Sway bar links (1 Viewer)

[nukegoat]

You said "spring rate"

The motion ratio is not going to be different, you'll just alter the starting point... but that doesn't matter other than slightly changing the loads on the end links. The anti roll effect will be unchanged as the load equalizes across, end to end... if you are concerned that the increased loading on the end links is going to cause them to fail, that's valid, but historically that is not what we have seen.

OK, I'm doing a poor job explaining on my phone, apparently.

Do you agree that for a given amount of suspension travel, the initial position of the sway bar arms will have an effect on how much rotation is induced to the main part of the bar? I hope so - because obviously there's even practical limits. You can't have suspension travel beyond 2x the arm length - the arms will be pointed straight up or straight down...

So given that, the relative amount of angular displacement for a given amount of vertical travel of the end of the arm is a function of the position(s) of the end of the arm(s). I agree, it's MORE complicated because the axle moves in another arc, the links themselves also relate the axle to the sway bar ends in an arc, and you have bushing compliance and other things, but to say that the starting position of the sway bar doesn't have an impact on the "effective linear spring rate" of the sway bar is incorrect.

 

[Somebodyelse5]

OK, I'm doing a poor job explaining on my phone, apparently.

Do you agree that for a given amount of suspension travel, the initial position of the sway bar arms will have an effect on how much rotation is induced to the main part of the bar? I hope so - because obviously there's even practical limits. You can't have suspension travel beyond 2x the arm length - the arms will be pointed straight up or straight down...

So given that, the relative amount of angular displacement for a given amount of vertical travel of the end of the arm is a function of the position(s) of the end of the arm(s). I agree, it's MORE complicated because the axle moves in another arc, the links themselves also relate the axle to the sway bar ends in an arc, and you have bushing compliance and other things, but to say that the starting position of the sway bar doesn't have an impact on the "effective linear spring rate" of the sway bar is incorrect.

I need to think on this a bit. Are you saying that with a torsion bar starting perpendicular, you'll get more angular displacement in the bar for any given vertical displacement of the end link? More displacement = more load. I can concede there.

Now, in application, are we approaching that regime where we are losing enough angular deflection for any given vertical displacement, that it will make a difference? I'm still going to say no. I just put an angle finder on my rear arm, can someone with extended rear links, and someone with factory links and no lift, provide something similar? I'd like to see what the delta's look like.

Note, my rig has OME heavies, Slee rear bumper, and factory end links. Sitting level in my sideyard:
I realize this number is not a perfect measurement, it isn't perfectly in line with the pivot of the end link or the bushing centerline on the bar... but seeing the difference when measured similarly on other rigs, we can use it to see how much angular change the extend arms induce.

 

[Mike NXP]

Geez way to over think this one

 

[Somebodyelse5]

Geez way to over think this one

tech to discuss tech? I overthink everything, and this is our safe place for use to nerd out

 

[yukon]

Geez way to over think this one

I think this is an excellent discussion on a relevant topic.
Go spend $250 on parts that don't (or do?!) make a difference, and weigh in on thread #2346 about wheel bearings, steering racks, and shocks instead of cluttering up good conversation.

 

[nukegoat]

Geez way to over think this one

You can go hang out on Facebook if you don't appreciate it

 

[nukegoat]

I need to think on this a bit. Are you saying that with a torsion bar starting perpendicular, you'll get more angular displacement in the bar for any given vertical displacement of the end link? More displacement = more load. I can concede there.

Now, in application, are we approaching that regime where we are losing enough angular deflection for any given vertical displacement, that it will make a difference? I'm still going to say no. I just put an angle finder on my rear arm, can someone with extended rear links, and someone with factory links and no lift, provide something similar? I'd like to see what the delta's look like.

Note, my rig has OME heavies, Slee rear bumper, and factory end links. Sitting level in my sideyard:
I realize this number is not a perfect measurement, it isn't perfectly in line with the pivot of the end link or the bushing centerline on the bar... but seeing the difference when measured similarly on other rigs, we can use it to see how much angular change the extend arms induce.
View attachment 2215781

I love it

 

[hoser]

From 4crawler.com:

"Sway Bar Operation:
So, why is it important that the sway bar end link matches the suspension lift? Ideally, you want the arms on the end of the sway bar to be sitting horizontal to the ground and the end links sitting vertical at rest. This ensures that you get equal up and down force on each side of the bar when the body/frame tips to the side. This is because as the bar twists under load, the arms will bend up and down at equal angles from horizontal. If the arms were at an angle below horizontal (as would be the case if the suspension has been lifted) the two bar end angles would not be equal, resulting in a lessened anti-sway affect.

As you can see in the sketch below, on the left hand side is a sway bar set up with the ends parallel to the ground (the dotted bar outline in the center shows the rest position). Under cornering load, the bar is twisted up by the suspension loads, F1 is the force of the outside side being compressed upward, F2 is the force of the inside side pulling the sway bar downwards. If the bar starts out horizontal and then the two effective bar end lengths (L1 and L2) are equal, since one end is twisted upward to the same angle as the other end is twisted downward. On the right had side is an illustration of what happens if the sway bar does not start out horizontal. This would be the case if a suspension lift were installed (thus raising the frame and the sway bar attached to it) without extending the end links. In this example, you can see that as the one end of the bar twists upward, it's effective length, L1, gets longer and longer as the angle is decreased towards horizontal. And the effective length of the end of the bar twisting down, L2, gets shorter as it's angle increases. Since the torque in the bar must necessarily be balanced, F1*L1 must equal F2*L2. Since L2 is less than L1, F2 must be higher than F1 to maintain the equality of the torque in the bar. This means that there is less force supplied by the sway bar to the outside suspension component in the turn so the vehicle will lean farther than it would if the forces and lengths were equal, as they are on the left side of the sketch. Thus if the purpose of a sway (or anti-roll) bar is to resist body roll, then the most efficient setup is to have the ends of the sway bar as close to parallel to the ground at rest as possible."

 

[reznunt]

pause, i need more popcorn.

okay go

 

[bluesquirrel]

I'm smart enough to understand, and dumb enough to comment.
+1 for extended sway bar links.
Answer me this:
Why would Toyota engineer OE swaybar links that were not perpendicular to the swaybar, at ride height?

 

[nukegoat]

I'm smart enough to understand, and dumb enough to comment.
+1 for extended sway bar links.
Answer me this:
Why would Toyota engineer OE swaybar links that were not perpendicular to the swaybar, at ride height?

They may have preferred the increase in roll resistance when pointing downhill (unloaded rear suspension)

Or just something dumb like ground clearance

 

[dividedan]

From 4crawler.com:

"Sway Bar Operation:
So, why is it important that the sway bar end link matches the suspension lift? Ideally, you want the arms on the end of the sway bar to be sitting horizontal to the ground and the end links sitting vertical at rest. This ensures that you get equal up and down force on each side of the bar when the body/frame tips to the side. This is because as the bar twists under load, the arms will bend up and down at equal angles from horizontal. If the arms were at an angle below horizontal (as would be the case if the suspension has been lifted) the two bar end angles would not be equal, resulting in a lessened anti-sway affect.

As you can see in the sketch below, on the left hand side is a sway bar set up with the ends parallel to the ground (the dotted bar outline in the center shows the rest position). Under cornering load, the bar is twisted up by the suspension loads, F1 is the force of the outside side being compressed upward, F2 is the force of the inside side pulling the sway bar downwards. If the bar starts out horizontal and then the two effective bar end lengths (L1 and L2) are equal, since one end is twisted upward to the same angle as the other end is twisted downward. On the right had side is an illustration of what happens if the sway bar does not start out horizontal. This would be the case if a suspension lift were installed (thus raising the frame and the sway bar attached to it) without extending the end links. In this example, you can see that as the one end of the bar twists upward, it's effective length, L1, gets longer and longer as the angle is decreased towards horizontal. And the effective length of the end of the bar twisting down, L2, gets shorter as it's angle increases. Since the torque in the bar must necessarily be balanced, F1*L1 must equal F2*L2. Since L2 is less than L1, F2 must be higher than F1 to maintain the equality of the torque in the bar. This means that there is less force supplied by the sway bar to the outside suspension component in the turn so the vehicle will lean farther than it would if the forces and lengths were equal, as they are on the left side of the sketch. Thus if the purpose of a sway (or anti-roll) bar is to resist body roll, then the most efficient setup is to have the ends of the sway bar as close to parallel to the ground at rest as possible."

View attachment 2215973

I love this s***, but admittedly my academic pursuits have been more biological than mechanical so no formulas to back this up.

Wouldn’t the force exerted on the end of the sway bar be a product of the length from it’s rotational axis to its connection on the end link and not the length along a horizontal plane as this sketch claims? Like a bike wheel?

 

[dividedan]

I love this s***, but admittedly my academic pursuits have been more biological than mechanical so no formulas to back this up.

Wouldn’t the force exerted on the end of the sway bar be a product of the length from it’s rotational axis to its connection on the end link and not the length along a horizontal plane as this sketch claims? Like a bike wheel?

Nevermind ignore my ignorance. We’re talking about forces exerted on the suspension components by the sway bar which is a different vector than the rotational force.

 

[nukegoat]

Nevermind ignore my ignorance. We’re talking about forces exerted on the suspension components by the sway bar which is a different vector than the rotational force.

Forgiven

 

[CruiseLanderAZ]

I'm smart enough to understand, and dumb enough to comment.
+1 for extended sway bar links.
Answer me this:
Why would Toyota engineer OE swaybar links that were not perpendicular to the swaybar, at ride height?

Perhaps by the same logic they put the starter under the intake

 

[bluesquirrel]

Perhaps by the same logic they put the starter under the intake

Touché
I'm not asserting by any means that everything is perfect, but perhaps the set up the sway bar links at perpendicular angles at ride height, because that's the way they function the best. I think that's a safe assumption, and I think it's a good idea to keep that geometry when lifting a vehicle. I am certainly willing to pay for it or build it myself.

 

[nukegoat]

Perhaps by the same logic they put the starter under the intake

Lol

 

[hoser]

Is this laid to rest?

 

[Somebodyelse5]

Is this laid to rest?

idk I was hoping someone would post some angle measurements and we could hash through it some more. I’ve been rebuilding jdm axles and drinking heavily all weekend

 

[LXPlore]

Here's an install video and my thoughts of the extended links and the replacement of the sway bar bushings.