New Product: Super LSD
06-13-2012, 10:25 PM
#31
Former Sponsor
No, what he is saying is that each chassis, engine, power level, and transmission and handling envelope requires effort to make everything work together. And the LSD is an integral part of both pre-corner braking and turn in, as well as mid and late corner acceleration and power-on steering. He is suggesting the testing of the unit would determine which disk types are used, lockup ratios, ramp ratios for unlocking under braking, etc.
Hell - Formula one in 2012 has differential and "limited slip" controls on the steering wheel that are changed multiple times A LAP - which means with all their millions they cannot make a unit that does everything all the time. This technology is controlled, but in its limited slip (traction control) nature - not lockup.
Hell - Formula one in 2012 has differential and "limited slip" controls on the steering wheel that are changed multiple times A LAP - which means with all their millions they cannot make a unit that does everything all the time. This technology is controlled, but in its limited slip (traction control) nature - not lockup.
06-13-2012, 11:40 PM
#32
Three Wheelin'
The latest "iteration" of the "Cup Car" limited slip is one of the main things that makes these cars so much quicker than the same cars, just a few years ago. Look at what has "happened" to lap times at Daytona....when the "cars" are "fresh" and "unmolested". Compare the percentage of change at this "early in the year" track event and then look at the percentage of change at the tracks run at the middle/end of the year.
Porsche found that the "smoothness" of the lock-up and the release between off throttle and on throttle was very, very important.....in order to not "upset" the car when working near the limits. Any "jarring" of the rear tires, once a "slip angle" has been established, is going to reduce the cornering limits of that vehicle.
Porsche doesn't employ many "fools".
I'd submit that the clutch discs in these differentials is an integral part of that smoothness and putting in a more "aggressive" disc may not be the fastest way around a race track....
Porsche found that the "smoothness" of the lock-up and the release between off throttle and on throttle was very, very important.....in order to not "upset" the car when working near the limits. Any "jarring" of the rear tires, once a "slip angle" has been established, is going to reduce the cornering limits of that vehicle.
Porsche doesn't employ many "fools".
I'd submit that the clutch discs in these differentials is an integral part of that smoothness and putting in a more "aggressive" disc may not be the fastest way around a race track....
06-14-2012, 10:15 AM
#33
Developer
Thread Starter
The latest "iteration" of the "Cup Car" limited slip is one of the main things that makes these cars so much quicker than the same cars, just a few years ago. Look at what has "happened" to lap times at Daytona....when the "cars" are "fresh" and "unmolested". Compare the percentage of change at this "early in the year" track event and then look at the percentage of change at the tracks run at the middle/end of the year.
Porsche found that the "smoothness" of the lock-up and the release between off throttle and on throttle was very, very important.....in order to not "upset" the car when working near the limits. Any "jarring" of the rear tires, once a "slip angle" has been established, is going to reduce the cornering limits of that vehicle.
Porsche found that the "smoothness" of the lock-up and the release between off throttle and on throttle was very, very important.....in order to not "upset" the car when working near the limits. Any "jarring" of the rear tires, once a "slip angle" has been established, is going to reduce the cornering limits of that vehicle.
Then you should be very happy with our choice of OS Giken for the 928. With up to 24 sets of disks and plates, the transition from open spooling to 100% lockup is known to be super-smooth. This is not from the OS Giken advertisements, but rather from the racers who are driving them and been driving the OS Giken Super-LSD for several years now. It's the reputation they have earned that drew me to select them for my project.
06-14-2012, 12:13 PM
#34
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06-14-2012, 02:42 PM
#35
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Hey there everyone,
Carl asked me to pop in here and see if I could help answer some of the questions that everyone has regarding this new differential. I guess I am not really sure where to start, so someone want to ask me something? I will do my best to answer reasonable questions, but I am not here to be a part of anyone's arguing.
Erik Johnson
GBox LLC
Carl asked me to pop in here and see if I could help answer some of the questions that everyone has regarding this new differential. I guess I am not really sure where to start, so someone want to ask me something? I will do my best to answer reasonable questions, but I am not here to be a part of anyone's arguing.
Erik Johnson
GBox LLC
06-14-2012, 03:07 PM
#36
Developer
Thread Starter
Thanks for coming, Erik. I know your busy and I appreciate it.
In post #21 I am hearing a concern as to how the new diff will be tested, and secondly, how it can satisfy multiple drivers with different car configurations. Can you address those questions?
In post #21 I am hearing a concern as to how the new diff will be tested, and secondly, how it can satisfy multiple drivers with different car configurations. Can you address those questions?
06-14-2012, 06:41 PM
#38
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First of all I think that Carl should be praised for his efforts to accomodate people's desires to have a limited slip differential for their 928 cars.
OS Giken differentials have legendary durability and performance. They build differentials for not only Porsche cars, but also the following: Acura, Alfa Romeo, BMW, Chevrolet, Chrysler, Dodge, Ferrari, Ford, Honda, Hyundai, Infiniti, Lamborghini, Lexus, Lotus, Mazda, Mercedes Benz, Mini, Mitsubishi, Nissan, Scion, Subabru, and Toyota. They know what they are doing and I am sure that at the end of the day, the people who spent the money with Carl to make their cars even better on the track are going to be very glad that they did.
In reference to the questions of testing, I will leave that to Carl to answer as it is his project, and we are simply helping to make his request a reality for everyone. As to the the ability for one differential to satisfy all drivers and all car configurations, this is simply a unrealistic expectation to place on any manufacturer. I will however say that in terms of finding a setup that seems to agree with a broad stroke of users who install this brand of differential, OS Giken appears to have found a good middle ground for most.
Erik Johnson
OS Giken differentials have legendary durability and performance. They build differentials for not only Porsche cars, but also the following: Acura, Alfa Romeo, BMW, Chevrolet, Chrysler, Dodge, Ferrari, Ford, Honda, Hyundai, Infiniti, Lamborghini, Lexus, Lotus, Mazda, Mercedes Benz, Mini, Mitsubishi, Nissan, Scion, Subabru, and Toyota. They know what they are doing and I am sure that at the end of the day, the people who spent the money with Carl to make their cars even better on the track are going to be very glad that they did.
In reference to the questions of testing, I will leave that to Carl to answer as it is his project, and we are simply helping to make his request a reality for everyone. As to the the ability for one differential to satisfy all drivers and all car configurations, this is simply a unrealistic expectation to place on any manufacturer. I will however say that in terms of finding a setup that seems to agree with a broad stroke of users who install this brand of differential, OS Giken appears to have found a good middle ground for most.
Erik Johnson
06-14-2012, 06:51 PM
#39
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Sorry Adam, I did not mean to not answer your question regarding case construction material. My understanding is the source of this concern arises from case failures in the stock OEM piece, do I have this correct?
If this is ultimately the concern, here is something that I think you will all enjoy. Should you happen to break a OS Giken LSD, they will replace it, with a brand new, or redesigned if needed piece for FREE. While they are not the first to offer this, they are the first as far as I know to do so in a plate type differential design, rather than say a torque biased differential. OS Giken stands behind their products 100%, and I believe that Carl has made a wise choice here to choose this company to construct this part for the 928.
Erik Johnson
If this is ultimately the concern, here is something that I think you will all enjoy. Should you happen to break a OS Giken LSD, they will replace it, with a brand new, or redesigned if needed piece for FREE. While they are not the first to offer this, they are the first as far as I know to do so in a plate type differential design, rather than say a torque biased differential. OS Giken stands behind their products 100%, and I believe that Carl has made a wise choice here to choose this company to construct this part for the 928.
Erik Johnson
06-14-2012, 08:44 PM
#40
Former Sponsor
First of all I think that Carl should be praised for his efforts to accomodate people's desires to have a limited slip differential for their 928 cars.
OS Giken differentials have legendary durability and performance. They build differentials for not only Porsche cars, but also the following: Acura, Alfa Romeo, BMW, Chevrolet, Chrysler, Dodge, Ferrari, Ford, Honda, Hyundai, Infiniti, Lamborghini, Lexus, Lotus, Mazda, Mercedes Benz, Mini, Mitsubishi, Nissan, Scion, Subabru, and Toyota. They know what they are doing and I am sure that at the end of the day, the people who spent the money with Carl to make their cars even better on the track are going to be very glad that they did.
In reference to the questions of testing, I will leave that to Carl to answer as it is his project, and we are simply helping to make his request a reality for everyone. As to the the ability for one differential to satisfy all drivers and all car configurations, this is simply a unrealistic expectation to place on any manufacturer. I will however say that in terms of finding a setup that seems to agree with a broad stroke of users who install this brand of differential, OS Giken appears to have found a good middle ground for most.
Erik Johnson
OS Giken differentials have legendary durability and performance. They build differentials for not only Porsche cars, but also the following: Acura, Alfa Romeo, BMW, Chevrolet, Chrysler, Dodge, Ferrari, Ford, Honda, Hyundai, Infiniti, Lamborghini, Lexus, Lotus, Mazda, Mercedes Benz, Mini, Mitsubishi, Nissan, Scion, Subabru, and Toyota. They know what they are doing and I am sure that at the end of the day, the people who spent the money with Carl to make their cars even better on the track are going to be very glad that they did.
In reference to the questions of testing, I will leave that to Carl to answer as it is his project, and we are simply helping to make his request a reality for everyone. As to the the ability for one differential to satisfy all drivers and all car configurations, this is simply a unrealistic expectation to place on any manufacturer. I will however say that in terms of finding a setup that seems to agree with a broad stroke of users who install this brand of differential, OS Giken appears to have found a good middle ground for most.
Erik Johnson
I'm not sure if you have gone back and read some of my specific questions or not. Obviously the 928, with its unique rear suspension has considerable "change" when accelerating versus de-acceleration. Much like the Kinematic on a 993, the tow changes are significant enough to consider this movement to be a rear "caster" change. Also obvious is that this "movement" of the rear suspension is going to affect how any torque bias differential reacts, since the "loads" that the differential "sees" are going to be dampened by the suspension movement.....until that movement reaches its limits of travel. And when the suspension does reach the limits of its designed travel, the resulting force is bound to be a sudden and fairly violent reaction, as far as the loads seem by the differential. Is this a specific factor in the design of the differential for the 928 vehicle or all the differentials that you make basically all the same and "tuning" is left to the individual?
I guess the really easy, quick way to answer this question would be:
Are the internal components of the current differential that you offer for the G-50 5 speed transmissions (964) different (other than dimensionally different) than the internals for the 6 speed version of this transmission, found in the 993?
Another question is how do these differentials compare with the latest iteration of the factory differentials from Porsche Motorsports? Certainly, you guys must be aware of what the Porsche factory is doing. What are your "lock" and "unlock" percentages of slip? What kind of force is required to get the cross shaft to climb the ramps, in comparision to the factory pieces? How does this "change of direction" affect the friction discs...specifically, how smooth is the lockup, release, and re-lock of your differential (as the vehicle transitions from accleration to deacceleration) compared to the latest factory pieces?
The factory Porsche race cars have become significantly faster, over the past few years, and the "sum" of the power and handling improvements doesn't get close to explaining the decreased lap times. Their differential changes are responsible for a huge percentage of the decreases in lap times that these vehicles have been able to produce. Porsche figured out that any even slight changes of the differential locking would "upset" the slip angle that the rear tires had already established and has worked very hard to make the transition extremely soft. Yes, this required friction discs that wore, in order to be soft enough, but that seems to be part of the price.
What is your spin on this thought?
The question about housing material was pretty basic. Porsche made their differentials out of a casting that got machined. Virtually all of these castings broke right at the radius where the housing meets where the ring gears sits. After several iterations, they found that they needed to built their housings out of a billet chrome moly material. Both Guard and Porsche now only offer their differentials made from billet chrome moly. And, almost all of the 928 engines that I build, these days, have a tremendous larger amount of torque than any of Porsche's six cylinder engines that "destroyed" the factory castings. While a "warranty" is a great thing, very seldom will a warranty replace the resulting ruined ring and pinion, nor pay for the set-up of a new ring and pinion. So the obvious question is: Machined from a casting or carved out of billet?
Anyway, thanks for coming on here and talking to all of us. We are honored. Any "light" that you can shed on these questions would be educational, at the very least.
06-15-2012, 06:43 PM
#41
Rennlist Member
I recently had to choose a differential for my track car, as I didn't have a whole lot of confidence in the clutch pack setup found in stock Corvettes. Three strong possibilities were considered, OS Gilken with its vast array of friction plates, Kaaz with slightly fewer friction plates and the Quaife diff with its Torsen style self locking geared setup. In the final analysis, I went with the Quaife because I perceived it to be an "install it and forget it" situation, whereas the other two benefited from being "set up" to match requirements, but they also had to deal with plate wear.
In my mind the Gilken AND the Kaaz are the BEST diffs for all out road racing. They can be dialed in to match requirements and their performance under braking is superior to the Quaife. I have a heavier, high speed car and I like big, smooth, fast tracks, which is where the Quaife works best. However, it doesn't like bumps and exhibits some quirks on exits of extremely tight radius turns.
There is also no question in my mind that a properly set-up Gilken diff will be vastly superior to the 928 LSD, performance wise. As to its durability, no idea.
Gilken, Kaaz and Quaife all make OEM limited slip differential for various high performance car manufacturers.
In my mind the Gilken AND the Kaaz are the BEST diffs for all out road racing. They can be dialed in to match requirements and their performance under braking is superior to the Quaife. I have a heavier, high speed car and I like big, smooth, fast tracks, which is where the Quaife works best. However, it doesn't like bumps and exhibits some quirks on exits of extremely tight radius turns.
There is also no question in my mind that a properly set-up Gilken diff will be vastly superior to the 928 LSD, performance wise. As to its durability, no idea.
Gilken, Kaaz and Quaife all make OEM limited slip differential for various high performance car manufacturers.
06-15-2012, 07:18 PM
#42
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Hey there Greg and everyone else.
As there seemed to be a number of questions that you had, and as I wanted to make sure that I did not get anything phrased incorrectly, I asked Mark Mendoza at OS Giken to comment on your questions. I also have a really good information sheet that I can email directly to you Greg if you want to send me your email address. I am pretty sure it will address any of your questions and/or concerns.
Thanks for your questions.
Erik Johnson
LSD testing methods:
Our basic process for R&D on a new LSD project is as follows:
1. Receive R&D request from a customer, investigate the sales potential, propose the idea to the executives for their review and approval to initiate development.
2. Acquire related OEM components for OS Giken engineers to evaluate and assess potential development challenges. Depending on the spline designs and other manufacturing concerns, estimated pricing is determined based on the proposed production lot sizes, needs for creating new tooling, etc.
3. If the engineers feel a suitable OS LSD can be developed, design parameters are set and prototypes are created.
4. Based on basic vehicle specifications and the LSD engineer’s “6th sense”, settings for ramp angle, lock timing, etc. are estimated and implemented to the first prototypes. Unless specified for a particular use, the settings are estimated by the LSD engineer to provide the best all-around performance (quiet operation, smooth locking, low maintenance, safe yet good performance).
5. Once a prototype is ready it is typically installed to the OEM carrier and returned to the customer for testing. Based on customer feedback changes can be made before units are slotted for normal production.
LSD setting notes:
OS LSD can be configured to a variety of different settings.
SPEC-S is the “standard” setting for most OS LSD’s. This setting is designed to be the most suitable for most types of usage. Typically, SPEC-S setting has a lower preload and moderate lock progression timing on a non-aggressive cam angle.
SPEC-X is a custom setting; OS LSD can be built to customer specification. More/Less aggressive cam angle, alternate cam configuration (1.1way, 1.5way, 2way), specified lock progression timing, higher/lower preload (in most cases)
There are different disk types available as well:
Superlock LSD: standard disks, locking properties are slightly on the aggressive side
TCD: precision machined disks with oil holes; oiling channels are also specific to the TCD design. Locking properties are more progressive, oil flow properties are maximized. Originally designed for luxury-car applications, they also have been tested to have significant value for racing (particularly endurance) usage. (consistent locking properties regardless of diff temps, overall lower operating diff temps)
OS LSD construction notes:
High-grade steel alloy is used for all components
Chemical heat-treatment is used for all components, for added durability.
Gears are raw-forged for maximum strength
Case is billet steel construction (may be changed to forged construction in the near future)
Disks are machined simultaneously on both sides to very tight tolerances (only 2 machines exist in Japan capable of this operation)
All the design, development, manufacturing and assembly is done in Japan
OS LSD design notes:
Most Salisbury type clutch limited slip differentials share the same basic design; OS LSD is unique within the family of clutch-type limited slips. Pressure ring is miniaturized to allow for more disks to be utilized, yet durability/strength is high due to usage of strong materials and manufacturing processes. Lock-timing control system is unique to the OS LSD. Spline-through-side-gear design allows for stronger side gears and more/larger disks.
Check out the attachment for some nice comparisions between OS LSD and “normal” clutch type LSD’s.
Basically, OS Giken really over-engineered the LSD in my opinion. Which is good, because it results in a really good product that has excellent performance for any kind of driving, typically lasts longer than the car, and doesn’t require much maintenance at all. I suppose the main drawback is the higher cost, but unlike a lot of goods in today’s society, there is definitely a lot of added value for the added price.
Regards,
Mark Mendoza
Toyota Tsusho America, Inc.
Los Angeles Branch
1977 W. 190th St #200
Torrance, CA 90504
tel 310.243.1313
fax 310.516.0858
As there seemed to be a number of questions that you had, and as I wanted to make sure that I did not get anything phrased incorrectly, I asked Mark Mendoza at OS Giken to comment on your questions. I also have a really good information sheet that I can email directly to you Greg if you want to send me your email address. I am pretty sure it will address any of your questions and/or concerns.
Thanks for your questions.
Erik Johnson
LSD testing methods:
Our basic process for R&D on a new LSD project is as follows:
1. Receive R&D request from a customer, investigate the sales potential, propose the idea to the executives for their review and approval to initiate development.
2. Acquire related OEM components for OS Giken engineers to evaluate and assess potential development challenges. Depending on the spline designs and other manufacturing concerns, estimated pricing is determined based on the proposed production lot sizes, needs for creating new tooling, etc.
3. If the engineers feel a suitable OS LSD can be developed, design parameters are set and prototypes are created.
4. Based on basic vehicle specifications and the LSD engineer’s “6th sense”, settings for ramp angle, lock timing, etc. are estimated and implemented to the first prototypes. Unless specified for a particular use, the settings are estimated by the LSD engineer to provide the best all-around performance (quiet operation, smooth locking, low maintenance, safe yet good performance).
5. Once a prototype is ready it is typically installed to the OEM carrier and returned to the customer for testing. Based on customer feedback changes can be made before units are slotted for normal production.
LSD setting notes:
OS LSD can be configured to a variety of different settings.
SPEC-S is the “standard” setting for most OS LSD’s. This setting is designed to be the most suitable for most types of usage. Typically, SPEC-S setting has a lower preload and moderate lock progression timing on a non-aggressive cam angle.
SPEC-X is a custom setting; OS LSD can be built to customer specification. More/Less aggressive cam angle, alternate cam configuration (1.1way, 1.5way, 2way), specified lock progression timing, higher/lower preload (in most cases)
There are different disk types available as well:
Superlock LSD: standard disks, locking properties are slightly on the aggressive side
TCD: precision machined disks with oil holes; oiling channels are also specific to the TCD design. Locking properties are more progressive, oil flow properties are maximized. Originally designed for luxury-car applications, they also have been tested to have significant value for racing (particularly endurance) usage. (consistent locking properties regardless of diff temps, overall lower operating diff temps)
OS LSD construction notes:
High-grade steel alloy is used for all components
Chemical heat-treatment is used for all components, for added durability.
Gears are raw-forged for maximum strength
Case is billet steel construction (may be changed to forged construction in the near future)
Disks are machined simultaneously on both sides to very tight tolerances (only 2 machines exist in Japan capable of this operation)
All the design, development, manufacturing and assembly is done in Japan
OS LSD design notes:
Most Salisbury type clutch limited slip differentials share the same basic design; OS LSD is unique within the family of clutch-type limited slips. Pressure ring is miniaturized to allow for more disks to be utilized, yet durability/strength is high due to usage of strong materials and manufacturing processes. Lock-timing control system is unique to the OS LSD. Spline-through-side-gear design allows for stronger side gears and more/larger disks.
Check out the attachment for some nice comparisions between OS LSD and “normal” clutch type LSD’s.
Basically, OS Giken really over-engineered the LSD in my opinion. Which is good, because it results in a really good product that has excellent performance for any kind of driving, typically lasts longer than the car, and doesn’t require much maintenance at all. I suppose the main drawback is the higher cost, but unlike a lot of goods in today’s society, there is definitely a lot of added value for the added price.
Regards,
Mark Mendoza
Toyota Tsusho America, Inc.
Los Angeles Branch
1977 W. 190th St #200
Torrance, CA 90504
tel 310.243.1313
fax 310.516.0858
06-15-2012, 07:28 PM
#43
Developer
Thread Starter
Thank you, Chris, and thank Mark Mendoza for me too. I appreciate your time as I am sure many other Rennlisters do as well. Great info.
And Larry - thank for your post sharing your personal experience with your LSD and your application. Good stuff!
And Larry - thank for your post sharing your personal experience with your LSD and your application. Good stuff!
06-15-2012, 07:35 PM
#44
Developer
Thread Starter
To clarify this:
...that would be me. I am providing them one of my G28.13 boxes to tinker with, and I am having Gbox go through it at the same time so we are certain the gearbox is healthy when I test it. I thought that best as I wouldnt want some annomoly being blamed on the diff when actually the gearbox is at fault - so we have Gbox rebuild the whole thing to get a clean install.
Then I install it in the GWS and run it at 750 HP or so on the same tracks we are frequenting this season. Lap times, tires temps, transmission temps, and other performance markers will tell us how we are doing. The specs of the car it will be tested on are here:
http://www.928motorsports.com/our928sc/
Once a prototype is ready it is typically installed to the OEM carrier and returned to the customer for testing. Based on customer feedback changes can be made before units are slotted for normal production.
Then I install it in the GWS and run it at 750 HP or so on the same tracks we are frequenting this season. Lap times, tires temps, transmission temps, and other performance markers will tell us how we are doing. The specs of the car it will be tested on are here:
http://www.928motorsports.com/our928sc/
