GOLFMK8
GOLFMK7
GOLFMK6
GOLFMKV

front sway bars

DerHase

Autocross Champion
Location
Hampton Roads, VA
Car(s)
2019 GTI Rabbit
  • 034Motorsport (Soft) - 153% Rate Increase vs. Factory Volkswagen GTI (20mm) Rear Sway Bar ...which is why I plan to increase the rear rate a bit by re-adjusting the 25.4mm rear bar. These rate increases come from 034...
  • 034Motorsport (Stiff) - 174% Rate Increase vs. Factory Volkswagen GTI (20mm) Rear Sway Bar

This looks like fun, and well balanced...I should be clear that I am not autocrossing this car, road courses only. I autocrossed a fair amount in the early to mid 80s...never went very far with it because I began to go to road courses and dual setups were tedious...but I very much enjoyed autocrossing...maybe I should give it try again...


Yeah I primarily track mine as well.

H&R actual measurements and calcs done here:

https://www.datadrivenmqb.com/suspension/swaybartheory

Actual track testing done here:

https://www.datadrivenmqb.com/suspension/fsbdata

There's a reason I didn't go with the H&R recommended 28mm front with the 26mm rear. I had no measurements to go off of initially, but wanted to err on the side of a softer FSB upgrade. I suspect more bar would require a grippier tire and/or increasing rear spring rate to further help balance/overall grip.
 

tigeo

Autocross Champion
Yeah I primarily track mine as well.

H&R actual measurements and calcs done here:

https://www.datadrivenmqb.com/suspension/swaybartheory

Actual track testing done here:

https://www.datadrivenmqb.com/suspension/fsbdata

There's a reason I didn't go with the H&R recommended 28mm front with the 26mm rear. I had no measurements to go off of initially, but wanted to err on the side of a softer FSB upgrade. I suspect more bar would require a grippier tire and/or increasing rear spring rate to further help balance/overall grip.
I need to try my 27mm H&R on the softer setting at some point.
 

meb58

New member
Location
Wappingers Falls, NY
Car(s)
2015 MK7 GTi
Yeah I primarily track mine as well.

H&R actual measurements and calcs done here:

https://www.datadrivenmqb.com/suspension/swaybartheory

Actual track testing done here:

https://www.datadrivenmqb.com/suspension/fsbdata

There's a reason I didn't go with the H&R recommended 28mm front with the 26mm rear. I had no measurements to go off of initially, but wanted to err on the side of a softer FSB upgrade. I suspect more bar would require a grippier tire and/or increasing rear spring rate to further help balance/overall grip.
...I agree!
 

meb58

New member
Location
Wappingers Falls, NY
Car(s)
2015 MK7 GTi
So, found something interesting today...the shop that installed my FSB connected one side to the soft setting and the other to the stiffer setting. I never heard of this and it was called the middle setting...which I guess might work well if the end links were adjustable. But the logic feels sound at one level and not at another; the twist in the bar is determined by the locations of each lever arm...okay...but one is longer, the other shorter...just rambling thoughts here. Part of me wonders about some asymmetry...I'm perplexed. Thoughts? Interesting tuning technique...
 

meb58

New member
Location
Wappingers Falls, NY
Car(s)
2015 MK7 GTi
Yeah I primarily track mine as well.

H&R actual measurements and calcs done here:

https://www.datadrivenmqb.com/suspension/swaybartheory

Actual track testing done here:

https://www.datadrivenmqb.com/suspension/fsbdata

There's a reason I didn't go with the H&R recommended 28mm front with the 26mm rear. I had no measurements to go off of initially, but wanted to err on the side of a softer FSB upgrade. I suspect more bar would require a grippier tire and/or increasing rear spring rate to further help balance/overall grip.
I never read your testing link...impressive...I'm so old, seat of the pants with thumb in the air seemed to work. :love: But, nice info about the front bar...and if XxDavidXx isn't tired of me by this point, my initial reflection of the larger FSB are all seat of the pants in very poor conditions; cold, AS tires, public roads. Certainly relative, especially when looking at your graphs...which I have to study and learn to read. Your commentary was informative for sure! Thanks for sharing.

I'm sure that my car will understeer less if I remove the 60lb sun roof - wink
 

xXDavidCXx

Autocross Champion
Location
AZ
Car(s)
2017 GTI SE DSG
I never read your testing link...impressive...I'm so old, seat of the pants with thumb in the air seemed to work. :love: But, nice info about the front bar...and if XxDavidXx isn't tired of me by this point, my initial reflection of the larger FSB are all seat of the pants in very poor conditions; cold, AS tires, public roads. Certainly relative, especially when looking at your graphs...which I have to study and learn to read. Your commentary was informative for sure! Thanks for sharing.

I'm sure that my car will understeer less if I remove the 60lb sun roof - wink

Isn't this a bit of semantics? Which ever bar is strongest - not a technical term - will dominate the balance characteristics. A rear bar increases oversteer, a front bar increases understeer...whichever is the dominant in a given setup, determines the balance characteristics - all else equal...ideally, a little slow speed oversteer leading to a little high speed understeer...this is the balance that I am after. Unfortunately, I cannot really push the car on the street...

...except, the front wasn't lacking front end grip before installing the larger front bar - this is relative to my given setup. My option here - all else equal - is to go back to the stock front bar. There is something else at work here too; I installed 15mm spacers on the front, 10mm on the rear, as an experiment a while back. Increasing the front track width - all else equal - increases front roll stiffness - more understeer...raises the front roll center - also softens the camber (compensation) curve. So, I'll remove those first so that I can begin base line my changes. The front bar and the wavetrac were installed together, so I've no way to understand either might work on their own.

The 4Ss are my DD tire in summer...always had a dedicated wheel and track tire package. Pilot Sport 2...?

This makes no sense to me, and I'm not challenging you, but my experiences are completely different. A stiffer front bar will at some point lift the inside front wheel off the ground (why we can see track focused RWD cars lifting the inside front wheel just a hair as the larger front bar helps to keep the rear tires planted ) as is transfers energy diagonally across the car to the rear. The rear bar does the exact opposite by keeping the front wheels on the ground, the nuances of alignment and spring/wheel rates aside. If I go back to a stock rear bar while using the larger H&R bar, the car will understeer more, more than it is now...and I for sure understand that stickier tires will help, but the balance will remain the same.

I am also focused on this new front bar because the balance clearly isn't working for my current setup. Going back to a more basic path, remove the spacers, increase rear spring rate, then tune with the swaybars...

xXDavidXx, if you are racing competitively, I imagine that you are also testing tire heat across the tread to aid in your setup decisions? I've done no such thing...balance and front end grip...

What I was trying to say about your specific situation is this:

You put front and rear bars on, but you don't have the supporting mods to take advantage of the increased roll resistance. You need more front camber and better tires to do this.

So then you try to compensate by raising the rear bar rate, which is a band aid and lowers your overall grip potential.

You don't have enough grip to take advantage of increased roll resistance with your current setup so my advice in descending order for best grip is:

1. Get better tires and more camber then run both bars on soft
2. Install the OEM rear bar and run the front bar on soft
3. Install the OEM front bar

Also you can mix in rear-toe out with any option for better rear rotation. Unsticking the rear with roll stiffness is my least favorite way for rear compliance.
 

plastermaster

Passed Driver's Ed
Location
Gualala
I put larger swaybars in the rear and the front. I can't remember the sizes but I do know the one in the rear is larger diameter. I find the back ends swings out before the front. I'm not sure why this is considered unsafe. I would rather my rear end swing out a bit on a right curve (in the USA) than having understeer plowing me into oncoming traffic.
 

Nineeightyone

Autocross Champion
Location
Pennsylvania
Car(s)
19 GTI | 10 MZ3
I put larger swaybars in the rear and the front. I can't remember the sizes but I do know the one in the rear is larger diameter. I find the back ends swings out before the front. I'm not sure why this is considered unsafe. I would rather my rear end swing out a bit on a right curve (in the USA) than having understeer plowing me into oncoming traffic.
IIRC it was determined the average driver can correct understeer easier than oversteer, particularly in a situation where neither is expected. FWD also makes a difference with this. It could ALSO be because of additional crumple zones/safety measures/things between you and the [upright object you're about to hit] in the front, versus the side. Side impacts suck a lot. Not that front don't, but side is a lot less material to deal with the impact. That last bit is purely speculation, though in general I know it took me a while to get comfortable with the rear end trying to come around and successfully catching it.

Oh, and when it comes around and you're facing the wrong direction looking at the corpses of all the cones you just slaughtered, you don't see where inertia is trying to carry the car. Now copy/paste that to the street, you can't see to (potentially) correct for other upright objects/vehicles on the road.
 

meb58

New member
Location
Wappingers Falls, NY
Car(s)
2015 MK7 GTi
What I was trying to say about your specific situation is this:

You put front and rear bars on, but you don't have the supporting mods to take advantage of the increased roll resistance. You need more front camber and better tires to do this.

So then you try to compensate by raising the rear bar rate, which is a band aid and lowers your overall grip potential.

You don't have enough grip to take advantage of increased roll resistance with your current setup so my advice in descending order for best grip is:

1. Get better tires and more camber then run both bars on soft
2. Install the OEM rear bar and run the front bar on soft
3. Install the OEM front bar

Also you can mix in rear-toe out with any option for better rear rotation. Unsticking the rear with roll stiffness is my least favorite way for rear compliance.
...and I for sure appreciate your thoughts and advice! Did you catch my thoughts about asymmetric sway bar adjustments?
 
Last edited:

meb58

New member
Location
Wappingers Falls, NY
Car(s)
2015 MK7 GTi
IIRC it was determined the average driver can correct understeer easier than oversteer, particularly in a situation where neither is expected. FWD also makes a difference with this. It could ALSO be because of additional crumple zones/safety measures/things between you and the [upright object you're about to hit] in the front, versus the side. Side impacts suck a lot. Not that front don't, but side is a lot less material to deal with the impact. That last bit is purely speculation, though in general I know it took me a while to get comfortable with the rear end trying to come around and successfully catching it.
...and that's the balancing act. A little slow speed/off throttle oversteer with high speed understeer...
Oh, and when it comes around and you're facing the wrong direction looking at the corpses of all the cones you just slaughtered, you don't see where inertia is trying to carry the car. Now copy/paste that to the street, you can't see to (potentially) correct for other upright objects/vehicles on the road.
...right, the armco is infinitely less forgiving.
 

krs

Autocross Champion
Location
Las Vegas, NV
Car(s)
MKVIIS R
So, found something interesting today...the shop that installed my FSB connected one side to the soft setting and the other to the stiffer setting. I never heard of this and it was called the middle setting...which I guess might work well if the end links were adjustable. But the logic feels sound at one level and not at another; the twist in the bar is determined by the locations of each lever arm...okay...but one is longer, the other shorter...just rambling thoughts here. Part of me wonders about some asymmetry...I'm perplexed. Thoughts? Interesting tuning technique...

Yes that’s the method for setting your bar on medium. Adjustable bars have two holes, but are three way adjustable based on configuration.

This is how I run my FSB for my setup.
 

meb58

New member
Location
Wappingers Falls, NY
Car(s)
2015 MK7 GTi
...and I guess, that if the end links are adjustable, the twist in the torque tube is sum total of the length of the combined lever arms? I wrote adjustable because one has to longer...
 

2019 Golf R

Passed Driver's Ed
Location
Charlotte, NC
Ordered a SuperPro FSB 26mm with endlinks to match up with my SuperPro RSB 24mm with endlinks after reading this thread. Currently, I have the RSB set to full stiff and when pushed it's hardest, can get the rear to step out briefly on track. Looking forward to what the FSB changes will bring - thinking of running it at full soft with the rear staying at full stiff.

Background - Factory springs and DCC dampers with the Clubsport S chassis/suspension upgrades.
 

tigeo

Autocross Champion
Ordered a SuperPro FSB 26mm with endlinks to match up with my SuperPro RSB 24mm with endlinks after reading this thread. Currently, I have the RSB set to full stiff and when pushed it's hardest, can get the rear to step out briefly on track. Looking forward to what the FSB changes will bring - thinking of running it at full soft with the rear staying at full stiff.

Background - Factory springs and DCC dampers with the Clubsport S chassis/suspension upgrades.
Don't be a quitter, full stiff/full send.
 
Top