Beanboy Posted October 16, 2006 Author Share Posted October 16, 2006 Here's the STI: http://www.subaru.com/common/news/article_details.jsp?file=prod_info_index.xml&articleId=20060414&attrNavItemId=NEWS_PRODUCT_INFORMATION "system uses a planetary-type center differential to provide a 41:59 torque split" "Increasing the locking factor keeps more power at the front wheels (max. 50:50 torque split with 100 percent lock-up selected)" Explain to me how a system that starts at 50:50 with an open diff can change the torque split when the limited slip locks when a system that starts at 41:59 becomes 50:50 at full lock? Remember, at full lock any of these systems acts like one driveshaft...ie 50:50 split at the center diff.* -B http://www.standardshift.com Link to comment Share on other sites More sharing options...
Beanboy Posted October 16, 2006 Author Share Posted October 16, 2006 Here's something from the EVO crowd talking about their 50:50 split center diff, along with the electronic locking coupler: D. How the Tarmac/Gravel/Snow switch influences the ACD Despite popular belief, this switch DOES NOT change the torque split. The differential is geared at 50:50 and cannot be changed by the push of a button. -B http://www.standardshift.com Link to comment Share on other sites More sharing options...
Beanboy Posted October 16, 2006 Author Share Posted October 16, 2006 here's decent explanation of how a center diff is 50:50 when fully locked: http://www.4x4abc.com/4WD101/awd.html Part time 4WD Vehicles always distribute torque inside their transfer case 50/50 to front and rear when the shifter is in one of the 4WD positions (Hi or Lo). Most of the time each of the 4 wheels gets 25% of the torque - that minimizes wheel spin. This system is very strong and reliable - unfortunately it can't be used on pavement. Should one of the wheels or one axle lose traction - the other axle will still receive a reliable supply of torque (up to 100%) through the transfer case The center diff is locked 50:50 yet either axle can receive 100% of torque. This is what I'm trying to get at with my comment about the center diff always being 50:50. Sorry for not explaining it well. Now, since the "lock" on our cars is a viscous system, it can't really lock, so either axle will never see the full 100%, so power can't fully transfer from the wheels that slip to the wheels that grip; but the idea that the center diff always stays 50:50 was the point of all this, hehe. -B http://www.standardshift.com Link to comment Share on other sites More sharing options...
SubiGT Posted October 16, 2006 Share Posted October 16, 2006 Warning, you have exceeded my attention span. Auto un-subscribing in progress. Many Shuvs and Zuuls knew what it was to be roasted in the depths of the Slor that day, I can tell you! Link to comment Share on other sites More sharing options...
GTTuner Posted October 16, 2006 Share Posted October 16, 2006 Put in on an ice rink and settle the lousy ten bucks! BYW, do you take cashiers checks? Link to comment Share on other sites More sharing options...
CasopoliS Posted October 16, 2006 Share Posted October 16, 2006 is this thread serious? RTFM This is from the 2005 Legacy GT Service manual. Also info on the Viscous LSD Link to comment Share on other sites More sharing options...
CasopoliS Posted October 17, 2006 Share Posted October 17, 2006 ha... shut this thread up I guess Link to comment Share on other sites More sharing options...
meier motor sports Posted October 17, 2006 Share Posted October 17, 2006 ok im with roa and cas on this one and not cause they are cool but because they are right. yes the subaru differential is 50/50. any diferential is when its going in a straight line. and open diff can send up to 100% to once side or front or back or however u want to look at it. a fully locked diff as in a 4X4 truck would be 50/50 or 0/100 only. no inbetween. (well actualy due to gear ratios it will be different tq to the wheels. but im talking at the shaft coming out the diff not at the wheels.) no the viscous coupling in the subaru or any other viscous will be say 90/10 split at the max. but that slipage will cause less viscousness in the fluid and come closer to a 50/50 split. as it comes closer to a 50/50 there is less slip and so the diff becomes more viscous and can get a larger split as in say 90/10 or 10/90... whatever. diffs send power where its easy. the viscousness part trys to stop that. most likely it will get to a half way point and become say a 30/70 split and stay there.. now a halladex system or a quiafee diff or whatever works differently. google the different types cliff notes. the subie diff can be but is not always 50/50 or 10/90 or 0/100 or any thing. its variable Link to comment Share on other sites More sharing options...
meier motor sports Posted October 17, 2006 Share Posted October 17, 2006 DIFFERENTIALS LIMITED SLIP DIFFERENTIAL (LSD) (VISCOUS COUPLING TYPE) DI-5 2. Limited Slip Differential (LSD) (Viscous Coupling Type) A: GENERAL The limited slip differential (LSD) automatically limits the differential action and distributes torque to the left and right wheels adequately to enhance driving stability when the left and right wheels are rotating at speeds different from each other during driving on a slippery road (muddy, snow-covered or slushy road) or cornering. B: CONSTRUCTION The V/C (viscous coupling) type LSD has outer plates and inner plates arranged alternately. Each outer plate is splined to the inside of the differential case at its outer periphery and each inner plate is splined to the outer circumference of the left side gear at its inner periphery. The outer plates are held in position by spacer rings while the inner plates can slide in the axial direction along the spline teeth. The space between the differential case and the left side gear is filled with a mixture of high viscosity silicone oil and air and hermetically sealed with X-rings. (1) Spacer ring (6) Pinion gear (2) Inner plate (7) Side gear (right) (3) Outer plate (8) Differential case (4) X-ring (9) Side gear (left) (5) Pinion shaft (10) X-ring (1) (2) (3) (4) (5) (6) (7) (9) (8) (10) DI-00295 DIFFERENTIALS LIMITED SLIP DIFFERENTIAL (LSD) (VISCOUS COUPLING TYPE) DI-6 C: OPERATION 1. WHEN RIGHT AND LEFT WHEELS ROTATE AT THE SAME SPEED During normal straight-ahead driving where the right and left wheels rotate at the same speed, the differential case and side gears rotate together, just as in conventional differentials. As a result, driving torque is distributed equally to the right and left side gears. DI-00296 DIFFERENTIALS LIMITED SLIP DIFFERENTIAL (LSD) (VISCOUS COUPLING TYPE) DI-7 2. WHEN RIGHT AND LEFT WHEELS ROTATE AT DIFFERENT SPEEDS When a speed difference occurs between the right and left wheels, the differential case and the left side gear do not rotate at the same speed any more. The speed difference between them corresponds to that between both the wheels. Because of the shear force caused in the silicone oil, a differential torque is then generated, which limits differential action. For example, if the left wheel spins due to small road resistance, a speed difference occurs between the right and left wheels. Since there is the V/C between the differential case and left side gear, a differential torque corresponding to the speed difference is generated in the V/C. This differential torque is transferred from the left wheel to the right wheel. As a result, a greater driving torque is distributed to the right wheel which is rotating at a lower speed. When the right wheel spins, the differential torque is transferred from the right wheel to the left wheel. Also in this case, a torque greater by the differential torque than the torque to the spinning wheel is transmitted to the wheel rotating at the lower speed. When left wheel spins DI-00297 DIFFERENTIALS LIMITED SLIP DIFFERENTIAL (LSD) (VISCOUS COUPLING TYPE) DI-8 When right wheel spins D: SERVICE PROCEDURES FOR LSD It is not recommended to disassemble the LSD assembly as component parts of LSD assembly are not available individually. DI-00298 Link to comment Share on other sites More sharing options...
rao Posted October 17, 2006 Share Posted October 17, 2006 So I'm not cool? Rob IF YOU CARE ABOUT YOUR CAR YOU SHOULD NEVER DRIVE IT Link to comment Share on other sites More sharing options...
bosco Posted October 17, 2006 Share Posted October 17, 2006 So I'm not cool? you are way cool, i don't know why anyone would agrue with you. btw after reading all this my head is starting to hurt. bosco Stay Stock Stay Happy Link to comment Share on other sites More sharing options...
rao Posted October 17, 2006 Share Posted October 17, 2006 you are way cool Thanks, I feel better now I was worried there for a minute . Rob IF YOU CARE ABOUT YOUR CAR YOU SHOULD NEVER DRIVE IT Link to comment Share on other sites More sharing options...
Beanboy Posted October 17, 2006 Author Share Posted October 17, 2006 a fully locked diff as in a 4X4 truck would be 50/50 or 0/100 only. no inbetween. cliff notes. the subie diff can be but is not always 50/50 or 10/90 or 0/100 or any thing. its variable So if you take a truck and it is locked 50/50 in 4WD and lift one set of wheels up and put the other set on a dyno, what % of torque will you see? You aren't going to see only 50%, the driveshaft is "one piece" You are going to see nearly 100%, even with the torque split in the center diff being physically locked at 50:50. It is variable as well then, sending nearly 100% of torque and any ratio inbetween depending on traction. Do the same thing to a Subaru, and you will see what, 90% or so since the viscous coupler can't fully lock, but that has nothing to do with the torque split of the center diff. ANY 4WD system with some type of limited slip device/locker should see close to 100% of torque transfer front or rear depending on which set of axles has most traction and how well the limited slip device holds, it has nothing to do with the set gear ratio of the center diff. -B http://www.standardshift.com Link to comment Share on other sites More sharing options...
rao Posted October 17, 2006 Share Posted October 17, 2006 If you do that with a locked center differential the car will fly off of the dyno, the drivetrain will break or both Rob IF YOU CARE ABOUT YOUR CAR YOU SHOULD NEVER DRIVE IT Link to comment Share on other sites More sharing options...
Beanboy Posted October 17, 2006 Author Share Posted October 17, 2006 Okay, the split second before the truck flies off the dyno/drivetrain breaks then... Remember one set of wheels are off the ground though, so if you can lock the truck down, it won't fly off the dyno. See where I am going with this though? A truck with a 50:50 split can send nearly 100% of torque to either set of wheels. Does that mean the center diff torque split is variable? No, just the phsyical property of power transfer through one "virtual" one piece driveshaft and available traction. Subaru is similar, except for the fact it can't physically lock, so with a 50:50 center diff split, it can send up to around 90% or so to either axle. -B http://www.standardshift.com Link to comment Share on other sites More sharing options...
CasopoliS Posted October 17, 2006 Share Posted October 17, 2006 I am having a limited slip installed in my pelvis for maximum jogging performance under wet and dry conditions. Link to comment Share on other sites More sharing options...
rc0032 Posted October 17, 2006 Share Posted October 17, 2006 ^ They call it joggin now? Best thread of the day Link to comment Share on other sites More sharing options...
Beanboy Posted October 17, 2006 Author Share Posted October 17, 2006 Hehe, it is... I suxors at explaining. -B http://www.standardshift.com Link to comment Share on other sites More sharing options...
forestir Posted October 17, 2006 Share Posted October 17, 2006 I am having a limited slip installed in my pelvis for maximum jogging performance under wet and dry conditions. Remember to fill with the correct viscous fluid. Link to comment Share on other sites More sharing options...
Beanboy Posted October 17, 2006 Author Share Posted October 17, 2006 Rao, do you agree to the following: Truck with locking center diff 50:50 Put rear wheels on dyno. Lift front of truck so front wheels are off the ground. Lock truck down tight. Torque number measured at rear wheels will be very close to 100% of possible engine output. Put front wheels on dyno. Lift rear of truck so rear wheels are off the ground. Lock truck down tight. Torque number measured at front wheels will be very close to 100% of possible engine output. Repeat the same with a Subaru with a 50:50 center diff with viscous coupler limited slip. Torque number measured at rear wheels with front wheels off the ground or front wheels with rear wheels off the ground will be 90% (or whatever the number is based on locking ability of the viscous coupler) of possible engine output. I don't see with this above thought process how this is true, and what many seem to believe: "Originally Posted by meier motor sports a fully locked diff as in a 4X4 truck would be 50/50 or 0/100 only. no inbetween. cliff notes. the subie diff can be but is not always 50/50 or 10/90 or 0/100 or any thing. its variable" -B http://www.standardshift.com Link to comment Share on other sites More sharing options...
ineedone Posted October 17, 2006 Share Posted October 17, 2006 So what you are saying is you were wrong? After reading this whole thread, that is what I took from it. Link to comment Share on other sites More sharing options...
Beanboy Posted October 17, 2006 Author Share Posted October 17, 2006 I give up... No, I am right. Do you agree with my above post? If you do, I am right. -B http://www.standardshift.com Link to comment Share on other sites More sharing options...
Beanboy Posted October 17, 2006 Author Share Posted October 17, 2006 Rao, I think the problem may be the fact you thought we just had a viscous center diff... "What do you think a viscous differential is?" question from a few pages ago. If we just had a viscous center diff, torque split would indeed change, but we also wouldn't be able to have 50:50 default either. -B http://www.standardshift.com Link to comment Share on other sites More sharing options...
LittleBlueGT Posted October 17, 2006 Share Posted October 17, 2006 I think the fact that this thread is in the generally funny section speaks for itself. Full tune of 68HTA, KSTech 73 MAF, Racer X FMIC and ID1000s................by the DataLog Mafia!!! Link to comment Share on other sites More sharing options...
Beanboy Posted October 17, 2006 Author Share Posted October 17, 2006 Hehe... My head was asplode if it were anywhere else, be triple the number of posts, hehe. -B http://www.standardshift.com Link to comment Share on other sites More sharing options...
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