Thanks for the write up. I was on the fence about getting this mod, but after seeing the positive reviews I'm sold, so now I have to wait for it to travel across our beautiful country from California to my doorstep in Miami Florida

 

Take a staple... try to twist each end apart. You WILL GET some torsion. But the problem here is how it's held. If you're using your hands, you basically end up pulling the ends apart (tension/bend).

Now... consider this, the Progress bar has a long flat mounting location. This is different from the one in your picture. Why does this matter?

With the flat mount, it forces the bar arms to stay in a particular direction, twisting all three sides of the shaft.

Take the staple... and two pliers or better yet, vice grips. Grip them onto the ends of the staple, make sure there's NO slippage at all. Then, twist like you tried with just your hands... you'll see the torsion twist.

The only difference at that point is exactly that, with a 3rd location, it twists the main shaft and bends the two arms (depending on where the bushing is located, you'll need two). With only one bushing (in the center) or no bushings at all, it twists all three sides (main shaft and two arms), but again, this requires the mount to not slip/twist/move (flat 3 point mount vs 1 point pivot bushing).

In other words, yes, there is a torsion twist. Any other bushing only makes it twist in reference to that point, nothing more. I'll admit, it's not as straight forward as having the main shaft mounted onto a 3 point of reference.

edit: sorry, to really see the effect of the staple example... let go of one side and move the side you are holding onto.

 

This isn't exactly correct. The problem with your staple example is that you are providing torque to the system since you are twisting your fingers/pliers. The suspension cannot apply this twisting force; it simply applies a directional force on the end of one of the legs. The post you quoted is correct in that the sway bar needs a fixed fulcrum in order to operate the way it was intended.

To be more precise about this, use the following frame of reference:

Line from front-to-back of car is y-axis.
Line from driver's window to passenger's window is x-axis.
Line from floor to ceiling is z-axis.

A compressed suspension provides a force in the upward z-direction. However, this force is applied at the end of the bar that goes along the x-axis. Since there is no fixed fulcrum, there is no downward force to allow for rotational motion in the y-z plane where the bar makes the L-turn. However, the other side of the car provides a downward force which allows the bar to rotate in the x-z plane, which is not beneficial to handling.

If the bar was placed flush to the torsion beam, then it would end up slapping the beam whenever you come down from a speed bump. The saving grace of the Progress bar is that it has a decently-sized contact area where the bar meets the lower suspension brace. However, this is still a relatively small area, and is not nearly as effective as having an actual fulcrum. It also reduces the bar's ability to twist in the y-z plane.

 

Sorry, I still don't see how anything twists? I assert that this 'staple' shaped bar, if connected only at the two end-points, works exactly like a straight bar connecting the end points. The ends of the bar experience an up/down motion... when one end of the bar goes 'up' the whole bar just moves with it... like one of these doors:


Or, put a pen/ruler/whatever on the desk, lift one end. The other end is just a pivot-point.. it doesn't experience any significant force due to the lifting.. certainly not an upward [away-from-the-desk] force?









EDIT: I thought of the mother of all analogies! Something we all did as kids, which was to adjust the handle-bars on our sweet BMX!

So, can we agree that the RSB works by appling the same force to both sides? When one side is compressed, the other side is also compressed... thus keeping the car level and helping to distribute weight. This works exactly like bike handle-bars with the neck loosened: If you push forward on the left grip, the right grip also goes forward. Pull back on the right, and the left grip moves back too.



Now then, what happens when you disconnect the neck all together? Hold the disconnected handle bar up in the air, with one hand on each grip. What happens when you push the right grip forward? Does the left grip also go forward like we want?

 

I'll answer that for you: No, it doesn't

So why is Progress scamming people? Why don't the ship with hardware to attach the center of the bar?

 

Did you read the very last sentence I put? I know it was an edit, but it was edited well before you posted.

If you put both ends of the staple in hand grips that don't slip, let go of one side and move the other side up and down. Don't let the hand grip rotate and you'll see the other side moving up and down.

In the staple example, the other hand grip will rotate, but in the car, it won't because it's forced to stay in a specific direction do to the mounting on the axle.

Neither of you two appear to have very strong spatial cognitive abilities. But try for a moment to follow this simple example.

Put both of your hands out, face the palms towards each other. Imagine a "sway bar" opposite of you, with your hands as the end links.

In order for there to be NO torsion what so ever, and just a simple X-Z rotation, do you know what happens? You hands have to rotate and continue to face directly towards each other.

Because if don't rotate your hands to follow the other, you are providing, at the VERY LEAST, torsion on the arm, which can transfer onto the main beam depending on the various stiffness aspects of the material.

If either of you have RSBs... or access to one. Take a look at it.

Lift the car up, take out ANY "fulcrum" mounts.

You will see YOUR claims on the RSB, if it has pivot mounts, because you should notice that the pivot mount is doing EXACTLY that... pivoting on it's mount.

But if you have an RSB that has a flat mount, you will see torsion.

 

The utter lack of specific formulas, equations, geometry measurements, etc. Worries me here. I have the feeling that when Honda was at the drawing board asking how to make our car not handle like ass, there were some actuall figures done that fly right over most of our heads.

 

Hey goob, yeah, I did - sorry - just had trouble picturing it in my mind. I was incorrectly picturing the spring seat simply rising and falling, rather than actually changing angle relative to the trailing-arm. Fortunately it finally dawned on me what you were talking about when I read this from another thread:
Sorry for being so dense

 

The problem is... we are talking generalities here, not specifics.

How much do we need to know? Do we need to be civil/structural engineers to rotate tires? Okay, a little less ridiculous example is, do you need it to MAKE your own sway bar, as one member has?

No, if you can understand the concepts behind them, as I'm sure you don't have a degree in a field concentration of fluid dynamics when you made your own DIY turbo, do you?

For most of us, we can work in generalities. Example: add pre-made RSB... "handling better." *ding* *ding* *ding*

The specifics actually come in when you have to factor in time and cost to production. Because that forces you to select materials and understand their strength and weakness.

Take Progress RSBs or Swift springs. Some materials are stiffer than others, but be more brittle. Different diameters give different results. One can resist twisting, but bends too easily. And so on.

It would be GREAT if every consumer of every product made understood every detail that went into making it... but it doesn't happen that way.

Not to knock you, but take your DIY turbo. Did you build the compressor? No, you selected among a range of compressors knowing input and output pressures and efficiency. Not the structural/thermal strengths of the compressor fins, right? They were all "assumed" to be strong enough... otherwise you would've heard problems with them, correct?

But here's a thought for you... without equations, but with the conceptual knowledge of how things work... could you trial-n-error build a car similar to the Fit?

Yes, because if the concepts didn't work, the specifics can't exist.

 

I'm kind of just going to sit here on the fence in this one because I can be a bit of a polarizing figure it feels, and this conversation is good in my mind as it should at least provoke thought in all participating parties and that is something I really like to see here.

I would wager Lyon knows that there are inherent flaws in the design of his china turbo addicition, just like he knows that there are some flaws in the fashion in which the Progress bar is designed. I think he just has a mind that likes to question things, as do you Goobers, Whiskey, et al.

That doesn't mean neither functions, but instead they do so while we accept their imperfections. The merits of either can be debated.

In much the same way he likely questions the Progress bar, I pester him about his turbo choices lol Yet both seem to turn positive results for their respective parties.

FWIW I have machined/ported my own compressor & turbine housings.. clipped wheels changed thrust bearings and center cartridges, "mismatched" wheels from beyond the dictated golden ratios. But in spite of that I am not an expert like the folks working at Honeywell-Garrett, Holset, or Borg-Warner... I just have a ton of observations of my mildly educated experiments. Some hypotheses worked, some didn't. Some liked one particular setup, others "worked" on a variety of platforms.

Will you see any of my frankenstein bits in mass production? Well I hope not because none are patented.. in any event it's unlikely lol

I will also say that I have purchased a second hand Progress RSB for my own witnessing and pending the outcome of that I had intentions of possibly modifying it to compare. I expect it to have tangible results right out of the box, though I also expect that I could improve upon it.

Regardless, keep up the good banter, it may yield something yet more insightful for the spectators!

I hope that all makes sense, I am quite sleep deprived..

 

I guess what I was trying to say is...

you can use equations to dial into exactly what you what... and as DSM brought up, what flaws/issues you are willing to accept.

Without the equations, yet, with conceptual knowledge, you can come pretty close with:

I think I'll leave it at that.

edit: speaking of which... anyone remember where the animation for how the torsion beam works?

 

Yes, yes. I like this alot. I still crave data as always but my expections are too high here. Rather, it would be nice to see some data points. The same way I compare one half-baked idea to another half-baked idea, compare results. Now for me that's easy because there is little subjectivity in my results. 0-60 is 0-60. Spool time is spool time. IATs are IATs.

But here we are entering a realm where results are extremely hard to measure. There is no real standard for measuring what difference, if any, occurs. Only the subjectivity of individuals experiences, unless someone had the patience to do some slalom runs and perhaps an absolute grip (Gs) test.

This is why I default to theory, with no objective means of measuring the results all we can really do is fall back on theory.

I guess what I mean is that the effect of my turbo is specific and measurable. Here we first have to make sure we aren't just experiencing a mass placebo effect. Maybe we could get the 'stig' to give his informed opinion?

And really I apologize if I come off as a nay sayer it's really just in my programming to question the positive statement until sufficient probable proof is provided.

 

Don't give me so much credit! At the time I primarily selected the fleabay t25 because it has been successfully utilized in the r18. Really getting to know compressor maps came later. Once again though the outcome could be compared in an easily measured fashion. Just knowing that the R18 flows more air got me by to accept the t25 would work of the l15. Concepts ARE enough. But what do we really have to work with here? Are there any examples of this particular implementation of the RSB available on other twist beams where the results are measurable.

Individual experience is not to be completely discredited though. I have an exit ramp I take over and over again. When I switched to the megan springs my exit speed increased a full 5 mph. But even here that's not truly reliable. Was it due to the reduce body doll and lower CoG or just improved driver confidence. And does it mater which it is?

 

If you want some measurable effects of the RSB... it's simple.

Jack the rear of the car up, using the central jacking spot. Take off both wheels on an axle. Without a RSB, measure the current height of both sides (say from the bottom of the rotor to the ground. Then, using a second jack, and lift one side. First, move it enough to see a little rise on the opposite side. Then, measure the heights again. Jack it up some more and do another measurement. The more data, the better... but without some more stable platform for the car, you won't be able to go far up. Put the data in one column (or row) of a chart.

Then, install an RSB... and try jacking them up in about the same amount as before. Put the data into the adjacent column/row to see the change in the lift of the wheel when the opposite side is jacked up. If you couldn't match up the jacking heights, plot it into a graph.

If the "free" wheel is moving MORE with the RSB, then, it's doing it's job.

You can also use this data, if you know the relationship between the lean of a car and the traction capabilities of the tires.

some more edits:

There's a ramp I take from work. And when I had stock springs, I pushed that turn until I started slipping. So, I can tell you that when I put the Swifts in... I was able to take the turns quicker. And even more so, once I put the new tires on, since I did those two changes separately. So, even in an individual standpoint, the data can be valid, if you are testing "limits," so long as you show there's a change in the limit. It's true, that if you never took the ramp beyond a certain speed to feel vehicle limits, not driver limits... then comparison may not be statistically valid.

But as you said, sometimes driver confidence might be all you need.

 

If you reread my post, I do address the fact that the RSB has a large mounting plate. However, I am positing that a fulcrum would do the job much more efficiently due to simple physics.

 

Agreed - but if it was a center-pivot bar, it would need to redesigned - it could be thinner and provide the same effect.

 

sorry to bump an old thread, but it looks to be that you can install both! yeah, i get what whiskeysix is saying, mostly in part to me seeing most conventional sway bar setups utiziliing a mount or fulcrum point in the middle of the chassis. with the progress setup being free-floating, it looks like there would be a loss of motion from one side to the other when you're getting deflection on one side.

 

Best explanation for how they work:

 

I am interested in the rear sway bar as well. Does it fit for an 09 base AT model and who has the best price for it? Thanks.

 

Got my Progress rear sway bar for $160(free shipping) from CorSport.
K Series Parts.com sells it for $153(free Shipping), a lot cheaper but they're out of stock right now.