Jacobs ladder length?
 

What are the differences in running a 13 5/8" Jacobs ladder compared to a 14"?

Re: Jacobs ladder length?
 

one is shorter than the other

Re: Jacobs ladder length?
 

Originally Posted by zeroracer:
one is shorter than the other

You got to love a GENIUS

Re: Jacobs ladder length?
 

A 13 5/8 will react faster, a 14 will take more to get similar movement but in my opinion possibly generate more leverage

Re: Jacobs ladder length?
 

Thanks, does one free up the chassis more?

Re: Jacobs ladder length?
 

I have been researching this same question. In my opinion, the longer arc should hold the car up longer, to free the car up entering the corner, the shorter arc should load the RR quicker.I think!but I am no genius. So if somebody could explain, in idiots terms, that would be real nice.

Re: Jacobs ladder length?
 

In my past experience, a shorter ladder hooks up harder than a long ladder.

Re: Jacobs ladder length?
 

I have heard about guys running different length arms to change the reaction. Like longer on top or bottom. Anybody want to help me on this? Thanks

Re: Jacobs ladder length?
 

A 14" ladder is definetely going to free the car up on entry as well as all the way thru the corner,out here on the west coast I've run both a 13 5/8 and a 14" ladder,the 13 5/8 is what i normally run but if the the track is very tacky with a big cushion and I'm having a tough time getting the car to rotate thru the corner thats when I would run the 14" ladder.

Like what some guys mentioned earlier,the shorter ladder reacts a little quicker in getting RR bite into the car,the longer ladder delays the reaction time.

Re: Jacobs ladder length?
 

Originally Posted by LEADERS EDGE:
In my past experience, a shorter ladder hooks up harder than a long ladder.

i am uncertain of what you mean by, a shorter ladder hooks up harder than a long ladder. Do you mean it is harder to get the car to hook up, or the car hooks up better?
Sorry if I am a little ignorant, but terminology is different in some regions than others.
I just want to be clear, on my interpretation, because LEADERS EDGE seems to be the Guru. So whatever he says, goes!:thumb

Re: Jacobs ladder length?
 

got an email address?

Re: Jacobs ladder length?
 

Just my HMO, I've seen guys run links, they had sawed out, in a curve, to clear something on the chassis, maybe that was their problem, I never tried it, but common sense, or theory, tells me, that if the upper, and lower links, are different lengths, then would it not put things in a bind? Just a thought! Bob

Re: Jacobs ladder length?
 

While I appreciate the "Guru" compliment, I learn with each passing day that I know less and less. I am just lucky to have smart people around me.

I meant that the car got more bite with the shorter ladder.

By changing the ladder strap length they are tricking the car into thinking that the roll center has changed without changing the actual heigth or arm angles. If you take construction paper and lay out your ladder length and use different strap lengths(pinned to the ladder) you can see the different ways the ladder travels in it's arc.

Re: Jacobs ladder length?
 

Scotty, I spent most of one winter, in my slack time, doing that, I even went as far as using 16ga aluminum, that I sheared about a half inch wide, and drilled holes a quarter inch apart, and used the push pins to change the lengths of all the pieces. If nothing else, it's fascinating, especially if you do all the combinations, and plot the curves, or lack of curves you can get. Velly intellesting! Bob

Re: Jacobs ladder length?
 

If you draw a line intersecting all the points on the ladder to a point you will have found your rear roll center. The longer the ladder the bigger the arc thus the less leverage the ladder can achieve. The real important matter is the angles of the straps. If you go back to drawing the intersecting lines you can see that as you angle the "Straps" you can move the roll center up and down. Also lowering the ladder on the birdcage also effectively raises the roll center, by moving that invisible "Roll center" up.

Re: Jacobs ladder length?
 

I think I can agree with that, I make my own clevis, and I have three holes in them, in a triangle pattern, one on center, and one each above and below, so I can make a quick adjustment as the track changes on dirt. If you use a std 3/8in clevis pin, and drill the holes, so you leave only about 1/8in of stock between them, then the center line changes 1/2in, which is very noticeable. Bob

Re: Jacobs ladder length?
 

At one time I saw some midget cages at Leaders Edge in which the clevis mount on the cage was slotted for adjustment up and down. They were serrated in the slot to keep them in position once you locked the nuts down. A very nice piece but I never did hear how they worked out.

I think messsing with the strap lengths is a bad idea unless you want to spend the time mapping out the arcs as described. If you are going to do that you also need to map the side to side movement of the rear end created by the rear arm/radius rod configuration so you can match the arc of the ladder to it. Which holes the radius rods are in will change the side to side movement of the rear end as well.
Also, the side to side movement is slightly different in roll than it is in bounce.

Maybe that is why the mount spacing (14"), strap length (7") and spacing of the straps on the ladder (7") have stayed the same for so many years. It is a good compromise for all conditions based on current tube heights, arm lengths/angles and radius rod lengths/locations/angles.

Man, time to quit cause I'm starting to sound like LarryO.

There was a very good article on this in an old edition of Open Wheel. I have it somewhere, but am too lazy to dig for it right now.

Re: Jacobs ladder length?
 

A 13 5/8 jake ladder will essentially tighten up the car. It will react faster & change your roll center and also make the car drive off the right rear more. With a longer ladder the car will plant the left rear more & be looser thru the corner. I don't know if anybody does it with sprint cars, maybe non wing cars but I know the midget guys will build "tilt" or angle into the jake ladder mounting brackets to achieve different outcomes on the car.

Re: Jacobs ladder length?
 

The original question was: what is the difference between a 13 5/8 and 14" ladder?
The shorter ladder will pin the car on the RR. When you go into the corner, the car rolls to the right, the arc(length) of the ladder determines how quickly the center of gravity will move upwards. Think of it like this, the shorter the ladder, the more likely the car will bicycle on entry. If you get really good sidebite, use a 14" to slow down the raction time and make the car easier to drive. If you run a swaybar in the front, you probably need a shorter ladder. If you only run four bars, use a 14" ladder to keep the car planted. Jack and JJ used to "spike" the ladder when the track was really slick. Basically just putting a six inch strap in the top and readjusting the clevis. It REALLY makes the car get sidebite. Ladders at the track aren't marked, so you can't really tell who runs what. A slick way to tell is to look at the birdcage. Sometimes guys will machine off some of the birdcage to accomidate a larger ladder on a car that gets really good sidebite. But here's the problem; the younger drivers always want the car tighter, tighter, tighter. They would hate the longer ladder. They eventually learn that freeing the car up will make it easier to drive and a whole lot more predictable. Changiny the ladder is an easy way to "calm" the car down. Lots of info here but its no BS. Ladders aren't rocket science and they do matter, but I'm almost sure everyone could improve on something else before the ladder needs changing......

Re: Jacobs ladder length?
 

Well said RR>LR=LTO!

I run 13 5/8'' almost all the time, except for a high banked hooky track such as Premier Speedway

Re: Jacobs ladder length?
 

I was reading the post on jacobs ladder and am LOST on how to find the roll center of a jobs ladder can you give me more detail on this. not sure how to connect the points. thanks

Re: Jacobs ladder length?
 

The longer the arc should be maintained more permanent car release of cars entering the corner, the shorter arc RR load faster.

Re: Jacobs ladder length?
 

Originally Posted by Go Fast:
At one time I saw some midget cages at Leaders Edge in which the clevis mount on the cage was slotted for adjustment up and down. They were serrated in the slot to keep them in position once you locked the nuts down. A very nice piece but I never did hear how they worked out.

I think messsing with the strap lengths is a bad idea unless you want to spend the time mapping out the arcs as described. If you are going to do that you also need to map the side to side movement of the rear end created by the rear arm/radius rod configuration so you can match the arc of the ladder to it. Which holes the radius rods are in will change the side to side movement of the rear end as well.
Also, the side to side movement is slightly different in roll than it is in bounce.

Maybe that is why the mount spacing (14"), strap length (7") and spacing of the straps on the ladder (7") have stayed the same for so many years. It is a good compromise for all conditions based on current tube heights, arm lengths/angles and radius rod lengths/locations/angles.

Man, time to quit cause I'm starting to sound like LarryO.

There was a very good article on this in an old edition of Open Wheel. I have it somewhere, but am too lazy to dig for it right now.

I remember this article also, I made many a different length straps and never got to use them. My father who made me read and study the article in Open Wheel and I wanted to try it but have not yet. My current driver chose to spend money on Cages to do something that is being spoken of about different length straps. I wanted to try the straps first and save the money. Straps are cheap compared to bird Cages. But I don't know anything LOL! oh well.

Re: Jacobs ladder length?
 

If you can find Open Wheel Dec 94 pg 50 " Jacob's Ladders and Rear Suspension Geometry" might help out. They show how your roll center changes as it moves. Good Luck.

Originally Posted by CRA91:
A 14" ladder is definetely going to free the car up on entry as well as all the way thru the corner,out here on the west coast I've run both a 13 5/8 and a 14" ladder,the 13 5/8 is what i normally run but if the the track is very tacky with a big cushion and I'm having a tough time getting the car to rotate thru the corner thats when I would run the 14" ladder.

Like what some guys mentioned earlier,the shorter ladder reacts a little quicker in getting RR bite into the car,the longer ladder delays the reaction time.

Is this advice on a non wing set up or a wing car?