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Author Topic:   Trailing The RR
bachshute
Member
posted September 28, 2003 08:48 PM
yes


boas51
Member
posted September 29, 2003 06:21 PM
I have always thought trailing the rr will loosen entry. When the right side lengthens, it "turns" the rear wheels towards the outside wall, trying to bring the rearend around (spin out). Could definitely be wrong though, just how I thought it was.


Greggie
Member
posted September 29, 2003 07:45 PM
I'm with dluna on this one. This is about the only adjustment that you make that does the SAME thing going in and coming out.

Greg

tilley88
Member
posted September 30, 2003 01:24 AM
Ditto.


#46
Member
posted September 30, 2003 09:32 AM
I am with most of the other people Boas51, moving the right rear back further than the left rear WILL make the car looser going in. You might not be understanding what he is saying, but when the lr is forward and the rr is backward it makes the car looser. If you think about it that is the whole reason somebody invented the four bar, so when you get back in the gas it puts roll steer in your car and turns it around the corner (the lr goes forward, the rr back) This way the whole rearend is pointed towards the wall which makes that part of the car (the rearend) drive toward the wall which in turn loosens the car on entry and on exit. When the lr is trailed the rearend is pointing toward the inside of the track which makes the back of the car drive toward the inside of the track and tightens on entry and exit. Thats why, when you get on a bigger track you move your top rods (4bar) down because you dont need as much roll steer to get you through a turn that is longer. Maybe all that makes sense.


bachshute
Member
posted October 02, 2003 03:51 PM
I don't see how you can trail the RR by using offsets. Maybe we are thinking of something totally different when it comes to trailing one side. Trailing one side is going to point the rear tires away from running straight inline with the frame rails. Switching around the offsets will only change the latteral position of the tires, not change the angle that the rear-end sits in the car. Just trying to make sense of this.


grigs24
Member
posted October 03, 2003 09:00 AM
bachshute,
Start with RR about 1/2" trailed. If that is too much shorten it up until you are happy with it.If your car is still too tight getting in the corner I would look for other problems meaning don't go any more than about 1/2". This adjustment will also loosen the car up coming off the corner. I see some different opinions on the site but I think of a long firetruck with the driver in the rear. when the driver in the front tuns to the left the driver in the rear must turn to the right to get the rear end around the corner. good luck!!


dirtbuster
Member
posted October 03, 2003 12:28 PM
I am going to have to agree with the majority and say that trailing the RR will loosen a car all the way through a corner. As long as the wheels are turning the rearend is always going to have a tendency to swing to the right of center. If the car were moving backward then it would be opposite, but noone races backwards...at least on purpose.

I can see where if you had no front brakes at all and the rear brakes were doing 100% of the work then yes with the rearend trailing to the right of the center of front end then when you hit the brakes it would try to straighten the car out..or tighten it. But most cars have all 4 brakes working.

Just my opinion anyway


As for how much, there again it all depends on car and driver..we have trailed rr by as much as 1/2" or led it by 1/4" but I know guys that have trailed 1" or lead 1".



fastow
Member
posted October 03, 2003 08:29 PM
would have to agree with the majority, trailing the right rear (making right side wheel base longer than left side) will loosen the car.
a point to think about though, if you lengthen both top & bottom rods 1/2" you will index the birdcage (top rods will be pointing upwards so the amount the wheel goes backwards is not equal to that of the added length, you will also change the rate (speed of roll steer) and amount of indexing because the arc that the arms move in will become larger.
this is where it's probably best to spend some time jacking the rear end up and down and watch the axle and birdcage movement.
my car is set with 1/2" trail on RR (chassis builders specs) and I leave it alone, just move rods up and down.

[This message has been edited by rocket36 (edited October 04, 2003).]

boas51
Member
posted October 04, 2003 05:34 PM
The only way the trailed RR will pull the rear to the left is if you are backing up. If your rear wheels are rolling forward and the RR is trailed, it is still steering the rear-end to the right. No matter what you are doing, on the gas or off, the rear-end is still pointed to the right and its still steering to the right.

Greg

dluna
Member
posted October 05, 2003 04:19 PM
I see it the same way as Greggie. I do not understand the whole offset/rear-steer talk. Trailing the RR is going to point the front of the tire out more than the back of the tire if you were to draw a line straight down the chassis frame rail. An offset would just move the location of this, not change the angle. Simply put, when the rear end is sitting square in the car, you could make a 90 deg. angle by drawing a staight line down the center of the driveshaft and instersecting it with a staight line running down the center of the rear axles. When you are trailing the RR, that 90 deg angle bumps up to greater than 90 deg. depending on how much you trail.


boas51
Member
posted October 05, 2003 05:53 PM
As long as the rear tires are not completely skidding, the RR trailing will still rotate the rear of the car to the wall. More so on the gas but the effect will be the same.

On that note, if you are trying to loosen the cars entry, "I THINK", (notice the capital letters..just my opinion!!!) you are crazy for trying to lead or trail the rearend. You are screwing up your exit by crab walking the car down the straight. A few things "I WOULD DO".

More LR bite will loosen your entry (as long as your off the gas getting in that is). Some people can't do this because they might also be tight coming off and in the middle. You really need to counter more bite with more stagger. Stagger will get you through the turn better if you are starting out too tight.

Leave your rearend square and work elsewhere. It is a huge crutch that will take away from another point in the track.

Just my humble opinion

boas51
Member
posted October 09, 2003 08:43 AM
I am running a mono leaf modified and have found that I need all the rr back that I can get. Has any one considered the fact that when you exit the corner you lift the front and transfer more weight to the rear and this pushes the front toward the wall.