for our cars is a 1.5 way? I gather that it’s tunable but you can get away with 100% locking due to the progressive locking characteristics meaning slow speed turns on the street should not be much of an issue.
[MENTION=16275]SteveW[/MENTION] where did you order your diff from? Are any additional parts required for the install? I would like to change to a shorter final drive at the same time. Maybe 3.73 or 4.09
Yep, from what I've been told it's 1.5 way as a stock unit but it can be custom tuned if you want something different. I don't have any idea if other than 1.5 was would be better so just going with what Giken says is great for the car. Their main guy is actually the STX national champ this year and knows way more than I about what would be best for autox so going with what he recommends.

You have to order from a dealer and I went with a race shop in Portland, OR who can also assemble the whole thing for me. I don't know if additional parts would be required if you are just replacing the diff. I'm building a whole new assembly out of the aluminum carrier case so hoping I got enough parts on order for everything.
 

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tienlo

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I just ordered a 1.75 way Kaaz LSD for my Mustang.

Weirdly enough the entire Mustang6g forum hasn't got any mention of the word "Kaaz" except this thread!

Kaaz makes 2 models of clutch-type differential, an RS "Road Spec" model (which is 1.75 way, weird sounding hey) as well as a 2 way model.


https://www.mdspares.com.au/products/13473/KAAZ-LSD-REAR-131-DAG3850RS-FORD-MUSTANG

--------------------------

Website description:

Kaaz L.S.D. is the pioneer in the large sized clutch plate design. It's effectiveness and durability has been proven at the race scene around the world.

SPECIFICATIONS:

Transmission - MT/AT
Diff position - rear
Standard diff - LSD
LSD type - basic
Plate count - 16
Plate size - L
Ramp angle - 1.75 way
Note: Replaces Ford super 8.8 factory LSD with 34 spline axles

--------------------------


I have been running a 1.5 way Kaaz LSD in my stock engine 350z for 10 years, very happy with its characteristics when oversteering (how do I describe it... predictable breakaway, predictable around that point where you straighten up the steering wheel)

I'll keep you all updated once it's installed.
 

strongholdsteve

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A friend of mine has Wavetrac installed. He says he would never do it again.
 
 




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