7s Ranger

Tomack

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Dude, if racing is fun how come some things cant be said for fun. In a jokin sense. Your truck cant be any cleaner. It is a nice pice of work. I am not going to protest anybody, that is not the way we race. We are out there for the fun!!!! Just like you, your out there for fun. So why cant we have fun on this board talking trash. This board is for fun not to start [censored]. And that is not what I was trying to do. So I will say sorry if you took it the wrong way. Relax and have a cold one on me....

"If you aint racin, you aint livin"
 

Curtis Guise

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Here is one for the experts to comment on.

I have almost the same exact design mounted on my rear end in my 7 truck that still has leaf springs as the Fireguys. I was told by a class 8 racer / fabricator that it is not the right design at all to use with leaf springs, but it is right to use it for a 3 link setup because it is what keeps the rear end located in the center.
If used with leaf springs it would end up limiting the travel and make the suspension stiffer. But not for perfectly straight up and down with both wheels at the same time. His reason was that when one wheel is traveling up with leafs, then the top of the rear end where that mount is, is trying to move to the side. But with that single heim and the two up on the frame there is no way it will allow side movement. I can understand exactly what he was saying but never rebuilt it with two separate track bars instead of one triangle style one like it is now.

Anyone know how much of a difference it would make in the travel and/or stiffness of the suspension???

maybe this is for the shop thread, but we are on the subject here...

curtis
 

Kritter

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I do not understand why he would say it would move to the side. When one is bumped and one is drooped..it still pivots about the center...nothing wants to move left or right...that is the whole purpose of the heim. The center line of the rearend will always be the same but the rearend can rotate in the same plane as much as the heim will let it...which I believe is +/- 15-20 degrees and that translates into about 16" of opposing travel before binding the heim and according to the guy you spoke with causing the rear end to move to the side. 16" of opposing travel would put the leaf springs in a bad situation becasue then they would be taking a torsional load becaseu they must rotate at the same angle as the rear end since they are clamped. I dont think I have never seen a 7s truck have almost one rear wheel at full bump and one at full droop, but I may be wrong. I may not understand what you are asking but the heim keeps the rear end from moving side to side but does not keep the rearend from rotating in its own plane (perpindicular to the frame rails) and will not cause any lateral motion unless the heim binds. If built properly and used within its means it should not effect give an ambiguous springrate.



Kris
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Jack

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This same concept makes it act like a sway bar for the rear. I don't see this as a problem. But what you do need to look at is that it is much more efective controling rap if it is spring under, if not you need to raise the mount off the top of the housing. If the spring line (main leaf) and the bar are at the same level it will not do anything for rap but will put the least amount of bind on the springs during a crosup (duckwalk).
 

orvacian

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I want to agree with JDFAB. The 3-link seems like it would try to bend the springs to one side any time one rear wheel was higher or lower then the other. I don't think the differential piviots exactly on one point at the top of the housing. I would not be surprised if the top of the diff piviots 4" from side to side during articulation of the rear end. I would think that a single bar with heims on both ends would be better for a spring-under truck, but I may be wrong.
 

Kritter

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Its not a 3 link...its a v bar with one mount on the housing. If 1 pivot will cause a transmission to "walk" out from underneath the truck instead of rotate...imagine what 2 mounts spaced apart would do...there would be less pivot action due to antagonistic reactions. Balance a ruler on one finger and then move either side up and down...it rotates at the same point...now balance it with 2 fingers equidistance apart...a lot harder to pivot with respect to only 1 finger.

Kris
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orvacian

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Kritter, I think you are missing the whole point of what I am talking about. The ruler analogy also has nothing to do with this. The end of the v-bar on the axle housing can not move side to side, correct?
A traction bar is just to stop axle wrap, not side to side movement.

<P ID="edit"><FONT SIZE=-1>Edited by orvacian on 06/14/02 01:06 AM (server time).</FONT></P>
 

Kritter

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A vbar is is there to keep the axle under the truck and alsoto keep the wheels from hopping.

Kris
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martininsocal

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you have to look at the operation from a multi problem aspect- the center section of the axle will move sideways while rotating. the reason is because when you ahve a movement where one wheel is firmly on the ground and the other is rising, the center of the axle rotates up and towards the wheel planted, it creates an arc through the travel. this does not occur when one wheel is rising and the other is falling at similiar rates. also- if the geometry is wrong and the traction triangle is not in a parallel plane with the leaf movement, as one wheel compresses, it will also move rearward, the triangle will cause the center section to rotate up or down depending on angle and also can cause the rear axle to twist off its centerline cuasing a crab walk situation.

to learn more, buy LEGO's, the advanced sets, they have some of the parts you can apply these thought to without firing up the welder!

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StandOnTheGas

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We also run a "wishbone" style traction bar. I was told the wishbone or three link helps the truck "duckwalk" where it would allow the rear wheels to move more independant of eachother and keep the truck hooked up better. In addtion, using two, two point tractioin bars can sometimes lead to "barber poling" where the twist on the rear axle can have a funky rear wheel steering effect. I don't know that much about it. However, we did cycle the rear axle for days with a mock up set of leaf springs made up of just the main leaf a two or three others just to keep the main leaf from breaking during cycling. We measured the rear wheel travel and set it at 17 7/8". 1/8" shy of the limit of 18"



THROTTLE DOWN
 

rdc

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Bruce,

Are you saying there is a rule limiting the rear travel on a 7S truck? The only limit on travel for a 7S in the SCORE rules is 12" for the front.

The SCORE rules due state that "Two (2) single point anti-wrap up bars may be used on the rear differential" So I would say that the Y bar is not legal, but if everyone agrees that they want to run a Y bar then I don't see a problem.

Don't you have a 3.8L T-bird motor in your truck? Did they change that rule about the motor had to be listed as an option in the particular chassis and body series of the vehical when they up'd the displacement to 4000 cc ? I don't ever remember a ranger having a 3.8L as an option... Just wondering? I only have the 2001 rule book..

Tony
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Kritter

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Bruce does not have a 3.8 in his truck anymore. The V-bar from my perspective is a single attachment to the rear differential and therefore perfectly legal.

Kris
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JasonHutter

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I have only seen a limit to how long your rear leaf springs can be, 57 and a half I think.

Jason
 

martininsocal

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it used to be 12 front, 16 rear...but it also used to be non-bent beams, suspension parts in strebgthened parts only, not modified, etc... it specifically says 2-2 point anti wrap bars for the rear...

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BIG_FAT_LOSER

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So a 2wd Toyota can have tubular uppers?

Duct tape is like the Force.It has a light side and a dark side,and it holds the universe together.
 

rdc

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Pat,

You can have tubular uppers if you still retain the stock arm. Meaning you could cut and add the tubes to the arm but you cannot totally disguard the stock part as far as I know... Plus all the piviot points must remain the same.

Tony
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BIG_FAT_LOSER

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Maybe this belongs in the shop section.

and also the post title is 7s ranger but.....

Judging from this pic of fire guys 7s they have non toyota issue tubular uppers???
Just curious, for future refferance. If I win the lotto my truck may actually enter a race some day and I do not want to out build the class specs. Maybe I'll ask them.....duh



Duct tape is like the Force.It has a light side and a dark side,and it holds the universe together.
 
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