Author Topic: Beginner Needing help???  (Read 489 times)

Offline Competitor41

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Beginner Needing help???
« on: April 30, 2019, 09:13:25 pm »
I am going to list my numbers below, looking for some help on the best way to free up my son’s car center off...my son definitely has a tight/loose issue.

1/5 mile asphalt with very little banking

Tire Pressures      Springs.                    Stagger
LS=16.                LF=250  RF=275.       F=3/8”
RS=26.               LR=185   RR=200.      R=3/8”

Caster.                               Camber
LF= 1.0 degree back.          LF = +2.5
RF=2.5 degree back.           RF = -4.5

LS Weight = 50.73%
Rear Weight = 53.28% (almost full of fuel)
Cross Weight = 48.11%
Total Weight = 1305

Toe=1/16” out

We are about 3 tenths off which is not bad for being only 2 races in and coming from go-kart racing. I can watch the “fast” cars rolling through the corner while our car has a lot of front wheel in it and breaks loose as he comes off.

Thanks in advance for any help!
LEGEND 41







Offline justfreaky

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Re: Beginner Needing help???
« Reply #1 on: May 01, 2019, 03:07:53 am »
Welcome to the LegendsRacer family. Glad to have you aboard!

 Not doing bad at 3/10ths off the fast cars for his second race. I'm going to mention seat time, as I usually do. Perhaps more time and experience in the car... ???

 Is the rear axle square in the chassis? Some people like a little bit of lead in the rear end and some don't. I prefer square.

 Tire pressures, spring rates look fair. Some people are really pushing the lighter spring rates. Stagger: Stagger is usually used on the rear of a car with a locked rear end. Perhaps taking the stagger out of the front end. Again I really don't know... We used stagger on both front and rear when I raced modifieds.

 Here is a bit of a quick and dirty trouble shooting guide:

Car Is Loose Going Into A Turn

Stagger: Decrease
Toe-out: Not enough
Front springs: Too soft
Rear springs: Too stiff
Brake bias: Too much rear
Suspension bind: Exists in rear
Cross weight: Increase

Car Pushes Off Corner

Stagger: Increase
Toe-out: Decrease
Front springs: Too stiff
Rear springs: Too soft
Cross weight: Decrease
 
 With that said, lets take a look at your weights: First we need to know which engine you are running to determine the minimum and maximum amounts of weight allowed per rules. Looking at your weights, I am going to assume you are running the 1200 or 1250 engine. As per rule book weights are calculated both with and without driver.
 
75. WEIGHT using a FJ1200/XJR1200/XJR1250 Engine: The minimum weight of the car with the driver (as raced) is 1300 pounds.  The minimum weight of the right side of the car with the driver (as raced) is 640 pounds. The rear weight percentage can be no more than 52.0% without the driver.
 
WEIGHT using a FZ09 Engine: The minimum weight
of the car with the driver (as raced) is 1250 pounds.  The minimum weight of the right side of the car with the driver (as raced) is 615 pounds. The rear weight percentage can be no more than 52.0% without the driver.

I don't know your corner weights with and without driver so have to assume that you scaled car WITH Driver (because you are at 53.28% on rear weight).  I think your cross may be a bit low. ??? Again, not 100% sure.

I am not a front end alignment expert so this stuff is always hit or miss for me. Do you take tire temps? That can help you with where you need to be on front end set up. I'll post some front end tid bits for you to consider. I took these from Kevin Yeatts about 2001:

"The first thing we'll check is CAMBER, CASTER and then TOE.
Camber is the angle of the tire relative to the ground.... Basically, "camber" is meant to give your front tires a better chance of gripping the pavement in a turn. The way to check whether your tires require more or less camber is to take tire temperatures after a practice session. Temps running hotter on the inside of the tire means you have too much camber in the wheel. Temps running hotter on the outside of the tire means you don't have enough camber.
REMEMBER: Adding camber can add to the width of your car...

The best example of caster that I can give is the wheels of a shopping cart. The wheels are mounted in such a manner that they are behind the point where the wheel bracket is mounted to the cart. Were a straight line to be drawn from the mount point to the center of the wheel, the angle degree would represent caster.... It is generally accepted that a 3 degree split from right to left is the proper amount.... A safe caster setting to start with is LF 1 degree, RF 4 degrees. As your skills progress, try moving the casters down the scale a little until you've found a setting on the brink of uncomfortable."

Anyway, your toe- out is likely on spot at 1/16". Never more than 1/8th".

As I said; I am no expert (still learning myself). Hopefully this will give you good food for thought.

Best of luck this season!

Steve
 

Better to be hated for who you are, Than to be loved for who you are not.

Offline Competitor41

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Re: Beginner Needing help???
« Reply #2 on: May 01, 2019, 07:17:02 pm »
Yes these numbers are with driver, we will be checking tire temps next week during practice sessions and that will tell me if we are good on camber....from what you are saying I may be a little light on caster. Just looking for better rotation middle of turn and off. We went down on cross because I have seen people stating that more cross tends to be tight.

If anyone else has anything to add feel welcome to add anything that might jump out at you on our set up.

Again thanks to all for any help.
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Offline justfreaky

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Re: Beginner Needing help???
« Reply #3 on: May 02, 2019, 12:31:10 am »
I am sure some of the others will get back to you. Give them a little time. Most of our members are gearing up for their season as well.

Steve
Better to be hated for who you are, Than to be loved for who you are not.

 

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