PGT Posted July 16, 2006 Share Posted July 16, 2006 From Zerosports..... auction link the translation and pics make me think it's a front LSD, but there's two Perhaps the axle cv's or something? http://img189.auctions.yahoo.co.jp/users/4/0/5/1/dogfightpro-img600x450-1152785874ro-rusenta-__2_.jpg http://img189.auctions.yahoo.co.jp/users/4/0/5/1/dogfightpro-img600x450-1152785881ro-rusenta-__1_.jpg Link to comment Share on other sites More sharing options...
mwiener2 Posted July 16, 2006 Share Posted July 16, 2006 they kind look more like ride height leveling thingys to me My Mods List (Updated 8/22/17) 2005 Outback FMT Running on Electrons Link to comment Share on other sites More sharing options...
Th3Franz Posted July 16, 2006 Share Posted July 16, 2006 Yeah they are for lowered cars.. -Franz The end of a Legacy http://www.youtube.com/th3franz Link to comment Share on other sites More sharing options...
PGT Posted July 16, 2006 Author Share Posted July 16, 2006 meaning what? where does it mount? what does it do? Link to comment Share on other sites More sharing options...
Opie Posted July 16, 2006 Share Posted July 16, 2006 Replaces the front ball joints... Link to comment Share on other sites More sharing options...
Deer Killer Posted July 16, 2006 Share Posted July 16, 2006 Because when the engineers designed the suspension, the designed it with a nominal ride height in mind. You should really fix things if you mess with their engineered geometry. Link to comment Share on other sites More sharing options...
oister Posted July 16, 2006 Share Posted July 16, 2006 When your car is lowered, the front lower arm pivots up higher when compared to stock height car. That new ball joint is physically taller than the stock piece, so if you put that in, you can restore the OEM geometry while maintaining the lowered ride height. (your entire spindel and wheels "move up" relative to the chassis) By maintaining stock geometry, you avoid bump steer. Link to comment Share on other sites More sharing options...
LittleBlueGT Posted July 16, 2006 Share Posted July 16, 2006 When your car is lowered, the front lower arm pivots up higher when compared to stock height car. That new ball joint is physically taller than the stock piece, so if you put that in, you can restore the OEM geometry while maintaining the lowered ride height. (your entire spindel and wheels "move up" relative to the chassis) By maintaining stock geometry, you avoid bump steer. Interesting info. Has anyone done this. I can understand the advantages of it. 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...
Waxiboy Posted July 16, 2006 Share Posted July 16, 2006 Nice explanation below from an old RC site: Predicting how a car will react when forces are applied at the tires is not easy. The force can be absorbed, split, converted into a torque... by all sorts of suspension components. To avoid all of this you can try to find the roll center of your car and try to predict the reaction of the car from there. A roll center is an imaginary point in space, look at it as the virtual hinge your car hinges around when its chassis rolls in a corner. It's as if the suspension components force the chassis to pivot around this point in space. Let's look at the theory behind it first. The theorem of Kennedy tells us that if three objects are hinged together, there are at most three poles of movement, and they are always collinear, i.e. they are always on one line. To understand what a pole really is, consider the analogy with the poles of the earth: as earth rotates, the poles stay where they are. In other words, the earth rotates around the imaginary axis that connects the two poles. Now this is a 3-dimensional analogy, in the case of the roll center we only need two dimensions at first. So a pole of an object (or a group of objects) is like the center point of a circle it describes. http://users.pandora.be/elvo/c2/RC1.gif If we look at the suspension of a typical R/C car, with a lower A-arm and an upper link, we see a bunch of objects that are all hinged together. These objects include the chassis, the upper link, the A-arm, and the hub. For now we consider the hub, the axle and the wheel as one unit. First, let's look at the chassis, the upper link and the hub. They are hinged together, so the theorem of Kennedy applies. The pole of the upper link and the hub is the ball joint that connects them, because they both hinge around it. The pole of the upper link and the chassis is also the ball joint that connects them. So if we now look at the chassis, the upper link and the hub, we have already found two of the three poles, so if there is a third one, it should be on the imaginary line that connects the other two. That line is drawn in red on the next drawing. The same applies to the bottom half of the suspension system, the pole of the lower A-arm and the hub is the outer hinge pin, the pole of the A-arm and the chassis is the inner hinge pin, so if there is a third pole it should be on the line that connects the other two. That line is also drawn in red . If your car uses ball links instead of hinge pins, the axis through the centers of the two balls makes up a virtual hinge pin. http://users.pandora.be/elvo/c2/RC2.gif If the two red lines intersect, the pole of the hub/wheel and the chassis is the intersection point I . Point I is sometimes referred to as 'virtual pivot', or as 'instantaneous center'. This pole can give us information about how the suspension moves. The distance from point I to the centerline of the tire is sometimes referred to as 'swing axle length' , it's as if the hub/wheel is attached to an imaginary swing axle which hinges around point I. Having that long swing axle would be equivalent to having the double wishbone-type suspension, but the actual construction would be very impractical. Nevertheless it serves as a good simplification. The swing axle length, together with the angle, determine the amount of camber change the wheel will experience during the compression of the suspension. A long swing axle length will cause very little camber change as the suspension is compressed, and a very short one will cause a lot. If the upper link and the A-arm are perfectly parallel to each other, the two red lines won't intersect, or, in other words, the intersection point I is infinitely far removed from the car. This isn't a problem though: just draw the green line (in the next drawing) parallel to the two red ones. The two red lines should always intersect on the side of the center of the car, if they intersect on the outside, camber change will be bizarre: it will go from negative to positive back to negative, which is not a good thing for the consistency of the traction. The wheel and the ground can also move relative to each other; let's assume the wheel can pivot around the point where it touches the ground, which is usually in the middle of the tire carcass. That point is the pole of the tire and the ground. As it is drawn, a problem might arise when the chassis rolls: the tires might also roll, and hence the contact point between the earth and the tire might shift, especially with square-carcass tires that don't flex much. Now we can apply the theorem of Kennedy again: the ground, the wheel and the chassis are hinged together, we have already found the pole of the wheel and the ground, and the pole of the wheel and the chassis. If the pole of the ground and the chassis exists, it should be somewhere on the line that connects the other two poles, drawn in green in the next drawing. http://users.pandora.be/elvo/c2/RC3.gif The same procedure can be followed for the other half of the suspension, as in the picture below. Again a green line will be found the pole of the ground and the chassis should be on. The intersection point of the two green lines is the pole of the ground and the chassis. (Circled in purple) http://users.pandora.be/elvo/c2/RC4.gif That point(purple), the pole of the chassis and the ground is also called the roll center of the chassis. It gives us information about how the chassis moves in relation to the ground. Theoretically, the ground could rotate around it while the chassis would sit still, but usually it's the other way around; the chassis rotates around it while the ground sits still. The roll center is also the only point in space where a force could be applied to the chassis that wouldn't make it roll. The roll center will move when the suspension is compressed or lifted, that's why it's actually an instantaneous roll center. It moves because the suspension components don't move in perfect circles relative to each other, most of the paths of motion are more random. Luckily every path can be described as an infinite series of infinitely small circle segments. So it doesn't really matter the chassis doesn't roll in a perfect circular motion, just look at it as rolling in a circle around a center point that moves around all the time. If you want to determine the location of the roll center of your car, you can either 'eyeball' it by imagining the lines and intersection points, or you can get a really big sheet of paper and make a scale drawing of your car's suspension system. Now that we know where the roll center (RC) is located, let's look at how it influences the handling of the car. Imagine a car, driving in a circle with a constant radius, at a constant speed. An inertial force is pulling the car away from the center point, but because the car is dynamically balanced, there should be a force equal but opposite, pulling the car towards the center point. This force is provided by the adhesion of the tires. http://users.pandora.be/elvo/c2/circ.gif In principle, the inertia force works on all the different masses of the car, in every point, but by determining the center of gravity (CG) it's possible to replace all of the inertia forces by one big force working in the CG. It's as if the total mass of the car is packed into one point in space, the CG. If the CG is determined correctly, both conditions should be perfectly equivalent. The forces generated by the tires can be combined to one force, working in the car's roll center. Viewed from the back of the car, it looks like this: http://users.pandora.be/elvo/c2/RCCG.gif Two equal, but opposite forces, not working in the same point generate a torque equal to the size of the two forces multiplied by the distance between them. So the bigger that distance, the more efficiently a given pair of forces can generate a torque onto the chassis. That distance is called the roll moment. Note that it is always the vertical distance between the CG and the RC, since the forces always work horizontally. http://users.pandora.be/elvo/c2/romo.gif The torque generated by the two forces will make the chassis roll, around the roll center. This rolling motion will continue until the torque generated by the springs is equally big, only opposite. The dampers determine the speed at which this happens. Note that the roll torque is constant, well at least in this example where the turning radius is constant, but the torque supplied by the springs increases as the suspension is compressed. (See chapter 'springs') The difference between the two torque's, the resultant, is what makes the chassis lean. This resultant decreases because the torque supplied by the springs increases. So the speed at which chassis roll takes place always decreases, and it reaches zero when both torque's are equal. So for a given spring stiffness a big roll moment will make the chassis roll very far in the corners, and a small roll moment will make the chassis lean over less. So at any given time, the size of the roll moment is an indication of the size of the torque that causes the chassis to lean over while cornering. Now; a different problem arises; the location of the roll center changes when the suspension is compressed or extended, most of the time it moves in the same direction as the chassis, so if the suspension is compressed, the RC drops. http://users.pandora.be/elvo/c2/rcchange.gif This little animation shows how the height of the RC changes as the suspension is compressed. The height of the CG also changes a little, because the position of all of the unsprung mass changes relative to the chassis changes. So it's really hard to tell if the roll moment actually increases or decreases. Also, when the car corners, and the chassis leans over, the RC usually moves away from the chassis' centerline. http://users.pandora.be/elvo/c2/rollbase.gifhttp://users.pandora.be/elvo/c2/RCcenter.gif Most R/C cars allow for the length and position of the upper link to be changed, and thus change the roll characteristics of the car. The following generalizations apply in most cases. An upper link that is parallel to the lower A-arm will make the RC sit very low when the car is at normal ride height, hence the initial body roll when entering a corner will be big. An upper link that is angled down will make the RC sit up higher, making the initial roll moment smaller, which makes that particular end of the car feel very aggressive entering the corner. A very long upper link will make that the roll moment stays more or less the same size when the chassis leans over; that end of the chassis will roll very deeply into the suspension travel. If not a lot of camber is used, this can make the tires slide because of excessive positive camber. A short upper link will make that the roll moment becomes a lot smaller when the chassis leans; the chassis won't roll very far. Until now, we've ignored the fact that there are two independent suspension systems in a car; there's one in the front and one in the rear. They both have their own roll center. Because the 'chassis' parts of both systems are connected by a rigid structure, the chassis, they will influence each other. Some people tend to forget this when they're making adjustments to their cars; they start adjusting one end without even considering what the other end is doing. Needless to say this can lead to anomalies in the car's handling. Having a very flexible chassis can hide those anomalies somewhat, but it's a far cry from a real solution. Anyway, the front part of the chassis is forced to hinge on the front RC, and the rear part is forced to hinge on the rear RC. If the chassis is rigid, it will be forced to hinge on the axis that connects both RCs (purple), that axis is called the roll axis. (red) http://users.pandora.be/elvo/c2/rolax.gif The position of the roll axis relative to the cars CG tells a lot about the cornering power of the car; it predicts how the car will react when taking a turn. If the roll axis is angled down towards the front, the front will roll deeper into its suspension travel than the rear, giving the car a 'nose down' attitude in the corner. Because the rear roll moment is small relative to the front, the rear won't roll very far; hence the chassis will stay close to ride height. Note that with a car with very little negative suspension travel (droop) the chassis will drop more efficiently when the car leans over. With the nose of the car low and the back up high, a bigger percentage of the cars weight will be supported by the front tires, more tire pressure means more grip, so the car will have a lot of grip in the front, making it oversteer. A roll axis that is angled down towards the rear will promote understeer. Remember that the position of the roll centers is a dynamic condition , so the roll axis can actually tilt when the car goes through bumps or takes a corner, so it's possible for a car to understeer when entering the corner, when chassis roll is less pronounced, and oversteer in the middle of the corner because the front RC has dropped down a lot. This example illustrates how roll center characteristics can be used to tune a car to meet specific handling requests, from either the driver or the track. In general, you could say that the angle of the upper link relative to the A-arm determines where the roll center is with the chassis in its neutral position, and that the length of the upper link determines how much the height of the RC changes as the chassis rolls. A long, parallel link will locate the RC very low, and it will stay very low as the car corners. Hence, the car (well at least that end of the car) will roll a lot. An upper link that's angled down, and very short will locate the RC very high, and it will stay high as the chassis rolls. So the chassis will roll very little. Alternatively, a short, parallel link will make the car roll a lot at first, but as it rolls, the tendency will diminish. So it will roll very fast at first, but it will stop quickly. And a long link that's angled down will reduce the car's tendency to roll initially, but as the chassis rolls it won't make much of a difference anymore. In terms of car handling, this means that the end where the link is angled down the most (highest RC) has the most grip initially, when turning in, or exiting the corner, and that the end with the lowest RC when the chassis is rolled will have the most grip in the middle of the corner. So if you need a little more steering in the middle of the corners, lengthen the front upper link a little. (Be sure to adjust camber afterwards) If you'd like more aggressive turn-in, and more low-speed steering, either set the rear upper link at less of an angle, or increase the front link's angle a little. Now you might ask yourself: what's the best, a high RC or a low one? It all depends on the rest of the car and the track. One thing is for sure: on a bumpy track, the RC is better placed a little higher; it will prevent the car from rolling from side to side a lot as it takes the bumps, and it will also make it possible to use softer springs which allow the tires to stay in contact with the bumpy soil. On smooth tracks, you can use a very low RC, combined with stiff springs, to increase the car's responsiveness and jumping ability. More about this in chapter 6. Link to comment Share on other sites More sharing options...
LittleBlueGT Posted July 17, 2006 Share Posted July 17, 2006 Holly crap! 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...
Wangspeed Posted July 17, 2006 Share Posted July 17, 2006 Elongated ball joints are not the right way to raise the roll center. Warren Link to comment Share on other sites More sharing options...
OhBe1 Posted July 17, 2006 Share Posted July 17, 2006 Perhaps, but this is a bolt-on. 06LOB2.5i MT, JDMRSB, GYTTs, HPS, LGT Mufflers & Leather Wheel, SubiMomo Knob, Inalfa Moonroof, Clutch Switch Bypass, DeDRLd, DeChimed, & Straight Headrest. Link to comment Share on other sites More sharing options...
Waxiboy Posted July 17, 2006 Share Posted July 17, 2006 Elongated ball joints are not the right way to raise the roll center. Warren +1 It should be done on the inboard side of the suspension arm. Link to comment Share on other sites More sharing options...
ebpda9 Posted July 17, 2006 Share Posted July 17, 2006 like removing the washers from the arm rear bushing, but those are about .25" only Link to comment Share on other sites More sharing options...
TSiWRX Posted July 17, 2006 Share Posted July 17, 2006 Damn, that was uber-cool, brother Waxiboy! Thumbs-up! ---- I just wanted to post this link to beeyatch-slap brother PGT - search, you noob! http://legacygt.com/forums/suspension-brakes/31328-roll-center-adjusters.html?highlight=roll Joel Gat, GOTO Racing's crew-chief, contributes an excellent technical digest - but honestly, I think that for ease of visual reference, Waxi's referenced source has him beat! Don't get me wrong - I've got mad-respect for Joel, but the diagrams are just too cool! <-- I love Winky, my "periwinkle" (ABP) LGT! - Allen / Usual Suspect "DumboRAT" / One of the Three Stooges '16 Outback, '16 WRX, 7th Subaru Family Link to comment Share on other sites More sharing options...
Waxiboy Posted July 17, 2006 Share Posted July 17, 2006 Thanks! I used to read a lot of suspension literature back in the days when I was racing R/C (radio controlled cars for you noobs ). Modern R/C cars will beat even a full Cusco set-up full scale car in terms of suspension adjustability :D You can adjust the following in an R/C: F&R toe, F&R camber, Wheelbase, Upper-arm length & angle, Droop, Ride height, Shock oil weight, Shock piston, Springs (progressive & linear), Shock preload, Shock angle (inboard & outboard), Ackerman link/angle, swaybars, and of course Roll Center. Link to comment Share on other sites More sharing options...
PGT Posted July 17, 2006 Author Share Posted July 17, 2006 I just wanted to post this link to beeyatch-slap brother PGT - search, you noob! :suckit: n00b! I didn't even think to search as I had never seen anything on it. Not sure how I missed that other thread... At least we got more in-depth info out of it, so it's not all for naught Link to comment Share on other sites More sharing options...
eVoMotion Posted July 17, 2006 Share Posted July 17, 2006 Great write up Waxiboy. Who is going to be the first to buy and install these units? Where can we buy them other than auction? Link to comment Share on other sites More sharing options...
TSiWRX Posted July 18, 2006 Share Posted July 18, 2006 :suckit: Sucking now, SIR! <-- I love Winky, my "periwinkle" (ABP) LGT! - Allen / Usual Suspect "DumboRAT" / One of the Three Stooges '16 Outback, '16 WRX, 7th Subaru Family Link to comment Share on other sites More sharing options...
TRS Posted July 18, 2006 Share Posted July 18, 2006 I'm waiting for 6 Gun Racing's version which will have both balljoint and tierod adjusters. They're supposed to be in production soon. More info from their web site: coming-soon-6-gun-racing-upgraded-ball 6-gun-racing-completes-subaru-ball weve-got-ball-joint-adapters-installed Plus a thread over on NASIOC. Link to comment Share on other sites More sharing options...
eVoMotion Posted July 18, 2006 Share Posted July 18, 2006 thanks! I'm waiting for 6 Gun Racing's version which will have both balljoint and tierod adjusters. They're supposed to be in production soon. More info from their web site: coming-soon-6-gun-racing-upgraded-ball 6-gun-racing-completes-subaru-ball weve-got-ball-joint-adapters-installed Plus a thread over on NASIOC. Link to comment Share on other sites More sharing options...
zildjiank Posted July 18, 2006 Share Posted July 18, 2006 I just wanted to post this link to beeyatch-slap brother PGT - search, you noob! http://legacygt.com/forums/suspension-brakes/31328-roll-center-adjusters.html?highlight=roll Oh snap! PGT you got told! And you're a mod!:lol: Link to comment Share on other sites More sharing options...
Xenonk Posted July 18, 2006 Share Posted July 18, 2006 didnt we have a similar thread on all of this earlier on roll adjusters?? regardless, thanks for posting that up Waxiboy. Keefe Link to comment Share on other sites More sharing options...
PGT Posted July 18, 2006 Author Share Posted July 18, 2006 yes, and I missed it. Thanks for pointing that out. Again. Link to comment Share on other sites More sharing options...
Wangspeed Posted July 18, 2006 Share Posted July 18, 2006 I'd let someone else guinea pig those on a real racetrack first, in real race conditions. Warren Link to comment Share on other sites More sharing options...
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