assymetric ladder bar adjustment

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gnicholson
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assymetric ladder bar adjustment

Post by gnicholson » Wed Feb 05, 2014 1:51 am

besides preload on the springs or ladder bar to equal tire loading at launch i was wondering if anyone has ever tried different pivot points on the front ladder bar mount from right to left.in other words; in an effort to counter act the housing rotation at launch and try to apply equal torque to both tires has anyone put the right ladder bar in the top hole in the front mount while putting the left in the center hole for instance.seems to me this would allow more equal loading of the tires without preload so you dont have any handling issues down track

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woody b
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Re: assymetric ladder bar adjustment

Post by woody b » Sun Feb 23, 2014 3:36 pm

If you're having to run so much preload that down track handling is bad something is flexing on launch. Look real closely at the front ladder bar mounts. It could also be the rear end housing flexing. What kind of rear end is it? It could have a tube slipping where it goes into the center section.
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Alan Roehrich
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Re: assymetric ladder bar adjustment

Post by Alan Roehrich » Sun Feb 23, 2014 3:40 pm

gnicholson wrote:besides preload on the springs or ladder bar to equal tire loading at launch i was wondering if anyone has ever tried different pivot points on the front ladder bar mount from right to left.in other words; in an effort to counter act the housing rotation at launch and try to apply equal torque to both tires has anyone put the right ladder bar in the top hole in the front mount while putting the left in the center hole for instance.seems to me this would allow more equal loading of the tires without preload so you dont have any handling issues down track
Horrible idea. It will bind badly, and probably break something. That being said, someone will have done it.

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Re: assymetric ladder bar adjustment

Post by BirdMan » Mon Feb 24, 2014 12:21 pm

Horrible idea. It will bind badly, and probably break something. That being said, someone will have done it.[/quote]

Possibly with spherical ends there wouldn't be any binding?? If the initial hit is harder w/bar higher then maybe going down track the right side would steer left anyway and NOT be what you want or need??

I get needed pinion angle, then remove the front bolt in one of the bars.

I then install driver weight (driver?) in car and level chassis. On our Falcons I use spring spacers in coils, rubber spacer on top of front coil spring, even cut a 1" tall one in half, three quarters or whatever height/thickness you need or cut a 1/4 coil off at a time on right one to accomplish the same thing dependint on wanted/needed ride height.

With car level I adjust the loose ladder bar to fit bolt and adjust 3 flats up or down to get right rear slick loading.

Our cars always leave straight and go straight down track with pushing to one side or the other.

If you want more initial hit you need to raise the front position relative to chassis.

I wanted less hit for son't new higher hp engine which hit way too hard so I lowered the chassis via rear leaf spring adjustable slider's 1" and then I lowered the slick air pressure as tire wasn't being pushed down into strip as hard. This to level/equalize the contact patch.
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Re: assymetric ladder bar adjustment

Post by flyingwedge » Tue Feb 25, 2014 4:54 pm

If I understand this correctly... lowering the rear IC, of the ladder bar front pivots, in relation to, below the CG, will increase the "hit" ? :?:

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Re: assymetric ladder bar adjustment

Post by Brian P » Tue Feb 25, 2014 6:58 pm

Raising the side-view instant-center causes a component of the forward drive force to be directed downward on the axle and upward on the bodyshell; this offsets the tendency for weight transfer rearward to compress the rear suspension.

There was a comment above about binding. All parallel ladder-bar-type suspensions will bind in one-wheel-bump or body-roll situations. The left ladder bar wants to rotate (say) clockwise around its chassis-end pivot while the right one wants to rotate anticlockwise and the axle (extremely rigid in torsion) won't let it; the only difference allowed between left and right is that allowed in the flexibility of the bushings. Rigid pivots like rod-ends will break stuff before they let a one-wheel bump situation happen. Ladder-bar suspensions don't work in cornering or on rough roads (subject to "any bad suspension design can be made to work if you make the springs and dampers so stiff that it won't move at all").

One solution involves moving the forward chassis-end attachment points towards each other in top view (ideally to a single point, in practice, as close as possible together with only propeller-shaft clearance between them and with rubber bushings to take up the difference). This converts "ladder bar" to "truck arm" and that arrangement does work in cornering (it's mandated in NASCAR). Will not work with the diagonal locating link often found with ladder-bars ... it wants a panhard rod or Watts linkage.

Front-drive cars often have a geometry apparently not unlike "ladder bars" and with very short trailing arms at that ... but they're connected with an axle that is intentionally flexible in torsion; that's why this is called "twist-beam" or "twist-axle". Doesn't work if you want to have a live axle!

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