Cortex Torque Arm Racechrono Track Review

[barbaro]

Here goes, my shot at having an intelligent discussion with you.

You're lifetime track experience consists of approximately 100 laps on a single course. By your own admission lap times are probably in the 1.40 range. So we can estimate your collective track time at approximately 2 - 2 1/2 hours total or the equivalent of ONE typical track day/HPDE event. Yet you are attempting to establish yourself as an authority on this topic (torque arms). Neither your track/competition experience or chosen profession bear this out. You are certainly an authority on how this setup on your car makes you feel. But this does not qualify you in any way to make the sort of bold, overreaching statements you have provided throughout this discussion.

I stand by my statement that street time doesn't count for squat. I have never met a newbie who didn't learn more about high performance driving/car control/etc at a single track event then they did over there collective street 'experience'. You simply cannot compare the two environments as equals in regards to a learning tool.

100 laps at Big Willow is equivalent to one track day? Are you fucking kidding? What are you talking about? If you did 100 laps in a day at Willow there would not be much car left. That is 250 miles. Show me the school where you take your car out for 100 laps. So again you falsely denigrate my experience and by implication inflate your own.

How about this for experience. Take an S197 with BMR lower control arms and relocation brackets, put on a Cortex watts link. Drive it on the track for 125 miles like I did. Drive it on the street for 5000 miles like I did. Then add adjustable lower control arms and a Cortex Torque Arm like I did. Then drive that on the street for some 4000 miles like I did. Then drive it on the track for 125 miles like I did. At that point, you will be minimally qualified to offer your opinion on my opinion.

You can only definitively say that my comments are bold and overreaching if you have some experience with the set-up. Otherwise what you say is ill informed.

 

[barbaro]

Norm, the pitch of the car in the picture is kinda of what i am talking about. The nose is down as the car is turning. To me, this exaggerates the lean of the vehicle at turn in. With the torque arm less nose dive as the load transfers to my front outside wheel makes the car feel "flatter" at turn in. If that makes any sense.

 

[dontlifttoshift]

Reading comprehension IS hard.

sounds like you drive like a tool on the street

I never called you a tool....and did you just threaten me as you talk about being repsectful?

WoW, ported heads and an engine rebuild in 2010! The 30s called and said they learned it from the old timers down the street.

What are you thinking about building? Putting a torque arm on it?

 

[NDSP]

As someone who is having to sift through the banter and pick out the technical talk that I find quite enlightening and useful. I find it quite funny ( odd, not haha ) that barbaro thinks his S197 mustang is so unique and different than anyone else's that no one, no matter how many decades of experience with chassis set up and design could possible know how his setup works for him on his car. Because, you know, no one in here has a S197 mustang. Oh wait, everyone in here has an S197 mustang. Well, no one in here has a S197 Mustang with suspension modifications, that tracks their car. Oh wait. this subforumn is for autocrossers and track enthusiast. Shall I go on. Lets not.

For me, claims need to have a technical merit. They can't be subjective and hold any sway on me. If you where to say, actually compete with your car and win. Hell, not even that. If you where to have before and after lap times that showed a marked improvement. Then you could have something tangible to point at and say, this is what this setup did for me. Subjective analysis is as useful as a used piece of toilet paper.

 

[DTL]

Tell me about the the third link you would pull a torque arm off for? I would be interested to hear about that. Do you have any experience with the third link you are talking about. have you driven it?

There was a factory effort piece that is/was being used by a number of the teams that campaign the s197 chassis. At the moment, I don't recall who manufactured it, but I know it was pricey. There was some discussion a while back about trying to recreate it at a more reasonable price. It's my opinion that with a heavily sprung, road-race-specific chassis setup, the 3rd link design may be a better option than a torque arm soley for the weight savings. My biggest gripe with the 3rd link is the pinion angle and geometry swings as the rear end moves through the arc of ride height changes. In a heavily sprung (and possibly zero-droop) setup, that "problem" would be nearly eliminated. It's worth experimenting with, IMO.

 

[Norm Peterson]

Norm, the pitch of the car in the picture is kinda of what i am talking about. The nose is down as the car is turning. To me, this exaggerates the lean of the vehicle at turn in. With the torque arm less nose dive as the load transfers to my front outside wheel makes the car feel "flatter" at turn in. If that makes any sense.

Yes, because the pitch - that being what you perceive from inside the car as you start seeing pavement that's closer to the front bumper - is roughly equal parts the nose going down and the tail going up. Remove a significant portion of that tail rise and the car will not pitch as much, and even though the amount that the nose actually drops remains essentially constant it will still look like less because the less tail rise isn't letting you look over the nose as much. If that makes sense. Anyway, that is precisely what the braking side of your TA installation is doing for you.

As you roll off the brakes, the TA car doesn't have to "un-pitch" as far before you get to what's essentially pure roll, nor will it pitch as far nose-up as you roll into the throttle.

If you're well up into your powerband and using most of that power through appropriate gear selection, you should absolutely expect to experience more pitch happening at your power level than a car with stock-ish to mildly modified power levels would (this of course assuming that everything else was held fairly constant). I've been cognizant of what your power difference might mean since before the notion of anti-squat first came up, but I've been hoping it'd cross your mind to link power to pitch without too much direct explanation (it really makes me uncomfortable to find myself in a position of "leading the witness"). It is my suspicion that this right here explains some of the difference between your observations and what is to be expected as expressed in general terms.


Norm

 

[Norm Peterson]

There was a factory effort piece that is/was being used by a number of the teams that campaign the s197 chassis. At the moment, I don't recall who manufactured it, but I know it was pricey. There was some discussion a while back about trying to recreate it at a more reasonable price. It's my opinion that with a heavily sprung, road-race-specific chassis setup, the 3rd link design may be a better option than a torque arm soley for the weight savings. My biggest gripe with the 3rd link is the pinion angle and geometry swings as the rear end moves through the arc of ride height changes. In a heavily sprung (and possibly zero-droop) setup, that "problem" would be nearly eliminated. It's worth experimenting with, IMO.

If you are willing to step away from the OE UCA length (IOW, make it longer - which is something that Ford actually did to a small extent a few years back), you can bring the change in pinion angle due to geometry down. You're still stuck with the PA change due to bushing compliance, which you can minimize at some unavoidable cost in NVH. and you'd need to relocate either or possibly both of its pickup points. Probably why nobody has done this as a commercial effort (that I know of).


Norm

 

[barbaro]

Yes, because the pitch - that being what you perceive from inside the car as you start seeing pavement that's closer to the front bumper - is roughly equal parts the nose going down and the tail going up. Remove a significant portion of that tail rise and the car will not pitch as much, and even though the amount that the nose actually drops remains essentially constant it will still look like less because the less tail rise isn't letting you look over the nose as much. If that makes sense. Anyway, that is precisely what the braking side of your TA installation is doing for you.

As you roll off the brakes, the TA car doesn't have to "un-pitch" as far before you get to what's essentially pure roll, nor will it pitch as far nose-up as you roll into the throttle.

If you're well up into your powerband and using most of that power through appropriate gear selection, you should absolutely expect to experience more pitch happening at your power level than a car with stock-ish to mildly modified power levels would (this of course assuming that everything else was held fairly constant). I've been cognizant of what your power difference might mean since before the notion of anti-squat first came up, but I've been hoping it'd cross your mind to link power to pitch without too much direct explanation (it really makes me uncomfortable to find myself in a position of "leading the witness"). It is my suspicion that this right here explains some of the difference between your observations and what is to be expected as expressed in general terms.


Norm

I got you. Thanks.

 

[barbaro]

Reading comprehension IS hard.



I never called you a tool....and did you just threaten me as you talk about being repsectful?

WoW, ported heads and an engine rebuild in 2010! The 30s called and said they learned it from the old timers down the street.

What are you thinking about building? Putting a torque arm on it?

I didn't threaten you. I challenged you to be respectful. You are not respectful and you did call me a tool. It is easy to sit at a keyboard and call people names. There are no consequences to it. If there were consequences you would be more circumspect in your language.

What I am thinking of building is Type 65 Shelby Coupe. I am not thinking of putting a torque arm on it. The first car I ever did actual work on was my Uncle's 32 Ford Roadster. That was the days before unibody construction. ;-) As I remember it it had a frame that my uncle had to weld the shit out of.

 

[barbaro]

There was a factory effort piece that is/was being used by a number of the teams that campaign the s197 chassis. At the moment, I don't recall who manufactured it, but I know it was pricey. There was some discussion a while back about trying to recreate it at a more reasonable price. It's my opinion that with a heavily sprung, road-race-specific chassis setup, the 3rd link design may be a better option than a torque arm soley for the weight savings. My biggest gripe with the 3rd link is the pinion angle and geometry swings as the rear end moves through the arc of ride height changes. In a heavily sprung (and possibly zero-droop) setup, that "problem" would be nearly eliminated. It's worth experimenting with, IMO.

I think you are referring to the vertical movement of the rear end and that is what I found markedly improved with the addition of the torque arm.

 

[barbaro]

As someone who is having to sift through the banter and pick out the technical talk that I find quite enlightening and useful. I find it quite funny ( odd, not haha ) that barbaro thinks his S197 mustang is so unique and different than anyone else's that no one, no matter how many decades of experience with chassis set up and design could possible know how his setup works for him on his car. Because, you know, no one in here has a S197 mustang. Oh wait, everyone in here has an S197 mustang. Well, no one in here has a S197 Mustang with suspension modifications, that tracks their car. Oh wait. this subforumn is for autocrossers and track enthusiast. Shall I go on. Lets not.

For me, claims need to have a technical merit. They can't be subjective and hold any sway on me. If you where to say, actually compete with your car and win. Hell, not even that. If you where to have before and after lap times that showed a marked improvement. Then you could have something tangible to point at and say, this is what this setup did for me. Subjective analysis is as useful as a used piece of toilet paper.

Sorry don't have before and after lap times. Did not know that was a requirement. Thank you for your contribution and descriptive imagery.

 

[NDSP]

Sorry don't have before and after lap times. Did not know that was a requirement. Thank you for your contribution and descriptive imagery.

I know I didn't contribute anything useful.

Lap times aren't required, but at least they aren't subjective. The unfortunate fact of the matter is, most all of us only really have subjective data to draw conclusions from when trying to evaluate the performance of our own cars and the mods we've done to them. Track days don't usually come with lap times provided. Autocross events run a different course every event. What does that leave us with. Well, to alleviate as much "noise" as possible from our own subjective analysis, we have to understand what each mod/component can and can't do. Eliminate variables when possible. etc. Also go by others experiences and what results they have achieved with their modifications. Which is where this thread comes in. All anyone is trying to do, is eliminate the "noise" and get to the supportable claims.

 

[dontlifttoshift]

I didn't threaten you. I challenged you to be respectful. You are not respectful and you did call me a tool. It is easy to sit at a keyboard and call people names. There are no consequences to it. If there were consequences you would be more circumspect in your language.

Doubtful, I did have to google circumspect, though. Your vocabulary is obviously superior to mine, Kudos! If I were going to call you a tool, It would look like this, "you sir, are a tool". Instead my comment was "you drive like a tool" in response to your statement that you drive mountain roads as hard as you do on the track. Thanks for clearing up the threat thing, I was really nervous that I may have offended you.

What I am thinking of building is Type 65 Shelby Coupe. I am not thinking of putting a torque arm on it. The first car I ever did actual work on was my Uncle's 32 Ford Roadster. That was the days before unibody construction. ;-) As I remember it it had a frame that my uncle had to weld the shit out of.

Shelby Coupes are cool. I hope you're not as big as you sound, they are pretty small inside. Helping out with your Uncles 32 Ford roadster must have been cool. My 32 Ford roadster (just to the left on your screen) is a blast to drive and interestingly enough, it is unibody construction....now. Yes, much welding on old Fords to make them worthy of todays speeds and tires. Another strange thing about my car is the terrible 3 link I built for the rear suspension.

 

[TheViking]

100 laps at Big Willow is equivalent to one track day? Are you fucking kidding? What are you talking about? If you did 100 laps in a day at Willow there would not be much car left. That is 250 miles. Show me the school where you take your car out for 100 laps. So again you falsely denigrate my experience and by implication inflate your own.

How about this for experience. Take an S197 with BMR lower control arms and relocation brackets, put on a Cortex watts link. Drive it on the track for 125 miles like I did. Drive it on the street for 5000 miles like I did. Then add adjustable lower control arms and a Cortex Torque Arm like I did. Then drive that on the street for some 4000 miles like I did. Then drive it on the track for 125 miles like I did. At that point, you will be minimally qualified to offer your opinion on my opinion.

You can only definitively say that my comments are bold and overreaching if you have some experience with the set-up. Otherwise what you say is ill informed.

Every track organization I have run with offers approximately 2 hours (120 minutes) of track time PER DAY. Organizations don't schedule track time by # of laps. Based upon your approximate lap times I am suggesting you have little more than one day's worth of actual track experience. I am not suggesting whether you or your car would hold up.

But for arguments sake I will use your benchmark. 125 miles at an estimated pace of 1:40 per lap comes out to just over 83 minutes of track time for the entire day. So even by your own benchmark you have less then two days total track time as compared to a typical HPDE event. So yes, you are still not qualified in any way to make the sort of bold, overreaching statements you have provided throughout this discussion

I commonly use a phase which I suggest may help you here. When it seems like it's everybody else that has a problem, it's probably not everybody else.

Just sayin'

 

[kcbrown]

You seem to be implying that because I don't have relocation brackets that I wont experience the true benefit of the torque arm suspension and that my higher spring rates are the reason I'm not seeing the full benefits?

No. I'm implying that it's because you don't have relocation brackets that you weren't able to eliminate the need to go with a torque arm in the first place.

First and foremost, my spring rates are probably over double his at 440 front and 200 rear (the rears will be the closest to each other). I'm thinking about adding more, because, you know, springs control body motion not a torque arm, and because the car needs it desperately. Here is my car at the Nebraskhana event with the OEM 3 link, but otherwise unchanged suspension from now:

Here is my car at the MidDiv Championship with the Torque Arm:

And my car last weekend still with the Torque Arm:

Virtually unchanged. The last photo is even under braking. I'm getting that roll angle with 440 lbs/in springs. Cars with stock springs or Boss 302 springs will be worse and less than ideal.

Understood. But as you say in another one of your messages, you're coming at this from being used to driving around in cars that have relatively high levels of NVH. I've no idea whether or not that has desensitized you to NVH, but it's a possibility.

NVH is one of those subjective things. It can be measured, to be sure, but the degree to which a given change in NVH will affect someone is purely an individual thing.

In any case, my suspicion is that it is precisely because you're running with significantly higher spring rates that the effects of the torque arm are much less than they would be otherwise.

Why anyone would chose those rates is beyond me and "ride quality" is a load of bull. I would gladly put my Ground Control coilovers against the stock Boss 302 suspension in a subjective ride quality test.

Well, there's springs and then there's shocks. Would you put it up against a car with Boss 302 springs and AST dampers? The stock Boss 302 shocks are essentially Tokicos, which are not known as being the best dampers in the world (though they're reportedly decent if you can get a compression/rebound combination that works for you).

The roads here in Nebraska are far, far, far worse than anything Barbaro sees in California and I think my car rides better than it did stock.

This is why I'm looking forward to riding in a car with coilovers -- to see what the ride quality actually is for myself.

If the ride quality doesn't suffer any as a result of stiffer springs, and the handling characteristics are improved, then why are OEM springs so soft? Because the damper required to properly control a stiffer spring would cost more?

As for the control arm angles, do you honestly think that if I could change the angles of the control arms I would have gone with the Torque Arm setup in the first place? Nope, I wouldn't have

That's what I was attempting to say. Apologies if that wasn't clear.

About the only benefit I can conceptually see from the torque arm versus a proper 3-link, aside from NVH (and, perhaps, pinion angle stability), is a more stable anti-squat amount, since the lengths of the control arms in the 3-link are relatively short and thus the angles tend to change a fair amount with suspension movement. Obviously, a rear suspension that is more constrained with respect to that movement will control that variation, but it will also make for a harsher ride.

and I wouldn't have because I honestly don't think it adds much if anything over a properly set up 3 link. Sure, Filip and Bruce both have their reasons behind choosing the TA setup which includes "not being able to setup a 3 link with as much %AS without getting into roll steer issues" and I think that is noble, but I have yet to see a conclusive A-B test where the only change is the torque arm that shows the TA is either faster or easier to drive. I went with the TA because it had a quantifiable impact on forward bite in the broken SCCA rules.

Right.

I would also expect that the roll steer problem is a relatively minor one, something that will be concerning to someone who drives the car at its limits routinely, but something that would have much less impact on someone who doesn't. It depends on the magnitude of the roll steer, I suppose. In any case, I was under the impression that roll steer was primarily the result of the LCAs, and that the UCA had relatively little to do with it.

 

[kcbrown]

I've been cognizant of what your power difference might mean since before the notion of anti-squat first came up, but I've been hoping it'd cross your mind to link power to pitch without too much direct explanation (it really makes me uncomfortable to find myself in a position of "leading the witness"). It is my suspicion that this right here explains some of the difference between your observations and what is to be expected as expressed in general terms.

I also wonder if it's at least in part why Whiskey is seeing a relatively minimal contribution from the torque arm (which is not to say that it's contributing nothing, mind you, but it's apparently not the night and day difference that Barbaro has seen in his car).

 

[kcbrown]

If you are willing to step away from the OE UCA length (IOW, make it longer - which is something that Ford actually did to a small extent a few years back), you can bring the change in pinion angle due to geometry down. You're still stuck with the PA change due to bushing compliance, which you can minimize at some unavoidable cost in NVH. and you'd need to relocate either or possibly both of its pickup points. Probably why nobody has done this as a commercial effort (that I know of).

Right. But by how much can you reduce that change?

Generally speaking, the longer the controlling arm whilst keeping the amount of movement at the distant endpoint linearly constant, the more controlled the movement at the source will be.


You can certainly make the 3 link design do as well as a good torque arm plus LCAs, but it looks to me like that has a whole bunch of strings attached to it, with compromises in NVH, pinion angle sweep, and AS% variability. And that's from a pure engineering standpoint.

In engineering, you generally prefer to have individual controls over the variables involves, controls which do not have secondary effects. Which is to say, engineers tend to prefer clean, elegant, and direct solutions when they can get them. Controls with secondary effects are more difficult to use, complicate the process of setting up a given desired effect, and often yield compromises in the end results that aren't there with more direct controls. When sufficiently compromised, they tend to be regarded more as kludges than solutions.

Say what you will, but it looks to me like a properly-engineered torque arm is a simpler and more direct control in that way -- it controls one thing and one thing only, and has minimal to no impact on any other parameter. Additionally, because of its characteristics, NVH should be quite a lot less with its use for a given amount of control achieved. That's not a statement based on experience, it's one based on physics.

The TA certainly weighs more, and when one is primarily concerned with weight, one is probably going to go looking for other solutions, such as the UCA, which weigh a lot less and which may work adequately for the specific situation at hand (someone who is tightly controlling the motion of the rear suspension is not going to be concerned about the pinion angle variation the UCA will produce, and they won't be concerned about NVH either if they're building a car primarily for use on the track).


I've no skin in this game. I don't even have my car yet! But I do have an engineering mindset and I do try to think like an engineer (indeed, it's hard for me not to!). And from a pure engineering standpoint, when NVH is a significant concern and weight is a minor concern, the torque arm looks to have a lot going for it, more so than the UCA, particularly when viewed through the lens of simplicity and directness.

Of course, the torque arm isn't as simple with respect to installation as the UCA, but that's because the car was designed with the UCA...

 

[Sky Render]

KC, I fail to understand how having stiffer springs would make installing a Torque Arm less noticeable. As has already been said, a torque arm does not reduce body roll in corners; that is the purpose of stiffer springs.

 

[kcbrown]

KC, I fail to understand how having stiffer springs would make installing a Torque Arm less noticeable. As has already been said, a torque arm does not reduce body roll in corners; that is the purpose of stiffer springs.

Because stiffer springs reduce roll about both the longitudinal and lateral axes, not just the longitudinal one.

Going to significantly stiffer springs will significantly reduce both dive and squat, because both of those motions are the result of forces acting on the springs to compress them. Stiffer springs resist compression more than softer ones do.

Since the effect of the torque arm is to reduce squat and dive, i.e. motion about the lateral axis, and heavier springs also achieve that, it follows that a car with stiffer springs will show less of a change through the addition of a torque arm than a car with softer springs. Which is to say, simplistically speaking, the torque arm exerts a certain amount of force against squat and dive, and the springs exert the rest. The addition of a torque arm relieves the springs of the burden by the amount taken by the torque arm, and as a result, there isn't as much force being exerted on the springs -- and hence they compress less than they would otherwise, resulting in less squat or dive.

Springs generally exert force proportional to their compression (progressive springs are something of an exception to this, but the fact that more compression implies more force is still true). So you can tell how much force a spring is being subjected to (and thus how much it is exerting in return) by examining how much compression there is on it. But stiffer springs require less compression to exert the same amount of force (and thus to resist the same amount of force), so the amount of squat/dive one sees will be impacted by stiffer springs just as roll will be. And since the degree to which a change such as a torque arm impacts the end result is visible through the amount of squat/dive noticed, i.e. the linear change, a torque arm will have less apparent effect on a car with stiffer springs (which won't naturally exhibit as much squat/dive) than on one with heavier springs.


Now, the 3-link suspension also apparently has anti-squat characteristics when set up properly, so you might not see much of a change by going with a torque arm even if you have relatively soft springs. But that depends entirely on the specifics of your setup prior to the change.

 

[csamsh]

KC, I fail to understand how having stiffer springs would make installing a Torque Arm less noticeable. As has already been said, a torque arm does not reduce body roll in corners; that is the purpose of stiffer springs.

Stiffer springs make everything less noticeable. Think about the limiting case- you put a steel rod in place of a spring. Now nothing matters because nothing moves. Simple model but it gets the point across.