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Author Topic:   2-link bar angles
xhubby
Dirt Freak

Total posts: 376
posted June 30, 2004 05:07 PM  
I'm still trying to understand how bar angle changes affect handling. We have a 2001 DW-8 short bar 2-link. left side bar is in the top hole,(approx.13 degrees), & right side bar is in the middle hole,(aprox. 8 degees). Exactly when, where, & how would the car change if we moved the right side bar down 1 hole. The car is real good entering & exiting, but a little throttle tight at apex. on semi tacky track. Would this change allow the car to gain more rear steer at the apex, thus letting it turn better, or am I looking at this wrong? Thanks.

2nd2none
Dirt Forum Champ
Total posts: 755
posted June 30, 2004 05:10 PM  
more bar angle produces more rollsteer. If you are tight in the middle, raise the RR up 1 hole or add a little more stagger or trail the RR back another 1/4" or so.

mod70
unregistered Total posts: 755
posted June 30, 2004 06:44 PM           send a private message to 2nd2none   Edit/Delete Message   Reply w/QuoteBBBBBB
To be honest, I would say that it would remove rear steer. Going nearly horizontal with the RR bar will cause the RR wheel to move forward when the car rolls over. Think about the right side of the frame moving lower as the car rolls. If your bar is flat, the wheel is as far back as it can go. As the front mount of the bar moves down with the frame, the bar will pass horizontal and then begin to pull the RR wheel inward as it takes an uphill angle. If instead you have more of a down angle in the bar to begin with, it will move the RR wheel back as the bar goes toward horizontal.
To check this for yourself, put a piece of tape about 12" long verticaly on the body either in front of or behind the wheel well and measure from the center of the hub to the tape. Then jack up just the right side of the rear end and remeasure. (measure both on horizontal planes) That will simmulate the car rolled over in the corner.

2nd2none
Dirt Forum Champ
Total posts: 755
posted June 30, 2004 07:02 PM  
how does the RR trailing arm get flatter if it already has negative angle in it? The more the RR trailing arm is angled downward the more it is going to tighten the car as the chassis rolls.

If there is upward angle in the bar (as much as the LR) then you will get the maximum amount of loose rollsteer and it will help to turn the car in the middle, but be carefull too much and it will want to drive the back of the car to the wall.

mod70
unregistered Total posts: 755
posted June 30, 2004 08:27 PM           send a private message to 2nd2none   Edit/Delete Message   Reply w/QuoteBBBBBB
2nd - I was refering to xhubby's post about lowering the RR bar angle, not your note. (sorry bout the confusion)

xhubby - I was under the assumption that you were talking about lowering the bar on the frame side. If you ment lowering it on the rear end, (increasing down angle) that would add rear steer. (or did you mean lowering both ends?)

xhubby
Dirt Freak

Total posts: 376
posted June 30, 2004 09:06 PM  
I was talking abut lowering it on the frame mount. As I said, it is now at about 8 degrees, angled up towards the frame. The holes are aprox. 1" apart. Like I said, I'm still trying to learn what does what with the changes in bar angles. I don't want a drastic change, because in & out is good. It's just a little throttle tight at the apex.

2nd2none
Dirt Forum Champ
Total posts: 755
posted June 30, 2004 09:18 PM  
LOL mod70, I wasnt for sure, and a little confused too.

xhubby, if it was me, I'd raise the RR up a hole. On my DW cars I always had to run the LR and RR bars in the same hole, then i'd adjust the RR trail accordingly.

dluna
Dirt Freak

Total posts: 334
posted June 30, 2004 11:29 PM  
x -

are you running equal length arms on both sides?

xhubby
Dirt Freak

Total posts: 376
posted July 01, 2004 04:43 AM  
dluna, yes we are running the same length bar on both sides, with the rearend square.

[This message has been edited by xhubby (edited July 01, 2004).]

xhubby
Dirt Freak

Total posts: 376
posted July 02, 2004 03:17 PM  
Ok, bare with me guys,(like I said, I'm still learning). I now understand how raising the right side up on the chassis mount will increase rear steer. In the beginning, I wasn't taking into consideration that the right side drops as the car rolls entering the corner & the left side raises. Now, is rear steer more beneficial on a tacky track where the car is likely to be throttle tight at the apex, or on a dry slick track where the corner speeds are alot slower? Do I need to be changing the right side bar angle from heat,(tacky) race to feature (dryslick), or leave them alone, & adjust elswhere? Sorry for all the questions. Thanks.

[This message has been edited by xhubby (edited July 02, 2004).]

2nd2none
Dirt Forum Champ
Total posts: 755
posted July 02, 2004 04:08 PM  
First off, the correct terminology would be rollsteer, not rear steer. Just for clarification purposes so you wont get the 2 confused. Rollsteer is the amount the rearend moves with chassis roll. Rearsteer is the amount the rearend is out of square.


Ok, now for the real question. Usually you would want more rollsteer when the track is heavy to help get the car to turn in the middle. But there are so many variables to consider. You could add more stagger for the heats and take it out for the feature and never touch a bar. One other thing, if you move the RR up one hole you have to also lengthen the trailing arm so you get it back where you normally run it. If I remember right raising or lowering a bar on a DW one hole is 1/4" of rearend movement.

xhubby
Dirt Freak

Total posts: 376
posted July 02, 2004 04:32 PM  
Thanks 2nd2none for clearing up the rollsteer, rearsteer thing. We did lengthen the bar when we moved it up to keep the measurement the same as before. Thanks for all of the help!!

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