Great pic...thanks for sharing!!!I think the rear bar thing is kind of down to driver preference...but what do I know?
For autocrossing, I crank up the stiffness on the rear bar, and my times drop. Voodoo. I don't know. But it works somehow.
On track, I run it softer, as steady-state stiff rear bar oversteer can be terrifying.
I just leave the front bar cranked all the way up. Check this picture out...not even mid-corner...550# front spring, full stiff front bar. Still got that lean.
Question for the "You only need a stiffer front swaybar" camp
- Thread starter magnido45
- Start date
Norm Peterson
corner barstool sitter
Nope.
Path of least resistance logic applies to things like liquids that divide at a branch, where the discharge branches offer different amounts of restriction to flow.
Structural loads follow exactly the opposite logic when the structure being analyzed is "statically indeterminate" - load is attracted to [the greater] stiffness.
Norm
retired civil/structural guy
Gotcha Norm, thanks for the clarification. So if you had a vehicle with a super stiff front suspension and noodle rear suspension, the car wouldn't roll as much as you'd think?
Norm Peterson
corner barstool sitter
The amount it would roll would be a function of the total roll moment divided by the total roll resistance, with the front suspension providing the bulk of the roll resistance in this case. If the front was "super stiff" and the rear a noodle, the car wouldn't roll much, about the same as if both ends had stiffnesses equal to half of whatever "super stiff" happened to be.
Nrm
Nrm
sheizasosay
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I thought you could drive? I can't believe you knocked over all those cones....you messy CS.
I'm an autocross jedi. I can knock over cones before I even get to them on the course
This was how my car was setup in the beginning...stiff front, rear noodle...It felt soo odd and unbalanced for daily driving (rear too wobbly), and when I took the corners, it felt like the frontend drifted around the turns (definitely required some throttle)...even though the car remained flat...so I adjusted both ends to equal stiffness...backed off the front stiffness and stiffened up the rear...and it cornered/turned more like normal in terms of feel, even though the car leaned a bit more.
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I will inject just a little bit of tech, but there are mountains of data showing that a BIG front bar on these front-heavy cars HELPS improve balance and grip even though "according to the textbooks" that adding more front bar "should" make the cars understeer. The textbooks don't take into account how softly sprung these cars are or than each front tire has nearly 1000 pounds resting on it.
With that much load and that little spring the S197 can get into nasty roll situaitons where you lose camber and the front contact patch diminishes to the point of losing grip, even though the "balance" is supposedly better. We take a lot of pictures of our cars at autocross and track events looking for the angles shown above, to see VISIBLY how much bodyroll there is and trying to see the dynamic camber of the outside front tire. Modern radial tires need negative camber to maximize performance, even at full lateral load and max roll. The car above needed more FRONT spring rate (it was on 450#/in fronts) to deal with the tires/grip it was making (315/35/18 Kumho V710 R-compound race tires on 18x11/12 wheels). Soon after this test we upped the front rates to 550#/in, then 700, then 800#/in and it got faster every time. That level of tire required that level of spring to control the chassis' roll, dive and heave.
I've referenced some of our testing before - which is how you figure things out. Even after you have read the books and know the theory, testing is STILL required at all levels of motorsports. One event where we tested with our S197 early on was a private autocross test we did in August 2012, weeks before the Solo Nationals. We set-up a timed course and I made over 100 laps while Jason and Ryan changed settings on the car every 2-3 laps. We ended up doing full sweeps of each increment on the adjustable front Whiteline bar then the rear bar as well (these were the biggest bars on the market), sweeps of camber changes, tire pressure changes, ride height, and more.
The most remarkable improvements (time-wise) came from increasing the front swaybar stiffness until we ran out of adjustment. Same on the rear - both bars were full stiff once we honed in on the fastest set-up. We let THE TIMERS tell us what worked best, too.
Of course big swaybars are often a substitute for spring rate, but even if we had run the stiffer spring rates these tires/conditions needed, an adjustable bar is still helpful. I see folks trying to rationalize "no rear swaybar" set-ups but I remind them that virtually every racing car in the world has swaybars at both ends, even F1 cars. These "top of the ladder" F1 cars have not only swaybars but complicated FRIC systems as well, which are essentially a front-to-rear swaybar. Swaybars are always useful and every time I drive someone's "no rear swaybar" car it pushes like a pig.
Last but not least, be skeptical of everything you read on the internet, even what we write. Blindly following "Self Proclaimed Experts" from the interwebs is a sure fire way to becoming a Fan Boy idiot. Look at the SOURCE of your advice and see if they actually TEST and then RACE in competition, in a car/class similar to what you do. In the end, doing your own testing (proper scientific, data based testing) is a great way to prove these things for yourself.
Edit: One more thing to note. The aftermarket industry for the Mustang is HUGE, competitive, and has a lot of mouths to feed. That means, unfortunately, that there are a lot of "bolt-on doo-dads" being made that are sometimes not worthwhile to you. Just because a company makes a part for your car doesn't automatically mean it fits your uses or will make your car faster. Often I see things being sold just because, well, some folks will buy anything. We see a lot of "legacy" designs from previous generaiton Mustangs (namely the Fox/SN95) that have S197 versions, which are not usually worth the money or compromises they add. Just be wary of adding too many doo-dads to your car.
On an S197, here's what really matters most to handling:
1. TIRES and wheels. Go as WIDE and as sticky as you can afford. You can NEVER have too much tire on a Mustang. The rest of this list is only there to make the tires happy
2. SPRING RATE. None of the "lowering springs" come close to adding enough to control these heavy cars. Coilover set-ups in the 450-800#/in range are what you want to look for if lap times matter
3. Dampers appropriate to the spring rates you use (good shocks, with adjustments if you can afford it)
4. Camber adjustment in the front + removal of big rubber top bushing (aka: camber plates)
4. Swaybars, adjustable and big at both ends
5. Rear control arms/geometry fixes (LCAs first, maybe UCA if you need it) + lateral location adjustment or replacement (Panhard or Watts)
6. Front LCA bushings. The stock hydraulic filled massive lower bushings allow a lot of camber loss and toe change in heavy track/autocross use
That's about it, as far as worthwhile suspension mods on an S197. Everything else we see have very small "benefit-to-compromise" or "benefit to cost" ratios. Going beyond that and you better have a dedicated race car.
Cheers,
With that much load and that little spring the S197 can get into nasty roll situaitons where you lose camber and the front contact patch diminishes to the point of losing grip, even though the "balance" is supposedly better. We take a lot of pictures of our cars at autocross and track events looking for the angles shown above, to see VISIBLY how much bodyroll there is and trying to see the dynamic camber of the outside front tire. Modern radial tires need negative camber to maximize performance, even at full lateral load and max roll. The car above needed more FRONT spring rate (it was on 450#/in fronts) to deal with the tires/grip it was making (315/35/18 Kumho V710 R-compound race tires on 18x11/12 wheels). Soon after this test we upped the front rates to 550#/in, then 700, then 800#/in and it got faster every time. That level of tire required that level of spring to control the chassis' roll, dive and heave.
I've referenced some of our testing before - which is how you figure things out. Even after you have read the books and know the theory, testing is STILL required at all levels of motorsports. One event where we tested with our S197 early on was a private autocross test we did in August 2012, weeks before the Solo Nationals. We set-up a timed course and I made over 100 laps while Jason and Ryan changed settings on the car every 2-3 laps. We ended up doing full sweeps of each increment on the adjustable front Whiteline bar then the rear bar as well (these were the biggest bars on the market), sweeps of camber changes, tire pressure changes, ride height, and more.
The most remarkable improvements (time-wise) came from increasing the front swaybar stiffness until we ran out of adjustment. Same on the rear - both bars were full stiff once we honed in on the fastest set-up. We let THE TIMERS tell us what worked best, too.
Of course big swaybars are often a substitute for spring rate, but even if we had run the stiffer spring rates these tires/conditions needed, an adjustable bar is still helpful. I see folks trying to rationalize "no rear swaybar" set-ups but I remind them that virtually every racing car in the world has swaybars at both ends, even F1 cars. These "top of the ladder" F1 cars have not only swaybars but complicated FRIC systems as well, which are essentially a front-to-rear swaybar. Swaybars are always useful and every time I drive someone's "no rear swaybar" car it pushes like a pig.
Last but not least, be skeptical of everything you read on the internet, even what we write. Blindly following "Self Proclaimed Experts" from the interwebs is a sure fire way to becoming a Fan Boy idiot. Look at the SOURCE of your advice and see if they actually TEST and then RACE in competition, in a car/class similar to what you do. In the end, doing your own testing (proper scientific, data based testing) is a great way to prove these things for yourself.
Edit: One more thing to note. The aftermarket industry for the Mustang is HUGE, competitive, and has a lot of mouths to feed. That means, unfortunately, that there are a lot of "bolt-on doo-dads" being made that are sometimes not worthwhile to you. Just because a company makes a part for your car doesn't automatically mean it fits your uses or will make your car faster. Often I see things being sold just because, well, some folks will buy anything. We see a lot of "legacy" designs from previous generaiton Mustangs (namely the Fox/SN95) that have S197 versions, which are not usually worth the money or compromises they add. Just be wary of adding too many doo-dads to your car.
On an S197, here's what really matters most to handling:
1. TIRES and wheels. Go as WIDE and as sticky as you can afford. You can NEVER have too much tire on a Mustang. The rest of this list is only there to make the tires happy
2. SPRING RATE. None of the "lowering springs" come close to adding enough to control these heavy cars. Coilover set-ups in the 450-800#/in range are what you want to look for if lap times matter
3. Dampers appropriate to the spring rates you use (good shocks, with adjustments if you can afford it)
4. Camber adjustment in the front + removal of big rubber top bushing (aka: camber plates)
4. Swaybars, adjustable and big at both ends
5. Rear control arms/geometry fixes (LCAs first, maybe UCA if you need it) + lateral location adjustment or replacement (Panhard or Watts)
6. Front LCA bushings. The stock hydraulic filled massive lower bushings allow a lot of camber loss and toe change in heavy track/autocross use
That's about it, as far as worthwhile suspension mods on an S197. Everything else we see have very small "benefit-to-compromise" or "benefit to cost" ratios. Going beyond that and you better have a dedicated race car.
Cheers,
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Depends on wheel, tire, and the rules set you're using.
Example- I used to run STX. Wheels can't go bigger than 9, tires stuck at 265. However. I eventually ditched STX and ran the 265's on 10" wheels for a couple events. Kind of an odd combo, but definite improvement.
So my stance is- run the biggest wheel you can, with the largest tire that fits, unless your rules say otherwise. With stock fenders that's a 315 on an 11" wheel.
There are of course extenuating circumstances, like, why didn't I run a 315 rival instead of a 295? Well...the rival is huge, and the 295 is a 35 sidewall, where the 315 is a 30. I chose gearing and good fit over absolute width.
As with all things car related, everything is a compromise, and everything affects everything else. Remember that and it's easy. Lol.
I'm about to find out. Check my build thread for updates once the struts are back, hopefully this week.
Sounds like someone's read a good book on the subject.
The newest BMR front sway bar is one of the stiffest (if not THE stiffest) on the market. It made a HUGE handling difference.
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claudermilk
Senior Member
Good to hear. I think this will be the next major suspension part I upgrade, and I have the BMR units at the top of my list.
sheizasosay
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Were you going from the stock bar I take it? What are the rates of the BMR bar?
I believe he had the whiteline on there prior?
I agree, massive improvement with the 38mm bar, even on the softest setting. Kelly can correct me, but I believe the bar sweeps from ~700 to 1200 or so.
I'm contemplating upgrading to their rear bar as well, although it is pricey.
What kinda end links are you guys entrusting these big front bars to?
That's good to hear, I might go with them, then. The BMR are steel vs. aluminum, but I haven't really poked around in the front fender to see if their size or the little grease nubs sticking out will play nice with the brake ducting and big tires
sheizasosay
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Given this is 3-4 times the rate of many adj front swaybars, I am curious if the strut ears are a concern. Or better worded: any more of a concern than with the typical 400'ish in lb current bars.
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