Swaybar Lateral Locks

[PieEyedPiper]

Do the swaybars on DSMs shift position and slide in their bushings under hard cornering?

I came across a Whiteline JNZ thread in the vendors section today and I just began to wonder if there wasn't an easier[cheaper] way. I mean $31 is not a lot of money as far as suspension goes but I'm not even sure they will provide any purpose other than added weight, so:
http://legacygt.com/forums/showthread.php/lateral-swaybar-movement-fix-30276.html

Someone beat me to it. A brilliant way to monitor or test for sliding of the bar and then stop it in it's tracks by just cranking down the worm-clamp. Or go the McMaster route and pick up a pair of shaft collars.

I have a stock swaybar but I'm interested to see if there is any play so I'll be adding this one to my list. [Not the product, testing the concept]

 

[bjones18]

Is there a reason you do not want the bar to move laterally? Generally speaking, bar upsets (forged bump as lateral limiter) or hose-clamps on lateral stop are there for extreme off-road / durability scenarios where the bar can wrench itself out of position (due to lateral movement). I haven't heard of this happening on a handling track. If you hit 15 pot-holes out-of phase L/R at just the right speed you might get the bar to lodge out of position.

 

[PieEyedPiper]

Hopefully you will find this illustration illuminating.

 

[lilbro717]

I installed some shaft collars on my rear tanabe sway bar, just go that route

 

[bjones18]

I get the lateral shift concept... just not sure about the need to prevent it. Your bar will twist if it is shifted or not.

The only issue I have seen is when a bar shifts too far laterally... and the stabar link is now ~horizontal and the next bump causes that horizontal "sta-bar link" to jam the bar sideways (potentially breaking or disloging a mount). Again, this was on a full-vehicle MTS machine reproducing an off-road durability event with extremely violent wheel motions. Generally speaking, nobody drives on roads like this unless you are baja racing.

Lateral stops won't hurt anything, but they may squeak.

The original link suggested on that car (Subaru?) the bar might hit the caliper. I don't think this is the case for our stabar package.

 

[greengoblin]

We have beens in the bar to prevent it from moving to far. I'm sure lock would not hurt but I'm not sure they would help either. Here are some pics of a RM bar which has the same bends the OEM bar.

Ignore the measurements. This is a pic I post on link when I was calculating it's spring rate.

You must be logged in to view this image or video.

 

[PieEyedPiper]

My results are in line with that. Over 2 weeks in varying driving conditions with multiple measurements, I recorded a max of .65" of shift and an average of around .25".

I'm not too worried.

bjones, as silly as it is, the picture still illustrates the "why". The guy has to carry a load, much like the swaybar. It has a job to do and if it is moving and twisting or whatever it's not doing it very well. That is the reason you don't want it shifting 5 inches to the side, you can break links, wear them, reduce handling performance, eff up your corner weighting job, etc.
I want a stationary sway bar for the same reason race drivers use a harness and not a regular seatbelt. [TO REMAIN STATIONARY]

But to be clear, I use a regular seatbelt.

 

[TofastForU_99]

We have all the white line parts including the locks
Suspension/Steering

 

[bjones18]

My results are in line with that. Over 2 weeks in varying driving conditions with multiple measurements, I recorded a max of .65" of shift and an average of around .25".

I'm not too worried.

bjones, as silly as it is, the picture still illustrates the "why". The guy has to carry a load, much like the swaybar. It has a job to do and if it is moving and twisting or whatever it's not doing it very well. That is the reason you don't want it shifting 5 inches to the side, you can break links, wear them, reduce handling performance, eff up your corner weighting job, etc.
I want a stationary sway bar for the same reason race drivers use a harness and not a regular seatbelt.

But to be clear, I use a regular seatbelt.

I guess a dead horse needs a beating now and then. The analogy of the man is a bit different. He has a spine with disks that rupture giving pain, and the seatbelt analogy doesn't match the mechanics of the system.

A stabar twists with L/R suspension articulation (or body roll). The isolators at the body resist this articulation with opposing vertical loads. Horizontal loading (as resisted by flange-stops) is not part of stabar-function, but rather an error-state. This error-state doesn't affect most driving, hence many bars do not have them. If you want to improve bar efficiency replace the stabar isolator rubber with something really hard... such as a bearing (which I have done for testing - tight package) and enjoy the transmitted noise. This is possibly the biggest contributor towards efficiency that does not involve a major redesign of the bar package.

Body roll is not the enemy of HP driving, but rather weight transfer, positive-camber, and improper understeer are. Case & point is lifting an inside wheel under hard-cornering due to an overly stiff stabar (usually a front bar).

I guess I shouldn't have commented since I feel end-stops are not a big deal for most if not all DSM cars; effectively lenghtening a relatively useless thread. If you would like to know more about forces imparted to the body from stabar loading (and other suspension links) you can read SAE paper http://papers.sae.org/1999-01-0030 "Understanding vehicle roll using Mechanism Simulation Software."

 

[PieEyedPiper]

I guess a dead horse needs a beating now and then. The analogy of the man is a bit different. He has a spine with disks that rupture giving pain, and the seatbelt analogy doesn't match the mechanics of the system.

A stabar twists with L/R suspension articulation (or body roll). The isolators at the body resist this articulation with opposing vertical loads. Horizontal loading (as resisted by flange-stops) is not part of stabar-function, but rather an error-state. This error-state doesn't affect most driving, hence many bars do not have them. If you want to improve bar efficiency replace the stabar isolator rubber with something really hard... such as a bearing (which I have done for testing - tight package) and enjoy the transmitted noise. This is possibly the biggest contributor towards efficiency that does not involve a major redesign of the bar package.

Body roll is not the enemy of HP driving, but rather weight transfer, positive-camber, and improper understeer are. Case & point is lifting an inside wheel under hard-cornering due to an overly stiff stabar (usually a front bar).

I guess I shouldn't have commented since I feel end-stops are not a big deal for most if not all DSM cars; effectively lenghtening a relatively useless thread. If you would like to know more about forces imparted to the body from stabar loading (and other suspension links) you can read SAE paper Understanding Vehicle Roll Using Mechanism Simulation Software "Understanding vehicle roll using Mechanism Simulation Software."

You've taken a great deal of time(relative my investments) to discredit the thought that a stationary bar is a better bar.
I'm pleased you appear well-educated, I am. But, you see, none of the information you're trying to impart on me is necessary.

Maybe you should not have posted, as you indicated, since no one here thinks that it matters yet either. We all posted anyways, without regrets.

The only reason I started at you with retarded imagery and child-like analogies was because you straight up asked me why I'd even want such a thing as a more efficient bar. The fact that you asked and you might genuinely not understand is what lead to such simplistic examples that[heinously] don't take into account "ruptured discs" or "mechanics" that don't match. I wasn't trying to injure your pet horse.

I made this thread to test the idea that the bar might move. Vendors are trying to sell us the goddamned product so I wanted to know. I don't see the big deal - sorry if you were under the impression that this was a big deal or something. It was simply a fact finding mission.

But here's a thought. Since you do appear to have some background or education on the matter of suspension design do you have anything you could make a tech article out of? I've seen a few really crafty, quite intelligent posters in this section.. only to see them vanish or have their contributions muted. I look forward to more of your posts in this section.

 

[jtmcinder]

Yes, the RM bars on my 2G moved, especially the rear. I'd notice it after events with more turns one way than the other. Because the shifting is related to body roll in a particular direction, it implies a loss of roll resistance as the bar shifts to the point of least resistance for a particular direction of roll. Thus, a shifted bar will resist roll in one direction more than the other (until it shifts back), making the car less consistent and predictable.

However, since I didn't know about shift-stoppers like the Whiteline stuff, I never fixed this before selling the car. My Evo came with shift-stoppers.

Upshot, I'd get the stoppers if they are cheap.

 

[PieEyedPiper]

I was hoping you'd have a good data point for us. Thanks.

Do you think a stiffer bar is more prone to shifting?

 

[bjones18]

Here is a thought, remove your rear bar or put a soft (sponge) hockey puck between the isolator and body mounts. Then do a blind comparison (someone else makes the mod or doesn't make the mod). See if your driving consistency allows you to discern the difference. I have been through weeks of this type of training... blind comparisons where the driver must decide if a change has been made. It really isn't as easy as one might think even for huge changes (bar diameters, lateral compliance, roll centers, f/r tire pressures -a rather easy one, roll centers, roll steer, etc. It takes precise and consistent steering input/vehiclespeed, a high signal/noise ratio driving event,and the ability to feel yaw response & track steering wheel angle. Further, if the change is tested days later, you better have good notes and a repeatable test. Many times limit handling (either transient or ss) has the most pronounced effect. And a response difference from lateral stops? A real, (top professional) driver might find a difference, anyone else... my bet is no way.

As for tech articles I'd like to write some. First will probably be on crank-walk, I've written a few posts on it. Most handling stuff is well published (the SAE paper above is a rather novel approach) and can be gleaned quickly from Fred Puhn or Carroll Smith or for the scientists - Milliken. Getting a job that pays you to design and analyze chassis 40+hrs per week is how you really learn. But you have to put up with the bureaucracy which few "race" mentality guys can stomach.

 

[jtmcinder]

I'd guess that a stiffer bar is more likely to shift, but it's an educated guess, at best, based on my current theory of why they shift. (I won't write two paragraphs trying to convince you of how well-educated a guess it is; I'll just move on with life.)