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Author Topic:   Mid-turn drifter, part 2
tilley88
Dirt Forum Champ
Total posts: 879
posted April 12, 2005 11:15 AM  
OK, finally got the car on the scales and checked ride heights, angles, etc. I'm startin' to think my car was "kickstanding" in the middle of the turn after reviewing all the data. Here we go: Before changes- 1.5" of stagger in the front, 3" in the rear. Ride heights- LF 5.25", RF 6", LR 5.25", RR 5.5". 18* pullbar, 17* LR bar, 9* RR bar, 5.5" of rake in the j-bar. Chassis weighed 2410 w/50 lbs of lead and 25 gallons of fuel- 52.6% left, 58.9% rear, 48.4% cross, 22 lb left rear. 3" offsets all the way around.
Then I started making changes- 1.5" of stagger in the front, zero in the rear, 4" offset RR, 2" LR. Changed ride heights- LF 5.5", RF 5.75", LR 5.75", RR 6". I noticed the j-bar can move up 1.25" on the pinion side to get it even with the pinion, but left it alone, for now. This really changed the scale numbers- 52.1% left, 59.1% rear, 51.5% cross, 80 lb left rear. Weather permitting, I'm gonna try it Friday nite.

dirtywrench13
Dirt Freak

Total posts: 324
posted April 12, 2005 12:07 PM  
sounds like your headed the right direction.

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted April 12, 2005 12:34 PM  
If its still skaty I would leave the pinion side of the jbar and lower the frame side. If you still need a little more, move some lead to the right, or hang a piece of lead right on the upper right frame rail. Dont be afraid to get your left% down to 51.5% or so if its real dry. You'll know when you go to far because the car will be so tight into the corner and middle (before you get on the gas) that it wont turn.

Xtreme12x
Dirt Forum Champ
Total posts: 874
posted April 12, 2005 02:43 PM  
One thing to consider also is that your RR trailing arm doesn't have enough angle... On a Dirtworks if you run the STD housing mounts, you need to mount your LR arm in the top hole and RR in the Middle to start, if you get too much split one side trys to work against the other. This is good on a super dry track, the left rear see's more bite then the RR and it helps from the center out. Everything else looks good... Like Dirtbuster said don't be afraid to go down on left even more.

tilley88
Dirt Forum Champ
Total posts: 879
posted April 12, 2005 03:11 PM  
I had standard plugs with 3 holes, but could'nt get enuff angle in the LR. I made my own plugs, put the left in the top hole, right in the next to top hole. I can't lower the j-bar any more on the frame side because the plug gets in the way. I can move that weight to the right side if necessary. The car seems to have awesome forward bite on an extremely dryslick track.

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted April 12, 2005 04:10 PM  
Do you have the double sided panhard clamp on the frame? Do you have the jbar bolted on the outside the panhard mount or on the inside. IF its on the inside you should be able to go lower, but you may have to cut the outer half of the clamp off, or go to a 1 side clamp.

Ever think about a short panhard bar. Like 11-12" bar?

5.5" isnt that bad in a jbar but lowering it on the frame a little more might help. ACtually The next thing I would do is raise all the weight in the car and/or move it right like I mentioned. This will help the car roll over and stick better.

nvracer
Dirt Maniac

Total posts: 127
posted April 12, 2005 08:54 PM  
I don't believe you are kickstanding. The car will not skate if it kickstands, it will normally be super tight through the corner.
I was thinking you had the J-bar to low on the chassis but understand you made your own plug that has more holes. Your J-bar location is pretty close, it doesn't take very big adjustment to change the handling of the car.
If you are running the pucks I try and run 3/4" to 1 1/4" of stagger and adjust the rollsteer to get it through the corner.

tilley88
Dirt Forum Champ
Total posts: 879
posted April 12, 2005 10:26 PM  
Yeah, it's the double sided mount, j-bar mounted on the inside. I could run a shorter bar, probably 11-12" like you suggested. By adjusting roll steer, do you mean shortening the LR link?

[This message has been edited by tilley88 (edited April 12, 2005).]

nvracer
Dirt Maniac

Total posts: 127
posted April 13, 2005 11:27 AM  
You might call it rear stear.
I raise the right rear link up or down to loosen or tighten the car throught the corner.
Raise the RR lower link loosens.
Lowering the RR lower link tightens it.
For Bite:
Raise LR upper link tightens off.
Lower LR upper link loosens off.
These are the only links I change.

dluna
Dirt Freak

Total posts: 334
posted April 13, 2005 12:29 PM  
Is the reason for this on say…the RR because it is getting more or less drive off the corner? More angle will give the RR more drive, loosening the car?

OR

Is it when the body rolls, with little angle, the RR wheel base will shorten, and the opposite for a lot of angle? For instance, on a 20” bar, @ 10*, the right side has to travel a little under 3.5” before it goes below level…so if you car doesn’t roll any more than that, it will lengthen the wheel base the whole time…loosening the car. If you are on a 20” bar @ 5*, the right side only had to travel 1.75” before it goes below level, which will then start shortening the wheel base as the body rolls.

SO, if you take the first bar configuration @ 10* and your car only rolls over 3.5" on the RR, what effect does it have on the car if you raise the trailing arm up one more hole? You are still going to be lengthening the wheel base the whole time either way...one bar will be a little longer than the other of course.

Just trying to understand which one has more effect.


[This message has been edited by dluna (edited April 13, 2005).]

[This message has been edited by dluna (edited April 13, 2005).]

nvracer
Dirt Maniac

Total posts: 127
posted April 13, 2005 08:49 PM  
Dluna,
You are correct, raising the RR Lower trailing arm up increases the thrust angle increasing bite, but it also reduces the indexing of the birdcage. This offsets some of the thrust bite gained if the spring is on the birdcage in front of the axle.
It also increases loose roll steer, causing the handling to be looser over all.
On your last question, Lets say you have the lower trailing arm level in the static position, and the car then rolls over 3” past level, it will shorten the wheel base, raise the trailing arm up 1 hole as the car rolls over it will length the wheelbase and if it goes past level it will start to shorten the wheelbase, but well not shorten it as much, making the car looser. Same goes if you move it up another hole. It’s all referenced to how it was before the chassis change.
My personnel opinion is the upper bars are for bite and the lower bars are for roll steer. This keeps it simpler for me to adjust.

CCGRT9s
Dirt Full Roller

Total posts: 31
posted April 13, 2005 10:16 PM  
Why are you running 1 1/2" of "stagger" in front? 0-1" max. By having more stagger in RF, you end up putting more angle in your upper a-frame, inevertantly moving your front RC to the right. Stick to 1" and under. Remember, the only thing front stagger does is let LF brake catch a split second quicker than RF, until you go too big, and throw your front RC off to the right, which will lessen (stiffen) the roll of frontend. (example-it would be like running a 1300lb spring in rf, even though you have a 700 in there)

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