Removal of front sway vs large rear sway - Mazda3 Forums : The #1 Mazda 3 Forum
Reply
 
LinkBack Thread Tools
post #1 of 22 (permalink) Old 05-14-2013, 01:57 AM Thread Starter
Moped Rider
 
dsmith1739's Avatar
 
Join Date: Apr 2011
Location: Bluffton SC
Posts: 35
Removal of front sway vs large rear sway

Hello, I run in HS tire class. My mod list is below. I've read a few threads on installing a larger rear sway but not much on the removal of the stock front sway bar. As per section 13.7 page 77 in the 2013 scca rule book we can modify one. What are the pros and cons of doing each. Regardless of what the differences are I still have gone the way of a large rear sway bar (Hotchkis)(still not installed).

Buccaneer SCCA
2006 Mazda 3i touring
K&N air filter, Borla exhaust, 225/50/16 Hankook RS-3, Hotchkis rsb, Pulstar plugs, 5mm spacers, Koolertron indash gps, 25% tint,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
dsmith1739 is offline  
Sponsored Links
Advertisement
 
post #2 of 22 (permalink) Old 05-14-2013, 07:09 AM
F1 Driver
 
philrab's Avatar
 
Join Date: Apr 2010
Location: Louisiana
Posts: 8,599
The only con to installing a larger rear sway bar is cost vs. removing the front sway.

That being said, removing the front sway bar will almost certainly lead to more body roll/less front end traction which is the last thing we need in a FWD car. Installing a larger rear sway will better resist the car's tendancy to understeer, which should be your immediate goal.

Without recommending a particular brand, get an adjustable rear sway bar. That will allow you to select the amount of rear roll stiffness that's appropriate for your current spring rates and to a lesser degree (at the level you're racing at) track conditions. FE, a tight course with few straightaways and few long sweeping turns will favor a tighter rear sway bar (stiffer setting) which will help the car to rotate around turns quickly but may be too tail happy in other conditions and vice versa.

I spent several years racing in STS2 in a 96 Miata, so my experience in FWD racing is limited to helping tune the suspension on my friends' cars (Mazda 3, Mazdaspeed 3, civics.)
philrab is offline  
post #3 of 22 (permalink) Old 05-14-2013, 09:29 AM Thread Starter
Moped Rider
 
dsmith1739's Avatar
 
Join Date: Apr 2011
Location: Bluffton SC
Posts: 35
I can see the advantage of the cost difference lol. Wouldn't removing the front sway help put the power down coming out of the corner or am I off on that?

Buccaneer SCCA
2006 Mazda 3i touring
K&N air filter, Borla exhaust, 225/50/16 Hankook RS-3, Hotchkis rsb, Pulstar plugs, 5mm spacers, Koolertron indash gps, 25% tint,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
dsmith1739 is offline  
Sponsored Links
Advertisement
 
post #4 of 22 (permalink) Old 05-14-2013, 09:47 AM
F1 Driver
 
XCNuse's Avatar
 
Join Date: Jun 2009
Location: Atlanta, GA
Posts: 14,003
To an extent yes; but I wouldn't disconnect it unless you're on stiff springs.

But with that said, your times through a slalom will decrease with no FSB because it will take a lot more time for all the weight to transfer back and forth.

The Tripoint offers the most adjustment; that said... supposedly the Hotchkiss offers more strength. The Tripoint's stiffest is (according to their websites) 1000lbs, whereas the Hotchkiss they say their stiffest in the rear is just over 2000lbs which...
Something just seems wrong to me, but maybe I should just disconnect my front hotchkiss to see how that handles.

One immediate thing I noticed when I set my FSB to the softer setting is turn in times decreased and the feeling of turn in also got worse; so you kind of lose the feeling, but theoretically have more grip mid-turn.


I'm in the middle of this with you right now as too; told to go attempt autocross but I won't try that until probably next year, just get a few more trackdays down.

'06 Whitewater Pearl build |
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
XCNuse is offline  
post #5 of 22 (permalink) Old 05-14-2013, 09:49 AM
F1 Driver
 
philrab's Avatar
 
Join Date: Apr 2010
Location: Louisiana
Posts: 8,599
Here's the long answer from an experienced autocrosser; it depends. If the factory sway bar is overly stiff, removing it COULD increase front end traction. If not, it'll allow uncontrolled body motion which will decrease traction. It'll also decrease your car's response to steering inputs and hamper it's ability to rapidly change direction.

The short answer, based on experience, is no. Removing a sway bar, or decreasing roll resistance at one end of the car through softer springs or a softer sway bar ends up resulting in body roll. The only instance I can think of this helping is if you race on a particularly bumpy course, in which allowing the tires to respond to the bumps outweighs the loss of body control.

Personally, I say adjustable rear sway bar on the softest setting. From there, increase stiffness and see what the affect is. Worst case scenario, resell the sway bar if you find a negative effect. Test and tune is the mantra of autocrossing. Unless you find someone with a similar car and setup to get advice from (and even then, driving styles can lend themselves to different setups), you're just going to have to experiment.
philrab is offline  
post #6 of 22 (permalink) Old 05-14-2013, 09:54 AM
F1 Driver
 
XCNuse's Avatar
 
Join Date: Jun 2009
Location: Atlanta, GA
Posts: 14,003
Quote:
Originally Posted by philrab View Post
if you race on a particularly bumpy course
This is why I've kept away from autocross for this reason in particular, and still .. while the idea of autox is good in the theory of being able to test things out, still isn't appropriate for what I'm doing because I'm going for a track setup which is .. similar due to still being FWD, but still.. very, very different.

'06 Whitewater Pearl build |
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
XCNuse is offline  
post #7 of 22 (permalink) Old 05-14-2013, 10:39 AM
Grand Am Series
 
Join Date: Jul 2012
Location: Rochester, NY
Posts: 496
I've autocrossed with my front bar disconnected and a stock rear bar; I've also autocrossed with an aftermarket rear bar.

With the front bar disconnected you can put power down really well. The front wheels never lift, and you can get on the gas pre-apex with no wheel spin at all. It's cool in that respect. However, because we have struts in the front, all the body roll that results from a disconnected bar end up reducing grip severely. You end up being able to use the gas pedal a lot more, but carrying so little speed through turns that it doesn't help you overall. It also makes steering response feel like garbage, although that would be something you could easily drive around if it were the only downside.

A stiffer rear bar, on the other hand, has the same benefit as a softer front bar -- more front grip, you can use the gas more aggressively -- without the downsides of disconnecting the front bar. You have less body roll overall, and because you're keeping the front suspension in a less bad part of it's camber curve, you get more grip overall. Technically you lose a bit of rear grip, but we have such an abundance of rear grip in these cars that it's really no problem to trade some rear grip for some front grip. You retain a good steering feel too.

It's interesting what a difference there is with the front bar disconnected actually. It's a good lesson in suspension tuning. The stock front bar isn't particularly beefy, but because so much of the cars weight is on the front wheels, small changes to the front end have big impacts. Disconnecting that flimsy little front bar results in huge amounts of body roll.

Another thing I think needs to be said is that, while it's true in this case, body roll and soft steering response aren't necessarily bad. Body roll is bad for us because of our strut suspension, because the strut suspension doesn't gain camber under compression; when the body rolls, it puts the wheels at a bad angle to the ground, reducing grip. On the other hand, an a-arm suspension gains gamber under compression, so you can sometimes remove the front bar to get more grip in the front. You'd still get more body roll, but it wouldn't reduce grip nearly as much as it does on our cars.

I mention this because one of the biggest lessons in suspension tuning is that what feels fast and what is fast may not be the same. Don't get into the trap of over-simplified thinking like "body roll = bad" or "soft steering response = bad". That thinking happens to lead to the right conclusion in this case, but it's poor logic.

Last edited by ckingsley; 05-14-2013 at 10:41 AM.
ckingsley is offline  
post #8 of 22 (permalink) Old 05-14-2013, 10:51 AM
Grand Am Series
 
Join Date: Jul 2012
Location: Rochester, NY
Posts: 496
To take that point a little further, here is an example of something feeling worse and being faster:

When I installed my koni yellows, I played around in an empty parking lot and found that the car felt great with the front rebound set to 1.5 or 2 turns off full soft. I drove it that way for a while, then I went to an autocross. I spent the morning driving it like I'd set it. Both my codriver and I thought it was great, but agreed that we thought it was really pushy on corner entry. He said we should turn the front rebound down to near full soft. I said "are you nuts? We're both full throttle through the slaloms, we don't want to lose that transitional grip" but he convinced me to try it. Sure enough, it didn't feel as good in transition, although I found I could fix that by getting a little bit earlier on my steering input and maintain full throttle. The big difference though, was that it stopped pushing so bad on entry, letting us trail brake more aggressively. In the end it took about a second off both our run times! Sure didn't feel better, but it was much faster. Think about how odd that is: I actually turn my shocks down when I get to a race, and up when I leave! It's weird, but if you really want to be fast you need to listen to your instincts, but always remember that the clock is king.
ckingsley is offline  
post #9 of 22 (permalink) Old 05-14-2013, 11:38 AM
F1 Driver
 
XCNuse's Avatar
 
Join Date: Jun 2009
Location: Atlanta, GA
Posts: 14,003
Push the rear up then too and see how much that affects it.

Out of all of the RWD cars on my trackday the other weekend, I was trail braking the furthest... in a FWD car lol

I just got done reading this, definitely worth reading (and unfortunately, my tires, NT05s they weren't as happy with as they thought )

BUT as they state in there after adding the front sway and the NT05s, sometimes... consistency is more important than speed; and while some things lowered their Gs through the turns, the driver could handle the car better.

As said in the books, a happy car makes a happy driver; a mad car makes a mad driver, and no one wants to be a mad driver.

http://grassrootsmotorsports.com/articles/g-whiz/

Something we DO need.. and I want to start bugging companies are this, and this is what I was trying to aim for with the Dominant LCAs but turned out to be not possible to increase the angle. This is what's making me consider raising my car another inch.


'06 Whitewater Pearl build |
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
XCNuse is offline  
post #10 of 22 (permalink) Old 05-14-2013, 11:43 AM
Grand Am Series
 
Join Date: Jul 2012
Location: Rochester, NY
Posts: 496
What are those, roll center adjusters?
ckingsley is offline  
Sponsored Links
Advertisement
 
Reply

  Mazda3 Forums : The #1 Mazda 3 Forum > Technical / Model / Performance > Autocross, Track, and Dyno Results

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Mazda3 Forums : The #1 Mazda 3 Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



  LinkBacks (?)
LinkBack to this Thread: http://www.mazda3forums.com/90-autocross-track-dyno-results/461793-removal-front-sway-vs-large-rear-sway.html
Posted By For Type Date
Autocross, Track, and Dyno Results [Archive] - Mazda3 Forums : The #1 Mazda 3 Forum This thread Refback 09-06-2015 01:54 PM

Similar Threads
Thread Thread Starter Forum Replies Last Post
Actual Effects of Running Large Rear Sway Bars in Autocross (Stock Classes) mazda3az Autocross, Track, and Dyno Results 37 10-09-2012 09:06 PM
mazdaspeed acc. sway bars, shocks, springs. ms3 rear sway. cpe mount c_thur For Sale | M3F 30 01-18-2011 11:59 PM
Stock front sway bar, oem speed3 sway on 2007 mazda 3 sedan. spacers etc... Nissanfan Suspension / Brakes 7 08-12-2010 02:22 PM
WTB: Aftermarket Rear Sway Bar or Front/Rear sway bar set mz3frs For Sale | M3F 6 10-22-2007 06:19 PM
2007 Model Rear sway Bar update: Racing Beat Rear Sway speedfreak89 Suspension / Brakes 8 09-01-2007 06:41 PM

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome
8