Using scales to adjust ladder bars ?

Sometime in the next few days I'm borrowing a set of scales from a friend.
I don't have a clue what to look for other than just getting the trucks weight and front to rear %.
The truck wanted to go right when leaving the starting line. It wasn't real bad, just enough to know somethings not right.
Can I make any adjustments using the scales to correct the problem and if so what should I do?

Here is what I have for those that don't know
82 f150 2wd approx 4000lbs.
472ci
rollerized C6 with Franks Tbrake
9" with 3.50 gears and spool
Adjustable CE ladder link bars W/ coilover shocks
Hoosier 29.5x10.5 slicks
The only 1/4 mile pass was 1.69-60ft, 8.02-1/8@ 82.12mph, 12.98@ 102mph with a junk converter.

Mike

Make sure your vehicle is as race ready as possible. Tire pressures equal. driver or ballast in the seat. fuel in etc etc. If your scales are not set up to roll the vehicle on and off jack up the back end first and place the two rear scales first. (If you do the front first the tires will try to roll off the scale when you start jacking the back end up) Use plactic garbage bags between the scale itself and the tire to let the tires slide easy and equalize better. Once the back two are on then place the trans in park and raise the front.

You want to see even weight side to side as much as possible. Your front to rear cant be changed without moving weight but you can jack side to side with your adjustable ladder bars.

If it is driving to the right you should expect to see the left rear a bit heavier than the right to start with. It wont take much to move the weight around probably only a few flats on the adjuster.

I have seen some pretty messed up stuff in the past so I would also try measuring the height or the rear springs when you get the rear weight equal. If the springs are different lengths at that point then you need to look for why. Could be the upper mount is uneven or the lower spring perch's not equal.

I generally try to get the rear springs equal with no preload in the bars first then jack in some preload if required to compensate for how the vehicle drives off the line and or in the burnout box.

If the springs are way out then pull the pin on the right rear or right front ladder bar bolt until you get the springs adjusted then use the adjuster to shorten or lengthen the bar till the bolt goes back in.

dkp

Oh and try to get the scales set as close as possible to level at least side to side. I use one of those little laser levels and measure off the beam

dkp

bosshoss, thanks for taking the time to explain what I need to do and the little tricks.
I think I'll be ok to give it a try with the directions you gave.
I'm familiar with setting up the scales. We scaled my brothers stock car on a regular basis for different tracks. The garbage bag trick is new to me though.

mike

going to the right , right side is light(pass. side) . instead of cranking up the right spring get a higher rate for that side . truck will sit square when still. better yet anti roll

There is no reason for an anti-roll on a correctly installed "normal" ladder bar setup. The exception would be a set of ladder bars installed really, really, reeeeeally close together.

And normally there's no real reason the shift the side-to-side preload around with staggering spring height or spring rate either, just use the adjusters on the bottom of the ladder bars. If it's going right, usually you need to crank out the right side bottom adjuster a little. That raises the front of the right ladder bar a little making it carry a little more weight, and have a little more traction.

Of course if you have a bent bar (or incorrectly installed secondary component causing the bend) like this pic........

....no adjusting in the world will help until any possible problems are solved.

DILLIGASDAVE wrote:There is no reason for an anti-roll on a correctly installed "normal" ladder bar setup. The exception would be a set of ladder bars installed really, really, reeeeeally close together.

And normally there's no real reason the shift the side-to-side preload around with staggering spring height or spring rate either, just use the adjusters on the bottom of the ladder bars. If it's going right, usually you need to crank out the right side bottom adjuster a little. That raises the front of the right ladder bar a little making it carry a little more weight, and have a little more traction.

Of course if you have a bent bar (or incorrectly installed secondary component causing the bend) like this pic........

....no adjusting in the world will help until any possible problems are solved.

Dave How did that happen?

IDT-572 wrote:Dave How did that happen?

I found that pic on another Ford site (ford muscle I think), they were discussing what might have bent the bar.

From the pic I'm guessing the gold looking bar is the cause of the bent ladder bar. I'm thinking this because he said the gold bar was a panhard bar (and not a diagonal link). And installing a panhard bar diagonally across the suspension (instead of parallel to the housing) is going to cause all kinds of binding. And even if it was a diagonal link, installing it on the chassis (instead of the ladder bars) would still cause binding problems.

But I guess he shouldn't be too hard on himself for the incorrect install, I have seen a number of people install them wrong over the years. It's just a mistake that happens from time to time for some reason.

there is a reason --- little as 3/8" high difference in hight is a no in the rear . they want the level look around here. not a 70's look

What does it matter if a car has a perfectly level stance side to side in the rear & looks "pretty" while sitting there if it doesn't launch straight & drive straight down track?

Staggering spring heights and/or spring rates (or staggering air bag pressure if used) side to side in the rear is ancient chassis tuning thinking from the 70's & 80's. I was useful back then (and sometimes today) on cars with stock suspension points/components that from the factory have no way to adjust side to side preload around. It was also used on drag cars with aftermarket 4-links back before anti-rolls were invented as a method to try and control launch body roll.

Staggering spring heights/spring rates in the rear really shouldn't have hardly any effect on preload (and/or body height) side to side on a correctly built ladder bar car anyway since the ladder bars them selves & the rear housing all act as a giant anti-roll. Now days shifting weight side to side (and/or body height) on a ladder bar car is done with the ladder bar adjusters. If you can't get the job done with just the ladder bar adjusters, and have to resort to trying to stagger the spring height/rate, then something is way off (bent, broke, twisted, etc, etc) somewhere on the car.

In the past I worked on a ladder bar car where you absolutely had to use spring stagger (front & back) to try and get the car to even think about launching straight. This was because the ladder bar crossmember (and/or brackets) were bent/twisted, & the ladder bar adjusters just didn't have quite enough adjustment to offset the problem. The twist was either from hard use, or the way they tied down the car on the trailer, or it was built into the chassis by mistake. Once the chassis "twist" was fixed the car was able to work correctly without using any spring stagger.

Dave
This what I have under the truck.
The ladder bars are as wide as I could get them.
The diagonal link is all I'm using. No panhard bar or anti roll bar.
I was a little concerned with the diagonal bars length so I made it with cm tube.
The front cross over tube wouldn't clear the driveshaft. We made our own from scratch.

f250mike wrote:Dave
This what I have under the truck.
The ladder bars are as wide as I could get them.
The diagonal link is all I'm using. No panhard bar or anti roll bar.
I was a little concerned with the diagonal bars length so I made it with cm tube.
The front cross over tube wouldn't clear the driveshaft. We made our own from scratch.

Now that's a wide ladder bar stance. Should go a long way toward controlling any body roll as long as there is no end-to-end rear housing twist going on (a good reason for a back brace), or any twisting going on at the front ladder bar crossmember (more diagonal bracing on the crossmember is "more gooder").

The diagonal link length is kinda scary, but it would be more of a concern if the truck was street driven. And just be careful how you tie the truck down to the trailer. Tying down a race car incorrectly/unevenly car easily bend a diagonal link.

If nothing in the truck is bent/twisted/or flexing during the launch, then adjusting for the slightly "right" launch should be damn easy with just the bottom ladder bar adjusters. Since the ladder bars are so far apart, you shouldn't need to turn an adjuster very far at all to see a change.

still works (staggerd springs) looks pretty and goes straight .. is pretty a problem?

DanH wrote:still works (staggerd springs) looks pretty and goes straight .. is pretty a problem?

I don't know what the guys in your area are doing wrong where they have ladder bar cars that are sitting crooked/leaning a bunch to one side when using even spring heights/even spring rates side-to-side. But it's fine if you want to go to all the extra effort of swapping in/out different spring rates in a hit-or-miss attempt at adjusting the preload on one side vs making smaller more precise fine tuning adjustments with the ladder bar adjuster. Makes no difference to me, knock yourself out.

a bunch ? 3/8" is not a lot . I thought it was being to picky, when it can be done --why not do it ? anti roll -- no need for duing two rates or a turn on the bar and the car/truck looks better going down the track . FAST & COOL

I have only done one ladder bar car and it went straight as an arrow first time out with a 1.25 60'. Guys at the track couldn't believe that we didn't have to adjust stuff and asked me how I set it up. I told them that I know how to use a tape measure.LOL

DanH wrote:a bunch ? 3/8" is not a lot .

Yes......I know.

I said "a bunch" to point out your over obsessing about a tiny, almost unnoticeable 3/8" height difference side to side (if it's even that much). That amounts to less than half (1/2) a degree difference side to side for the average car body width.

But as I already said, do as you like. Makes no difference to me.

one of the owner's was within two feet of his car and could see it . I thought , no way- measured and he was right. I don't know if you can handle this .... it's not if you are right or me---- the owner wants is always right

Again Dan, adjust it how you want.

I was having problems with spinning at first after installing my ladderbar set-up in my old Ranger and I talked to friend that was great with them back in the day and this is what he told me to do. "With the vehicle at rest on a level surface all tire pressures equal put adjustable jackstands under the frame of it but do not lift the chassis any just hold it up to make adjustments. Place the front mounts in the holes one down from level. After you get this done remove just the passenger side front bolt and adjust the adjuster so that the front rod end comes up half a hole then pull the bar down by hand(not very easy to do on your own) and reinstall the bolt. With this the vehicle should launch hard and go straight as an arrow" I did as he said and he was dead on.