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Thread: Help on Ladder bar car

  1. #1
    Senior Member MASTER BUILDER
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    Oct 2003
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    Help on Ladder bar car

    I need some advice from a good chassis tuner, or somebody that is going thru the same stuff I am.
    I recently changed the engine in my 76 monza, It is a full chassis car 2100 lbs with ladder bar rear end 31.5 x 14 tires, gears are 4.56
    We had the car launcing pretty good with the old engine, a 414 sbc with about 600 hp. the ladder bar is at the bottom hole and it launced the car in the air possibly 25 inches and carried it thru the 60 foot. It had a turbo 400 three speed in it.
    Now we have changed the engine to a new 436 with aproximatly 825 hp ( I built it an dfigured my numbers thru head flow so aprox. only, also we had put a rons flying toilet on it.
    Now on to the first launches, we attempet to launch it at 4500 rpm, the car took off the line and started to go sideways , with a little correction it went thru the 1/8 ok
    60 foot was 1.17 sec.
    we had done some work to it, chaged the shocks for dual adjustable etc. and tried to set the rear end up paralell to the chassis, ( it was a bit off )
    We recenly went to the track, just to practice the launches and tune it in.
    I also changed the launch rpm to 4200 to mellow out the violent initial launch.
    It helped quite a bit, although the car , as usual looses a bit of traction on the drivers side which makes the car veer sideways a bit. We tried stiffening the passenger side to try to take some of the engine torqe off the passenger side and transfer it to the drivers. It works a little.
    I am just wondering where to go from here ? I don't get theat muh track time and need some guidence.
    any help really appreciated.
    thank all
    Al

  2. #2
    Senior Member RACING JUNKIE
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    I'd put a powerglide in it.

  3. #3
    Senior Member RACING JUNKIE
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    X2
    A glide with the higher or lower - first gear - which ever way you look at it, will soften up the launch considerably and probably pick you up a couple big numbers to boot. >Cp
    ***IN GOD WE TRUST***

  4. #4
    Senior Member MASTER BUILDER
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    Forgot to mention, yes we put a powerglide in it.
    I think first is 1.9 or something like that.
    Al

  5. #5

    ladder

    i would first make sure your ear tires are square with the front tires not the body or chassis, next i would put it in the middle hole and also what is your pinion angle did you change that at all, next i would adress the shocks that you put in it and try adjusting them also as they to will affect how the car lauches, you changed alot of things so now you need to try alot of thing

  6. #6
    Senior Member EXPERT BUILDER
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    You also want the suspension to be as free as it can be. Once I got mine loose it worked alot better. If the tires are even as far as roundness then it sounds like you need to preload it a little, just 1 flat at a time until it drives straight. It shouldn't need much.

  7. #7
    Senior Member MASTER BUILDER
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    How do you make sure the tires are square with the front?
    since they turn, not sure how to go about that.

    yea I think the front end is too tight also.

    what is the proper way to initially set the shocks in the rear? I can make the springs exactly the same length on the adjustable coils, but not sure how much preload I need.
    ??
    Sorry too many questions.

  8. #8
    Senior Member EXPERT BUILDER
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    The tires you can measure the diameter with a piece of string then measure the string with a tape measure, compare the one from the other.
    I would measure your whel base from the center of your front spindle to the center of your rear axle again check one side vs the other.
    Once these numbers are equal than you can adjust preload if you still have issue's.

  9. #9
    Senior Member DYNO OPERATOR
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    Most all stock front ends have at least 1" of stagger built in to them, meaning one tire is further forward than the other. The NHRA rule book allows for 1" variation in wheel base left to right in Pro Stock. The stagger gives the car more time in the start beam and will give a better 60' time and ET, exactly the same end result if you were to shallow stage but with more effect on ET and reaction time. I would caution on assuming that the front end after alignment is perfectly square and or perpendicular to the center line of the chassis, it's likely that it is not.
    This is how we build / lay out, chassis cars and all the other chassis types as well. You must have the engine and trans perfectly squared to the car meaning perfect north and south regardless of drive train offset if used. If your car is built correctly and has the engine in it, you need to level the car the best that you can on 4 stands with shims about 18" high or less, high enough for you to get under it to measure etc. Now plumb bob down from the exact center line of the crank up front and make a mark on the floor. Then remove the drive shaft and plumb down from the tail shaft center line and mark the floor. Now you take a string connected to a cylinder head or something heavy on both ends then line up the string exactly over the two marks you just transfered to the floor going past the rear bumper with your string. Now you have a perfect refrence to the chassis. Now with the tires off and rear end hanging on the shocks with out pre load, you plumb bob off the front or rear of the axle hub doing both the same way and transfer the mark to the floor with tape and a sharp pen like you did with the engine center line. The pinion had better be exactly over the string that you have pulled under the car. Now you can make a scribe out of a tig welding rod or two taped together to make a fixed dimension scribe. you can sharpen one end of one rod then put a bend about 1.5" from the sharpened end on a right angle, this is the pivot end of your scribe. Now you take the other rod and bend it about 4" from the end on a right angle but make it point the opposite way as the pointed end, this end will have a pen taped to it so the business end ( ink end) is pointing the same way as the sharp end on the other piece of rod. Tape the two rods together to make a scribe a foot or more longer than 1/2 your wheel base. Now take the sharp end and put it exactly over one axle end that you transfered to the floor and swing and arc crossing the string forward and behind the axle centerline. I use tape on the floor to mark easeier. Now you go to the other side and you are hoping to get both sides to cross exactly over the string or at least the same distance from the string if there is an offset in your drive line. If you can see any difference in the distance each end is from the string it is worth fixing. If you are within .030" that would be OK, but is .030" off of correct. When you do this you will have the satisfaction knowing how square your car is and how to get it that way. This may seem complex on the surface but is real basic stuff, you will realize, after you do it once and wrap your mind around the task. This takes a little time but there is not a short cut to checking the squareness of your chassis.

  10. #10
    Senior Member DYNO OPERATOR
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    Now that you have stringed your chassis you can look at the tire age? If these tires were used one year and than were frozen over winter you can not expect them to be very aggressive. The curing process of your tires never sleeps. If I were in your position I would be looking at D1 goodyears with stiff side walls for your car.
    As for the shocks, you are muddying up the water by adjusting the shocks independent of each other. They will be the same on both sides when you work out the other problems you may be tuning around.
    What you are seeing at the track getting 1.17 60' indicate that you dam sure are working the track well,even with the spinning problem.
    Ladder bars will require a lower setting as power increases in the same chassis. Having said that, You may need a lower hole than you have available in your chassis bracket and may not be able to adjust to maintain an appropriate pinion angle if you were to place the rod end low enough for your power level. You have a short car and a short instant center due to the suspension choice being ladder bar no doubt 32" long. I would like to see the ladder bar at ride height run down hill at least 5 degrees for starters. This will give you more traction 10' into the run and down track.
    If you tighten the shock's rebound and this helps traction, your car will prefer a lower ladder bar mount than what you are using. If the car responds positively to loosing the top or rebound of your shock your car will possibly like a higher ladder bar setting.
    As for the springs, what rate are they? 110# or less? If so you may try 130# ones to slow the hit and help prevent over planting of the tire's. This will help some if the instant center can not be lowered enough for your set up.


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