trigger1

iTrader: (28)

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?

Wyoming T/A

iTrader: (1)

yes.that is rite

trigger1

iTrader: (28)

Thanks.

cablebandit

iTrader: (37)

i think that is backwards.

XtremeLS1Z28

iTrader: (1)

Yup, Backwards!

GIZMO

iTrader: (8)

All you will be doing is changing pinion angle. Which is the only reason for having the adjustable bracket. Now if you were changing to a shorter torque arm.....

Daren

trigger1

iTrader: (28)

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....

SLowETz

iTrader: (12)

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

trigger1

iTrader: (28)

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.

GIZMO

iTrader: (8)

You can try moving the front of the torque arm up and down, but I really doubt that it will make much if any difference. If you get the angle too goofy it could put your rear suspension in a bind. A torque arm suspension is not the same as a four link suspension. I think that you will find that locating IC does not work the same way.
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

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.

GIZMO

iTrader: (8)

Everything that you just said contradicts itself.

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.

SLowETz

iTrader: (12)

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

GIZMO

iTrader: (8)

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?

GIZMO

iTrader: (8)

Also, where is the IC on a bone stock F-Body?

Fireball

iTrader: (21)

This would only be true if the front Torque arm mount wasn't floating. I have a chassis design book that defines the IC for a floating torque arm as the intersection of the LCA centerline with a line that goes perpendicular to the front mounting point of the TA.

kp

iTrader: (34)

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.

GIZMO

iTrader: (8)

Finally this thread is on the right track!

SLowETz

iTrader: (12)

Mmmm.... forgive my hard head but, on the BMR mount he's described, if you use the top most holes on the mount you are lengthening the bar's absolute length at the point/location on the bar in which it is pushing up.

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-