Stagger

[FURY 66]

i'm currently running a purestock division,i do run a 440 and have the tendency to push coming out of turns.My question is has anyone experimented with stagger? i have 255/70/15's all around 89" left side & 90" right side.A "chevy Racer" recommended i try 2" smaller on left rear ,any one think or know if this will help or hurt me?I do have alot of questions but this one will get me to the races this weekend with piece of mind/new tires or not.
TRYING TO LEARN
ALOT TO LEARN , thank you FURY 66

[sanborn]

I assume your rear end is locked. That's about the only way stagger will help.

Generally, the tighter the turns on the track, the more stagger you can use. for example on a tight 1/4 mile track you might can use 4-5" of stagger but on a sweeping turn 1/2 mile track maybe only 1" of stagger is needed. Try not to use more than 5" because this will cause the car to hunt down the straight.

If the track is tacky, use more stagger, as the track dries out, reduce the stagger. I hate to say this but more than 1" change in stagger is major on dirt. On pavement, 1/4" change can be drastic. So you really need rear tires that can give you 2", 3" and 4" at a minimum. And across the front you need sets that will give you 1" and 2" minimum.

I know that sounds like a lot of tires but that is why they have tire racks.

Hope that gets you started.

[Rich33]

Stagger can help on an open differential car as purely a crossweight adjustment. But, if the rear end's open, you need larger stagger adjustments to make a noticeable change as opposed to a locked rear end with a true stagger adjustment.

Fury 66, if you haven't already, spend 20 bucks and buy Steve Smith's "street stock technology" book. It covers mainly GM products, but the chassis and setup principles are the same and can be applied. It will provide you with immediate help. Check it out at www.ssapubl.com

[340king]

I always try to minimize the amount of stagger required for a given setup. In my opinion, too much stagger robs horse power and can reduce traction coming out of the corner(I was always underpowered when I ran Street Stock). Even though the car my be easier to drive, it may not be faster. If the stagger is mis-matched to the track and conditions, you either must spin one tire or drag/slide the other to move forward, assuming a locked rearend. This results in a loss of traction at best and loss of horse power at worst. You need to experiment with differing amounts of stagger and track the results, measuring success in performance and not comfort. Theoretically, they both should occur at the same time. I am also reminded of an old racer's wisdom. The remedy for a mild push can be more throttle, the remedy for a slightly loose car can be less throttle. Its like Darrel Waltrip said the other day. A car with a slight push is pretty driveable in his opinion(emphasis on slight). Lastly, car handling characteristics are very much driver preference. Go with what makes you fast. Stagger is only one possible remedy.

[FURY 66]

340 king,sanborn,rich 33, i really appreciate the info , all is helpful when trying to get started. alot of guys here are all chevy, or drag racers that really cant help me in areas i need help.boy this chat is so very helpful.going to take advice and go this weekend and try will try as much as i can.you all seem to know alot and i thank you again.
P.S.- my rear is locked and i run on asphalt w/ one real tight turn,well it seems tight ,prob get better if i get it handling a lil better.lol
fury 66

[9dodge]

Give us track size that may help us a bit.
You said it is a push off the corner, that would mean it is under acceleration, make sure your not giving it to much to soon. Stagger will help you comming off the corner, and I agree with 340, try to get away with as little stragger as possible.

Michael

[FURY 66]

your right dodge, 3/8 mile egg shape *
top of egg is prob,turn four. i will try what you guys are suggesting and let you know.was under acceleration,still learnin ,but WILL get better . thanks again
fury 66
NEXT WEEKS LESSON-Torsion bars LOL

[340king]

I just wanted to clarify why I made the suggestions I did. I revisited my post and the reasoning may not have come through. I think that the front end may be the problem, and like the NASCAR guys adding tape and such, I wanted you to maximize the front traction before possibly sacrificing rear traction. With an egg shaped track, it is always a compromise on one end or the other. With the increase of stagger, you will probably be loose on the big end. Good luck and let us know.

[FURY 66]

hey guys just wanted to let you know how i did. not good, had a brake line bust and did every thing in our power to get out for the main,missed half of practice +heat races ,hopefully will get this thing dialed in.we went out w/ what i had.didnt get a chance to play w/ stagger.all in all this was my third race n this fury and i was passin cars from fithteenth to seventh back to tenth, because a gm got into my rear quarter both got sent back.man the motor has it,im gettin there .thanks again.

[AVENGER29]

Stagger is one thing,tire pressure is another, never though much about it until we bought a set of real scales. We quickly discover that by changing pressures slightly,major changes would occur. A 5 psi pressure drop or increase in right front-left rear combination would affect cross 1 percentage point. When a car is fairly well dialed in, tire pressure can become a easy quick way to make minor changes to correct for changing track conditions.
Dont be afraid to experiment, even when it all seems right, if you dont, the guy beside you will and will beat you doing it.
From 2 to 4 inch of stagger is normal for a dirt hobby or street stock class. Front should have little to no stagger, however some stagger is beneficial to a new driver,may help to drive the car thru the corners. May also make the car feel better or more comfortable to drive thru the corners.
avenger

[9dodge]

Avenger, I agree with the tire presure changes. We do as little as a half pound of air and that can mean the difference of a pole or 5th place qualifing. I would say my truck is very sensitive to tire presure changes.

[FURY 66]

your right , this weekend i didnt touch the stagger at all. the guy who wins just about every week is turning out to be a big help too.i put the car on the scales first time,wow.didnt think i had to with purestock,boy was i wrong.i weighed in at LF 1056 Lr897 RF 1075 RR 698, and he told me bout tire press,and we did that plus two turns in on left torsion bar ,1 out on right,which got me to LF 1063 Lr 873 RF 1065 RR 725. still pushing until he looked at my car and said tocamber lf a-frame 1 side out 1 side in.i could actually turn the car now ! i'm learnin and all input is helpin alot , just trial and error.main thing was to take advantage of scales,lol.still trying+ learning getting much better, thanks guys. P.S._ i know this car is a tank as far as weight goes but rules are letting me gut more areas now,this will help a lot.

[krash]

nice to see someone else starting out with a tank/ i run a 67 charger w/ 383 on a 3/8 mile dirt. push out of turns? mine would not even turn till i found this chat forum. one thing more than anything that i took out of this room was front sway bar!! and ballast // of course out in the dirt this may work differently than on asphalt but i swear/ since sway bar and about 200# ballast startegically placed in rear i now gobble camaros like appetizers in turns

[FURY 66]

hey krash, yeah i was pushing bad too! but the dirt has got to be a lot diffrent than asphalt in turns.someone suggested that i try running some weight too, but rules wont allow it. so now between tire press,torsion bars and the camber i think im finally gettin the hang of this stuff.no tuning back now,compiling notes like crazy.oh,and make sure you have money to go to races,because i was short and put 5 gallons in for 35 lapper ,2 laps shy ,lol.finished but felt like a fool,suckin air.at least i got there right. good luck

[9dodge]

Hey Fury,

If you haven't bought a tire pyrometer buy one! If you don't have one buy a probe type. Give us some info on tire temps and maybe we can help you further. Maybe get you into the winners circle before years end.

[FURY 66]

ok 9 dodge , will get one.i dont own one .may take a week or two,tight budget for now ,let you know as soon as i get it and some temps. circle sounds good to me ,but a top five will definatly do . thanks dodge.

[Trueblue R/T]

Even though I no longer run circle track cars [still sponsor a couple out of my bar] I'm verry pleased to find a forum tht includes circle track racing..anyway to the subject at hand ..I'm suprised that none of you have inquired about spring [tortion bar]rates on his car..With that big ol motor that darlin is always going to be a handfull...

Barry

[krash]

well, to my understanding ther are no charts for torsion bar rates (such as coil spring rates) but hey i'm open for some enlightenment

[340king]

You can convert the bar diameters given for Mopar chassis to an equivalent spring rate for a given car. In other words, I can show you how to convert bar diameter to what it would be like for a single coil spring car. They all vary slightly due to the varying lower control arm lengths and spring mounting distances. In essence you need the bar diameter, effective length and control arm length from pivot to ball joint. I am ignoring the difference that wheel offset has for this example.

The formula for T-bar conversion is k=T(pie)G(D raised to the fourth)/32l. In this equation, k is the spring constant or rate(bar rate), T is pie or 3.14159265, G is the shear modulus, D is the outside diameter, l is the length. From this you could determine the bar rate and convert that to a wheel rate by using the length of the lower control arm as a lever arm. I don't have a steel book here to get the shear modulus. I will post it tomorrow if I can get it.

The coil spring's wheel rate is determined by using the distance from the pivot point to the coil spring mount squared divided by length of control arm squared (SD²/CL²). This is the motion ratio of the lower control arm. It is usually around .25-.28. Therefore a 1000 lb/in spring has a wheel rate of around 250 lb/in.

Once both springs are in this configuration, you can compare the effective wheel rates. I hope this help

[Rich33]

So, what that works to - and correct me if I'm wrong here, 340King - is that if you multiply a torsion bar rate by 4 you'll get approximately the equivelent GM style coil spring rate.

For example, the bars in the MP catalog for the "A" body cars goes like this:

1.140" = 350 lbs = 1400 lbs coil rate
1.090" = 300 lbs = 1200 lbs coil rate
1.040" = 250 lbs = 1000 lbs coil rate
.990" = 200 lbs = 800 lbs coil rate
.920" = 150 lbs = 600 lbs coil rate

It should go the same way with the "B" body bars. That's why you gotta take the recommendation by MP for the two stiffer bars with a grain of salt. I've used both on a quarter mile dirt track 3000 lb car, 53 % rear, 52 % left, just under 50% cross and pushed big time because the bars were too stiff. The 1.040 inchers work good on my car.

[krash]

ok im game i've weighed my car as a whole and it comes in at 4050/ and that is after i threw 150# in rear wheel wells. does this mean i need the equal of 1k and 14houndred left to right in the front? or should i use the smaller bars(which i have now) and just start twisting? with coil springs there is generally a formulae for weight adjustments per turn (i.e. every turn = 20% weigth increase or decrease) is there something similar for t-bars? i hope so of course i/ve been waiting for someone to give up the formulae that you just shared would appreciate greatly the rest?

[Rich33]

Krash, if it were me, I'd get heavier bars. Just twisting on the torsion adjustments will change ride height and thus corner weights. It wont change the rate of the bar. It's something you can do to play with cross weight, but if you start with skinny, soft bars you'll still have the same thing after you're done cranking on them.

I don't know about doing such a big spring split with the heavier torsion bars you mentioned. Since your car is pretty heavy, why not try the 1200 lb equivelent bars on both sides (save a little money by ordering just one set) and see how it does? And, if you do want to split rates between the two front bars, I'd go only one increment change between the left and right. Like, say a 1000 lb equivelent bar on the left and a 1200 on the right?

Be careful 'cause from my experience (even with a heavy car) it's easy to over spring the front end with torsion bars.

[krash]

thanx very much i'll give it a shot and get back to ya.