Lift Bar location on Rear-end

[racefastnow]

How does the location of the lift bar where is mounts on the rear-end effect the car. The location form front to back. I noticed some cars the heims mount closer to the center when looking from the side view. We have ours like 4 inches forward when looking from side view.

[hucktyson]

It has zero effect , the rear end can't tell where that's bolted on. Moving it side to side would probably create more loading on the tire you move it closer to but front to back means nothing

[rakracing]

I questioned mark bush on that and was told left to right on rear or front to back on rear does nothing, where it attaches to frame front to back and left to right mean everything, and of coarse I had to try it anyway and found no advantage.

[billetbirdcage]

I questioned mark bush on that and was told left to right on rear or front to back on rear does nothing, where it attaches to frame front to back and left to right mean everything, and of coarse I had to try it anyway and found no advantage.

I think you misunderstood Mark or least I wouldn't think he'd say that, as left to right on the rear end will have a large effect on the left vs right tire load coming from the torque arm. Yes front to rear on the rear end isn't going to effect anything, but left to right on the rear end sure will.

[rakracing]

billet I asked him left to right on rear and was told by him and mark Richards it makes no difference , I asked because I run a grt and they had a lift bar that mounted on the left side bell , was going to try it but they talked me out of it

[racer2e]

Billet, are you saying that if the 5th coil stays in the exact same place, but the lift bar heims are moved left to right on the rearend, it will change the handling?

[MasterSbilt_Racer]

Billet, are you saying that if the 5th coil stays in the exact same place, but the lift bar heims are moved left to right on the rearend, it will change the handling?

I will answer for Billet. The answer is yes!

[fwdbite]

Boy i would think front ti back would have an effect also, just thinking of leverage point.

[MasterSbilt_Racer]

Boy i would think front ti back would have an effect also, just thinking of leverage point.

It only matters if it changes the distance from the axle of the 5th coil. If you keep that the same, attachment point on rear, front to back, doesn't matter.

[racer2e]

I am no expert, but my contention is that the side to side does not matter either. I believe that if you draw a line from the 5th coil back to the rearend that is perpendicular to the rearend, that is the point where the force is felt.

[rakracing]

I asked this question at the racewise school during class and they through testing found no advantage, if it worked we'd all be running the grt left mount torque arm, where it mounts to frame means alot

[billetbirdcage]

I am no expert, but my contention is that the side to side does not matter either. I believe that if you draw a line from the 5th coil back to the rearend that is perpendicular to the rearend, that is the point where the force is felt.

I know this argument well and understand the principle behind that theory.

However the many times I've tested it with different drivers, They always got a reaction to the way it drives off the corner.

[billetbirdcage]

I asked this question at the racewise school during class and they through testing found no advantage, if it worked we'd all be running the grt left mount torque arm, where it mounts to frame means alot

I know the left side TA you're talking about, while I never tried it myself but several people that supposedly tried it told me it made the car "Not turn in a 40 acre field". (Never tried it as in that particular arm or moving one that far to the left)

Billet Shrugs

[MasterSbilt_Racer]

It is pretty simple. The rear "feels" the forces where the torque arm is applied. Move it far enough left, and it is a clamp bracket for a clamped lr that just happens to lift on the car closer to the CG.

[MasterSbilt_Racer]

Or, draw a free body diagram for a torque arm when the car is in the gas. The rear applies torque at the attachment point to the rear. This is counteracted by the 5th coil. Now, all moments are balanced. However, we have a downward force vector at the 5th coil attachment, but no upward force vector to cancel it out. That missing vector is at the center of the rotation. It is the rear end resisting being forced downward into space.

When you then move on to do a free body diagram of the rear, the location of that point certainly matters.

[Bcollins82]

I asked this question at the racewise school during class and they through testing found no advantage, if it worked we'd all be running the grt left mount torque arm, where it mounts to frame means alot

Makes no difference and found no advantage are two totally different answers... Lol Many people have tried a left mounted lift arm, but as you said, the forward upper mount is very important, and it puts that mount too far left. And that usually means the LF is in the sky, and the car won't turn in a 40 acre field. But it absolutely makes a difference moving the rearend mount left to right. The GRT arm you speak of, is that the one that had no side brace and had 4 mounting points, 2 right and 2 left?

[rakracing]

its been a few years since I looked, thought it attached to the left only but I might be wrong, I understand what your all saying, I myself thought it would help drive off on the slick ,I have run lift bar between the brackets and 2" out on the right and didn't feel a difference, never tried full left.

[billetbirdcage]

Let me try to explain this more clearly, so we all understand the different points of view whether you agree or disagree.

From the lower 5th coil theory (lower 5th coil mounting point and a line 90 degree back to rear end is loading point):

I used to disagree with this as I wasn't looking at it correctly and argued about this and had MasterSbilt_Racer's view on it. I was looking at it from a view that the rotation is following the angle of the torque arm and not 90 degree's to the rear end. Picture the T/A mount in the normal position and say it's half way between the tires if the arm where to run straight forward then half the weight goes to each tire. Now say the torque arm runs at a 45 degree angle towards the RF and the 5th coil bottom is mounted so its 75% towards the RR vs the LR. The argument is that when the T/A lifts it is trying to twist the rear end clockwise (looking from the back of car) thus moving the loading point to that 75% of the way to the RR which is in line with the lower 5th coil mount, which leads to application of the theory in the post of racer2e.

While I understand that theory and feel it SHOULD be correct, I have not found it to work that way for what ever reason. Whether I'm wrong and got some misdiagnosed feel from the multiple drivers during multiple private tests, I don't know but all came to the same conclusion multiple times so sort of hard to discount that. So until I see otherwise I stick to my original conclusion that it makes a difference.

A person could also argue that a pull-bar, how many modified guys move the pull-bar only on the rear end and swear they can tell a difference without moving the front end??? If that theory is correct it should apply somewhat to a pull-bar also. While there are differences, it should be causing some of the same twisting (rotation on the rear end from the rear view) that a torque arm is doing and thus effect it similarly as a T/A.

I know of 2 guys (one modified and one late model) that I made parts/torque arms for that mounted between the bells of the Q/C instead of the right side so they could move it left to right just like a pull-bar. While I’m not aware that they ever did any private test sessions and adjusted it then (without the track changing so you get decent info from the change), but they swear it makes a difference, this could be further confirmation of my findings also if you want to use their race day finding as good info. I’m suspect of any non private session testing info and take it with a grain of salt as it isn’t always reliable but then again so can testing info as it’s subject to interpretation.

Also many times when I moved the TA left or right, I didn’t readjust the side link to the frame. So if I moved it right on the rear end, the end of the torque arm swung a little the opposite direction due to the side link usually mounted more to the middle of the arm. So that means if I moved the TA right at the rear end (too loosen on throttle) then I swung the lower 5th coil mount left. So if the lower 5th coil position/90 degree line is the load point, then I moved it the opposite way (towards the left thus tightening on throttle by increasing the load on LR) so if anything I should have gotten a the opposite reaction but didn't according to the drivers. However I can't say I have ever moved it more then 2" so my info could not be a clear as it might be with moving it farther to get a bigger reaction.

The GRT torque arm I think he was referring to was one that mounted to the left side of the bell and zig/zagged to the right and mounted the 5th coil in the standard location, but I believe they also later on came out with one that had 4 rod ends and mounted to both sides at the same time but still zig/zagged with standard 5th coil mounting. I was referring to the left side bell mounted one that I was told wouldn’t turn in a 40 acre field. I never heard of anyone trying the dual mounted one to comment on.

Billet (confused and shrugs even more), LOL

Remember my opinions are worth what you paid for it, NOTHING (Grin)

The debate continues.....

[rakracing]

don't strain yourself billet I was just stating what mark and mark both said cant say I totally agree with them but i haven't tested to try it either, I also question what it wound do under braking.

[Windy]

pullbar makes more difference left to right because of the spring closer to rearend and more to the left makes a difference..rayburn had a far left bracket also....ahhhh anyone remember the old fiberglass crossover lift bars back in the day,the driveshaft through the lift bar, or am i the oldest one here..L.O.L. ..windy..~V~..

[Brian Gray]

it maters only because of the changes that occur during acceleration and deceleration. for explanation reasons forget about the rotational loading just for this explanation.

lets use extreme examples. if you mounted the liftbar on the axle at the furthest point to the left say near the birdcage. during acceleration while the car rises on the lr how does this effect the movement of the 5th coil mounting point on the bar vs if the lift bar were to be mounted at the extreme right hand side.

it will change the location of the effective plane and you will have a varying degree of change depending on a multitude of things such as bar lengths , amount of indexing, and if the lift bar is stablized by the rear end or a side link.

moving the bar mounts left to right will have an effect on what path of movement the lifting point takes and visaversa for the 6th coil .

even with that said, in my opinion moving it along the plane of the center section is not enough to make a noticable difference in the dynamic .

hope this simplifies this for you.