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Author Topic:   anti-dive--do I want it???
jello
Dirt Roller

Total posts: 16
posted October 19, 2004 04:22 PM  
do you want anti-dive in your race car
or not. I have had people tell me a few
things, but nothing too clear. Would taking
anti-dive out (or putting more in) necessitate any other front end changes?
how does anti-dive affect the car's handling?

I run a SIMS modified and they allow you to
move the upper a-arm stands--which opens up
a can of worms because people are changing
roll centers, anti-dive, etc. So I am looking for ways to help my little racing
program.

p.s. all SIMS cars are metric frame.
thanks again

mod70
unregistered Total posts: 16
posted October 19, 2004 05:21 PM           send a private message to jello   Edit/Delete Message   Reply w/QuoteBBBBBB
Yes. You do want anti-dive. It eliminaters bump steer which causes eratic steering changes when the front end moves up and down.

FlyNLoIMCA17
Dirt Forum Champ
Total posts: 753
posted October 19, 2004 07:13 PM  
I agree with Mod70 I think yes you do want it. I had a book that told about it, but I can't remember what book it was LOL!!! I also can't remember how much degree you needed. Sorry I'm not much help on this. I run a metric IMCA openwheel and I use the factory mounts right now, but planning on changing that this winter.

jello
Dirt Roller

Total posts: 16
posted October 19, 2004 07:43 PM  
my mounts are in stock location right now,
but I am considering moving them. Our rules
say you can move the mounts for caster/camber
but i see creative guys taking some anti
dive out by lowering the front of the mount
and they are raising the roll center by cutting an inch or so off of the mount before
they weld it back on. Also, the shaft on the
upper a-arms does not run parallel to the lowers, so some people are twisting the mount
before welding back on. I am just wondering if all this is worth my time and how it would change the feel of my car. Do you want roll center or anti-dive set any differently for a dry slick than for a heavy track??

Dman
Dirt Freak

Total posts: 270
posted October 20, 2004 08:02 AM  
Using a small amount of anti-dive lets you run softer springs in the front. As the car rolls the front suspension tightens up and makes the car think it is sprung stiffer.It is a point of conversation between true car designers/engineers whether it is good to have or not.Most of the stock clip race cars have it.Most of the Late models I have seen don't. Amazingly most of the modifieds I have seen don't even take it into consideration and place the upper a frames so static camber and caster can be set and so the a-frame will clear the shock, thats it.
Most worry more about the rear suspension than the front. Try calling a chassis builder some time and ask them some detailed questions about front end geometry.I tried talking to one once,A major builder of dirt mods and they told me "that stuff wasn't important on dirt"."You drive the car with the rear wheels anyway and the front end don't matter as long as the caster and camber and toe are set right". Amazing,At one time this builder was turning out almost 300 mod chassis a year and have no tech support accept for a set up sheet on the 6 or 7 different chassis they build.If you want help you have to call one of the hotshot drivers in one of their cars.Good Luck!
Dman

dirtywrench13
Dirt Freak

Total posts: 324
posted October 20, 2004 12:37 PM  
FORGIVE ME GUYS,BUT WHAT IS INTI-DIVE? AND HOW DO I USE IT ,AND DETERMINE HOW MUCH I NEED?

jello
Dirt Roller

Total posts: 16
posted October 20, 2004 02:29 PM  
my understanding (which could be wrong, that's why I am asking so many questions)
is that anti-dive is having the front upper
a-arm mount higher than the rear upper a-arm
mount (i havent really thought about the lower a-arms yet) and having them mounted this way keeps the front of the car from
diving when you run it off into a corner.
But I don't know how much you want, i guess
like everything else it might be a compromise
thing.

jello
Dirt Roller

Total posts: 16
posted October 20, 2004 02:33 PM  
i hadn't thought of the softer springs idea,
but it makes sense. thanks

dirtywrench13
Dirt Freak

Total posts: 324
posted October 21, 2004 11:57 AM  
OK I WAS WONDERING FOR A MINUTE, BUT WHEN I RESTUBBED THE DW 8, I PUT THE OLD MOUNTS ON IN THE SAME PLACE AS THE ORIGINAL STUB.
SEEMS TO WORK JUST FINE FOR NOW. IT'S GETTING REPLACED WITH A KINGPIN CHASSIS THIS WINTER. IT'LL BE FUN TO WORK WITH SOMEONE LOCAL FOR A CHANGE. DIRT WORKS ISN'T MUCH HELP,NORMALLY.

WPP
Dirt Freak

Total posts: 451
posted October 21, 2004 04:50 PM  
Your right

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