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Ladder Bar Set-Up

Posted: Sun Aug 02, 2009 5:40 pm
by 76camaro
I am not sure how to put this but I have a 76 Camaro back-halved ladder bar car.
They are 27.5" bars eyelit to eyelit. The car pulls to the right hard at launch. Also, the right front corner is around an 1" lower than left corner without me in car. When I pull the drivers side front bolt with no driver the bar goes up in car and back. Also, car settles on drivers side when I do this. If I install drivers bolt back in and pull passengers side bolt, it doesn't move very much. Wasn't sure if this is a preload condition, and wasn't sure why the rear end is moving back. All the springs (front and rear) are new. Any suggestions would be great. I do have the door slammers book but am not sure how to correct this problem. Also, when I weighed the car without driver rear weights were very close. Adding driver, right rear becomes 120 pounds light.

Again, any help would be appreciated.

Re: Ladder Bar Set-Up

Posted: Sun Aug 02, 2009 9:33 pm
by want-a-be
Are the front springs adjustable? Do the ladder bars have an adjustable link in them? What spring rates are you using on the front and rear?

The difference in front corner heights concerns me a lot. More then if it were in the rear. This does sound like a preload condition. But it sounds pretty out of wack on the set up.

Don

Re: Ladder Bar Set-Up

Posted: Sun Aug 02, 2009 10:45 pm
by 76camaro
the front springs are moroso 213 lb with 1 1/4 coil cut off, rear springs are qa1 110 lb 12'' installed on car 9'' with lower platform adj. up 2''.

car weights no driver
LF-733 RF-691
LR-570 RR-598


with 200lb driver
LF-742 RF-757
LR-709 RR-582


The bars are adjustable..

Re: Ladder Bar Set-Up

Posted: Mon Aug 03, 2009 7:13 am
by John_Heard
Kinda strange that the left front doesn't gain much weight with you in the car. It should be going higher than 9 more lbs. with the driver.

Re: Ladder Bar Set-Up

Posted: Mon Aug 03, 2009 8:30 am
by want-a-be
Looks like you are weighing in at about 200 lbs. So,..unless you are driving this car remotely without any driver weight behind the wheel you need to scale the car with that weight in the drivers seat.

That being said, looks like you have a ton of preload in the passenger side ladder bar. This is proven to me by 3 things.

1: The right front is 1" lower then the left front is. The reason for that is the drivers side ladder bar is trying to lift the left rear of the car more then the passenger side is. Cross corner weights affect each other more then people think.

2: Because of the overly preloaded condition, when the driver sets in the car those 2 corners, LR and the RF, take most of the weight.

3: The car darts to the right upon launching it.

Try this when scaling the car. Take the Passenger side lower bolt out of the rear end mount for the ladder bar, (not the front one), that has the turn buckle adjuster on it...hopefully the lower one. This takes all preload out of everything which you want when doing the initial weighing of the car. ( I'd bet that the front levels out at this time) Then scale the car at that time with drive weight in the seat. Move things around as best you can if you're wanting to get corner wheights as close as you can....but usually it is what it is. Especially if you do not have adjustible front coil springs.

Now to add in some preload. Make the turn buckle so that it's adjustable, (loosen the jam nuts). Try sliding the bolt in...unless you have already adjusted things around I'm betting it's not just going to slide in. Adjust the turn buckle until the bolt slides in and out pretty easy. (I'm going to assume the turn buckle is on the bottom of your ladder bars if they are on top the it will be a bit different but much the same. instead of shortening the turn buckle you'll lengthen it.) Now,..shorten the turn buckle until the bolt gets snug when you try to move it in and out. This is just starting to give you some preload. Install the bolt as it is to be ran.

From here your car sets with pretty much zero preload with the drive weight in place. Now,..from here you need a starting place on preload. No matter what the weight on all 4 corners are at this moment, adjust the turn buckle, (on the passengers side), until you gain about 50 pounds on the passenger side rear tire scale. (shorten the turn buckle if on the bottom, length it if it's on the top) (This means add 50# to that corners current weight,...not make it 50# heavier then the drivers side.)

Note that this is just a starting point. From here you'll need to have someone watch the car carefully when you launch. Car moves to the right,...you need more preload on the passenger side,...moves left you need less preload on the passengers side.

Always adjust the preload on the passenger side. The drivers side link, be it ladder bar or 4-link, is used to set up the pinion angle.

Hope this helps if you need more help with this I'd be glad to. Might need to talk some on the phone from here though.

Don