body roll and sway bar question

[bryant]

this pic is from the autocross practice last saturday.
https://www.pro-touring.com/attachment.php?attachmentid=111981&stc=1

it looks like too much body roll to me. right now i dont have the rear swaybar on. im thinking of adding it for the next practice. i felt the car had a bit of understeer. i had just finished my panhard bar and it made the car much more predictable and handled better.

does anybody have any observations from the pic they can give? any advice? any funny comments?

[Kcorrigan2]

It's really hard to tell what is going on from one picture. If you were in a very hard corner, pushing the limits, I really don't see excessive body roll. Looking at the front air dam and comparing side to side it does not look like you have rolled more than a couple of inches and co spidering you are not driving a cart that is pretty good.
You can measure the amount of body roll by measuring how far the shocks are traveling from q resting position. Ron Sutton has a ton of information on this site about body roll, suspension geometry etc....it would be helpful for you to read his posts and take lots of measurements on you car to know just what is going on.
Aside from that there is always the good old Butt Dyno. Make a change, like a larger bar, and see how it feels. It it feels better to you and your time improves you have made a good change...if not put it back and change something else. Keep lots of notes about these changes so you will know what worked well and what did not.

[Rod]

depends on the school of thought about your chassis setup....some like soft springs and big sway bars, some like stiff springs and softer bars...and so on, we kinda need to know were your starting from to help you get were you want

[nokones]

Is it loose or pushing? You may want to add a little bump and rebound in the front and see what happens. You won't know until you try it.

[High Plains Mopars]

IIRC, you had a mis-match front/rear bar set up last year. Did you step up the size of the front bar? If you did and you have some slight understeer, it may be time to hook up the rear bar. If you didn't change the front bar out, it might be time to step it up in size, then re-attach your rear bar.

Generally speaking, I've seen any number of guys who feel they have too much body roll add a rear bar to flatten the car out, then start chasing the oversteer condition it produces.

[bryant]

heres the setup the car has now.
varishock double adjustable front coilovers. i dont know the spring rate
tcp upper and lower control arms
addco 7/8s front sway bar (also have a 1 1/8 sway bar on the shelf)
rear 4 leaf springs, dont know the rate
varishock double adjustable rear shocks
panhard bar that is height adjustable
i have 2 rear swaybars that are not on the car right now, a 3/4" addco bar and a 7/8" addco bar

i felt that the car had just a tad bit of understeer last time. the panhard bar and better tires are the change from the previous outing where it would oversteer and would want to spin out coming out of corners if any real power was applied. with the pan hard and tires i can roll into the throttle as i unwind the steering wheel and the car stays in control.

im planning on trying the 3/4 rear swaybar at the next practice and seeing what the effect is.

[Rod]

I'm going to pretend you have magic springs and there optimum for your car......

so for sway bars from your selection...I would use the 1 1/8 in front and and 3/4 rear

soften everything on the shocks to NOTHING! front and rear then I would start adding rebound to the shocks in major movements (5 or 6 clicks) it will suck at first.... till it gets better....then keep going till it sucks again then go back 2 clicks at a time till its good again.....and WRITE it all down same for compression.....and WRITE it all down

[Carl @ Chassisworks]

Hey Bryant, Here's what we suggest for your car based on the information that you have supplied.

Add the 1-1/8" front bar and install the 3/4" rear bar, but leave one rear endlink detached.
The front bar will either make it push more, or possibly, the opposite affect and give it more bite due to reducing body roll and better managing the front contact patch. You'll have to test to see what happens. You didn't say whether or not you have our dropped UCA pivot shafts, or if you did the Shelby drop, so I'm assuming the UCA is in the stock mount position. That means you could be riding on the outside edge of the tire too much which would also contribute to the push condition. If the larger bar makes the push worse, just hook up the rear endlink and go from there.

Shock adjustments will help to tune vehicle transitions later. But, I'd worry about getting the component list settled first before chasing shock settings.

Once you have the component list determined, you can start to play with the shocks. Don't bother to zero the shocks and NEVER make a five-click adjustment. The VariShocks are specifically designed to have a very wide adjustment range so that each click will make a noticeable difference in the vehicle. That's why there are only 16 clicks. Anyway, if you want to start from square one, set all four shocks so that the compression and rebound are at 5 clicks in from full soft. That's what I was going to recommend, but I double checked the QuickSet 2 Tuning Guide (http://www.cachassisworks.com/Attachments/Instructions/899-031-214.pdf#page=4) and, wouldn't ya know it, that's what it recommends as well. :)

Testing is what makes this stuff fun. It's all about experimenting to see what your car wants and what best suits your driving style.

[Rod]

Don't bother to zero the shocks and NEVER make a five-click adjustment. The VariShocks are specifically designed to have a very wide adjustment range so that each click will make a noticeable difference in the vehicle.



guess i don't know what I'm talking about

[Carl @ Chassisworks]

guess i don't know what I'm talking about

Well, I wouldn't say that. I agreed with you on the ARBs. It's just that I'm a little more familiar with our shocks than most people.

[bryant]

i do have the dropped uca.

on the springs, i think the fronts are around 400 lb, and rear are around 650. im trying to contact the original owner and see if he has those numbers.

[Carl @ Chassisworks]

i do have the dropped uca.

on the springs, i think the fronts are around 400 lb, and rear are around 650. im trying to contact the original owner and see if he has those numbers.

Replied to your PM. The fronts appear to be 450s. I would guess the rear leaf springs to be around 155/160. We don't carry a Mav spring. For reference, our 4 leaf Mustang springs are 165#/in.

[High Plains Mopars]

Ahhh, found it. Yeah, back in November you posted the first autocross results. Recommendation then was to ditch the .875"" front bar for the 1.125. Guess its time to bite the bullet on that and get it swapped out.

[bryant]

i did put the 1 1/8" bar on once and the car pushed so bad going into turns it was crazy, but the car had other problems like poor brakes and the twichy rear end. ive got the brakes sorted out and the rear pan hard bar took care of the twichy rear. also i have much better tires. so im feeling like im starting over. on my last outing where that pic was taken, i could see more wear on the outer edge of the tires.
i plan on putting the 1 1/8" bar on the front and the 3/4 on the rear for the practice this saturday. then evaluate for sunday.
thank you for everybody's help.

thanks carl for looking up the springs and the pm reply. ive never seen leaf spring rates as you posted them. usually i see rates referenced in a range of 500 to 900. i assumed that is pounds per inch. im know im missing something here.

also ill try to get my 4 corner weights. the car weighed 845lbs at the nationals last month.

this site is great. thank you everybody for the help.

[GrabberGT]

.. the car weighed 845lbs at the nationals last month.


:hammer:


I say put the 1-1/8" back on the front and tput the rear on as well. The rear sway bar would be easy to disconnect if you find you do not like it. Dont forget though that you can tune out your understeer by also changing the roll center with your PHB. I think if you raise the bar up, you'll stiffen the rear end allowing it to be loose which will balance out the front.

"All else being equal, raising the rear roll center increases the rear roll stiffness and thus the percentage of the transferred weight that goes to the outside rear tire. That loosens the car up. Lowering the rear roll center has the opposite effect. So, when a team makes a “track bar adjustment,” they are actually changing the understeer/oversteer balance in the turns."

[bryant]

thanks chris.
i got the front bar swapped out today. tomorrow ill do the rear bar.

looking at my tires today, the fronts show a lot of scrub wear on the outer edge. i didnt take a pic. i feel that the stiffer sway bars will keep the front tires flatter on the ground in turns. ill find out this saturday.

[High Plains Mopars]

Do you know how much caster/camber you are running in your alignment? You might have to add more positive caster to the alignment so it will generate a more dynamic camber curve in concert with your body roll. The sway bar will keep the body flatter in relation to the ground, but that is just band aiding the symptom of positive camber wear on your tires.

[Rod]

Well, I wouldn't say that. I agreed with you on the ARBs. It's just that I'm a little more familiar with our shocks than most people.

I have used your shocks and I am familiar with them...

[bryant]

chris, opps its 2840lb weight
the rear bar is now installed.
i dont know what my caster is. i set the camber to -2.0. on the caster i had maxed out the caster adjustment in the upper control arms and took it to an alignment shop and asked them to just one side to match the other with minimal reduction of cater. this shop wouldnt put much real camber in claiming rapid tire wear. im done with that shop. now i set my own camber using an angle finder and my own toe using tape measures. i have octagonal shaped cams that came with my tcp lower control arm. each side seems to be 1 degree of camber. so its easy to to put it to 0 camber for street use and -2 for autocross.
ill try to figure out a way to measure caster tomorrow. the problem i have is how to measure the 20 degrees for the sweep. does anybody have any suggestions on that?

[SSLance]

I use a Joe's racing caster camber gauge. I put masking tape on the steering wheel and steering column and make a mark on both with the steering wheel straight ahead. I then sweep the steering to the right until the end of the gauge which has a 20* point on the end is flush with the car and make another mark on the steering wheel tape, then repeat for the left.

It's not scientific, but the marks on the tape help me to get the steering back to the exact same spot left and right to aide when setting caster.

[Carl @ Chassisworks]

i have octagonal shaped cams that came with my tcp lower control arm. each side seems to be 1 degree of camber.

This makes me curious. You didn't purchase the lower arms directly from us, did you? We currently make a square plate with three holes which yields 11 different settings. This serves as an eccentric eliminator (http://www.totalcontrolproducts.com/eccentric.html). It locks the lower arm position so your alignment doesn't change when you hit a bump. The stock eccentric adjusters seem prone to moving when you run over a quarter. I haven't ever seen one that's an octagon before.

[bryant]

112241

here it is. i do have the square ones also. i may have had these left over from another suspension job. they do work nice on being able to do repeatable camber adjustments between race set up and street set up.

[GrabberGT]

Thats a pretty neat design.

[Carl @ Chassisworks]

Here it is. i do have the square ones also. i may have had these left over from another suspension job. they do work nice on being able to do repeatable camber adjustments between race set up and street set up.

Interesting. I've never seen that one before. Thanks for sharing the pic. Now go drive it! :)

[bryant]

chris, i think that came with the top ranger belly bar for mavericks.

drove the car home today. feels really great. i had the shock well past 5 clicks. now at 5 clicks it feels nice. the swaybars feel good. new front hawk black compound pads in the front feel really good.
the cones should have to work harder to hit me tomorrow!

[bryant]

Thank you everybody! the car was incredible! it has never felt so good. now ive got to figure out how to fix the loose nut behind the wheel!

i would say the car felt very neutral in turns. i could drive it with the throttle now.

thanks again everybody.

[Carl @ Chassisworks]

Excellent! Don't be afraid to experiment with different settings. It will help you to understand how to make the car even better. The best investment you can make in the car's performance at this point IS the nut behind the wheel. Training now will pay dividends later on. Practice doesn't make perfect; practice makes PERMANENT!

[Rod]

Thank you everybody! the car was incredible! it has never felt so good. now ive got to figure out how to fix the loose nut behind the wheel!

i would say the car felt very neutral in turns. i could drive it with the throttle now.

thanks again everybody.

make notes now....shock settings, tire pressure, temp of day and type of surface and so on, I even draw out the track, that way I know what key components where on that course and how the car handled it so when i come across a similar key component I have a base setting to start with in my note book