First Look: IS-F LSD Swaps w/pics (been happening in Japan)
10-01-09, 09:43 AM
#17
Hmm maybe the prices on bulletproof is marked up and the costs of bringing it over here are included as well. Cuz i know when i use to order stuff from japan, it was never exact converted prices to our dollar. Have to add the duties and shipping costs for bringing it over here.
-Patrick
10-01-09, 04:24 PM
#18
I made a post about clutch-type LSD's in the Cusco thread. I'll leave the differentiation of the Cusco LSD's in that thread, but here is my explanation of clutch-type LSD's:
The above information applies to the OS Giken and TOM's differentials as well. These are true LSD's in that they literally limit slip.
The Torsen LSD is doesn't really limit slip. Instead, it biases torque based on traction. This is great unless until one wheel has a lower percentage of traction than the differential can distribute. Then a Torsen will act much like an open differential. Torsen's have some inherent benefits which are attractive to OEM's like very low maintenance and NVH. However, factory Torsens are often replaced in modified cars by clutch-type LSD's because they have many benefits of their own and have extremely high tolerance for abuse.
I hope this clears things up somewhat. If you have any questions I'll be happy to answer them to the best of my ability so ask away!
-Patrick
LSD's are somewhat complicated both in design and in function, so please feel free to ask questions if any part of my explanation is not easily understandable or coherent.
All of Cusco's LSD's are clutch-type. The clutches limit slip by creating friction when a wheel slips. When the car is standing still or coasting the clutches are pushed together by springs. The amount of pressure the springs create is called pre-load. Too little pre-load could allow slip in certain situations and too much pre-load can create unnecessary wear and chatter.
When torque is applied, special plates transfer more pressure to the clutch plates. In a 2-way LSD, the plates apply pressure during both acceleration and deceleration. This can aid stability during turn-in as well as when applying power. In a 1-way LSD, the plate only applies this pressure when the car is accelerating. This allows the car to have quicker turn-in. Your driving style, needs and goals will determine which option is best for you.
All of Cusco's LSD's are clutch-type. The clutches limit slip by creating friction when a wheel slips. When the car is standing still or coasting the clutches are pushed together by springs. The amount of pressure the springs create is called pre-load. Too little pre-load could allow slip in certain situations and too much pre-load can create unnecessary wear and chatter.
When torque is applied, special plates transfer more pressure to the clutch plates. In a 2-way LSD, the plates apply pressure during both acceleration and deceleration. This can aid stability during turn-in as well as when applying power. In a 1-way LSD, the plate only applies this pressure when the car is accelerating. This allows the car to have quicker turn-in. Your driving style, needs and goals will determine which option is best for you.
The Torsen LSD is doesn't really limit slip. Instead, it biases torque based on traction. This is great unless until one wheel has a lower percentage of traction than the differential can distribute. Then a Torsen will act much like an open differential. Torsen's have some inherent benefits which are attractive to OEM's like very low maintenance and NVH. However, factory Torsens are often replaced in modified cars by clutch-type LSD's because they have many benefits of their own and have extremely high tolerance for abuse.
I hope this clears things up somewhat. If you have any questions I'll be happy to answer them to the best of my ability so ask away!
-Patrick
10-02-09, 11:08 AM
#20
Lexus Test Driver
In simplified definition is 1 way LSD means that traction is dispursed to each wheel only when your on throttle, 1.5 way means 100% traction on throttle and 50% off throttle, 2 way means 100% both on and off throttle. This is just my knowledge of the differences between 1, 1.5, 2 way LSD's. Correct me if I'm wrong.
LSD (clutch type) can also be described by how much torque the distribute to either side when sensing slip and this torque can also be different depending on if you are accelerating or decelerating. typical for a street car is 60/40 like in the Porsche GT3.
10-02-09, 11:10 AM
#21
Lexus Test Driver
10-02-09, 01:47 PM
#22
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Just thought I'd chime in and instert a picture showing a basic diagram of how each clutch type diff works:
Had to make sure the link still worked before I added the info. The part in the middle would basically be the pinion inside the diff. The two outer blocks (forget what theyre called right now) engage the clutch discs and engage both wheels accordingly. 2 way, accel and decel are fully engaged regardless of speed (sorta) 1.5 way, accel is fully engaged , but decel is dependent on speed. 1 way, is fully engaged in acceleration, but will not engage on decel.
I hoped I helped explain a little better with the diagram.
Had to make sure the link still worked before I added the info. The part in the middle would basically be the pinion inside the diff. The two outer blocks (forget what theyre called right now) engage the clutch discs and engage both wheels accordingly. 2 way, accel and decel are fully engaged regardless of speed (sorta) 1.5 way, accel is fully engaged , but decel is dependent on speed. 1 way, is fully engaged in acceleration, but will not engage on decel.
I hoped I helped explain a little better with the diagram.
Last edited by GS Yakuza; 10-02-09 at 01:53 PM.
10-03-09, 02:35 PM
#23
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That's awesome there are going to be swaps available!
I went an saw a new 2010 and saw the LSD on there, which is the sole reason I didn't get a IS-F in the past. Now I'm in love. I'll be waiting for a Quaife diff when I start modding
I went an saw a new 2010 and saw the LSD on there, which is the sole reason I didn't get a IS-F in the past. Now I'm in love. I'll be waiting for a Quaife diff when I start modding
10-03-09, 07:49 PM
#24
Tech Info Resource
iTrader: (2)
??? A Quaife and a Torsen work exactly the same way. I can see removing the Torsen for a clutch type, but I wouldn't want to swap one torque biasing spool for another unless the replacement has better tuning ability (additional gearsets to change the TBR).
For you guys believing driving both wheels through a turn is better, think about what happens when the inside wheel is receiving equal torque to the outside wheel - the car goes straight! If you watch karts, you'll see the drivers leaning outside through the turns to lift the inside wheel and prevent this.
The LSD is giving you the ability to transfer torque when one wheel slips more than expected rather than spin the spool uselessly as an open diff does. You really don't want a lot of torque going to the inside wheel - just enough to keep from overwhelming the outside wheel and oversteering/understeering depending on your chassis setup. At the end of the day, it's just getting more rubber available to put down the power, but it still needs to be tuned.
The beauty of the OEM part is, it's tested by Lexus and tuned by Lexus to work on the car. It will be quiet, and require practically no maintenance other than diff oil changes.
The beauty of the clutch type spools is they can be tuned for the track you're running so you can squeeze maximum performance from them. They're going to eventually (some sooner, some later) chatter in street use, and if you never tune the thing, you'll wonder why you bought it 6 months later.
Think realistically about your application, and choose the appropriate tool for what you want to achieve.
10-03-09, 08:16 PM
#25
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lobuxracer
edit: They are 99.9% equivalent, mainly construction differences and SOTP feel. A conventional clutch pack or cone type will achieve similar end results, but its all about feel sometimes.
The Quaife uses a helical gear arrangement vs the more "common" worm gear. It comes to what bias ratio.
Similar philosophy for both -- on-power differentials, but different construction and activation manner. The Torsen has slightly different loading characteristics; but both have similar unload behavior (i.e. torque variance between the wheels when completely unloading the rear heightens the likelihood of swapping ends). It's akin to picking what measuring system you prefer; I'm just particularly accustomed to one subscribed school of thought.
edit: They are 99.9% equivalent, mainly construction differences and SOTP feel. A conventional clutch pack or cone type will achieve similar end results, but its all about feel sometimes.
The Quaife uses a helical gear arrangement vs the more "common" worm gear. It comes to what bias ratio.
Similar philosophy for both -- on-power differentials, but different construction and activation manner. The Torsen has slightly different loading characteristics; but both have similar unload behavior (i.e. torque variance between the wheels when completely unloading the rear heightens the likelihood of swapping ends). It's akin to picking what measuring system you prefer; I'm just particularly accustomed to one subscribed school of thought.
Last edited by okcfunky; 10-03-09 at 08:27 PM.
10-03-09, 11:03 PM
#26
Nice sniff Joe, you spend a lot o time on the internets 
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-- We are your Lexus suspension experts--
BCR - KW - PENSKE - OHLINS - HKS - GREDDY - STANCEPARTS
Links - Arms - SuperPro Poly Bushings - Solid Bearing Conversions - Motor Mounts
RB BBK's and 2P Rotors, G-Loc pads, Radium Fuel Systems
Custom Fabrication Design and Machining - Industrial 3D Printing - Laser Cutting
2018 USTCC Sportsman Class Champions - 2018 NASA ST5 National Champions
10-04-09, 05:10 AM
#29
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Yes clutch LSD's chatter very loud as I had a Spoon 1.5 way clutch LSD on my s2000 and it clunked/chatter in low speed turns...I maintained it everytime I went to track with it and changed the diff fluid often...Anyhow trust me if your not a track junkie with your F you would not want this clunk/chatter sound as it sounds like broken cv joints...especially on a luxury car.