[Cloud9...68]

Sorry to bring this back to OS Giken, but it strikes me as odd that a part that is intended primarily for track use, would not be recommended for use in cars with transaxles, which disqualifies an awful lot of popular track cars, e.g. all Porsches, Corvette, Lotus Elise, Toyota MR2, all Subaru's, Mitsubishi Evo, all Hondas except the S2000, anything with front wheel drive, anything with all-wheel-drive, all formula cars, etc. Yes, that leave plenty of other cars (all Detroit iron, Miatas, Nissan Z's, etc.), but still... Strange...

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[flash]

it doesn't surprise me at all, in fact it makes a lot of sense. as soon as you start pushing the envelope, and developing parts for performance use, you narrow the field on application flexibility. it happens with almost everything, not just diffs.



big difference between a pumpkin and a transaxle. the fluid you use in a transaxle is not always the same as in a differential. the fluid they want in the giken is heavier. on top of that, as a clutch type, the friction modifiers are apparently very specific. that doesn't necessarily work well with a transmission, and if you run the fluid that works well with the transmission, it doesn't necessarily work well with the diff.

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[pure&simple]

First of all, kudos to Pete for finding a high-performance diff at a reasonable price (OS Giken) and bringing it to market. With both supply and demand shrinking for aftermarket 944/968 parts, I think it's important to recognize the effort involved in doing this. Also, thanks to Bob for taking the initiative to contact OS Giken and get their recommendation. Your attention to detail and commitment to the community is respected and appreciated.



Since I am one of Bob's data points, have 25,000+ miles and at least 20 track days with the OS Giken, I'd like to put in my 2 cents. On the track it is awesome. On the street, noise or lack of smoothness is apparent only during slow, tight cornering, such as in a parking lot, or making a right-hand turn at a stoplight. Given that the difference in distance traveled between the inner and outer wheels is the most during tight corners, this makes perfect sense. To put this in context, my commuter car (2011 Subaru legacy with all-wheel-drive), makes more noise and has worse engagement than my 968 in tight corners. By my standards, I would say my OS Giken diff is performing as expected and I don't regard a slight noise/grumble on engagement in tight corners to be a problem. Having said that, I see no reason not to use the recommended Eneous fluid and plan to change to that next time my car is in the shop as a preventative measure. Using the recommended fluid seems like cheap insurance.



Based on that, I think it would be a mistake to characterize this diff as a track-only product that has no place in a street-driven 968. While I'd like to avoid discussion about whether or not 968s belong on a racetrack (I think we all remember that thread), the fact is that there are a number of 968 owners who drive their car on the street but would like to get the most out of it on the track as well. For them, a clutch-type diff seems to be a good choice. If you are not going to track or autocross, you probably don't need a <acronym title='Limited Slip Differential'>LSD</acronym> at all unless you've added significantly more power. And even with more power, I agree that if you are not going to track or autocross, the type of diff (clutch vs. torsen) is largely irrelevant.



[quote name='flash' timestamp='1354288680' post='135519']



if you want to go against manufacturer recommendations, AND you are wiling to put up with the pop off the line, AND the low speed issues, AND the constant noise, all in a street car that would never be able to take advantage of any performance bump over other <acronym title='Limited Slip Differential'>LSD</acronym> diffs, feel free. everybody has their own priorities.

[/quote]





Bob, judging by the tone of your post, you seem intent on convincing people not to buy this diff. Perhaps one car had problems with it, but both Jay and myself offer counter-examples, and OS Giken offered two counter-examples from the guys that are using it successfully with the Eneous fluid. Manufacturer recommendations notwithstanding, issues with noise/engagement are clearly not universal.



EEZATOY, hopefully you got the info you needed. Sorry to take your thread further off track - the OS Giken debate really belongs in a separate thread.

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[pure&amp;simple]

[quote name='Cloud9...68' timestamp='1354371113' post='135549']

Sorry to bring this back to OS Giken, but it strikes me as odd that a part that is intended primarily for track use, would not be recommended for use in cars with transaxles, which disqualifies an awful lot of popular track cars, e.g. all Porsches, Corvette, Lotus Elise, Toyota MR2, all Subaru's, Mitsubishi Evo, all Hondas except the S2000, anything with front wheel drive, anything with all-wheel-drive, all formula cars, etc. Yes, that leave plenty of other cars (all Detroit iron, Miatas, Nissan Z's, etc.), but still... Strange...

[/quote]



The product configurator on the OS Giken website lists an application for every single one of the cars you mentioned (and didn't mention, such as the Porsche 944). There are also at least a dozen success stories from racers of various transaxle cars. So clearly they are marketing this product to those applications.



Only their synthetic gear oil is not recommended for use with transaxle cars - from the website: "The OS-250R [Full Synthetic Gear Oil] was specifically formulated to provide maximum performance and smooth comfort for the OS Giken Super Lock <acronym title='Limited Slip Differential'>LSD</acronym>. SAE Rated at 80w-250, it is the top choice by race teams for protection and durability, yet maintains street-driveability. (Not recommended for transaxle applications.)"

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[flash]

you can't go by only the website.



as i said, i had a long conversation, specifically to try to cure a problem. that conversation resulted in them being clear that this was not designed to be used in a transaxle, though many people do it. that's why they don't spec a fluid for transaxle applications either. they were clear that "grabbing" clutches and noise were known issues in transaxles. they were clear to use Enous Touring fluid to try to fix it, and even gave me the name of a local place to get it, but that it may not work, and that he may have to live with the problems.



perhaps they are a bit more forthright with me, since they knew i was only trying to fix one, and that since they are in my back yard, and that if this did not work, i would be banging on their door. they may have felt it was easier to be honest. when you take the motivation of money out of the equation, that tends to happen.



by the way, i hated the noise it made in your car too. i commented on it at the time. i asked what the heck the racket was. i'd never put up with that noise. your car is not a street car. you may drive it on the street, but it really is a track rat. you may be able to get used to it, but most of us wouldn't. the 968 is a pretty quiet GT, when everything is right. departing from that in a street car is a direction most of us would not go.



for a street car, or a dual purpose car, a torsen LSD is more than sufficient. for a dedicated track car, there is a modest improvement to be had by a clutch type diff.



this is not specific to the 968 either. clutch diffs have been around for decades. they really haven't changed much. they still have the same ups and downs.



as for convincing anybody of anything, i am only trying to show the product in a fair light. i have no interest or investment one way or the other. i think the product has good applications. i just don't think a street car (read "daily commuter") is one of them. i think most people would find the noise as annoying as tire noise, pinion whine, or wind through a bad window seal. jay's car doesn't count, as it is a cab, and already has 15db more cabin noise to begin with. i'm not sure i'd hear it in mine either, and i've done a ton of work to deaden sound in there, but i think the rest of the remaining noise would still drown out the diff noise. the popping would make me bats*** crazy though, just like clunks in a suspension, rattles in a dash, squeaks, or any sort of brake noise. i thought something was broken, until i found out it was a clutch diff. all this time i thought it was a torque bias diff. my car is a street car and by definition absolutely must be smooth and quiet. no chance i'd put any type of clutch diff in there.

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[pure&amp;simple]

I think we agree on a couple of points:

• The OS Giken diff has good applications, such as on a track rat like mine
  
  
• On a commuter car, you'd be better off with a torsen <acronym title='Limited Slip Differential'>LSD</acronym>, or no <acronym title='Limited Slip Differential'>LSD</acronym> at all.
  
  

The only thing we disagree on is how much noise constitutes a problem, and whether it occurs universally on all transaxle cars with the Giken installed.



I remember your comment about my car - I was trying to figure out what you were talking about at first because I had never really noticed the noise from the diff before. The thing that annoyed me about my car was the popping sound coming from the solid suspension bushings on stop/start. That drives me bonkers... still haven't gotten it taken care of. <img src="/forum/images/smilies/968/whine.gif" class="smilie" alt="" />

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[flash]

no worries. i think the issue of noise is going to be very subjective. for me, no noise is acceptable, and i will spend whatever it takes to make it go away, and will sacrifice performance to get there as well. i am about to change back to the DMF purely because i cannot stand the noise in the transaxle that the solid flywheels create. i am more than willing to spend $2k to get there. some people would not go that route. i think the same can be said of the diff.



i've had and driven a lot of different kinds of diffs in many different kinds of cars. i am bothered by the same things regardless. my denali makes the typical locker kind of popping and jumping in really tight corners. makes me nuts. if there was anything i could do about it, i would.



as for universality of the problem, i've only been in 3 cars with this diff. they all felt and sounded the same to me. couple that with the conversation i had with the manufacturer, and i would never put this in a street car. but as i have continually said, i would not hesitate to put it in a track car. i think it's a great product in the right application.



re: bushings - i may have another one popping. i noticed a couple of pops the other day. i need to investigate. it may just be time for front wheel bearings.

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[94SilverCab]

I'm firmly on Andy's side for OS Giken, I will probably change the fluid, thanks for the tip...I bought it, I love it, it was worth the money to me. YMMV.



No matter how many times Flash tells me its noisy I won't care, I don't think that anyone who drives or rides in my car would care either...that's his Mishegas



.I also wouldn't spend $150k to make the world's fastest, most tuned 968... If I had that kind of coin I would have bought a better car.



JMHO,



Jay

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[RS Barn]

So when I Originally responded to this post about adding a OS Diff (like Jays)to a street car. I was only trying to point out the fun factor of the OS unit while cornering. The progressive nature of engagement (while driving normally)really gives the driver a sense of confidence both entering and exiting a corner. If I had to relate the improvement to any other product it would be upgrading the sway bars. "Most" owners feel the reduction of body roll makes the car feel more stable and planted in corners. The ride suffers just a bit, but to "most" there is a positive trade off. BTW, I dislike stock 968 cabs in general due to body roll, noise, and allergy causing wind in my eyes. But Jays with several suspension, engine mods and the OS diff is a blast to drive.

Jay (who doesn't race) told me how happy he was with his OS Diff on the street. Their clutch style diff is not the typical clutch style that has been around for decades as Bob describes. There is completely new technology and offers many improvments for both normal actuation in street use and pure racing performance.

I for one don't like Gear style LSDs for several reasons. They are very quiet in a straight line and mild cornering but are a bit jumpy when locking up from wheel spin on a wet corner. They don't have any "Feel" in the corner. So their virtue to some is a detractor to me. I installed a GT gear diff in a customers car who later wished he had installed a clutch style. He had a 944 before and missed the "more planted" feeling during cornering. He may speak up here....

So I think there should be more than one "Approved" option for 968 drivers.

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[flash]

again, i'm willing to be that your customer that wished he went clutch style was a track guy



again - track fine - street not so much. driving around in a parking lot, it feels like there is something wrong with the car. driving down the freeway, you have to crank up the stereo. that is just not acceptable for a street car.



more importantly, the manufacturer does not recommend this for this car for street use for the above mentioned reasons. so, i'm going to take the word of them, and not somebody trying to sell something.



track yes - street no. pretty simple. even andy agrees.

"The OS Giken diff has good applications, such as on a track rat like mine"

"On a commuter car, you'd be better off with a torsen LSD, or no LSD at all."

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[pure&amp;simple]

Bob, I've gotta say, I think you're standing pretty much alone on this noise/engagement complaint. Although I appreciate the perfectionism that you bring to your products and I'm sure it's helped make you successful in business, just because the Giken doesn't meet your standards for complete silence and transparent operation doesn't mean that anyone else shares your view. Where are all the other folks who feel this is a problem? Google "OS Giken differential noise engagement problem" and you'll find nothing but raves about how great it is.



Second, it seems like you are trying to present track vs. street as a binary decision, when it is actually more of a range. Many of the folks on this board that drive their 968 daily have autocrossed or tracked it, or plan to in the future. These are folks who would benefit from an <acronym title='Limited Slip Differential'>LSD</acronym>. The OS Giken is one of the most advanced out there, has proven reliability, and is priced competitively.



For the record, I'm probably not the ideal source to cite, since I've never actually driven a torsen. You said it was smoother and quieter, and I was taking your word for it. If all you're doing is driving to work, getting groceries, and relaxed country drives, you don't need an <acronym title='Limited Slip Differential'>LSD</acronym>.

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[Cloud9...68]

Note to self - must read up on the differences between the different types of available <acronym title='Limited Slip Differential'>LSD</acronym>'s...

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[flash]

i'm not alone. there will be a less than stellar review written fairly soon.



in fact, only you, pete and jay are of the mind that noise is acceptable in a 968 street car. it is no coincidence that you all have a number of other things in your cars that are not appropriate for street cars. that's your choice. you weighed the pros and cons and made your own decisions. that's fine.



perhaps it was the installer. perhaps it is the incorrect fluid. either way, i have a pretty good finger on the pulse of what people like (note the long list of products developed and successful). i heard the noise in all 3 cars. i immediately commented on it. i don't think i'm the only one with that kind of hearing. i felt the engagement issues in this car. i know that many people would not tolerate either flaw.



certainly some will. look at how many people run around on those bilsteins. they are harsh and abusive. but, for some, they are just what they want, as they plan to track their street car. that's fine.



all i am saying is that full disclosure about this unit, or any other product, is something that needs to be out there, and nobody should be blindly recommending anything for a street car, that is track oriented in nature, without providing all of the information about it, both good and bad. that's just irresponsible, and something i, as a site owner, will not tolerate.

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[flash]

one of the main purposes of this site is to provide unbiased and complete information to the membership. this includes products and services.



this item is no different than any other. it's no different than the supercharger. i had to disclose that it makes a bit of noise, will cost you fuel if you are on it, and makes service a bit tougher. it would be no different than the header, where while it make the top end snappier, it does so at the expense of making your exhaust sound like a kazoo. it would be no different than a light flywheel, which can make for better acceleration, but at the expense of rattle in the transaxle. the list is endless.



everybody gets to make their own decisions. our job is to provide as much information as possible, so those decisions can be made eyes wide open.

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[94SilverCab]

I did not purchase my car to run it on the track, I did however design my personalized upgrades to suit my own specific desires. If I could have a silent vehicle that would deliver the performance I want, then my car would glide past you in a whisper (I drove an Rx-7 for years...whoosh). Also, if silence was my primary goal, I wouldn't have bougt a 968 cabrio, I would have bought a Lincoln Towncar.



The three things I wanted to improve in my own specific personalized 968



1) Improved traction and handling

2) Improved Braking

3) A modest gain in horsepower and torque



In making the decision to focus on these items, with the understanding that some other elements of an otherwise stock car might be compromised I happily and gladly expended the funds toward those "improvements".



I have reached, what I feel is pretty close to my own list...albeit at a fraction of what you have spent. My car is sporty, quicker than casual onlookers "expected" and it makes me feel good when I drive it. I feel like I got good advice on my mods (including the ones you produced), and I like the results.



I get that you want to "warn/notify" people about potential modifications or upgrades, but tthere is no need to call this out specifically. Folks, if you put somethig on your car that wasn't put there by the manufacturer, be a bit skeptical, buy from a trusted source and make sure it meets your needs.



One more time (so that, for once, someone other than Flash gets the last word, I am prepared to continue posting forever)...I love my OS Giken <acronym title='Limited Slip Differential'>LSD</acronym>



Jay

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[flash]

lol - post away. i am working on the pros/cons lists for a bunch of stuff, and plan to post it soon.



i think you would like a torsen type diff better, no matter which one you choose. for your use, you would have all of the performance you could use, none of the noise, none of the popping, and a few hundred bucks left in your wallet for another toy. you'd also have something the manufacturer actually recommended for a 968.



but everybody is entitled to do whatever they want. i've certainly made some mistakes with some parts, and one by one, they are being removed, either for reasons of resultant problems, or because they detracted from the things that make the 968 the car it is.



if i wanted a noisy, rattly, twitchy, car that sounded like a kazoo, i'd have bought a japanese car.



the best advice is not to buy anything on recommendation, particularly that of somebody selling it. instead, check it out for yourself. if you can't work that out, at least talk to more than one somebody else who has whatever it is.

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[94SilverCab]

"It isn't nearly as expensive to do it right as it is to do it wrong."



Oh, by the way, I spoke to the Giken folks at SEMA in Las Vegas last year face to face.



Jay

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[Cloud9...68]

[quote name='94SilverCab' timestamp='1354548164' post='135626']

.I also wouldn't spend $150k to make the world's fastest, most tuned 968... If I had that kind of coin I would have bought a better car.



JMHO,



Jay

[/quote]

This discussion about differentials has been fascinating, but the above quote from one of Jay's earlier posts speaks to something I've been thinking about lately (and is maybe just a tad closer to the original topic of this thread). A large chunk of the money Flash spent on his car went to the trial and error associated with developing new products (makes me wonder if his estimate of $150K isn't actually a bit on the low side!). So, I wonder how much cash it would take to reporduce Flash's end product - the ultimate street 968 - including purchase price, now that the parts have been developed and are presumably available. $60K, maybe? Seems to me this really isn't an unreasonable amount of money for a car that is probably competitive with cars like the Boxster/Cayman, Corvette, Lotus Evora, Aston Martin Vantage, and maybe even a new 911, in a classic and unique body style.

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[pure&amp;simple]

[quote name='flash' timestamp='1354566710' post='135639']

all i am saying is that full disclosure about this unit, or any other product, is something that needs to be out there, and nobody should be blindly recommending anything for a street car, that is track oriented in nature, without providing all of the information about it, both good and bad. that's just irresponsible, and something i, as a site owner, will not tolerate.

[/quote]



Full disclosure = good thing! <img src="/forum/images/smilies/968/clap.gif" class="smilie" alt="" /> However, if someone doesn't perceive something as a problem, they will not feel the need to disclose it. There is nothing malicious there. So it is enough to point out that there is a differing opinion - then you have full disclosure. Nobody has to "win" the argument. It's the nature of people to never universally agree on anything.



In this case full disclosure about the OS Giken diff should read something like this:

• The OS Giken is a reliable, technically advanced, diff at a reasonable price
  
  
• There is noise and vibration upon engagement
  
  
• Some folks feel that the noise/vibration is so slight as to be almost unnoticeable, are very happy with the product, and would not hesitate to recommend it.
  
  
• Some folks feel that this noise/vibration is unacceptable
  
  • If these folks are using the 968 purely as a commuter/weekend cruiser and have not increased the power, they have no need for an <acronym title='Limited Slip Differential'>LSD</acronym>, so it's a moot point.
    
    
  • For those that are using the 968 purely as a commuter/weekend cruiser and have increased the power, they should try to find a different kind of <acronym title='Limited Slip Differential'>LSD</acronym> that meets their requirements if they are having traction issues.
    
    
• Installation and brand/viscosity of diff fluid may influence the level of noise/vibration (I think this could be said of any diff or even any transmission)
  
  
• Regardless, it's a good idea to drive a car with the diff you want before purchasing it to ensure it meets your requirements (this is a good idea with any aftermarket product).
  
  

So now, can we please agree to disagree and move on? I think we've generated enough posts that anyone interested to make an informed decision. The repeated posting of the same opinions over and over doesn't serve anyone.

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[flash]

that's nice.



i just got off the phone with them again. really nice guy. they do not recommend this diff in any rear drive transaxle that cannot use their fluid. it seems that front wheel drive transaxle applications are much more successful. they make diffs that fit transaxles like ours, but you have to play around with fluids to see if anything works. they were very clear not to use friction modifier additives.



they reiterated that noise and popping is a known potential issue, in varying degrees, depending on the application.



they further went on to say that a design change resulted in higher pre-load (where have we heard this before?). this could be responsible for the "popping". there is another design change coming up that may resolve this. they recommended contacting your dealer so they could contact giken, and get a different spring and washer package to correct the preload issues.



the constant noise they think is attributable to the fluid.



the guy i talked to is going to talk to japan, as well as a couple of other dealers who install these units in porsches. he's going to get back to me with the results. hopefully something will come from this that will resolve the issues, and make the unit more civilized.

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