37 replies to this topic

[Steve Scheifler]

I would be interested in tire temps and psi gains front vs rear with that setup on the 1.8.

[Rob Burgoon]

I would be interested in tire temps and psi gains front vs rear with that setup on the 1.8.

 

 

In other words "Booo-oooo-oooo-gus!"

 

It's a shame NASA requires the 1.6 bar for champs.  Otherwise I'd put the 1.8 bar back on.

[Steve Scheifler]

Since nobody seems to think it offers any advantage, no harm sending in your letters asking for it to be allowed. Worst case, I waste time playing with it and you get to sell me your unwanted bars. Seems to me it could be done immediately as a mere oversight in the original rule change.

[davew]

As I was the Chairman of the SMAC when the rule was changed, I can tell you first hand with 100% certainty that allowing the 1.6 an option on front sway bar was discussed and determined not to be a good idea. The term "not within class philosophy" applies. Definately NOT an oversight.

 

If you wish to experiment, do so on a test day or as an ITA class car.

[Tom Sager]

In other words "Booo-oooo-oooo-gus!"

 

It's a shame NASA requires the 1.6 bar for champs.  Otherwise I'd put the 1.8 bar back on.

 

We agree.  The biggest difference I noticed with the larger bar is that the car turns in more quickly and more consistently.  At Mid-Ohio last year I tried both bars same weekend and was faster with the larger bar and preferred the feel of the car. The car feels a bit "flatter" with the bigger bar.   I tried the smaller bar a few years ago at Road America in back to back sessions and didn't experience any real difference on the clock but the car seemed more consistent with larger bar.

[Tom Sager]

Second holes from the ends. Max stiff, shortest effective arms/least leverage to twist the center section.
Rear typically the opposite.

and the angle of the link is different (depending on spacers too) when using either bar or either hole in the 1.6 bar so that has to be factored in. 

[Rob Burgoon]

and the angle of the link is different (depending on spacers too) when using either bar or either hole in the 1.6 bar so that has to be factored in. 

 

How so?  Say you have a 45* angle in your end link.  What's the difference in sway stiffness between that and having it at 90*, other than forces trying to bend your end link tab?

[Diller]

I tried to fit a 1.6 front bar on my car this weekend to replace the nonadjustable 1.8 bar and really didn't like the angle of the end links. I used spacers to move the end link on the control arm all the way forward and could barely get the bolt through the swaybar. I don't even think it would get to the stiffer setting on the bar. Is this normal or am I missing something?

[Rob Burgoon]

I tried to fit a 1.6 front bar on my car this weekend to replace the nonadjustable 1.8 bar and really didn't like the angle of the end links. I used spacers to move the end link on the control arm all the way forward and could barely get the bolt through the swaybar. I don't even think it would get to the stiffer setting on the bar. Is this normal or am I missing something?

 

pics.

[Ron Alan]

This is normal with original NA style LCA with the 2 thin tabs. With a newer replacement LCA which is what all NB cars came with, a little easier to get a more straight up and down angle with spacers on one side of the thicker single tab.

 

Not sure where I got them but on one of my NA cars the end link had a sleeve that fit perfectly in between the 2 tabs and i then put the end link on the outside. BTW...there are different styles of end links out there...I only use a heim joint style vs a bushing or single ball joint style.

[Diller]

Sorry for no pics but I went ahead and put the old bar back on to get it setup for next weekend. I have some control arms from a 96 that I need to look at to see if the mounting tabs are any different. I am also using the heim joint style endlinks. The end links would fit in the softest setting but there was no more movement forward before it would bind. 

 

Thanks for the input.

[Bench Racer]

Another data point referencing a 1.6 anti roll bar on a 1.6.

 

The OEM front lower control arms had two thin tabs which I replaced with Mazda Motor sports parts which were/are one thicker tab. There are two anti roll bar end link adjustment holes. I used a spacer to the front side of the one thick tab to locate the end link bottom end mid distance between the two adjustment holes of the anti roll bar. A very slight angle horizontal to either hole. Never bent the bolt or single thicker control arm tab.

 

Rob, do a load calculation. Think in terms of a straight vertical end link would be the maximum load and a straight horizontal end link would be zero load. 

[Rob Burgoon]

 

 

Rob, do a load calculation. Think in terms of a straight vertical end link would be the maximum load and a straight horizontal end link would be zero load. 

 

Yeah, was thinking about that.  So if it's horizontal, you'd have zero load, I agree on that.

 

However, if you have a 45* angle and the arm moves up 1 inch, you're going to have a force attempting to push the bar through its mounts and bend the tab on the control arm.  Assuming your tab doesn't bend much at all, isn't the sway bar going to still have to move about an inch upward?

[Bench Racer]

Rob, I'll risk showing my ignorance with the anti roll bar end links as I did with my track tested thermocouple temperature numbers for an unwrapped tube from the AFM to the throttle body versus a wrapped tube. Yes readers, that is my sarcastic sense of humor.

 

For the moment forget about bending tabs and other stuff you mentioned. As for my comment of having an end link straight horizontal, you'll never have that condition. You couldn't have that condition when using two spherical ball at 90* to each other because the spherical ball on the lower control arm will BIND and break.

 

Under ideal conditions the anti roll bar arm will be parallel to a line drawn across the center lines of the front and rear axles. The end links will be perpendicular/90* to the anti roll bar arm and attached perpendicular/90* to the bolt attaching the spherical ball to the lower control arm. With all that said if you have a 100 pound load/force thru the end link, there will be no horizontal load. Provided there is no binding in the anti roll bar bushing or any place else you have an ideal anti roll bar to lower control arm condition. When the end link becomes anything other than 90* as previously mentioned there will be less than an ideal anti roll bar to lower control arm condition. Why, because when the end link is changed from the 90* condition the 100 pound load/force thru the end link is less than 100 pounds and there is a mathematical horizontal force, creating a less than ideal anti roll bar to lower control arm condition. If the condition was such that I mentioned where the end link was straight horizontal there would be no anti roll bar function.

 

Comments???   

[Rob Burgoon]

Rob, I'll risk showing my ignorance with the anti roll bar end links as I did with my track tested thermocouple temperature numbers for an unwrapped tube from the AFM to the throttle body versus a wrapped tube. Yes readers, that is my sarcastic sense of humor.

 

For the moment forget about bending tabs and other stuff you mentioned. As for my comment of having an end link straight horizontal, you'll never have that condition. You couldn't have that condition when using two spherical ball at 90* to each other because the spherical ball on the lower control arm will BIND and break.

 

Under ideal conditions the anti roll bar arm will be parallel to a line drawn across the center lines of the front and rear axles. The end links will be perpendicular/90* to the anti roll bar arm and attached perpendicular/90* to the bolt attaching the spherical ball to the lower control arm. With all that said if you have a 100 pound load/force thru the end link, there will be no horizontal load. Provided there is no binding in the anti roll bar bushing or any place else you have an ideal anti roll bar to lower control arm condition. When the end link becomes anything other than 90* as previously mentioned there will be less than an ideal anti roll bar to lower control arm condition. Why, because when the end link is changed from the 90* condition the 100 pound load/force thru the end link is less than 100 pounds and there is a mathematical horizontal force, creating a less than ideal anti roll bar to lower control arm condition. If the condition was such that I mentioned where the end link was straight horizontal there would be no anti roll bar function.

 

Comments???   

 

 

Ok, I think I'm getting closer.  There's a vertical component to the force and horizontal when the link isn't quite straight up.  The horizontal might be 10 lbs.  The tab on the control arm will act as a spring and deflect a tiny bit (10lbs worth), and whatever is left (not 90lbs, but close, need to do trig) will operate the sway bar and try to lift the inside tire.

 

 

So if your end link is crooked, you'll have extra spring rate from deflecting the control arm tab, but you'll be lifting the inside tire less.  Huh.

 

So if you wanted to harden the front sway beyond its hardest hole, would you try to make the end link more vertical or less vertical?

[Rob Burgoon]

cue the crickets

[Tom Hampton]

Ok, I think I'm getting closer.  There's a vertical component to the force and horizontal when the link isn't quite straight up.  The horizontal might be 10 lbs.  The tab on the control arm will act as a spring and deflect a tiny bit (10lbs worth), and whatever is left (not 90lbs, but close, need to do trig) will operate the sway bar and try to lift the inside tire.
 
 
So if your end link is crooked, you'll have extra spring rate from deflecting the control arm tab, but you'll be lifting the inside tire less.  Huh.
 
So if you wanted to harden the front sway beyond its hardest hole, would you try to make the end link more vertical or less vertical?

More vertical---more precisely, less perpendicular/tangential to the ARB axis of rotation. Remember all these forces and movements are really circular, and the forces are torques. so, what really matters is the included angle between the ARB and the end-link.  the relationship to gravity means nothing.

When the end link is perpendicular to the ARB, 100% percent of the force is translated into bending the sway bar, and therefore create the softest condition. All other conditions decrease the force that is transferred to the sway bar, effectively stiffening the anti-roll effect.

 

Note however, there is a complicating factor, which is the angle formed between the LCA and the end-link.  The same triangulation is occurring there.  The amount of force from the LCA that is passed through the end-link is again a function of that included angle.  So, the softest condition is going to be when the sum of the two included angles is maximized (closest to 90*2).  All other conditions will be more stiff.

[Tom Sager]

More vertical---more precisely, less perpendicular/tangential to the ARB axis of rotation. Remember all these forces and movements are really circular, and the forces are torques. so, what really matters is the included angle between the ARB and the end-link.  the relationship to gravity means nothing.

When the end link is perpendicular to the ARB, 100% percent of the force is translated into bending the sway bar, and therefore create the softest condition. All other conditions decrease the force that is transferred to the sway bar, effectively stiffening the anti-roll effect.

 

Note however, there is a complicating factor, which is the angle formed between the LCA and the end-link.  The same triangulation is occurring there.  The amount of force from the LCA that is passed through the end-link is again a function of that included angle.  So, the softest condition is going to be when the sum of the two included angles is maximized (closest to 90*2).  All other conditions will be more stiff.

Thank you for the detailed explanation.  Helpful and a much better answer than many of us could ever offer. 

 

Anyone that's looked closely at either sway bar will conclude that neither fit our cars very well and the 1.6 bar is the worst fit of the two.  Both need to be longer.