Author Topic: Sway Bar-Thinking Out of the Box?  (Read 6243 times)

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Offline Engineer

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Re: Sway Bar-Thinking Out of the Box?
« Reply #45 on: January 20, 2013, 10:24:50 PM »
So here is an outline of the linkage points.  Pardon the paint skills.



Now if we compress only the right side and move the linkage to this position, the top spring will increase the pressure on both sides, but the pressure on the right side will be more than the pressure on the left side because of the mechanical advantage.  (The right side is 90 degrees to the lever while the left is still around 45 degrees.)

« Last Edit: January 20, 2013, 10:29:42 PM by Engineer »

Offline gap351

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Re: Sway Bar-Thinking Out of the Box?
« Reply #46 on: January 20, 2013, 11:26:06 PM »
two things two remember the real name for a sway bar is an anti swaybar and this is all acting against that big lump of steel aluminium fuel oil and meat in the middle (granted not so much on an rc car) .It will still increase the spring rate on the other side and make more body roll, remember we are going around a corner ,it not just the wheel in bump as this is ride rate not roll rate and it will increase the ride rate just as you have explained

Offline Engineer

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Re: Sway Bar-Thinking Out of the Box?
« Reply #47 on: January 21, 2013, 07:09:10 PM »
two things two remember the real name for a sway bar is an anti swaybar and this is all acting against that big lump of steel aluminium fuel oil and meat in the middle (granted not so much on an rc car) .It will still increase the spring rate on the other side and make more body roll, remember we are going around a corner ,it not just the wheel in bump as this is ride rate not roll rate and it will increase the ride rate just as you have explained

More?  Surely you mean less.  It increases the spring rate on both sides but more on the depressed side.

So if the ride rate increases on the depressed side then that will create less body roll.  Or have an anti sway affect.



Fingers crossed...  Someone sees how it works.  ;D
« Last Edit: January 21, 2013, 07:10:42 PM by Engineer »

Offline BDKW1

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Re: Sway Bar-Thinking Out of the Box?
« Reply #48 on: January 21, 2013, 07:14:50 PM »
Now if we compress only the right side and move the linkage to this position, the top spring will increase the pressure on both sides, but the pressure on the right side will be more than the pressure on the left side because of the mechanical advantage.  (The right side is 90 degrees to the lever while the left is still around 45 degrees.)

What your describing would be a spring rate increase for a one sided suspension load. This I can see. Body roll from lateral cornering forces would be moving both bell crank pivots equally. There may be some resistance due to the mechanical progression curves but I doubt it would do much. I would have to draw that one up to see for sure. The upside that I can see is that it would be a dampened spring unlike a normal sway bar that screws up your spring rate.

Offline fabr

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Re: Sway Bar-Thinking Out of the Box?
« Reply #49 on: January 21, 2013, 08:23:08 PM »
Now you guys are talking about what I thought at the beginning ,I think.....................
"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

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"I fear the day that technology will surpass our human interaction. The world will have a generation of idiots" Albert Einstein  (IT'S OFFICIAL THAT DAY IS HERE NOW!)

Offline Engineer

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Re: Sway Bar-Thinking Out of the Box?
« Reply #50 on: January 21, 2013, 09:41:21 PM »

What your describing would be a spring rate increase for a one sided suspension load. This I can see. Body roll from lateral cornering forces would be moving both bell crank pivots equally. There may be some resistance due to the mechanical progression curves but I doubt it would do much. I would have to draw that one up to see for sure. The upside that I can see is that it would be a dampened spring unlike a normal sway bar that screws up your spring rate.

I agree 100%

It would be moving them equally, but the one being compressed would be getting more leverage while the one being uncompressed would be getting less leverage.  Basically increasing the spring rate on the compressed side and reducing it on the uncompressed side.   That is why the shape and geometry of those bell cranks are so important.

I agree that it would have very little affect, a few percentage points change in spring rate from one side to the other.

Offline Engineer

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Re: Sway Bar-Thinking Out of the Box?
« Reply #51 on: January 21, 2013, 09:45:33 PM »
Now you guys are talking about what I thought at the beginning ,I think.....................

I think so.

Last picture, just like the shock to A-arm discussion the closer you are to 90 degrees, the more resistance your spring and shock will develop.  So assuming the right side is compressed and the linkage was as shown in red below, the shock/spring will be pushing with the same pressure on both sides, but the right side is at 90 degrees, therefore putting maximum torque into the right linkage noted #2.  While the left side is at 45degrees to the linkage pivot and putting less torque into the left linkage noted #1.

You can also look at the distance from the blue line representing the shock center line down to the linkage pivot.  At #1 the distance is shorter thus it has less leverage, while at #2 the distance is greater thus it has more leverage.

In the scheme of things it isn't a very large difference but it will have some affect.

« Last Edit: January 21, 2013, 09:56:32 PM by Engineer »

Offline gap351

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Re: Sway Bar-Thinking Out of the Box?
« Reply #52 on: January 21, 2013, 09:54:43 PM »
ill put it another way the porsha LMP2 car in the pic i posted its the same set up just packaged diferent so why do they still run a sway bar?

Offline Engineer

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Re: Sway Bar-Thinking Out of the Box?
« Reply #53 on: January 21, 2013, 10:15:26 PM »
ill put it another way the porsha LMP2 car in the pic i posted its the same set up just packaged diferent so why do they still run a sway bar?

Probably tuneability.  I think BDKW1 pointed it out that the shock would provide damping to the anti sway.  The linkage ratios do not allow for any adjustability to the anti sway affects so the anti sway bar could be used to add or reduce the total anti sway resistance or to add preload to one side or the other.  I notice that there are still shocks on both sides so that total damping could be adjusted for each side independently and would function independently.  The only spring on the car is on the center shock so based on the linkage it would provide some anti sway, but the few percentage change probably isn't enough to eliminate the need for a sway bar.  The small amount of wheel travel on that car is going to make the effects even less.

Offline fabr

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Re: Sway Bar-Thinking Out of the Box?
« Reply #54 on: January 22, 2013, 06:02:57 AM »
Personally,I feel that the small amount of change is exactly what they are looking for given that the suspension it is used on has very little travel . IMO,that is the very fine adjustment they are looking for. WE ,on the other hand ,with long travel would likely see little to no benefit from such minute adjustments considering the infinite terrain we run on.
"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

-----------------------------------------------------------
"I fear the day that technology will surpass our human interaction. The world will have a generation of idiots" Albert Einstein  (IT'S OFFICIAL THAT DAY IS HERE NOW!)

Offline gap351

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Re: Sway Bar-Thinking Out of the Box?
« Reply #55 on: January 22, 2013, 08:15:35 AM »
the main reason they use them is on high speed tracks with long straights aero load can get so high it will push the car into the track(aero cars are sencitive to ride hight changes) but if they increase the main spring rate or preload the car would be less compliant a round corners on lower speed tracks they some times remove the spring (as with all race cars we try to run the softest springs we can)

the second reason is under acceleration it tends to load both rear tries more evenly ,genrally they are only on the rear of the car

Offline gap351

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Re: Sway Bar-Thinking Out of the Box?
« Reply #56 on: January 22, 2013, 08:24:20 AM »
Probably tuneability.  I think BDKW1 pointed it out that the shock would provide damping to the anti sway.  The linkage ratios do not allow for any adjustability to the anti sway affects so the anti sway bar could be used to add or reduce the total anti sway resistance or to add preload to one side or the other.  I notice that there are still shocks on both sides so that total damping could be adjusted for each side independently and would function independently.  The only spring on the car is on the center shock so based on the linkage it would provide some anti sway, but the few percentage change probably isn't enough to eliminate the need for a sway bar.  The small amount of wheel travel on that car is going to make the effects even less.

there are two torshon bars as well