Which hole on this Antirock is firmer?

kmas0n

kmas0n

I have no idea what I'm talking about
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Trying to wrap my head around this little corner of physics.

Custom rear sway bar with the antirock mounted in front of the rear axle.

PXL_20220824_211838192.jpg


The AR comes with a little bracket that has 3 adjustment holes. Which is firmer... the one closer to the axle...

PXL_20220824_211844485.jpg


Or the one further away...
PXL_20220824_211908041.jpg


My brain is saying the closer the mount gets to the AR pivot point is going to be firmer. Even if its on the axle instead of the AR arm.

Thoughts?
 
Hmm? That would be thought too. Closer to the front arm pivot point would make it stiffer...
 
From the manual. Increasing the rate = stiffer

“The sway bar rate may be increased by moving the linkage toward the sway bar, thus shortening the arm. The sway bar rate may be decreased by moving the linkage toward the end of the arm, away from the sway bar, thus lengthening the arm. NOTE: Each hole
toward the sway bar that you move the linkage, you will lose approximately 1/2” of articulation.”
 
kmas0n said:
Trying to wrap my head around this little corner of physics.

Custom rear sway bar with the antirock mounted in front of the rear axle.

View attachment 353679

The AR comes with a little bracket that has 3 adjustment holes. Which is firmer... the one closer to the axle...

View attachment 353680

Or the one further away...
View attachment 353681

My brain is saying the closer the mount gets to the AR pivot point is going to be firmer. Even if its on the axle instead of the AR arm.

Thoughts?
Click to expand...

Moving the mounting hole on the axle side will have a negligable effect on the stiffness of the swaybar. You need to move the swaybar link mounting location along the swaybar arm to make the swaybar stiffer.
 
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LJGreg said:
From the manual. Increasing the rate = stiffer

“The sway bar rate may be increased by moving the linkage toward the sway bar, thus shortening the arm. The sway bar rate may be decreased by moving the linkage toward the end of the arm, away from the sway bar, thus lengthening the arm. NOTE: Each hole
toward the sway bar that you move the linkage, you will lose approximately 1/2” of articulation.”
Click to expand...

This would only apply if the holes were on the arm, as in the front.

There would be a slight mechanical advantage to having the link more perpendicular to the arm; achieved my moving the bottom of the link toward the axle. Easier to move = less stiff.
Moving it toward the axle will also increase the amount of travel, usually a good thing.
 
Last edited:
The angle can play an important role. When the link is perpendicular to the arm it exerts more torque on the bar like @LONGJP2 says. If different sides reach 90 at different times you can tune the imbalance. This is pretty common in stock suspensions like our Jeep. In a turn the inside wheel drops setting the link at about 90 degrees increasing the force or rate on the outside wheel reducing body roll even more than the size of the bar might otherwise do. It also sets the sway bar softer at ride height because the angle isn't 90. If you have a choice you want the bar to be at 90 degrees to the link when the axle is dropped about what you'd expect the inside wheel in a turn would be dropped. That'll give you the best anti-roll characteristics and a softer ride. At least that's what I'd aim for and what Jeep does on our rigs. If you are more concerned with turn-in setting the bar to 90 at ride height will give you better initial steering response but more overall roll in a turn and the bar will be a little stiffer at ride height. If you have really soft suspension and want a nice linear response 90 at ride height will give you that. If you have adjustable links in the front the stock bar is huge and the difference is pretty obvious if you play with the length. Obviously making sure things clear and getting full travel is most important and some people can't tell if they've got a flat tire but if you are used to your rig you'll be able to tell. The important part is unlike moving the link at the arm end which changes both the rate and position of the link this doesn't change maximum rate, it just changes where the rate maximum is in the travel. That's the physics, you asked.
 
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Great input, thanks
I'll go back to plan A, make a mount on top of the axle so the angle is acute at ride height and 90 degrees at about 2" of droop. This should make for a softer ride (as far as side to side tossing is concerned) but limit excessive lean.
 
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kmas0n said:
Great input, thanks
I'll go back to plan A, make a mount on top of the axle so the angle is acute at ride height and 90 degrees at about 2" of droop. This should make for a softer ride (as far as side to side tossing is concerned) but limit excessive lean.
Click to expand...

I need to go look at my rear AR out in the parts pile.
 
Edit never mind, I forgot this was about a rear Antirock.

Rock Jock's instructions verify the holes affect the stiffness of the Antirock which I have always firmly believed was their purpose. Mine has always been set to their loosest/most flexible setting which was the hole all the way at the end of the arm. And yes I fully understand moment and arm which is why I couldn't understand a few of the above arguments against that.

"Step 19 Install the new links as shown with the upper heim joint on the outside of the sway bar arm, and the lower heim joint on the inside of the differential housing tab. NOTE: current arms only have 3 holes - not the 5 as shown in these photos. The 3 holes in the new arms coincide with the back 3 holes on the older style 5 hole arms. On the 3 hole arms, we recommend your starting point setting be the front-most hole. That is the stiff est setting. If you would like to soften the sway bar, you may go back and move the heim joint back into one of the other 2 holes."
 
Jerry Bransford said:
Rock Jock's instructions verify the holes affect the stiffness of the Antirock which I have always firmly believed was their purpose. Mine has always been set to their loosest/most flexible setting which was the hole all the way at the end of the arm. And yes I fully understand moment and arm which is why I couldn't understand a few of the above arguments against that.

"Step 19 Install the new links as shown with the upper heim joint on the outside of the sway bar arm, and the lower heim joint on the inside of the differential housing tab. NOTE: current arms only have 3 holes - not the 5 as shown in these photos. The 3 holes in the new arms coincide with the back 3 holes on the older style 5 hole arms. On the 3 hole arms, we recommend your starting point setting be the front-most hole. That is the stiff est setting. If you would like to soften the sway bar, you may go back and move the heim joint back into one of the other 2 holes."
Click to expand...

For the front AR, yes. This thread is talking about the rear AR and the 3 holes on the axle side. There's no adjustments on the rear's arms.
 
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LJGreg said:
From the manual. Increasing the rate = stiffer

“The sway bar rate may be increased by moving the linkage toward the sway bar, thus shortening the arm. The sway bar rate may be decreased by moving the linkage toward the end of the arm, away from the sway bar, thus lengthening the arm. NOTE: Each hole
toward the sway bar that you move the linkage, you will lose approximately 1/2” of articulation.”
Click to expand...

Didn't know the loss of articulation part...thanks!
 
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