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View Full Version : Lf anti dive?



CHRISTINE
02-14-2011, 09:42 AM
Would less anti dive in the lf tighten the car up on entry? Im trying to tightin the car up on entry without having alot of front spring split.

dirt2
02-14-2011, 10:31 AM
Which chassis & type of suspension?
What percentages & spring rates?
dirt2

CHRISTINE
02-14-2011, 10:44 AM
O7 peirce i got 650lf and 600 rf 175 lf 200rr 4-4 bar spring behind setup.

FLYNBRYAN
02-14-2011, 06:35 PM
If the left front is on the ground, then yes( in my opinion) the braking froce would or should pin the left front down. Then again you could get to much front traction and cause the rear to break loose.
I think first I would make sure the car is square and the rear end is in line.

Dirtrunner35
02-14-2011, 07:47 PM
This might help

Drawing lines through the upper control arm pivots and the lower control arm pivots will result in an instantaneous center (IC) where those two lines intersect.

Drawing another line from the tire contact patch through this IC - the "force vector" line or "reaction" line - will result in the line crossing the Center of Gravity (CoG) plane or moment arm at a certain height.

Where the reaction line crosses the CoG moment arm determines your anti-dive.

Higher decreases the leverage the CoG mass has on the front suspension while a lower point increases it.

Generally speaking, lowering the rear pivot point of the upper control arm INCREASES anti-dive because it causes the IC to move forward, resulting in the tire contact patch line hitting the CoG line higher - closer to the actual CoG - thus reducing the leverage that the CoG mass has on that wheel.

I have has some success increasing the right side anti-dive while decreasing the left side anti-dive. That has a tendency to make the car dive onto the left front, increasing LF tire temperatures - which tells me that the LF is working a bit harder to get the car through the turns.

On a 108" Metric chassis, this would mean lowering the rear pivot or raising the front pivot point on the right side and raising the rear/lowering the front pivot point on the left.

1Blacksheep
02-16-2011, 05:41 PM
35 you went from askin questions to given class on the subject ! Impressive

Dirtrunner35
02-16-2011, 07:16 PM
Thanks. I was only asking questions as to why people did things the way they do them.

If you're not winning and don't ask any questions, don't complain.

If you ask ten people a question on one subject, you can get ten different answers. They all can't be right, but 9 of them can be wrong.

Racing starts soon :)

HEAVY DUTY
02-16-2011, 10:32 PM
more antidive on the LF would stiffen the LF on the brakes.Think about it.What happens when you stiffen the LF spring? Antidive would be like temporarily stiffening the LF until you lift off the brake pedal.Be careful when using anti dive as it doesnt take much movement to really screw things up.The angle of the upper A arm from level, the angle of the lower a arm from level, and the angle from parallel with the centerline of the car all effect antidive. Antidive is figured as a percentage not as degrees and change with the wheelbase and the center of gravity height. It takes a 3D program to accurately figure the anti dive which most readily available circle track front end programs dont have.Anything that causes caster gain raises the antidive percentage, and just about everybody has a different opinion on what is best.

zachmckenzieracing
02-24-2011, 03:24 PM
the information provided was very accurate, and very technical. knowing those things make a huge difference in your racing team. seldom does a winning team not understand this technology. i insist that if you or your crew cheif does not know this information, learn it. there are several ways to learn this information. if you would like private lessons, i offer them at a reasonable rate. knowledge is power, and that knowledge is what sets a winning team apart from an average team,