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Author Topic:   To lead or trail?
driver27
Dirt Maniac

Total posts: 194
posted May 17, 2004 11:16 AM  
Ok here is the question. If you lead the right rear (move it forward in the car), will this tighten or loosen the car, and at what part of the corner will it have the most effect?

I get differing opinions based on who I ask.

Thanks

mod70
unregistered Total posts: 194
posted May 17, 2004 01:15 PM           send a private message to driver27   Edit/Delete Message   Reply w/QuoteBBBBBB
It should loosen up the car mid corner out, especially on a dry/slick track. The heavier the track, the less rear steer is needed. If you lead the RR you're removing some of the right rear steer that tightens you up comming off. On a very heavy track you might be able to put a little lead on it, but I always prefer to keep mine square at ride height and allow the control (trailing) arms to do the rear steering for me.

nvracer
Dirt Maniac

Total posts: 127
posted May 17, 2004 07:16 PM  
If you lead the right rear it will tighten the car every where.
Example: If you increase roll steer in a car it shortens the LR compared to the right rear (when the car rolls over)which loosens the car.

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted May 17, 2004 07:27 PM  
Leading RR will tighten, trailing RR will loosen. Either one pretty much affects the car throughout the corner. Trailing can often be helpful on a tacky track when the car has a slight push under power as it will help turn the car through the middle. Also helps on dry slick because the rear of the car will help turn itself through the corner without the tires breaking loose meaning faster corner speeds which helps the car come off the corner better.

udecide66
Dirt Freak

Total posts: 229
posted May 17, 2004 07:48 PM  
So if you lead the right rear it will help on a dry slick track? if so how much do you lead (inches)?
instead of moving the RR forward can you move the LR backwards to get the same effect?

mod70
unregistered Total posts: 229
posted May 17, 2004 08:18 PM           send a private message to udecide66   Edit/Delete Message   Reply w/QuoteBBBBBB
nv & buster - this goes against everything I've read & been tought. Right rear steer is suposed to tighten up the car because as you come off the corner in a slide, the car is pointed to the left, therefore if the rear is cocked to the right it is in effect pointed straighter down the track. Now I may be wrong about this, but it made sense to me. After all, most people will increase the angle of the LR control arm when the track goes slick, which will induce more right rear steer. I can understand your point that pointing the rear left would want to pull it back in line, but in a sideways slide it should be better to point it straight down the track, shouldn't it?

driver27
Dirt Maniac

Total posts: 194
posted May 18, 2004 06:43 AM  
Thanks for the responses, which are pretty much what ive been hearing. Seems everyone has a slightly different opinion on exactly what leading the rr does. Ive always ran my rear end square in the car, but this week im going to try leading the rr by a 1/4 inch. Was hoping to have some clear idea of what this change will actually do. Im interesting in hearing anyone elses opinion on this subject.

Thanks

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted May 18, 2004 08:06 AM  
mod70,
I have never read anywhere that leading the RR will loosen a car. In fact just the opposite. Check out this page from the DW setup book. http://www.thedirtforum.com/dwsetups/7.jpg. look under rear steer.

The idea is to not come off the corner in a slide. If you are sliding you are breaking traction. If you keep the tires from spinning you will come through and off the corner better. When you can get better traction due to this you may actually find you car is a little tight due to other factors in your setup. If you go too far it will make the car too loose but can help the car flow through the middle better. Increasing the angle in the LR arm like you say will pull the LR wheel forward or in effect trail the right rear. if you have up angle in both of your trailing arms then as the car rolls over the RR goes back and teh LR comes forward, this is known as loose roll steer, because it will make the rearend try to drive counterclockwise around the front and make the car feel loose, as long as your front tires have grip.

driver27,
maybe your car needs the RR lead ea car is different. Whenever we tried it on our DW car it did make the car tighter on exit but it also made it harder to get it to turn into the corner and the driver had to break the rearend loose to get the car to turn which then screwed up the exit. We eventually trailed RR by almost 1/2" and car rolled into and through the corner better.


[This message has been edited by dirtbuster (edited May 18, 2004).]

Ego Racing
Dirt Forum Champ
Total posts: 724
posted May 18, 2004 11:06 AM  
On 4 link and three link cars when on the gas the left rear will move farther forwad than the right, The left rear will ove back slightly causing the rearend to push the car out of the corner. The amount of rear steer depends on the chassis setup the track and the driver. If you reverse this and lead or shorten the rear on the reigh and extend the left rear, when you get on the gas and the rear sets the rear will be driving to the left and the front of the car is going to go to the wall.
Get a shopping cart. now think how your car comes off of the corner If you push the cart with the left rear in line with the right front the cart will go straight, This is the same as the left rear shortning, now set the cart at the angle of corner exit and try to push it straight, it turns right. This is as the right rear is leading. If you lead the right rear and the chassis rolls up on it it is either going to straighten the rear and push to the wall or turn the car right.

[This message has been edited by Ego Racing (edited May 18, 2004).]

Ego Racing
Dirt Forum Champ
Total posts: 724
posted May 18, 2004 11:09 AM  
quote:
Originally posted by mod70:
nv & buster - this goes against everything I've read & been tought. Right rear steer is suposed to tighten up the car because as you come off the corner in a slide, the car is pointed to the left, therefore if the rear is cocked to the right it is in effect pointed straighter down the track. Now I may be wrong about this, but it made sense to me. After all, most people will increase the angle of the LR control arm when the track goes slick, which will induce more right rear steer. I can understand your point that pointing the rear left would want to pull it back in line, but in a sideways slide it should be better to point it straight down the track, shouldn't it?

If you are increasing the LR bar angle you are leading the left rear more when the chassis rolls over this is "Leading" the left rear not the right rear.
You have the right answer but the wrong question, Your answers are leading the left rear and the question was for the right rear.

mod70
unregistered Total posts: 724
posted May 18, 2004 12:30 PM           send a private message to Ego Racing   Edit/Delete Message   Reply w/QuoteBBBBBB
OK guys, now I'm really corn-fused. First things first, buster-I clicked on your link and it said file not found (URL unavailable), and Ego - on the first line of your first post you said left twice, I'm sure you ment right on one of them but which?
buster - I agree, and probably phrased my response wrong in regards to comming off in a slide, however, there is a time through the corner that we are sliding. Anytime you have to back steer, the rear is trying to pass the front end. Now by the time I'm truley comming off the corner, I'm pointing straight ahead (at least hopefully!), but until then I'm usually back steering. I see this often in others. Does this meen that the car is way too loose, or is it somewhat typical? Do you find yourself back steering at the mid point, or are you starting to straighten out the wheel, or even turning left?
My next question refers to both of your statements. You both agree that increasing the LR arm angle (and please realize I have a 3-link, no experience with a 4) will pull the LR wheel farther forward as the car rolls over, creating right, or loose as you phrased it, roll steer. I have been told at the track by more experienced drivers to increase this angle to get more bite in the LR. I've also seen this solution given numerious times on this website. It sounds contridictary ($10 please) to me. How can increasing this angle create more bite as well as loosen the car up? Are you setting the RR arm angle so shallow that as the chassis rolls over it's going past horizontal and actually pulling the RR back forward canceling out the right steer? (That may be 2 seperate questions)
One other thing, (Ego, this pertains to your first post) when you get back on the gas, the rear end will try to ride up the pinion gear thus rotating the rear end forward. (correct?) If you have different angles on the bars wouldn't this also create right steer? (more angle on LR than RR) I've seen the rear end rotate so much it looked like the LR tire was under the driver's seat.
I'm not trying to be a pain, I just want to get this straight in my head, and I don't want to be giving out sh**y information.
Thanks for the help.

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted May 18, 2004 01:33 PM  
Increasing the LR arm angle increases bite when you are powering out of the turn because the left rear tire is trying to drive up under the car and you are actually trying to lift some of the weight of the car on that bar which in turns plants that tire harder making it bite harder thus tightening the car like adding LR bite. But at the same it does provide more loose roll steer so that is how it loosens or more accurately frees the car through turn. Adding static rear steer (RR trailed for instance) helps free the car in the same way but if you go too far it will make it too loose on exit because the rear is steered to far to the right and the driver cant compensate for it. There is a fine line there.

A car that has a lot of rear steer like a 4bar car or some 3 link do most of the steering in the rearend, the driver just has to keep the front of the car headed in the right direction so it is imperative that the front end of the car sticks. Watch a lot of late models and you can see they rarely come out of the corner straight, they are usually a little sideways until the rear settles down and the rear steer comes out of it. While it looks like they are backsteering, (and technically they are) its not because they are sliding, they are simply lining the front of the car up with the back of the car.


Did any of that make since. Not trying to confuse you but not sure i explained it very well.

[This message has been edited by dirtbuster (edited May 18, 2004).]

driver27
Dirt Maniac

Total posts: 194
posted May 18, 2004 01:49 PM  
Exactly the type of information and discussion I was trying to generate. I thank everyone. I think a bit of lead in the rr will compensate for a bit too much left rear steer when trying to generate alot of bite on the lr tire under power. We shall see this weekend. I see everyone has been getting different answers on this question too, so Im glad it not just me...

mod70
unregistered Total posts: 194
posted May 18, 2004 02:29 PM           send a private message to driver27   Edit/Delete Message   Reply w/QuoteBBBBBB
So as I understand it, the right roll steer helps to free the car up in mid turn, alowing it to pivot. As the power is applied, the angle in the LR bar allows the LR wheel to drop down farther in relation to the RR wheel, causing it to support more weight on that corner, which ads cross.
Ohhhhh!
Dude! Thanks, I've finaly got it. All this time I thought it was the roll steer tightening it up. COOL!

Hey 27, let us know dude.

[This message has been edited by mod70 (edited May 18, 2004).]

Ego Racing
Dirt Forum Champ
Total posts: 724
posted May 18, 2004 04:47 PM  
Driver 27 the confusion here is most are takling about right rearend steer NOT trailing or leading the right rear tire but letting the suspension cause the left wheelbase to shorten and the right wheelbase to lengthen, which causes the rearend to steer to the right. When setting static the rearend is square to the chassis the rear steer is only through chassis movement.
Dirtbuster- we run a super latemodle and I had some pictures that would show what you are talking about but I cannot find them right now. On a dry slick track our car goes all of the way down the straight with the left rear tire track almost inline with the right front. Threar is hiked up and the car is down on the right front and the car stays like this until I lift the throttle, then it straightens out to set it for the next corner then gight back up on the bars.

Ego Racing
Dirt Forum Champ
Total posts: 724
posted May 18, 2004 04:51 PM  
quote:
Originally posted by mod70:
OK guys, now I'm really corn-fused. First things first, buster-I clicked on your link and it said file not found (URL unavailable), and Ego - on the first line of your first post you said left twice, I'm sure you ment right on one of them but which?
buster - I agree, and probably phrased my response wrong in regards to comming off in a slide, however, there is a time through the corner that we are sliding. Anytime you have to back steer, the rear is trying to pass the front end. Now by the time I'm truley comming off the corner, I'm pointing straight ahead (at least hopefully!), but until then I'm usually back steering. I see this often in others. Does this meen that the car is way too loose, or is it somewhat typical? Do you find yourself back steering at the mid point, or are you starting to straighten out the wheel, or even turning left?
My next question refers to both of your statements. You both agree that increasing the LR arm angle (and please realize I have a 3-link, no experience with a 4) will pull the LR wheel farther forward as the car rolls over, creating right, or loose as you phrased it, roll steer. I have been told at the track by more experienced drivers to increase this angle to get more bite in the LR. I've also seen this solution given numerious times on this website. It sounds contridictary ($10 please) to me. How can increasing this angle create more bite as well as loosen the car up? Are you setting the RR arm angle so shallow that as the chassis rolls over it's going past horizontal and actually pulling the RR back forward canceling out the right steer? (That may be 2 seperate questions)
One other thing, (Ego, this pertains to your first post) when you get back on the gas, the rear end will try to ride up the pinion gear thus rotating the rear end forward. (correct?) If you have different angles on the bars wouldn't this also create right steer? (more angle on LR than RR) I've seen the rear end rotate so much it looked like the LR tire was under the driver's seat.
I'm not trying to be a pain, I just want to get this straight in my head, and I don't want to be giving out sh**y information.
Thanks for the help.

First Sorry I corrected the error in the post above. Second check my last post as to rear steer, we are talking about the rear of the car using the left rear to steer the car to the right NOT trailing or leading the right rear

mod70
unregistered Total posts: 724
posted May 18, 2004 05:40 PM           send a private message to Ego Racing   Edit/Delete Message   Reply w/QuoteBBBBBB
Ego - I'm sorry for the confusion, but my orgional thought was that leading the RR would be offset by the rear steer. I didn't mean to take this post in the wrong direction, but I was confused about it.

zeroracing
Dirt Forum Champ
Total posts: 1875
posted May 19, 2004 03:10 PM  
you add lr bar angle on slick tracks to increase thrust angle so you get more bite. thats what tightens up the car. as far as rear steer, when alot of cars rearsteer, the lr goes forward and the rr goes back the car will loosen up. but alot of guys will claim the car feels tighter when in reality they are turning the front wheels to the right in order to keep the rear end from coming around. then all 4 wheels are pointed towards the wall and the car feels as if it is pushing to the wall. you will note alot of 4 bar cars doing a 4 wheel drift up off the corner and sliding high. in reality the rear is loose, but the driver is correcting with the front end and makes him think it is tight. that is where alot of people get messed up. but if you rearsteer alot and do not compenstate then the car will be super loose.
some guys start out with lead in the cars to tighten or to loosen up the cars overall.
also to get thrust angles up good you have alot of rearsteer sometimes so that is another reason to run lead in the car to compensate for rearsteer and keep thrust angles.

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