How does pinion angle affect traction and launch?
Are you sure you are adjusting it the right way?
As an example:
My driveshaft points down towards my pinion 2 degrees (-2 degrees). In order for my pinion angle to be 0 (at rest) I would have to point the pinion up 2 degrees to meet the -2 (-2+2=0) degrees of the driveshaft. If I want 0 degrees under load I would have to set the pinion to 0 degrees and as the rear rises 2 degrees under load my pinion angle would return to 0.
John
As an example:
My driveshaft points down towards my pinion 2 degrees (-2 degrees). In order for my pinion angle to be 0 (at rest) I would have to point the pinion up 2 degrees to meet the -2 (-2+2=0) degrees of the driveshaft. If I want 0 degrees under load I would have to set the pinion to 0 degrees and as the rear rises 2 degrees under load my pinion angle would return to 0.
John
Last edited by JNorris; Apr 16, 2005 at 07:37 AM.
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Not sure I follow ..
My driveshaft and pinion make a V with an angle of 2 degrees.
I guess the theory for most cars is that under load the rear end will move or there may be some give in suspension components which causes the pinion to "twist" upward more making the V into a -- with a 0 degree angle..
My driveshaft and pinion make a V with an angle of 2 degrees.
I guess the theory for most cars is that under load the rear end will move or there may be some give in suspension components which causes the pinion to "twist" upward more making the V into a -- with a 0 degree angle..
Originally Posted by JNorris
Are you sure you are adjusting it the right way?
As an example:
My driveshaft points down towards my pinion 2 degrees (-2 degrees). In order for my pinion angle to be 0 (at rest) it would have to point the pinion up 2 degrees to meet the -2 degrees of the driveshaft. If I want 0 degrees under load I would have to set the pinion to 0 degrees and as the rear rises 2 degrees under load my pinion angle would be 0.
John
As an example:
My driveshaft points down towards my pinion 2 degrees (-2 degrees). In order for my pinion angle to be 0 (at rest) it would have to point the pinion up 2 degrees to meet the -2 degrees of the driveshaft. If I want 0 degrees under load I would have to set the pinion to 0 degrees and as the rear rises 2 degrees under load my pinion angle would be 0.
John
Last edited by Loudmouth LS1; Apr 16, 2005 at 09:00 AM.
Originally Posted by Magnus
Aren't we just measing the angle between the driveshaft and the pinion?
Ground reference is not required afaik.
Ground reference is not required afaik.
Originally Posted by Magnus
Aren't we just measing the angle between the driveshaft and the pinion?
Ground reference is not required afaik.
Ground reference is not required afaik.
Correct .
Both of the links below do a good job of explaining the process.
http://www.streetissuecustoms.com/pinionangle.html
http://www.carcraft.com/howto/91758/
Last edited by JNorris; Apr 16, 2005 at 07:44 AM.
Rossler trans had a good write up about setting pinion angle and I thought it did not actually measure the DS angle, but the angle that the tailshaft was and the bottom (flat part) of the pinion on the rear end.
And I can see how the trans could be one angle and the DS being a different one since their is a slip yoke and the U-joint on that side along with the U on the pinion side.
In my LT1 A4 car I did the measurement on the front of the DS where it went into the trans and the pinion area and set it at -2 but I think I was lucky,the car didnt make a lot of power and launched softly for some reason....never hit hard....unlike most of you guys.
And I can see how the trans could be one angle and the DS being a different one since their is a slip yoke and the U-joint on that side along with the U on the pinion side.
In my LT1 A4 car I did the measurement on the front of the DS where it went into the trans and the pinion area and set it at -2 but I think I was lucky,the car didnt make a lot of power and launched softly for some reason....never hit hard....unlike most of you guys.
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I use the flat part on the bottom of the rear as my plane for the rear end as well.
I'm just going to set it at 0 and be done with it. I find it hard to believe it moves at all in my car... however, I could be wrong as I am no expert.
madman is the expert here.
what is istant center???!!! Share your wisdom o wise one.
I'm just going to set it at 0 and be done with it. I find it hard to believe it moves at all in my car... however, I could be wrong as I am no expert.
madman is the expert here.
what is istant center???!!! Share your wisdom o wise one. LS1 Tech Stories
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Magnus are you coming to Atlanta????
Instant center is where the suspension is lifting the front end and planting the rear.
I know that there are alot of different ideas on pinion angle and what it does. The proper way that works for me is disregard the driveshaft AND the ttrans. Measure off the pinion(NOTHING ELSE) and set your pinion angle.
Magnus another possibility is now the car is actually hooking and bogging the motor. Why not trying to add air in the rear tires.
Instant center is where the suspension is lifting the front end and planting the rear.
I know that there are alot of different ideas on pinion angle and what it does. The proper way that works for me is disregard the driveshaft AND the ttrans. Measure off the pinion(NOTHING ELSE) and set your pinion angle.
Magnus another possibility is now the car is actually hooking and bogging the motor. Why not trying to add air in the rear tires.
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I agree with Mad man 100%, but would like add a little about instant centers.
Instant centers are unseen points in a moving suspension that can be drawn and scaled for blueprinting suspensions. They are called "instant" because they could be anywhere due to the dynamics of the suspension... When the suspension moves the component moves: Thereby, the movement can be plotted.
When we apply instant center to the rear suspension, Instant Center refers to the center of the arc that the rear housing makes as it moves through it's verticle movement, hence, instant center is an effective lifting point...The higher the instant certer the greater the load transfer and harder the car hits the tire.
When the front of the Torque arm is moved, even in very small amounts, the the pinion angle MUST remain the same. If the instant center is changed even a small amount the pinion angle will need adjustment.
The closer the pinion angle is to 0 the better the total efficiency of the combo. Pinion bind uses up power but is sometimes necessary to launch effectively... It is ALL just tools of the racer.
Instant centers are unseen points in a moving suspension that can be drawn and scaled for blueprinting suspensions. They are called "instant" because they could be anywhere due to the dynamics of the suspension... When the suspension moves the component moves: Thereby, the movement can be plotted.
When we apply instant center to the rear suspension, Instant Center refers to the center of the arc that the rear housing makes as it moves through it's verticle movement, hence, instant center is an effective lifting point...The higher the instant certer the greater the load transfer and harder the car hits the tire.
When the front of the Torque arm is moved, even in very small amounts, the the pinion angle MUST remain the same. If the instant center is changed even a small amount the pinion angle will need adjustment.
The closer the pinion angle is to 0 the better the total efficiency of the combo. Pinion bind uses up power but is sometimes necessary to launch effectively... It is ALL just tools of the racer.
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Sean, you run a mans tire while I'm still on a girlish 28x10.5x15 ET Drag...
I kinda understand the "theory".. but not enough to make sense of it.
What I do know is this.. My car is now not hooking beacuse its too hard for the front end to come up. I have enough seat time in the car to know what is exactly happening at launch.. and beacuse the front end is very "heavy" the tires just slip a little... Before the front end came up much easier taking some load off of the torque arm and thus shocking the tires a little less..
I'm gonna go back to 0 and just see how that works. The way my torque arm mounts will make my pinion angle the same at any small variance in height in the back..
I kinda understand the "theory".. but not enough to make sense of it.
What I do know is this.. My car is now not hooking beacuse its too hard for the front end to come up. I have enough seat time in the car to know what is exactly happening at launch.. and beacuse the front end is very "heavy" the tires just slip a little... Before the front end came up much easier taking some load off of the torque arm and thus shocking the tires a little less..
I'm gonna go back to 0 and just see how that works. The way my torque arm mounts will make my pinion angle the same at any small variance in height in the back..
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I set our car up with -3 since it has poly bushings everywhere. If we get some more track time I'd like to mess around with it a little more as the car since we bought it as a roller has only made maybe 20 passes total (only 3-4 were cam-only, never had a chance to tune the setup). Best 60' cam-only was a 1.38 but it did seem the suspension unloaded a little. I 'think' it hits the tires too hard off the line to where it unloads the suspension after the car gets moving though.
If I'm understanding right Instant center can also be controlled by lower control arms if relocated to where there is an upward plane from F-R, and not just torque arm itself?
If I'm understanding right Instant center can also be controlled by lower control arms if relocated to where there is an upward plane from F-R, and not just torque arm itself?
Well I used to hook a 27x11.5(10" tread) DOT Hoosier to 1.46's consistantly.
I consider myself lucky to never have done much suspension tuning.
set the pinion to zero, drop the tire pressure a 1/4# at a time.
You hooked a 1.37 that day, so you are probably on the ragged edge of traction.
It shouldn't take much to dial it back in.
REMEMBER- SMALL CHANGES!
I consider myself lucky to never have done much suspension tuning.
set the pinion to zero, drop the tire pressure a 1/4# at a time.
You hooked a 1.37 that day, so you are probably on the ragged edge of traction.
It shouldn't take much to dial it back in.
REMEMBER- SMALL CHANGES!
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Originally Posted by -Joseph-
If I'm understanding right Instant center can also be controlled by lower control arms if relocated to where there is an upward plane from F-R, and not just torque arm itself?
But keep in mind, to fully understand IC, you have to realize that each seperate component of the suspention that moves through an arc has it's own IC.
Think of it this way, If we have a long skinny triangle on it's long side and we anchor the bottom of the short side of the triangle so that it can only move in an arc around its anchor point. Then, if we push on the short side of the triangle it will move the long end of the triangle in a downward arc because the force of motion is above the anchor point. if we move the anchor point up higher on the short side of the triangle so that when we push on the short side a greater amount of force will be applied below the anchor point the long end of the triangle will be pushed up creating "lift".
Now, if we were to put a rod from the rear left connecting point of the lower controll arm to the rear right lower controll arm connecting point and mark a point directly under the torque arm that mark would represent the bottom of the short side of our triangle. The top of the torque arm would represent the top of the short side and the snout of the torque arm would be the long end of our triangle.
Hmm. maybe I better quit before I get everyone really confussed!
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if someone can get me dimensions and a sketch of a stock suspension I can draw it up in 3-D using CAD software. I can do motion, although I have never really used it......yet.
Frank
Frank
Originally Posted by Maggie
Instant center can be changed or "influenced" by any of the seperate components of (in this case) the rear suspension.
But keep in mind, to fully understand IC, you have to realize that each seperate component of the suspention that moves through an arc has it's own IC.
Think of it this way, If we have a long skinny triangle on it's long side and we anchor the bottom of the short side of the triangle so that it can only move in an arc around its anchor point. Then, if we push on the short side of the triangle it will move the long end of the triangle in a downward arc because the force of motion is above the anchor point. if we move the anchor point up higher on the short side of the triangle so that when we push on the short side a greater amount of force will be applied below the anchor point the long end of the triangle will be pushed up creating "lift".
Now, if we were to put a rod from the rear left connecting point of the lower controll arm to the rear right lower controll arm connecting point and mark a point directly under the torque arm that mark would represent the bottom of the short side of our triangle. The top of the torque arm would represent the top of the short side and the snout of the torque arm would be the long end of our triangle.
Hmm. maybe I better quit before I get everyone really confussed!
But keep in mind, to fully understand IC, you have to realize that each seperate component of the suspention that moves through an arc has it's own IC.
Think of it this way, If we have a long skinny triangle on it's long side and we anchor the bottom of the short side of the triangle so that it can only move in an arc around its anchor point. Then, if we push on the short side of the triangle it will move the long end of the triangle in a downward arc because the force of motion is above the anchor point. if we move the anchor point up higher on the short side of the triangle so that when we push on the short side a greater amount of force will be applied below the anchor point the long end of the triangle will be pushed up creating "lift".
Now, if we were to put a rod from the rear left connecting point of the lower controll arm to the rear right lower controll arm connecting point and mark a point directly under the torque arm that mark would represent the bottom of the short side of our triangle. The top of the torque arm would represent the top of the short side and the snout of the torque arm would be the long end of our triangle.
Hmm. maybe I better quit before I get everyone really confussed!
OK Maggie this is getting fun.What Would moving the front of the t/a up do???
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I think I got the jist of the first part, see the pics and let me know if they illustrate what you're refering to. I am assuming something is connected to the lower "short side" of the triangle? Lower torque arm mounting point?
I labeled each edge so that it can be better explained.
Still working on the second part....
I labeled each edge so that it can be better explained.
Still working on the second part....