You remember that episode of Batman, where one of the super villains, possibly female, that'd be Catwoman or ???, makes it into the Batcave, and winds up falling into the "reactor", and Batman's instant epitaph for her is "Poor Deluded Creature"?

Well, this isn't about that, or like that, or whatever. I spent tonite at a funeral at a Buddhist Temple, breathing incense and listing to chanting, and hearing rememberances of a fine lady who was given a name many years ago that had something to do with lifting or raising those that were suffering and deluded beings. And in that instant, at that mention, do you know what I thought about?

That's right. Sway bars. That's what I'm suffering from. Deluded in the thought that I can figure it out. But this wonderful woman couldn't have helped me. Sure, she could have smiled and uplifted my spirit. But she couldn't have relieved me of my burden. And within my own frame of reference I'm surely damned. If I make it so far as the pearly gates, I think they'll see me coming, and a crowd will gather, and I'll raise my eyebrows and part my lips and then suddenly a preemptive and authoritative voice will say "Don't Even". "But...but I just gotta know".

So God takes me into his office, and he asks if I've ever heard of the Uncertainty Principle. Of course. Well, he tells me, it's like that, only in reverse. If you don't have any barz you don't know how much faster you'd have been if you had them. And if you do have barz you don't know how much faster you'd have been if you hadn't had them. I give him a look. And he looks back and shruggs his shoulders. He says I'll probably get over it eventually.

You know there's a new Ferrari out that has fancy Monroe-ological dampers of some kind and they've put out a graphic comparison to last years model that's interesting in a damnable sort of way.

Scott, who is always thinking about the wrong thing at the wrong time...naked women when I should be shifting down thru the gears instead of skip shifting...I just like to go straight for 3rd gear.........sway barz...

 

yeah sound about right lol I am confused too.

I noticed also on the RTR Acuras they run huge sway bars called MOMBO and it like 5" thick and really high spring rates?

Pic by Descartesfool

 

Love the post scott.

Curious, have you done the calcs to see what the sway barz come out to in wheel rate?

The typical front barz are a tiny fraction (%-wise) of the front wheel rates... I think my front sway bar is somewhere around 8% of my front wheel rate.

While the rear (typical) barz are still a small part of the rear wheel rate (~20%)

I think... Maybe my swaybar wheel rate calcs are a little off, I'm just going by memory...

 

Sooo.... did you throw a coin into the trough at the Buddhist Temple and make a wish about sway bars? :p

 

Scott, I love your posts. Please make more.

sander

 

I think the bottom line is we often try but we each need to spend a few serious sessions bolting on and un-bolting different bars, springs and shock combos and see what happens.Even I speculate on other avenues of setup,so why judge,when I realize I have never tried them myself.I can read all I want,but just like racing,I never learned as much as I did 'till I actually did it!

I can not really name one person(maybe renan) who does sessions back to back with a gnarly change to the car(be it diff or bars etc),and like Yoda,learns the keys and keeps the wisdom to himself.Maybe I should take note..

 

I feel the best way to make the best use of time is to fabricate or have it done by a competent person (they are not commercially available) a cockpit adjustable rear anti-roll bar and use a TEIN EDFC system to quickly test a couple of different roll stiffness distributions and damping setups per session. I would also setup my car with a lower spring rates in both front and rear and then use spring rubbers to increase incrementally the spring rates in different corners of the car. You can change spring rates using this method much quicker (in seconds verses 5 to 10 minutes per corner) than by physically changing out the coil springs. Spring rubbers, which are actually made from urethane, are available in different levels of hardness so you car increase corner spring rates incrementally over a good range of stiffness.

I would do this on test days prior to race weekends where track time is plentiful. Before making changes, make sure you're up to speed on the track and that your racing line is fast and consistent - meaning not only consistent lap times but also segment times. If you are still learning or getting re-acquainted with the track, don't make changes to the setup unless the car is diabolical. Because doing so before you're ready to go ten-tenths consistently, changing your setup will probably be a waste of time.

Do your mechanical grip stuff first for slow speed and medium speed corners and then tune your aero to bring the car to your liking in the high speed stuff. Once again, if the car doesn't have any diabolical high speed antics I wouldn't start doing too much with the aero until you're happy with the low to medium speed handling.

Last but not least, try to know what each change will do to your car's handling before making the change. Sometimes a change in one direction will result in a change opposite to what you expected. For example, tire pressure changes can result in opposite affects depending on your current pressure. Lets say the hot pressure on a given tire is too low for optimum grip but you either don't know or don't realize this and you think that lowering the pressure will result in more grip. Guess what, your tire will now generate even less grip than before due to the fact that you now have moved farther away from the tire's grip sweet spot. This pressure occurs when the contact patch has the optimum pressure accross the tread width. Each tire has its own sweet spot depending on sidewall stiffness, rubber composition, pressure, tire/wheel fitment, camber, and temperature. However, if your hot pressure was higher than the grip sweet spot and you lowering the the pressure to the sweet spot will now likely result in an improvement in grip. So the expected result from a change in pressure would only occur if the pressure was higher than optimum and opposite result would likely occur if the pressure was lower the optimum.

The tire has this tendency to give opposite results based on the current value of it's pressure but so do a large number of other parameters like camber, toe, castor, ride height, spring rates, damping rates, and a combination of these parameters.

 

Yeah they do Johnny Mac

http://www.hrpworld.com/index.cfm?fo...ction=category

http://www.1speedway.com/Swaybars.htm

 

lol

You can't just "bolt" that onto your car and go...

 

yeah I know but it should be to hard and they make one for Hondas

 

Yeah, some of the parts are available, but you still need to fabricate various pieces to make it work. And, you need to determine the ARB stiffness ranges for your application. I am familiar with the components available from HRP (blades, cockpit adjuster, cables, ect. $$$) and Speedway engineering bars. This type of system is somewhat expensive but if you pull the trigger and go for it, I think you'll be way ahead on just about all club racers on finding your "setup".

 

jmac. great post(earlier) in general.

 

hi there does anyone else sell blades besides genesis they are really pretty expensive

 

Learn something from the circle track boys about sway bars:

http://www.circletrack.com/chassiste...ues/index.html

 

is it a problem i liked my car without bars at all?

(i like it more with a front bar though....stocker...maybe i'll go to a tiny stock rear someday. baby steps)

 

I thought I was the only person that thinks God has an office.

 

The miracle of the modern cars. No more manual gearboxes for any new Ferraris, replaced by DCT gearboxes, faster than a speeding bullet, as for the GT-R and the Veyron. Magnetically controllable dampers than do away with a ton of the evil sway bar rate. Vehicle dynamic control that does it all for you. What to do with a lowly Honda?

But if you want to tune it manually, here is how RTR does it. Pictures show it all. As you can see RTR really believe in using big sway bars. And they win, so they can be all bad.

Scott once sold me his Mugen rear bar. Must have been a devilish plan;-)

 

And here is the man, Randy Pobst's Tri-point Mazda sway bar setup. He's pretty quick too with that big rear bar. Notice tricky way of adjusting the evil bar's lever arm length for tuning the roll stiffness. And that trunk mounted (spring perch?)adjuster ala NASCAR.
Notice how all these pro teams fab their own stuff. And I like their throttle pedal linkage, golden.

 

Those blade-type sway bars are super common on all modern race cars. They offer incredibly accurate roll rate tuning on the fly. Most Riley-style cars (just since here in the U.S. Riley Technologies is the most common user) use the ratcheting "push to adjust" adjuster and some Pratt and Miller GT cars use a **** that reminds me of something on a classic locomotive.

The general flavor of modern tuning is split as well as far as spring rates versus roll rates are concerned. Many cars are setup to have massive spring rates with fairly small sway bars (or bars adjusted fairly softly). This is often the "European Style" tuning setup. Pratt and Millers (factory ALMS Corvettes, Rolex GT Camaros, etc) now use VERY soft spring rates-- like 300lb/in on a 2800lb GT car-- but with MASSIVE sway bars. This is odd to drive but makes for incredible compliance under braking and power-on without much roll in the corners... just food for thought...

 

great post descartesfool

 

Something that is very important and overlooked as sway bars get larger.Alot of cars I see have very inconsistent sway bar resistance from side to side.Sometimes one side wears more or has mors slop than the other.So if you lift one side the other takes longer to react,giving one a different feel turning left to right and the balance is inconsistent.They should be even as possible.


Let's turn left shall we? Notice all the relocated attachment points on the arms.....


There are alot of scenarios here however in general,the longer the upper link,the more the car rolls or leans.This is because RC,which tends to get lower as the car leans,will go through a bigger change then a small upper link.

For example if you have a short upper link that is parallel to the lower arm,the car starts with low RC and thus will roll easily,however it will not have as deep a roll as a long upper link.If you make an upper link angle steeper,then the RC gets higher,reducing roll.

How does this apply- If you want a little more steering mid corner,increase the length of the front upper links.All you really need to know is that the higher the inner pivot point,the more the car will lean or roll.The lower the inner pivot point the less the car will lean or roll.With low traction surfaces you want more roll and with high traction you want less roll to have quicker response and flatter car.

As you may have assumeed,I do have more but I don't want to share all my yoda power just yet.

 

It used to be cut in dry in GT, but since Stevenson/LRPG/corsaPR1 have all taken full advantage of prep2 cars it is REALLY noticeable to see this. You didn't used to, the GXPR where the only thing that really rolled/squat/dive.

But now that you have a

P&M M6 vs Riley M6

OE prep1 vetts vs Riley vetts vs P&M vetts

The difference has became more noticeable.

I remember watching the GT cars come into madness, it was VERY interesting to see all the different cars (some the 'same') come into the corner. the GXPRs looked like they where going to Endo into china beach, while the P cars didn't have any dive (to my eyes).

 

Thats really interesting, cool info!

 

Great read.

 

Back in 2003/2004 I worked up several combinations of bar/spring using ICP's worksheet. I made really gross assumptions about the front bar (pretending it was a straight bar of whatever diameter when it is in fact a very twisted pretzel) and the rigidity of its mounting, and the rear where the offset mounting on the rubber bushed LCA must really Really soften the bar.

But admitting all of that, and other errors I surely make without being aware I got the following wheel rates for a typical vanilla setup:

Front: 860 spring, stock ITR bar: 421 + 83 lbs/in (84/16%)
Rear: 1086 spring, Mugen bar: 595 + 411 lbs/in (60/40%)

* The sheet doesn't give component roll rate per degree, so wheel rate will have to serve as surrogate.

Those bar numbers are probably significantly higher than actual reality.

Scott, who isn't sure about soft springs and big bars...the attendant pitch affects aero and dynamic camber for starters...