Quick instant center question
Quick instant center question I have a BMR torque arm relocation bracket. With the adjustable front bracket. I just need to double check myself, moving the mount up towards the top will bring the IC closer under the car, while moving it down will move the IC out further infront of the car correct?
Really, I was under the assumption that you adjust your pinion angle with the adjuster on the REAR mounting point on the torque arm. And you can adjust your IC with the front mount on the torque arm. Please elaborate Gizmo....
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That ^ is correct. PA is adjusted between LCA's and REAR TA mount adjustment.
Get your wheels where you want them (centered in wheel well), and THEN adjust PA at the rear TA mount. Then play w/IC at front TA mount. Back check your PA after adjustments to IC.
Here are a couple links that may help-
http://www.rosslertrans.com/Tips/Pinon.htm
http://www.wolferacecraft.com/pinionangle.aspx
Get your wheels where you want them (centered in wheel well), and THEN adjust PA at the rear TA mount. Then play w/IC at front TA mount. Back check your PA after adjustments to IC.
Here are a couple links that may help-
http://www.rosslertrans.com/Tips/Pinon.htm
http://www.wolferacecraft.com/pinionangle.aspx
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Verdad Gallardo Thanks a lot man, I was having problems with a dead hook issue. I am going to try more RPM and more tire psi first and if that doesn't solve it I was going to try and bring the IC a little further out infront of the car. Right now I have the pinion angle at -2 degrees.
Originally Posted by trigger1
Really, I was under the assumption that you adjust your pinion angle with the adjuster on the REAR mounting point on the torque arm. And you can adjust your IC with the front mount on the torque arm. Please elaborate Gizmo....
Either way, once you get your adjustable bracket in the optimum position, I would suggest drilling it and bolting it so it can't move around (Or weld it).
Take Care,
Daren
TECH Enthusiast
Joined: Jul 2003
Posts: 697
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From: Evansville, IN
Actually moving the front of the torque arm up or down does move the Instant center. Thats why people run shorter torque arms, because it moves the instant center towards the back of the car, which will make the car hit harder off the line. You can ask any of the suspension guru's and they will tell you the same. Do a little searching and you can find many threads where Madman gives some very good explainations of IC.
Originally Posted by smoknta
Actually moving the front of the torque arm up or down does move the Instant center. Thats why people run shorter torque arms, because it moves the instant center towards the back of the car, which will make the car hit harder off the line. You can ask any of the suspension guru's and they will tell you the same. Do a little searching and you can find many threads where Madman gives some very good explainations of IC.
TECH Enthusiast
Joined: Jul 2003
Posts: 697
Likes: 0
From: Evansville, IN
Would you like to explain yourself. The instant center of a car is found be looking at the side of the car. Draw a line through the center of the pinion yoke up to the center of the front mounting point of the torque arm. Then draw a second line through the mounting points of the control arm. Where the two lines intersect is where the instant center is located. You can move your instant center several ways. One is to get Lower control arm relocation brackets. This will move the instant center back. You can also move the IC by shortening the torque arm or by moving the front mounting location up or down.
IC = 
voodoo magic 
Where is JRP and the search button when you need them
...or better yet, where's MadMan when you need him
My bad.... there's Brian >>>>>>>>
I'm no suspension guru and will never claim to be, but basic geometry is just that. Remember the lever doing more work?
In lieu(sp?) of a short TA, moving the TA up will hit the tires harder, but using the lowest adjustment point will move/transfer more weight.
Smoknta has not contradicted himself near as I can see. But what do I know.... I am legally blind
voodoo magic Where is JRP and the search button when you need them
...or better yet, where's MadMan when you need him
My bad.... there's Brian >>>>>>>>
I'm no suspension guru and will never claim to be, but basic geometry is just that. Remember the lever doing more work?
In lieu(sp?) of a short TA, moving the TA up will hit the tires harder, but using the lowest adjustment point will move/transfer more weight.
Smoknta has not contradicted himself near as I can see. But what do I know.... I am legally blind
Last edited by SLowETz; May 29, 2006 at 09:37 PM.
OK, so you have have two identical cars one has a short torque arm and the other has a long torque arm. Both torque arms are at the exact same height. Which car will hit the tires harder?
Joined: Nov 2001
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From: Cecil County Raceway!!!
Originally Posted by smoknta
Would you like to explain yourself. The instant center of a car is found be looking at the side of the car. Draw a line through the center of the pinion yoke up to the center of the front mounting point of the torque arm. Then draw a second line through the mounting points of the control arm. Where the two lines intersect is where the instant center is located. You can move your instant center several ways. One is to get Lower control arm relocation brackets. This will move the instant center back. You can also move the IC by shortening the torque arm or by moving the front mounting location up or down.
Since the torque arm slides on the front mount all it does is push up. No matter where you put it on that mount it will push up in the exact same place. If the front of the arm was solid mounted then moving it up and down would change the IC.
Shorter torque arm will change things since its pushing up in a different place. Fireball's way of finding the IC of a torque arm car is correct.
Shorter torque arm will change things since its pushing up in a different place. Fireball's way of finding the IC of a torque arm car is correct.
Originally Posted by kp
Since the torque arm slides on the front mount all it does is push up. No matter where you put it on that mount it will push up in the exact same place. If the front of the arm was solid mounted then moving it up and down would change the IC.
Shorter torque arm will change things since its pushing up in a different place. Fireball's way of finding the IC of a torque arm car is correct.
Shorter torque arm will change things since its pushing up in a different place. Fireball's way of finding the IC of a torque arm car is correct.
If you use the bottom most holes, you are shortening the bar's length.
All be it a small/nominal amount of adjustment(aprox. 6' vertically top to bottom worth of adjustment)but it will change IC to a degree. To what degree/amount it changes could be figured w/some math which I have not done.
I do know from personal experience w/this bar and trying different mounting locations that it seems to hit the tire harder at any given rpm using the top mounting holes, and conversly will try to raise the front end harder at any given rpm when using the same shock settings on the lowest mounting hole..... again..... FWIW-
Last edited by SLowETz; May 30, 2006 at 05:42 PM.