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strawntech 02-27-2003 07:08 PM

ladder bar tuning
 
ladder bar tuning

I was wondering if any one could explain how to adjust a ladder bar setup

What does moving the front piviot point do?
and a little info on pinion angle too

the car has ca chassiworks double adjuster bars and qa1 coilovers (12 way)

how do i adjust it to pot the front end in the air?
thanks,

strawntech 02-28-2003 06:03 PM

I take it nobody knows?
i just need a starting point

TurboS10 02-28-2003 06:32 PM

Ladder bars are for the most part unadjustable. I believe the adjustors are just to set pinion angle. There is not alot you can do to get the front end in the air if it will not do it now. On ladder bars the instant center is where the front of the bars attatches. If you have multiple holes in this mounting point you may have a little bit of adjustment. If that is the case, the lowest hole should give you the most lift.

chris

[ February 28, 2003: Message edited by: TurboS10 ]</p>

4 Jaw Chuck 02-28-2003 08:19 PM

Moving the bar end pivot higher will give you what you are looking for. Moving the pivot higher tends to lift the front end and moving it lower places more "weight" on the front tires.

The effect is minor compared to what you can achieve with a 4 link setup.

Adjustment is explained here.

[ February 28, 2003: Message edited by: 4 Jaw Chuck ]</p>

roys63 03-01-2003 02:20 AM

And you may need to adjust your HP!!!!Like MORE!!!

[ March 01, 2003: Message edited by: roys63 ]</p>

TurboS10 03-01-2003 05:17 AM

I stand corrected. After going back to my trusty Door Slammers Chassis Book I will say that 4 Jaw is right here. Lowering the front of the bars will tend to hit the tires harder and give you better weight transfer. I was confusing 4 link IC which tend to work in an opposite effect, but that is due to the IC being much further forward in the car closer to the Center of gravity.

Chris

strawntech 03-01-2003 03:21 PM

i dont think power is the problem
the car (67 firebird) makes an honest(dyno)680hp to
the rear tires (540 merlin 345cc heads .780 lift solid roller 13to 1 etc....
not to brag about the power but wouldent i want the tires (28-12.50-15 M/T ET Streets) to hit harder? for more traction?

just tring to get it figured out

thanks for all the input guys

TurboS10 03-02-2003 05:20 AM

[quote]Originally posted by strawntech:
<strong>i dont think power is the problem
the car (67 firebird) makes an honest(dyno)680hp to
the rear tires (540 merlin 345cc heads .780 lift solid roller 13to 1 etc....
not to brag about the power but wouldent i want the tires (28-12.50-15 M/T ET Streets) to hit harder? for more traction?

just tring to get it figured out

thanks for all the input guys</strong><hr></blockquote>

Yes you want it to hit the tires harder. Sorry if my first bonehead post was confusing.

I am wondering if you are having traction problems now or if you have ever had it on the track to see how it runs. If it is not spinning, and it is not pulling the front end, I would say something in your combo is not right. Gear or converter come to mind. What kind of times does it run?

chris

strawntech 03-02-2003 10:36 AM

it hasent been to the track yet (no cage)
but...
it goes real strait and hard but when you jump on it it spins pretty good
the car weighs about 3100# so should be good for low 11's right?

btw 3500 stall
and 3.7 gear (detroit locker)

i want the car to hook
i know alittle tire spin is needed to launch the car as also a little lift from the front

but i kinda just want to set it up to do sick wheelstands when its not on the track

i know i know a little counterproductive but its a cool car

roys63 03-02-2003 10:53 AM

we useto remove the front shocks and hit the gas hard and let off when the front end just comes down we hit the gas to the floor and lift the wheels that way just playing on the street, can you get more tire under the car? wider, shorter

4 Jaw Chuck 03-02-2003 11:08 AM

Pull off the front sway bar and any other heavy unnecessary bits like bumpers (buy fiberglass) and steel hoods. The big problem is your car only weighs 3100 pds but probably 1800 pds of that is over the front tires, you need to get that car on a scale and dial in the chassis weights to get what your after.

No matter how you look at it you need to tune your chassis setup and get your weight distribution right, even wheel standing race cars have at least %50 of the weight on the rear tires to start. A four bar setup is a lot easier to dial in front end lift than a ladder bar, a ladder bar is setup to drive the car forward for quick times not for showing off. Instant centers for a ladder bar are in the wrong location for tire lift, it is too far below the CG of the car and not far enough forward.

I suggest you find a set of scales somewhere and do some math. ;)

strawntech 03-02-2003 08:17 PM

thanks every one
i guess the bottom line is move the bars up and soften the shocks... right?
il keep ya posted

TurboS10 03-03-2003 06:06 AM

If the car is making 680 RWHP as you say, it should run 9's if it is dialed in. If it just "spins pretty good" I am doubting you have that much power. It should "spin pretty good" at 120 mph with that much power to the ground and that small a tire.

Chris

[ March 03, 2003: Message edited by: TurboS10 ]</p>

willys36@aol.com 03-03-2003 07:15 AM

As previous posts point out, there are a lot of considerations in getting your nose off the ground. it isn't all hp or weight transfer, etc., rather it is the entire system. The thread below discusses this tropic in detail. I posted some basic equations which should get you into the ballpark of the setup you need. In summary, you need enough torque, enough weight on the rear tires, enough traction, and center of gravity far enough back or you can't get off the ground.

<a href="http://www.hotrodders.com/cgibin/ubb/ultimatebb.cgi?ubb=get_topic&f=15&t=004682" target="_blank">http://www.hotrodders.com/cgibin/ubb/ultimatebb.cgi?ubb=get_topic&f=15&t=004682</a>

strawntech 03-03-2003 07:42 PM

thanks willys36
for all the info
Il run some numbers tonite


and...turbos10
this is not the first nine second car i have driven. my idea of spins alittle and your idea may be a little different
so sorry i was not so clear with my wording

i also run a low nine second dragbike so my conception of speed is a little alterd too

anyway after thinking about it and waching the car leave a few more times it seems toleave real hard and then unloads the tires after about 5 feet(mabie 10)


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