https://www.youtube.com/embed/Sui9NzBDTzg?si=F8GjxVQixYWTmQhN
Sway bars or anti-roll bars can be the most effective performance upgrade you can buy for your car.
Grassroots Motorsports Tech editor J.G. Pasterjak is in the shop to tell you why you should install them, how they work and what difference it makes on track.
My takeaway,I would have liked to have seen deeper discussed, other than the one example of the rear inside tire lift with a stiff rear SB on a front engine car, is that all swaybars ultimately load the outside tire patch greater than the inside tire. That is the complete opposite of what many novices believe. That may result in a flatter chassis with all its inherent possible camber benefits, but that increase of greater tire imbalance also lowers the available total axle's grip, ignoring any increases from any better camber found.
I really liked those greaseable alum billet SB mounts. Curious if they are available ala carte?
Just like guys that post videos in car groups. If you're going to post a nearly 20 minute long video, give us a few paragraph summary to so I can tell if this something I already know, or if it's worth my time to watch.
Any chance there will be a video on anti-roll bars on a front wheel drive car in the future?
I started laughing the second I heard you had to drop the crossmemebers to install the sway bars. Hmmmm I vaguely recall someone mentioning German cars being needlessly complicated........sorry couldn't help myself.
So on the subject of sway bars; I installed a bigger set of bars on an otherwise stock Miata and actually made it slower at autocross. It was my Showroom Stock car that had an open diff, the bigger bars resulted in wheelspin off every corner.
On our D-sports racer the suspension was designed in a way that it didn't need Sway bars. Basically it had long control arms on a narrow chassis.
In reply to SeniorPBA2B :
Not a video, but here's a post when they changed the sways in their project GTI.
edit to add: link to video. https://grassrootsmotorsports.com/project-cars/2017-golf-gti/can-a-rear-sway-bar-really-make-our-gti-faster-on/
Tom1200 said:So on the subject of sway bars; I installed a bigger set of bars on an otherwise stock Miata and actually made it slower at autocross. It was my Showroom Stock car that had an open diff, the bigger bars resulted in wheelspin off every corner.
Yeah this is definitely the risk with open diff cars, and it was something we were definitely worried about with the BMW. So far, though, it feels like we've avoided disaster in the diff department. I still think a proper mechanical diff would improve things once we coded out the E-diff functionality, but for now at least it appears we haven't made thuings worse.
Tom1200 said:I started laughing the second I heard you had to drop the crossmemebers to install the sway bars. Hmmmm I vaguely recall someone mentioning German cars being needlessly complicated........sorry couldn't help myself.
So on the subject of sway bars; I installed a bigger set of bars on an otherwise stock Miata and actually made it slower at autocross. It was my Showroom Stock car that had an open diff, the bigger bars resulted in wheelspin off every corner.
On our D-sports racer the suspension was designed in a way that it didn't need Sway bars. Basically it had long control arms on a narrow chassis.
I've always heard your spring rates should be the first part of the equation to determining how the car handles and the sway bars are to fine tune it. Not the other way around.
z31maniac said:I've always heard your spring rates should be the first part of the equation to determining how the car handles and the sway bars are to fine tune it. Not the other way around.
There are two trains of thought on this.
1. Is make the car as soft as possible, for the purposes of suspension compliance and use larger bars to control the roll.
2. User a higher spring rate to control roll and then fine tune the balance with smaller bars.
The aforementioned sports racer used 25" long control arms mounted on a 18" wide chassis. It also used a rising rate suspension which allowed for really complaint suspension without the huge amount of chassis roll. All of these things negated the need for sway bars. As I set a class lap record with the car I'd say it worked very well. Unfortunately you can't do this on the production based cars most of us run.
If I am picking between the two suspension set ups I noted it's going to be the first one as I ride the kerbs religiously. My experience in really stiffly sprung cars is that slamming the kerbs tends to upset them.
In reply to Tom1200 : Any aero at play being impacted by a soft set-up and pitch being very braking /acceleration sensitive. I lean (pun intended) towards higher spring rate thinking.
Tom1200 said:z31maniac said:I've always heard your spring rates should be the first part of the equation to determining how the car handles and the sway bars are to fine tune it. Not the other way around.
There are two trains of thought on this.
1. Is make the car as soft as possible, for the purposes of suspension compliance and use larger bars to control the roll.
2. User a higher spring rate to control roll and then fine tune the balance with smaller bars.
The aforementioned sports racer used 25" long control arms mounted on a 18" wide chassis. It also used a rising rate suspension which allowed for really complaint suspension without the huge amount of chassis roll. All of these things negated the need for sway bars. As I set a class lap record with the car I'd say it worked very well. Unfortunately you can't do this on the production based cars most of us run.
If I am picking between the two suspension set ups I noted it's going to be the first one as I ride the kerbs religiously. My experience in really stiffly sprung cars is that slamming the kerbs tends to upset them.
After experiencing a low spring rate setup vs a high spring setup on the same car, same track, same tires.........I go for #2. I also use the kerbs where it makes sense to. Turn 10 at Hallett for instance, you don't want to touch those. Turn 1, the driver seat needs to be over the kerb for the best exit speed.
"Every time you miss a kerb, God kills a kitten."
Tom1200 said:There are two trains of thought on this.
1. Is make the car as soft as possible, for the purposes of suspension compliance and use larger bars to control the roll.
2. User a higher spring rate to control roll and then fine tune the balance with smaller bars.
I've been intrigued by the concept of Soft Spring Stiff Bar ever since reading about it. I've got time driving that setup on aggressive roads but never on track. Sadly my front sway on the racecar is effectively irreplaceable so i'm stuck with stock stiffness unless I add a second sway.
jcc said:My takeaway,I would have liked to have seen deeper discussed, other than the one example of the rear inside tire lift with a stiff rear SB on a front engine car, is that all swaybars ultimately load the outside tire patch greater than the inside tire. That is the complete opposite of what many novices believe. That may result in a flatter chassis with all its inherent possible camber benefits, but that increase of greater tire imbalance also lowers the available total axle's grip, ignoring any increases from any better camber found.
True for a single sway bar, but not uprated pairs.
If you uprate both ends the same %, the outside tire's load is unchanged. The equation for weight transfer cares not about springs and bars.
This ignores camber and other secondary benefits of reduced roll, of course. Which in some cases -- I'm looking at you, nose-heavy FWD -- can outweigh any roll couple changes. When there's not much weight at one end, it's pretty easy to transfer all of it in a corner. So the rest has to come from the other end.
Andy Hollis said:
The equation for weight transfer cares not about springs and bars.
Underappreciated point here. I didn't address it much in the video, partially because I didn't want it to become the only thing that got argued about in the YouTube comments, but bars themselves do not affect weight transfer. Weight transfer is a function of cornering speed and radius. Bars can affect the proportion of total transfer that occurs at each end of the car, nd how the car reacts to that transfer, but weight transfer itself is purely a function of physics.
In reply to jcc :
Our sports racer was what I'd call medium downforce. For reference it was about a second a lap slower than the Formula Mazda lap record.
In this case the spring rate should probably be referred to as "softer" rather than soft. The rising rate suspension seemed to be key to allowing us to do this. I am not a suspension engineer so I am not great about the technical details.
When you got on the brakes the car dropped enough that the front air dam would drag the ground and seal the car. The result was a car that pulled 3Gs on the brakes.
In reply to buzzboy :
I should probably clarify my version of soft set up:
The Datsun is 1652lbs. I run a 250lb spring in the front and a 148lb rear spring.
I raced a 1990 Showroom Stock Miata and would never intentionally run the stock 165/95 springs for a track car. Those are way to soft.
Tom1200 said:In reply to buzzboy :
I should probably clarify my version of soft set up:
The Datsun is 1652lbs. I run a 250lb spring in the front and a 148lb rear spring.
I raced a 1990 Showroom Stock Miata and would never intentionally run the stock 165/95 springs for a track car. Those are way to soft.
To be fair, comparing spring rates without noting the type of suspension or motion ratio is fairly useless. Tire type and any downforce also play a part in spring rates.
For example, on my S52 swapped E30, 550/750 lb/in f/r. Front was MacStrut, rear was semi-trailing arm.
My NA track rat? 800/500, but uses a double wishbone setup with different motion ratios than the E30.
IIRC, the BRZ is MacStrut front, multi-link rear. I run 392/450........but it's a little stiff for the street on mid-level dampers.
Thanks! I had been wondering if stiffening an anti-sway bar on one end "reduced" traction on that end of the car, or "increased" traction on the other end. This helps!
Question: what happened in turn 4 of your speed trace? Also, I may have missed it, but can you clarify the actual difference in time around the track, as well as what environmental factors may have been at play? (For example, surface temps, relative tire wear, experience on this track, etc)
Thanks!
In reply to z31maniac :
The Datsun is strut front, leaf sprig rear and so I get it's not always apples to apples.
I can't believe I forgot this part:
When working on balancing the car I'm of the fix the end that isn't working; per Carroll Smith.
For me It doesn't make sense to loosen the rear to fix understeer or vice versa; to my mind that leads to lower overall grip. I get that in some instances it's the only choice you have but I still try to fix the end that isn't working first.
In reply to Tom1200 :
This is basically my question. I've heard, for example, stiffening the rear bar "reduces" rear traction. Conversely, like this video, I've heard stiffening the rear bar "increases" front traction by "transferring" some of that cornering capacity to the front.
Which is it? Or, is it one of the other under various circumstances?
Lindenwood said:In reply to Tom1200 :
This is basically my question. I've heard, for example, stiffening the rear bar "reduces" rear traction. Conversely, like this video, I've heard stiffening the rear bar "increases" front traction by "transferring" some of that cornering capacity to the front.
Which is it? Or, is it one of the other under various circumstances?
Yeah typically stiffening a bar will increase lateral grip at the opposite end. So you're reducing the proportional amount of grip relative to the total amount of grip at the end you're stiffening, but the total amount of grip has increased.
Andy Hollis said:jcc said:My takeaway,I would have liked to have seen deeper discussed, other than the one example of the rear inside tire lift with a stiff rear SB on a front engine car, is that all swaybars ultimately load the outside tire patch greater than the inside tire. That is the complete opposite of what many novices believe. That may result in a flatter chassis with all its inherent possible camber benefits, but that increase of greater tire imbalance also lowers the available total axle's grip, ignoring any increases from any better camber found.
True for a single sway bar, but not uprated pairs.
If you uprate both ends the same %, the outside tire's load is unchanged. The equation for weight transfer cares not about springs and bars.
This ignores camber and other secondary benefits of reduced roll, of course. Which in some cases -- I'm looking at you, nose-heavy FWD -- can outweigh any roll couple changes. When there's not much weight at one end, it's pretty easy to transfer all of it in a corner. So the rest has to come from the other end.
Suspension tuning changes signs once you are cornering on three wheels....
In reply to JG Pasterjak :
Of course we are talking about incremental changes.
I would, with in reason, soften the bar on the end in question.
Pete. (l33t FS) said:Suspension tuning changes signs once you are cornering on three wheels....
Right?
I've written it up here in the forum before, but I should really write a story about it so I can just post a link.
You'll need to log in to post.
