tire stagger when scaling a car

[WENDEL ROCKET]

i was wondering how critical tire stagger is when scalling a car i mean there close just not exactly 1 inch in the front and 4 inch in the year. and how it affects the % and numbers. i have some tires left over from last year some hoosier and american racers and some havent had any air in them since last year and now the stagger isnt coming out right. i know in a perfect world you want everything exactly the way your going to race with but in this case i dont know that the tires im going to race with its going to be exactly like the tires im trying to scale with?

[merc123]

I don't know the answer but you can experiment. Stick it on scales the way it is, then reverse the back tires to give you a -4 inches of stagger. See what it does.

[Sprint76]

You can air them up or down to get whatever stagger you want on the scales. Your scaling not racing so it doesn't matter what the psi is set to.

This is not true. Air pressure can have a significant effect on scale numbers. Make sure air pressure is dead on when scaling. Stagger is also important. Every 1" of stagger difference is about 1/8" of ride height difference.

[MEB4U]

Put it on scales and air up the LR then let some out, you`ll be amazed at the number changes a a few pounds of air will make

[Matt49]

When changing stagger you're not going to see much if any noticeable difference in left side and rear percentages but you WILL see differences in wedge. More rear stagger will give you less wedge.
More front stagger will give you more wedge.
Using air pressure to make stagger on the scales is fools gold. That tire will react different to static load. Take two tires with the exact same diameter but different pressures and they WILL scale differently with all else being equal. The tire with more pressure but with the same circumference will be "heavier" if you follow my meaning.

[lovinlatemodels]

For Me it was stagger with in 1/4 inch and air pressure was always right on and we always would check air pressure at least 3 to 4 times during set up. Air pressure will make a difference on set up numbers so will stagger. But i think air pressure is more important then stagger for set up. Dirt tracks are always changing thru the night your going to adjust stagger thru the night any way if your keeping up with the track.

[Egoracing]

On a dirt late model you can change bite 200lbs with VERY little air pressure changes. Add 2 lbs to the RF and LR and take 1lb out of the RR and take 2 out of the LF and see for yourself. No matter what some people think it is true and you can use it as a tuning tool at the track. You need a little more LR add a little air in the LR and taks some out of the LF and RR and you are ready to run. It is easy to find, put it on the scales and play with 1-2lbs of pressure. Hoosier even has a page on it showing that 1lb of air is about equal to 40lbs of spring rate on stiff Arca tires.
http://www.hoosiertire.com/springrt.HTM

[drtrkr244]

Air pressure does change %'s on a dlm.

However, a driver once told me how he made big changes on the scales with a few air pressure changes. I immediately put the car back on the scales and proceeded to show him its not possible.

What most people forget to do is bounce the front and rear to settle the springs and shocks.It does change but only a small one.

[7uptruckracer]

I agree with some of your shock setups these days I notice a difference I back all my shocks off to something more normal for setup purposes and put my rods in the neutral locations so birdcage indexs don't effect my numbers. I always use the same scale tires if I can, and give the same resettling bounces after I jack the car. So many people get confused using single cell scale pads as well they are SUPER critical on wheel placement on the scale I HATE them get some double cell or better yet some grain scales sounds crude but I'd throw my brand new longacre scales off a cliff is someone brought me some grain scales. I pull both rear axles and put the front on a greased plate so the front doesn't bind on the scale. Any air pressure is going to be equal to the equivalent in weight that a collar change would be so don't get all caught up just be through and do it the same way every time even if it takes all night.

[Egoracing]

Air pressure does change %'s on a dlm.

However, a driver once told me how he made big changes on the scales with a few air pressure changes. I immediately put the car back on the scales and proceeded to show him its not possible.

What most people forget to do is bounce the front and rear to settle the springs and shocks.It does change but only a small one.

We saw consistant changes and we settled the car after every change. The tire is an air spring, it acts the same way as a spring change. If you put air in you are moving the point that the suspension acts on that corner up and making the air spring (tire) stiffer. This will and does change the weight on that corner of the car. If you air them all up equal you will see no difference but you can change your setup by chaning air just like adding gas to a shock. If it did not change them why not build blocks to hold the car to the condition you want and scale it on the blocks? you could build in adjustable stagger into the blocks and you would never have to worry about tires. The softer the tire the more effect air pressure has on the spring rate.

[7uptruckracer]

Ive seen changes but 200# its crazy talk? That means if you get the wrong tire buildup in the races your doing the same thing.....10-20 maybe.....

[merc123]

What about toe, caster and camber settings?

[Egoracing]

Ive seen changes but 200# its crazy talk? That means if you get the wrong tire buildup in the races your doing the same thing.....10-20 maybe.....

Try it, 2lbs in the LR 2 lbs in the RF 2 lbs out of the LF and 1lb out of the LR. I've done it and repeated it. The tires you use will come into play but do it and take notes. I like How people are dis agreeing but have not tried it them selves. Tire build up during a race is different as you are gaining in all tires and not loosing out of any. Why do you think when a tire that has 5-7lbs of air goes flat the car is almost un-driveable? The car does not know the tire is flat, All it knows is the that corner and the opposite diagonal corner just got lighter and the other two corners just got MUCH heavier.

[Egoracing]

What about toe, caster and camber settings?

Yes they need to be set before scaling, they induce wedge into the chassis.

[7uptruckracer]

Thats why I always use scale tires and match my race sets to scale sets if possible. A flat tire is totally different weight wise, contact patch wise, traction wise. A collar change adjusts bar angles which can effect your BC clocking as well as wheels weigh, a tire change just effects your spindle height you'd really have to run some heavly mismatched tires, and besides your not supposed to really use air pressure in a DLM tire to get stagger anyways baseline off recommended pressures and match your sets so a set change doesn't screw your numbers up. Maybe I don't see 200# swings cause I do the same scaling and tire management deal everytime, but I work with asphalt a ton and you can't get away with that with those shocks and sway bars.

[7uptruckracer]

Tire Pressures in the rear end effect your rear camber, and contact patch as well, even the front end. I've tried it I just don't see it but I roll my car off after every change and my scales are on roller pads If what your saying is true I'm going to go try a few things later Ive tried it before just never seen it Always worth a second look for the sake of learning

[MM90]

I have friends that raced stock cars for years and then moved up to LM. They always have the deer in the headlights look the first time they scale their LM. They tell me 1 PSI can change 30-60#. So I definately believe 2 PSI here and there can add up to 200# change.

[Egoracing]

I have friends that raced stock cars for years and then moved up to LM. They always have the deer in the headlights look the first time they scale their LM. They tell me 1 PSI can change 30-60#. So I definately believe 2 PSI here and there can add up to 200# change.

Hoosier said depending on the tire structure/compound you can eaisly see 40# per 1lb of air pressure.