Chassis Tech

[smac]

This thread can be used to ask and answer set up issues for SmacTrac.

[smac]

Found this on a post from Arnie Fie of Custom Works that may help with set ups...

1) Caster - How much is needed? How much split between left and right is needed? When and why would you change it? Is changing caster a good tuning tool or do you basically run the same caster set-up all the time?

-More castor usu equals more driveability/control. Start with the RF first then play with LF.
-Having castor split (more on the RF) will make the car want to turn left even while on straights. Paper Clip tracks = none Tracks you are always turning = some~5 deg diff.
-When the car is too aggressive on entry OR is uncorrectable off the corner, adding more RF castor will help ease both situations.
-Claytracks/Foam tire 20RF 15 LF
-Loose Dirt/Buggy Tire 25 RF 15 LF

2) On-center king pins - What do they do? Can you run on-center on one side and standard on the other?

For our cars, typically we see...
On center on the RF will increase steering into the corner
On center on the LF will decrease steering off the corner.
Yes for staggered set-ups, 90% of the time my sprinter is OC RF, standard LF.

3) Camber link locations - There's a lot of adjustment both front and rear and I'm not sure where to begin. What happens when the links are shortened or lengthened? How about when you raise or lower a link end? Where do they go when you use on-center king pins?

Camber link lengths: until they match the length of the suspension arm, has the feeling of increasing the traction on that corner of the car. Usu with dirt oval, you always want to plant the loose end of the car, not un-hook the better gripping end.

Examples:
-Shortening LR link length with no changes to angle will make the car turn more thru the center/off the corner esp on-power.
-Shortening the front links will make the front end less aggresive and gain overall stability.

Camber Link Angle: Will change tire's contact patch with the track AND change jacking force realtions to the chassis from the tire. This one can get perplexing very quickly and is not easily explained by someone who types less than 45 word per minute. For the RC car the biggest thing is the tire contact patch, if the chassis rolls and the tire rolls out of it's contact patch, that is less traction.

[smac]

More good stuff from Arnie...


*Changing shock angle basically changes the spring rate, only very slightly. In extreme cases (like an EDM/LM front end with shocks laid down) it can make the front end more sensitive to the track, but far less sensitive to adjustment in terms of changing springs, oil, or spring collar height. This is good if you are looking for VERY small changes.

To some degree, the more the shocks are laid down, the more change you have to create to get a response vs that of more verticle shocks.

In my own pit I will try other springs first, but when VERY close will...
-stand the RR OUT one hole to help TURN the car off the corner/on power.
-stand the RF OUT one hole to help SNUG the car up in the center of the corner.
-stand the LF OUT to make the car PIVOT in the center of the corner and off.
-stand the LR OUT to make the car DRIVE STRAIGHTER off the corner/on power.

You can change the capitolized words to the opposite to get the reverse effect.


*If it is just a touch loose off, try a slightly stiffer RR spring, or softer LR spring. This will help drive the LR off the corner. Also check your suspension shimming. Shim the play out of the front end so the LF is as far forward and the RF is as far back as you can go. This will help with stability off the corner.

[cmain]

Generic oval setup sheet

setup sheet moved to http://www.dirtoval.com/forums/showthread.php?t=39696

[ed gaines]

Generic oval setup sheet

Now thats a set-up sheet:thumbsup:

[cmain]

Mabey one day I will fill one in past the track name line:ha:

If it is missing anything let me know and I will add it.

[sps3172]

More cut and paste....this time from the Bumps and Jumps website....

Phase 1 (going into the turn)

If the vehicle is loose at turn entry then..(needs more traction)

(1) Right front spring is to soft use a harder spring
(2) You need to add more crossweight - by adding a round to the right front spring (add weight to the left rear tire).
(3) Change left front spring to a softer spring.
(4) Lower chassis - keeping it level with the rear.
(5) Reduce front right caster

OR If the vehicle is pushing into the trun entry then..

(1) Right front spring needs to be softer.
(2) You need to reduce the crossweight - by taking out a round to the right front spring (add weight to the front left tire)
(3) Increasing right rear spring tension by one round
(4) Increase front right caster

Phase 2 (the middle of the turn)

If the vehicle is loose in the middle of the turn then...(needs more traction)

(1) Increasing the crossweight by adding a round to the front right and left rear evenly (add weight to the left rear tire)
(2) Use a harder spring to the left rear
(3) The right rear spring needs to be decrease a round (less spring tension)

OR If the vehicle pushes in the middle of the turn then...(needs more steering)

(1) Decrease crossweight by taking out a round to the front right and left rear evenly
(2) Use a softer spring to the right rear
(3) The right rear spring needs to be increase a round (more spring tension)

Phase 3 (coming out of the turn..)

If the vehicle is loose coming out of the turn then..(needs more traction)

(1) Stagger needs to be decreased on the right side
(2) Increase crossweight by adding a round of spring tension to the right front and left rear evenly (add weight to the left rear tire)
(3) Check if right rear spring tension is to much - if it is then take a round out of spring.
(4) Decrease rear springs evenly to the right and left rear.
(5) Use a soft tire in the rear

OR If the vehicle pushes coming out of the turn then...(needs more steering)

(1) Stagger needs to be increased on the right side if present.
(2) Decrease crossweight by reducing a round of spring tension to the right front and left rear evenly (add weight to the front left tire)
(3) Increase right rear spring tension a round.
(4) Increase rear springs evenly to the right and left rear.