Cortex Torque Arm Racechrono Track Review

[Whiskey11]

The UCA mount can change the AntiSquat drastically. Should have clarified.

The rules state that only the axle side UCA mount can be moved. The UCA mount could arguably be replaced but you can't use any other mount than the factory equivalent.

 

[barbaro]

So through all the drang and sturm, political and personal attacks, the hyper-technical over-analysis, the thread shut down, and finally talking to the man himself, you have been persuaded? But I think you said you are not sure whether the torque arm has any advantage over the three link setup? Get the torque arm and you won't say that. If you don't like it, I will buy it from you. I can easily sell it out here. I wish you luck

 

[sheizasosay]

So through all the drang and sturm, political and personal attacks, the hyper-technical over-analysis, the thread shut down, and finally talking to the man himself, you have been persuaded? But I think you said you are not sure whether the torque arm has any advantage over the three link setup? Get the torque arm and you won't say that. If you don't like it, I will buy it from you. I can easily sell it out here. I wish you luck

That political "stuff" was definitively what turned the switch for me.

Is my question too complex to be answered? I don't think it is. I'll call him myself. It's not too much to ask to have the designer to answer that question. He's certainly got the qualifications. He should be able to. Then we can skip my constant asking of the same exact question asked over and over and over.

 

[Whiskey11]

So through all the drang and sturm, political and personal attacks, the hyper-technical over-analysis, the thread shut down, and finally talking to the man himself, you have been persuaded? But I think you said you are not sure whether the torque arm has any advantage over the three link setup? Get the torque arm and you won't say that. If you don't like it, I will buy it from you. I can easily sell it out here. I wish you luck

Actually, the reason I'm planning on buying one is because of the limitations the 3 link has in my case. If the rules were 100% open ended for modifying control arm angles I would put money down that a 3link is just as capable but since I can't change ANY of the angles, I'm left with little other choice.

The other reason is because you didn't answer our questions, so maybe I can add more to this conversation beyond subjectivity or at least provide some form of description that is easier to quantify.

The fact that Filip was kind enough to answer after hours just insured that he gets my business and not Griggs Racing.

Sheizasosay let us know what he tells you!

 

[Sky Render]

What low-profile Cortex diff cover are you referring to?

 

[Whiskey11]

What low-profile Cortex diff cover are you referring to?

http://www.cortexracing.com/shop/ford-8-8-10-bolt-rear-end-girdle-super-low-profile/

He mentioned that the reasoning behind it was because of the way the bolts for the torque arm matched up to the diff cover. Flat. I don't see why it wouldn't work with the stamped steel one other than the fact that the torque arm would be offset forward about a quarter of an inch. Maybe a spacer can be designed to fit there if necessary that replicates that mounting solution on the stamped diff cover.

 

[sheizasosay]

I emailed Filip. He has a link to this thread and I asked him a few questions. I imagine he's trying to catch up on the thread. These are the questions I asked him:

Can you please explain the advantages of your torque arm vs a 3-link with aftermarket articulating joints (we will say heim) for S197?

What can I accomplish with your TA that I can not with a UCA with an adj mount that can add A-S?

Given the exact same car with your TA and PHB vs the same car with UCA with adj mount and PHB what difference could one expect in lap times?

What anti-squat % does your TA generally deliver?

What is the available A-S range that can be adjusted with a conventional-spring equipped car (non height adjustable) ?

Thanks for your time. I plan to post your answers on a forum; as the questions don't seem to be able to be answered satisfactorily and I would like to skip assumptions and subjective ness.

 

[barbaro]

Actually, the reason I'm planning on buying one is because of the limitations the 3 link has in my case. If the rules were 100% open ended for modifying control arm angles I would put money down that a 3link is just as capable but since I can't change ANY of the angles, I'm left with little other choice.

The other reason is because you didn't answer our questions, so maybe I can add more to this conversation beyond subjectivity or at least provide some form of description that is easier to quantify.

The fact that Filip was kind enough to answer after hours just insured that he gets my business and not Griggs Racing.

Sheizasosay let us know what he tells you!

You must not have read the original link that I posted concerning the effects of the torque arm on handling. It appears that most people did not. I was attacked for not repeating it. And now some of the very same people that attacked me are purchasing one. I welcome any contribution you can make to the discussion. But you still persist in saying that a three link set up could be just as good. But you are at a disadvantage because you have not tried the torque arm yet. This is a hole in your knowledge that will soon be filled. thanks to me. But you can thank me personally at your leisure. Is it possible that a three link can give you a similar or even better track time? Possibly. But it will never control the axle or give you the ride quality and confidence that a torque arm will give you. Since you have seen fit to consult Filip, ask him and see what he says about it. I would be interested to hear his response. (I already know what it will be) And I will be more interested to hear your response after you put the torque arm on.

 

[barbaro]

From team Shelby: i think this is understandable as to just one of the reasons why the torque arm is superior to the three link:

"Yes there is a front axle roll center and there is a rear axle roll center and the line that is drawn between the two is called the roll axis . The relationship between the stiffness of the front to the stiffness of the rear is referred to as "Roll Couple". Momentary bind / roll bind causes excessive "stiffness" which causes the tires to be overloaded and lose grip . This is what happens with the UCA vs LCA and why you want to go to a torque arm ( which makes it virtually impossible ) ALSO when going over to a torque arm , the rear roll center is now determined predominately by the panhard bar / watts link . While lowering the car helps with the Center of Gravity (GC) it does not address the issues of the roll couple and roll axis. While it does lower both it does not fix the problem - in fact it can cause a worse condition by burying the front R/C and not lowering the rear enough which in turn makes the rear end "snap" out from underneath you while exiting a corner ( or breaks loose on launch ). This is how extended ball joints and bumpsteer kits made their way into the marketplace ( to raise up the front roll center ) and watts linkage setups that give you a lower pivot point than panhard bars .
Ideally we want the front R/C to be 1-3" above the ground and the rear R/C to be between 8-12" above the ground. JMO
If Cortex's T/A has a spherical bearing / slider instead of the poly bushing - the " LIGHT is GREEN - the trap is CLEAN "
I/C brings in the tire's contact patch and it's relationship to the next equation - have you got your chalk outline drawn on your garage floor yet ?"

 

[Sky Render]

Carlo, nobody "attacked" you. We asked you for a more technical explanation, and you basically called everyone here an idiot or "nonbeliever" for not listening and taking you at your word when you said the torque arm was the Second Coming of Christ. If you feel that I attacked you, then I apologize.

This is a very technical forum. A lot of people on here are engineers (like me), car builders, and semi- and full-professional race car drivers. We don't simply listen when someone tells us something is better because they say so; we want some sort of technical explanation to why, exactly, it is better.

Now, onto the technical discussion. What is the link for what you just posted there? Roll couples are usually referred to when talking about body roll left to right. I'm not sure what roll couple you are referring to; I am assuming it is the one between the CG and the "roll center" created by the car's acceleration and thus the rearward weight shift. In that case, I'm not entirely sure how replacing the UCA with a torque arm would change that, because that "roll center" is a function of the wheelbase of the car. Rearward weight transfer can be reduced through the use of LCA relocation brackets.

 

[Whiskey11]

Carlo, nobody "attacked" you. We asked you for a more technical explanation, and you basically called everyone here an idiot or "nonbeliever" for not listening and taking you at your word when you said the torque arm was the Second Coming of Christ. If you feel that I attacked you, then I apologize.

This is a very technical forum. A lot of people on here are engineers (like me), car builders, and semi- and full-professional race car drivers. We don't simply listen when someone tells us something is better because they say so; we want some sort of technical explanation to why, exactly, it is better.

Now, onto the technical discussion. What is the link for what you just posted there? Roll couples are usually referred to when talking about body roll left to right. I'm not sure what roll couple you are referring to; I am assuming it is the one between the CG and the "roll center" created by the car's acceleration and thus the rearward weight shift. In that case, I'm not entirely sure how replacing the UCA with a torque arm would change that, because that "roll center" is a function of the wheelbase of the car. Rearward weight transfer can be reduced through the use of LCA relocation brackets.

I am not sure what roll couple he is talking about but if he is galking about the rear roll center then removing the UCA will have an impact on the rear roll center but only because the UCA bushings have a small contribution to roll stiffness that can only be removed by using a spherical at both ends of the UCA.

Anyway, I am not attacking him and never have. I have read just about every S197 torque arm link on the net half a dozen times so... yeah...

 

[Sky Render]

I am not sure what roll couple he is talking about but if he is galking about the rear roll center then removing the UCA will have an impact on the rear roll center but only because the UCA bushings have a small contribution to roll stiffness that can only be removed by using a spherical at both ends of the UCA.

...In which case there would be no difference between the rear lateral roll center with a spherical bearing UCA and a torque arm...

 

[Whiskey11]

...In which case there would be no difference between the rear lateral roll center with a spherical bearing UCA and a torque arm...

Correct. It would be defined by the PHB, Watts link, or whatever is controling lateral location of the axle.

If he is talking about the instant center location then that will be different for both and each behaves differently in bump and extension of the axle. The 3 link will have a less "stable" IC and the TA a more stable one but that doesnt mean either makes the car more or less stable. Im using stable to describe the location of the IC not to describe the effect on handling.

 

[sheizasosay]

Filip will address questions after Laguna race this weekend.

 

[Norm Peterson]

"Roll couple" used by itself is confusing; what the team Shelby mention of it really means is "roll couple distribution", the last (and previously missing) word being exactly what you need to know to make any useful sense out of it. IOW, how much of the roll gets resisted up front and how much out back. That's how you go from lateral acceleration to lateral load transfer to actual tire loadings to slip angles and total front vs rear lateral grip to understeer effect vs oversteer effect.

I've been back and forth between barbaro's posts #188 and #189 and other stuff for the last three hours. There is almost but not quite enough there to really grab hold of and have a sudden clearing of the mist.

Engineers in particular will not get swayed by subjective or emotional content. I'm told its a common reason for engineers being dismissed at jury selection time by peremptory challenge, and not getting emotionally swayed is no different here. This isn't personal attack, just a statement that if you want an engineer's concurrence you've got to get him to understand it on his terms. Neither whining as a self-perceived victim nor gloating when somebody decides it's worth experiencing your preference helps here. Just let it happen.

It's too bad that we all can't have the benefit of both an engineering outlook and access to actual testing. Unfortunately, that doesn't come together very often for any number of reasons (individual strengths, geography, employment, available spare time, financial situation, other things in life, etc.).

I do think that copying and pasting the tech right here in this thread belongs on barbaro's shoulders. It's a PITA to have to flip back and forth, particularly between different sites (the other of which may or may not require you to register there just to see whatever it is). Remember that it's a matter of who best gains by bringing the tech in, not that the majority of the membership in the discussion necessarily has (or at least had) any personal reason to chase it down.

That there may be a few Cortex TA sales here is at best a function of people being able to satisfy themselves sufficiently with however much tech exists that it's worth the risk for their individual situation, that the end result is reasonably likely to justify the cost. That's still short of a slam-dunk. Maybe that will change, maybe not.


I do have a slightly better mental 3-D picture of UCA motion as a result of some of this, but I think I'll sit on it a bit and try to sort it out some more.


Norm

 

[barbaro]

Carlo, nobody "attacked" you. We asked you for a more technical explanation, and you basically called everyone here an idiot or "nonbeliever" for not listening and taking you at your word when you said the torque arm was the Second Coming of Christ. If you feel that I attacked you, then I apologize.

This is a very technical forum. A lot of people on here are engineers (like me), car builders, and semi- and full-professional race car drivers. We don't simply listen when someone tells us something is better because they say so; we want some sort of technical explanation to why, exactly, it is better."

I hear you Sky Render, but if what you say is true, and I am sure it is, torque arms and their efficacy should have been nothing new to any of you. You all should have been more aware than me about every aspect of their use. It is old technology that has been in use on mustangs for more than a decade. There is plenty on the internet about them and Griggs has been using them to great effect for years. If I preached, it should have been to the choir. I became defensive when I was accused of exaggerating, conflating, and just being ignorant. I knew that only the last accusation was true.

I could only say what I knew subjectively. I provided a link with more detailed subjective information I did not have before and after lap times or before and after skid pad results. All i could say was that traction improved, ride quality especially the up and down motion of the chassis over bumps improved, the car cornered flatter, the front did not rise on initial acceleration and the nose did not dive on braking and there was an overall increase in chassis stability.

But there is something about torque arms themselves, and I have seen it on other forums, that inspires something more than skepticism but outright denial of their usefulness and dismissal of any advocate. I apologize for my contribution to the misunderstanding. But what I am seeing here is a gradual change of opinion to the point where some who have expressed the greatest skepticism or dismissed it and me outright are now coming around to accepting the truth of my initial position.

My crime was being a caveman. To me, a torque arm is just a big steel bar that keeps my axle under control and I only needed to look at it to see that it would do a better job than a three link. Driving with one cemented my opinion to the point that I was in disbelief that a big steel bar attached longitudinally to my rear axle could improve the ride quality and handling so much. Nobody thanked me for sharing though.

 

[barbaro]

Sorry about triple post.

 

[Whiskey11]

The only problem with saying Mustangs have been using them for the past couple of decades is that the majority of those Mustangs are SN95 or Fox based cars. A fire would be better than the rear suspension on those cars so yes the torque arm is a huge and popular upgrade for those chassis'. The problem is that the S197 shares no DNA with the SN95/Fox suspension layout beyond being a live axle out back and struts up front. Both the live axle configuration and the strut configuration up front are vastly different and superior to the stock layout on the older cars for basically everything.

So far, the number of S197 guys with torque arms is pretty small and the number of them who can give more detailed feedback on the experience is extremely small. Those that have them on their cars are pretty quiet about them anyway.

I'm excited to see Filip's comments on the matter as there has to be a valid reason as to why they chose a torque arm setup over the 3 link setup. They don't have the excuse that Griggs had with his setup in that they just slightly tweaked their SN95/Fox one to work. The Cortex one is a completely different design to what Griggs uses.

I'm more excited to see what a torque arm can bring to the table for my ST build.

EDIT: Barbaro triple post 40 minutes apart?

 

[barbaro]

Point taken Whiskey. BTW i have followed your autocross thread and I am impressed. You have done quite well. Good luck.

 

[Norm Peterson]

Let me try to explain a few things. On edit - I've been picking away at this without seeing other comments that may be similar.

Although torque arms have been around for quite some time, the use on Mustangs of all vintages really is a small number compared to the number of Mustangs out there. Meaning that you really can't expect too many die-hard Ford fans to have ever had any direct experience with it. Among those who do, you'll find folks whose opinion involves the TracLink (IIRC a rather short TA primarily intended for drag-racing and consequently not of great interest to a corner-carving forum, nor will the opinion of a drag-race TracLink user on handling characteristics carry much weight).

If you start considering people with GM experience who are relatively new to Mustangs, which among the forums that you got your negative impressions from may well be the case, you're quite likely to get a mixed but somewhat negative overall response, courtesy of a few recent years of the F-body that suffered from horrible brake hop. While it's true that the TA was not entirely responsible for that problem, neither was it completely innocent. I think the way the anti-squat/anti-lift varies with ride height has something to do with it.

It takes time to sort out a new idea to the point where you're willing to back what may be little more than a hunch with your wallet. This is certainly true for engineers.

It's the internet, and this is one of the more technically demanding fora on it. I think you'll have to sit tight as far as expecting enthusiastic compliments and thanks is concerned until there are some actual results to base them on. The proof is in the pudding, or something like that.


Norm