SUSPENSION BINDING by using a 2 point traction bar or 4 / 6 point gusset bracing?

[Adub]

Hi All,

I was doing some research on the benefits of getting a front subframe brace and came across this comment on a Fiesta ST Facebook Group (see attached and quoted):

"a upgraded strut will not help without a stiffer spring, if you are trying to remain at stock ride height your only option to fix that would be a coilover. You can have considerably stiffer spring rates, a damper that is valved for the increased rate and keep OE ride height. They also offer the most adjustments in regards of Damping, modularity, and being rebuildable.
Another issue I have with all of the “bracing” like the front tq gusset as an example, you are connecting two parts that now are no longer able articulate that are a suspension point. This is a serious issue that creates a ton of bind, and does not like the suspension work as intended."

I know some have talked about the benefits of reducing deflection by adding a traction bar, but I am concerned about adding one of these.

FYI The person that I quoted has significant amount of track time with this car.

Any of you suspension experts mind chiming in on the validity of the statement in regards to binding and not allowing suspension to work?

 

[WannabeST]

It is true that you can have a car that is "too stiff" or "too rigid". In my opinion I really doubt a brace is doing that. A welded in half cage would do more for rigidity than that.
In the end of the day, everyone's car is built differently, everyone has a different driving style. Two cars built identical with different tires can handle far differently. If you feel your car needs a stiff front end, throw a brace on. If that doesn't work then un install and look elsewhere. It's very hard to make a perfect racecar first try. There is loads of trial and error.
For example in my previous Integra track car. I tried 3 different strut bars up front and tried 4 different spring rates. On top of multiple alignment and shock adjustments.

 

[Adub]

It is true that you can have a car that is "too stiff" or "too rigid". In my opinion I really doubt a brace is doing that. A welded in half cage would do more for rigidity than that.
In the end of the day, everyone's car is built differently, everyone has a different driving style. Two cars built identical with different tires can handle far differently. If you feel your car needs a stiff front end, throw a brace on. If that doesn't work then un install and look elsewhere. It's very hard to make a perfect racecar first try. There is loads of trial and error.
For example in my previous Integra track car. I tried 3 different strut bars up front and tried 4 different spring rates. On top of multiple alignment and shock adjustments.

Thoughts about the suspension binding with the traction bar? Any risk by running a bar like this?

 

[thecman02]

In my opinion you are better off having the brace. The car does okay stock when in good/stock condition, but as the chassis fatigues, or the loads increase from more speed/hp/traction the car is going to deflect/flex in ways it wasn't designed too. With all the extra flex it is going to possibly load the bushings in an akward manor allowing for accelerated wear beyond just what the additional forces would be.

 

[WannabeST]

Thoughts about the suspension binding with the traction bar? Any risk by running a bar like this?

A don't think a traction car will make the suspension bind. Is it possible? yes. Probable on our cars? Doubt it in my opinion.
I've never seen it done on a fiesta. But in the Honda scene it was common for people to take out the front subframe and add reinforcement bars or gussets to it.
Most of the times, cars don't come with this from factory because the average consumer won't care about chassis rigidity and suspension flex on their way to pickup groceries or go to a bar.

 

[Dpro]

A lot of people install traction bars and call it a day though another well respected longtime member here and I have discussed this in the past and the concept of upgrading the control arm bushings would go a long way towards the whole deflection issue on the stock car. I have another buddy also a member here who did this almost immediately after buying his 19 . Control arm bushings along with caster adjustable rear front control arm bushings , aluminum rack bushings and LSD . I drove his car and his front end felt dialed and solid. It pretty much confirmed our suspicions that a traction bar while helpful is a band aid for the bigger problem of stock rubber bushings in the control arms being too compliant for ride and comfort causing excessive deflection which magnifies TQ steer.
Every reports less TQ steer feel after putting in the traction bar would not uprated bushings first be a better correction. Ya it costs more but it’s all about doing it right IMO. Oh and yes I have a set of control arms with bushings going in.

 

[Adub]

A lot of people install traction bars and call it a day though another well respected longtime member here and I have discussed this in the past and the concept of upgrading the control arm bushings would go a long way towards the whole deflection issue on the stock car. I have another buddy also a member here who did this almost immediately after buying his 19 . Control arm bushings along with caster adjustable rear front control arm bushings , aluminum rack bushings and LSD . I drove his car and his front end felt dialed and solid. It pretty much confirmed our suspicions that a traction bar while helpful is a band aid for the bigger problem of stock rubber bushings in the control arms being too compliant for ride and comfort causing excessive deflection which magnifies TQ steer.
Every reports less TQ steer feel after putting in the traction bar would not uprated bushings first be a better correction. Ya it costs more but it’s all about doing it right IMO. Oh and yes I have a set of control arms with bushings going in.

Noticed you have the swave bar, which was the one I was considering. Curious on your thoughts about the user's statement: "Another issue I have with all of the “bracing” like the front tq gusset as an example, you are connecting two parts that now are no longer able articulate that are a suspension point. This is a serious issue that creates a ton of bind, and does not like the suspension work as intended."?

 

[Dpro]

Noticed you have the swave bar, which was the one I was considering. Curious on your thoughts about the user's statement: "Another issue I have with all of the “bracing” like the front tq gusset as an example, you are connecting two parts that now are no longer able articulate that are a suspension point. This is a serious issue that creates a ton of bind, and does not like the suspension work as intended."?

Good question. first off any front brace that ties in the front to the rear subframe mount points is really not going to over brace it anymore than the subframe, which is a big hunk of metal already attached to the rear pickup points .

What is even more fascinating though is to look at the underside of a BMW E36 M3 convertible . Which literally comes from the factory with a X brace that literally ties the control arms into the front subframe exactly like my Swave/ Summit brace. It’s in fact a common mod for M3 Sedan. and coupe owners to do almost immediately and it tightens up and makes the front end more responsive. Oh and if you ever did look at BMW front ends you would see their control arm design and ours mounting wise are really close to each other only difference is the rear pickup point being attached to the chassis vs subframe though geometrically and front mount wise damn near identical.
I have never seen anyone in the BMW world claim the X brace causes binding.

Now as far as the front control arms are concerned we are talking about designs to price point . Remember this is a econobox chassis not race car. To say the factory subframe is designed to the optimal is almost comical. So there is more design for limiting NVH and comfort than all out handling.
Now given that they are mounted in such away and with rubber bushings designed for street comfort ride compliance and at the front of the subframe. i.e. prone to flex back and forth. Add HP get more flex more flex causes wheels to deflect more more deflection intensifies TQ steer. lose/lose situation.

So by that persons theory even putting in uprated Bushings causing less deflection and in that persons view more Binding would be bad. Hmm tell that to all the autocross and track guys and rally guys who upgrade their busings and or add in a traction bar. In fact prior to your comment about that person on faceBook I have never heard of anyone saying the traction bars would cause to much bInding. That flies in the face of science so to speak.

Deflection bad Suspension designed for independent movement use though not excessive deflection. Look at an Open wheeled race car for example. No possible chance of deflection suspension is strutted every which way with spherical end balls joints for movement without deflection . movement good deflection bad stock rubber bushings deflect not a problem for average joe street driven car. They will never now they are not trying to push their car through a corner at the highest possible speed

 

[Adub]

Good question. first off any front brace that ties in the front to the rear subframe mount points is really not going to over black it anymore the subframe is a big hunk of metal already attached to the rear pickup points . What is even more fascinating though is to look at the underside of a BMW E36 M3 convertible . Which literally comes from the factory with a X brace that literally ties the control arms into the front subframe exactly like my Swave/ Summit brace. It’s in fact a common mod for M3 Sedan. and coupe owners to do almost immediately and it tightens up and makes the front end more responsive. Oh and if you ever did look at BMW front ends you would see their control arm deign and ours mounting wise are really close to each other only difference is the rear pickup point being attached to the chassis vs subframe though geometrically and front mount wise damn near identical.
I have never seen anyone in the BMW world claim the X brace causes binding.

Now as far as the front control arms are concerned we are talking about designs to price point . Remember this is a econobox chassis not race car. To say the factory subframe is designed to the optimal is almost comical. So there is more design for limiting NVH and comfort than all out handling.
Now given that they are mounted in such away and with rubber bushings designed for street comfort ride compliance and the front of the subframe. i.e. prone to flex back and forth. Add HP get more flex more flex causes wheels to deflect more more deflection intensifies TQ steer. lose/lose situation. So by that persons theory even putting in uprated Bushings causing less deflection and in that persons view more Binding would be bad. Hmm tell that to all the autocross and track guys and rally guys who upgrade their busings and or add in a traction bar. In fact prior to your comment about that person on faceBook I have never heard of anyone saying the traction bars would cause to much bInding. That flies in the face of science so to speak. deflection bad . Suspension designed for independent movement use though not excessive deflection. Look at an Open wheeled race car for example. No possible chance of deflection suspension is strutted every which
way with spherical end balls joints for movement without deflection . movement good deflection bad stock rubber bushings deflect not a problem for average joe street driven car. They will never now they are not trying to push their car through a corner at the highest possible speed

Really appreciate the response and thanks for the explanation! BTW This particular user was sponsored by a high quality coilover company... so I am assuming he is biased towards just using those, however he does have a lot of track time as well and has some course records in fwd class. However, that doesnt make him an engineer nor has he even tried the bracing on this car.

 

[Dpro]

Really appreciate the response and thanks for the explanation! BTW This particular user was sponsored by a high quality coilover company... so I am assuming he is biased towards just using those, however he does have a lot of track time as well and has some course records in fwd class. However, that doesnt make him an engineer nor has he even tried the bracing on this car.

I am guessing right now who it is and the suspension brand he sponsored by. One can also limit some deflection by running super stiff suspension shock and spring wise as it will eliminate movement as well to a point. He may be winning and depending on how much power he is using the deflection might not be a noticeable thing. Thing is more power in our cars make this a mor obvious issue . Not many people with totally stock cars feel the need for a traction brace it only becomes more apparent with more TQ i.e. tunes and going mods on turbo.

So I cannot comment directly on his setup i can say for him to make the observation without even researching the situation or doing real time testing of his theory makes it remain merely a theory not based in any fact. On the other hand we have people who have done bushings done braces and found no negative side effects that would make it a bad decision handling wise.
The stock FiST is pretty damn amazing handling wise in stock form as it is. Fast drivers can set track records in cars that are not the fastest HP wise on the track. The Datsun 510 won in SCCA Trans Am and IMSA under 2.5 liter 3 years in a row going up against the Alfa GTV and the BMW 2002 both of which had more power . Yet the 510 won.
So ya I don’t know what he is doing power wise but it’s possible he either A lives with TQ steer and adapts or is relatively stock in that department and its not an issue.

 

[WannabeST]

so I am assuming he is biased towards just using those, however he does have a lot of track time as well and has some course records in fwd class. .

Curious as to what FWD records he holds, are they in autocross?. I've never heard of a fiesta owning any FWD road course records. Unless its some lower tier organization that I'm unaware of.

 

[Adub]

I am guessing right now who it is and the suspension brand he sponsored by. One can also limit some deflection by running super stiff suspension shock and spring wise as it will eliminate movement as well to a point. He may be winning and depending on how much power he is using the deflection might not be a noticeable thing. Thing is more power in our cars make this a mor obvious issue . Not many people with totally stock cars feel the need for a traction brace it only becomes more apparent with more TQ i.e. tunes and going mods on turbo.

So I cannot comment directly on his setup i can say for him to make the observation without even researching the situation or doing real time testing of his theory makes it remain merely a theory not based in any fact. On the other hand we have people who have done bushings done braces and found no negative side effects that would make it a bad decision handling wise.
The stock FiST is pretty damn amazing handling wise in stock form as it is. Fast drivers can set track records in cars that are not the fastest HP wise on the track. The Datsun 510 won in SCCA Trans Am and IMSA under 2.5 liter 3 years in a row going up against the Alfa GTV and the BMW 2002 both of which had more power . Yet the 510 won.
So ya I don’t know what he is doing power wise but it’s possible he either A lives with TQ steer and adapts or is relatively stock in that department and its not an issue.

Thanks again for the feedback! I am currently on a stage 2 setup (mp215 + mountune rad + intercooler, 16x8 Dekgrams) and I am getting a Clarke built transmission with Wavetrac LSD + Vibratechnics motor mounts all around. I thought the wave 4 point traction bar would be a good compliment to do at the same time, since there was such mostly positive feedback on adding a 2 or 4 point brace. Do you think it would be a good mod to compliment my setup?

 

[Adub]

Curious as to what FWD records he holds, are they in autocross?. I've never heard of a fiesta owning any FWD road course records. Unless its some lower tier organization that I'm unaware of.

This person / team / car holds HPDE track records check out fiesta st nation on Facebook. You can also pm me if you are interested.

 

[WannabeST]

This person / team / car holds HPDE track records check out fiesta st nation on Facebook. You can also pm me if you are interested.

Didn't know there was a FB group. I'll join

 

[akiraproject24]

You could try a 2 pt traction bar and see if you like it. They are pretty cheap. Peirce and Whoosh each have one for like a hundred bucks or so. If you like it, can upgrade at some point to a 4 pt or even 6pt. I dropped a 2 pt on and really liked what it did. I think it helped smooth away a lot of torque steer but that could have also been from the sticky tires I put on at the same time. If you do it grab the 2 new bolts

 

[M-Sport fan]

I cannot see any of the braces doing any 'binding' harm to the suspension.

I agree with RAAMaudio in that I do question just how much quantifiable good they do in some unibody/suspension locations (front top strut tower bracing, and the discussed, not tied-in or triangulated, 2 point 'traction' braces, etc.), without doing any harm at all, save for adding weight, and reducing ground clearance.

Where I came from (the 4th gen f body handling world, vs. the vast majority only into drag/roll racing that platform), the one area where bind was found to be most harmful was in using polyurethane bushings in many of that ride's suspension points.
They were especially harmful when used in the rear lower control arms, where they would definitely bind, and wreak havoc on the articulation of the solid rear axle during hard cornering.
(This would not cause any harm to the drag race launches since there is no twisting action, just straight, linear movement during the weight transfer.)

The answer was to use high quality, delrin/teflon lined spherical bearing rod ends in that (and other) locations, even though yes, even those top tier ones could be noisy over rough broken pavement.

 

[Dpro]

This person / team / car holds HPDE track records check out fiesta st nation on Facebook. You can also pm me if you are interested.

Ya I know who you are talking about and he has maybe a tune on his engine with some bolt ons . Which in his case sure he could get away without a brace or bushings and still not have much TQ steer or deflections . Like said before it’s theory on his part.

Don’t get me wrong I am not a big I gotta stick chassis braces all over my car on this platform either. It’s a pretty solid platform to start but tying it up a little more with extra bracing I do not feel will be totally detrimental. Also ones driving style can determine stuff like swaybar tuning and camber changes .

I personally have tried out rear swaybar with my camber plates and while loving the camber plates for faster cornering and amore planted rear adding in the sway caused sudden high speed snap oversteer in corners. Off it came. Another member ran the same bar and found it did at lower speeds without the camber plates neither of us run rear swaps now. My Grey car came with a rear swaybar and everything else stock. I don ‘t like it and will probably remove it.

I cannot see any of the braces doing any 'binding' harm to the suspension.

I agree with RAAMaudio in that I do question just how much quantifiable good they do in some unibody/suspension locations (front top strut tower bracing, and the discussed, not tied-in or triangulated, 2 point 'traction' braces, etc.), without doing any harm at all, save for adding weight, and reducing ground clearance.

Where I came from (the 4th gen f body handling world, vs. the vast majority only into drag/roll racing that platform), the one area where bind was found to be most harmful was in using polyurethane bushings in many of that ride's suspension points.
They were especially harmful when used in the rear lower control arms, where they would definitely bind, and wreak havoc on the articulation of the solid rear axle during hard cornering.
(This would not cause any harm to the drag race launches since there is no twisting action, just straight, linear movement during the weight transfer.)

The answer was to use high quality, delrin/teflon lined spherical bearing rod ends in that (and other) locations, even though yes, even those top tier ones could be noisy over rough broken pavement.

And here we have some general truth yes Polyurethane suspension bushings can bind . in fact it’s shy back in the day in the 240sx world people would zerk fit wherever you were putting an aftermarket bushing and lube with polyurethane friendly lube. If one did not go all out with spherical rod end setups which were made for the S chassis by many different brands out of Japan and Taiwan.

I will add RaamAudio felt we only needed a front lower two point brace. He also had the car setup to prove it.

 

[Dialcaliper]

There’s so much wrong with that Facebook post that Inwonder if that guy has even touched suspension or if he’s just a sales rep that drives a car without actually knowing how his product works (way too common)

The control arm pickup points on a car are *never* intentionally designed to flex. That’s what bushings and control arm pivots are for, which can be much more easily controlled and designed.

The pickup points where the 2+ point braces pick up *will* flex regardless, and it’s up to the engineers to design it in such a way to minimize that effect, within the weight, and budget and performance target the project allows. Flexing/vibrating undamped metal creates NVH, which is entirely undesirable. Typically you’ll target something like 5:1 or 10:1 flex relative to the “controlled” flex in the bushings so that the flex doesn’t significantly alter the suspension functioning as originally designed.

But here we are increasing the power and especially peak torque of the engine, putting on sticky wider tires and removing 1st/2nd gear torque limiters all sorts of other things, at which point, yes, things like the pickup points and motor mounts start flexing more than they were designed to handle, and creating all sorts of problems like torque steer and wheel hop.

Also keep in mind the subframe was originally designed for the 20-year old 75hp Mk5 Fiesta and the design carried forward reused, altered and beefed up within affordable compromises without any fundamental redesign as is typical with econobox cars.

As for the strut comment, there may be some missing context, but for the most part, swapping for “stiffer” struts is usually a performance improvement, and they are typically designed around stock spring rates (Bilstein, Koni, KYB, etc), with only some like Koni taking into account adjustable damping for higher spring rates (and also so they can just use the same valved strut in multiple applications). Beyond that with no adjustable, it’s simply a matter of higher damping rates being conveniently able to control slightly stiffer springs, up to a point.

Coilovers are not a necessity by any means except for certain applications and that comment sounds like pure salesmanship, unless I’m totally missing something that was in the original question being answered.

 

[Dpro]

There’s so much wrong with that Facebook post that Inwonder if that guy has even touched suspension or if he’s just a sales rep that drives a car without actually knowing how his product works (way too common)

The control arm pickup points on a car are *never* intentionally designed to flex. That’s what bushings and control arm pivots are for, which can be much more easily controlled and designed.

The pickup points where the 2+ point braces pick up *will* flex regardless, and it’s up to the engineers to design it in such a way to minimize that effect, within the weight, and budget and performance target the project allows. Flexing/vibrating undamped metal creates NVH, which is entirely undesirable. Typically you’ll target something like 5:1 or 10:1 flex relative to the “controlled” flex in the bushings so that the flex doesn’t significantly alter the suspension functioning as originally designed.

But here we are increasing the power and especially peak torque of the engine, putting on sticky wider tires and removing 1st/2ng gear torque limiters all sorts of other things, at which point, yes, things like the pickup points and motor mounts start flexing more than they were designed to handle, and creating all sorts of problems like torque steer and wheel hop.

Also keep in mind the subframe was originally designed for the 20-year old 75hp Mk5 Fiesta and the design carried forward reused and altered within affordable compromises, as is typical with econobox cars.

As for the strut comment, there may be some missing context, but for the most part, swapping for “stiffer” struts is usually a performance improvement, and they are typically designed around stock spring rates (Bilstein, Koni, KYB, etc), with only some like Koni taking into account adjustable damping for higher spring rates (and also so they can just use the same valved strut in multiple applications).

Coilovers are not a necessity by any means except for certain applications and that comment sounds like pure salesmanship, unless I’m totally missing something that was in the original question being answered.

Ya you read his post I did not bother . I just came and answered the question that he managed to raise with his lack of knowledge . I think we both agree he has not a clue . I was trying to be nice . Good job

 

[Adub]

Thanks all for information and help!