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-   -   Ladder bar tuning / adjusting (https://classracer.com/classforum/showthread.php?t=65951)

joespanova 04-17-2017 08:49 PM

Ladder bar tuning / adjusting
 
From your experiences , did moving the bars up or down , make the car more wheelstand prone?

Hacksaw 04-18-2017 09:25 AM

Re: Ladder bar tuning / adjusting
 
Moving the front of the ladder bar up will raise the instant center and will be prone to wheelstands.

joespanova 04-18-2017 04:30 PM

Re: Ladder bar tuning / adjusting
 
Quote:

Originally Posted by Hacksaw (Post 532451)
Moving the front of the ladder bar up will raise the instant center and will be prone to wheelstands.

For some reason I always though it was the other way around..........damn it ,I'm still dumb:D

joespanova 04-18-2017 04:37 PM

Re: Ladder bar tuning / adjusting
 
Also..........I don't think I can get the pinion angle I want after I move the bars up..........extending the adjuster on the bottom bar is probably going to not allow me to get the bolts back in the housing bracket on the rear end.
In case someone would ask , the usual 2-3 degrees down is what I'm after......
In fact a well known chassis shop suggested just increasing the pinion angle would make the car more wheel stand prone?
Not sure why that would change anything.
Between bars up , pinion angle down , shock tuning...........damn.
The car leaves flat now...........I'm looking for more drama...LOL

James L Miller 04-18-2017 06:53 PM

Re: Ladder bar tuning / adjusting
 
Quote:

Originally Posted by joespanova (Post 532492)
For some reason I always though it was the other way around..........damn it ,I'm still dumb:D

My thought is the ladder bar rotates up due to axle torque and is pushed forward by the driving force of the tires. Moving the pivot up wouldn't affect the upward force on the chassis, but moving the pivot point down would be pushing further away from the center of gravity. I would think that would cause the nose of the car to go higher.

If you disagree, please explain your logic.

joespanova 04-18-2017 07:12 PM

Re: Ladder bar tuning / adjusting
 
Quote:

Originally Posted by James L Miller (Post 532505)
My thought is the ladder bar rotates up due to axle torque and is pushed forward by the driving force of the tires. Moving the pivot up wouldn't affect the upward force on the chassis, but moving the pivot point down would be pushing further away from the center of gravity. I would think that would cause the nose of the car to go higher.

If you disagree, please explain your logic.

Uh , yeah.......thats exactly what I thought also.
Some guys use the "refrigerator or box" logic..........so what you suggest coinsides with THAT explanation , anyway.....hell if I know........I guess trying and testing is the only validation.:confused:

nhramnl 04-19-2017 07:40 AM

Re: Ladder bar tuning / adjusting
 
I haven't owned a ladder bar car in a number of years, but I think I remember that the overall length of the bar has a significant effect on "hit" versus "wheelstand". Short bars smack the tire very hard, whereas longer bars tend to make the car wheelstand more. The principle still makes sense to me, because a longer bar essentially moves the intersect point forward, which would apply more rotational leverage to the chassis. I think...:D

SGSST109E 04-19-2017 07:59 AM

Re: Ladder bar tuning / adjusting
 
Move the bar up for a harder hit. I have run my car that way for 20 years. Adjust your front shocks to control wheel stands. If the car isn't pulling the wheel up loosen the front shocks.

FLEMING 04-19-2017 09:21 AM

Re: Ladder bar tuning / adjusting
 
:)

Hacksaw 04-19-2017 09:31 AM

Re: Ladder bar tuning / adjusting
 
Joespanova: You may want to modify the lower rear section of your ladder bar to make it adjustable. Lower adjuster link. This will give you the added length you require.


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