A Ladder Bar Hole Tuning/Adjustment
 

Hey Guys,

Bar Hole location Question = Relationship to Effects on initial Hit of Tire:

? Raising bar will Increase Hit which may bounce or crush the tire
? Lowering bar will Decrease Hit and soften initial hit of the tire

SO, if raising launch RPM from 3500 to 5000 will increase initial application of power -
THEN, raising the bar will help compensate for initial hit increase provided the tire stays applied to ground and avoids bouncing or crushing?

Thanks Guys for the clarification.
Craig

Re: A Ladder Bar Hole Tuning/Adjustment
 

Craig… Do you have a Specific Problem you are trying to overcome? MB

Re: A Ladder Bar Hole Tuning/Adjustment
 

yes break loose on initial hit - recovers guessing 10 feet.

Want to understand relationship of bars to torque input.

Thanks, Craig

Re: A Ladder Bar Hole Tuning/Adjustment
 

What is your Baseline Setting? What Tires? What type of Car? Springs, Shocks ? There potentially could be other variables that are compounding your problem. MB

Re: A Ladder Bar Hole Tuning/Adjustment
 

I race a ladder bar car. my car is set up with 2 degree down angle on the ladder bar with 2 degrees of down pinion angle. It will not work at all if the bars are past level or running up hill in the front. All measurements are taken in relation to the frame or rocker panel. if the car is set up correctly no preload is best. my car is 3140# and i have a 110 lb spring rate on the shocks. Typically the bolt holes are too coarse of an adjustment. I use ride height if i need to make any adjustments. Start with the shocks loose on the front and rear and the tighten as you test.

Re: A Ladder Bar Hole Tuning/Adjustment
 

HAve you ever set your car up on scales? Do you have equal weight on the rear tires?

Re: A Ladder Bar Hole Tuning/Adjustment
 

I think knowing height of front holes in relationship to rear end brackets holes would need to be first. Then plotting out if the bar is going down, straight or uphill.

Re: A Ladder Bar Hole Tuning/Adjustment
 

Hey thanks guys I really appreciate all your good input.

I think the next step is to follow through with many suggestions and is to be able to individually scale all four wheels, invest in a good pair of double adjustable rear shocks and look at springs and height adjustments – of course getting a good video to review and share.

Any other ideas are also greatly appreciated.

Thanks, Craig

Re: A Ladder Bar Hole Tuning/Adjustment
 

Craig… An afternoon with a friend, a level work area, a couple of measuring tapes, plumb-bob an 8’ straight edge, a square, welders chalk and a chalk line could make a big difference. Plotting the wheelbase and squaring are a priority. A good baseline would be trying to get the bottom bar as close to parallel to the ground as you can. Adjusting ride height may be required to establish this. Make sure nothing is binding. Once you have these simple essentials done, you can start with some minor tuning adjustments. It would be nice if you shared some details about your car. We are all here to offer assistance and the more information you give, the better the response and results will be. Assumptions of what your car is, may not be the best way to achieve positively. MB

Re: A Ladder Bar Hole Tuning/Adjustment
 

All the above comments are valid.

In my experience with engines in the 700-horse range and cars in the 3000-pound range, a 2 or 3-degree down angle works well. And as stated above, the down angle is in relation to the body, not the ground.

If you want the ultimate set of tools. Build yourself a set of stands or tables about 30" high. Set up the car, at ride height, driver weight in the seat, and rear wheels removed.
This offers an excellent view of your setup plus allows easy adjustments.

Beyond this, a drive-on rack is perfect but few of us have those.

Re: A Ladder Bar Hole Tuning/Adjustment
 

72 GTO.

Car launches straight, carries the wheels But now has a traction issue:
Initial hit and spins recovers 10 feet out with loss of .08 to .1 at 60 foot with 3500 launch on 2 step on 5000 convertor

New best with a 6.41 at 105.5 and later spun at 106.

That was an improvement of over 4 mph when I ran a 6.58 at 101.8 from a carb tune, slight port match and a change from 3.73's to 4.11.

Still launching at 3,500 - 2-step with 5,000 still to grab.
Turbo 400 4.11 Pro gears with MT 10.5w x 28 slicks

Front suspension:
QA1 Pro Coil Double Adjustable GM coil over conversion system with 350 # springs
Adjusted to 90/10 settings
Low friction control arm bushings and ball joints
Total Race Weight 3440
Front weight 1860
Rear weight 1580
Percentage Basis Front to rear 55% to 45%

Rear suspension:
Full length Competition engineering adjustable ladder bars
Bottom hole lowest front heim end setting
Right bar - slight preload
“5 #150 (?) lbs - springs with spring jacks
Stock Mount: 28 year old Koni single adjustable set at 1 turn tight from lightest setting=Issue(?)
Pinion angle 2 degrees negative
MT 10.5w x 28 slicks with tubes at 14 pds cold - best runs

Thanks Guys, Craig

Re: A Ladder Bar Hole Tuning/Adjustment
 

Try tightening the pull a part on rear shocks.

Re: A Ladder Bar Hole Tuning/Adjustment
 

Happy Thanksgiving to all you guys and appreciate all your support and technical help.
Take care, Craig

Re: A Ladder Bar Hole Tuning/Adjustment
 

Check your Koni shocks. After about 5 or 6 years and my car started acting up on launch. I found one of the Koni shocks was almost froze up. These were single adjustable and no setting adjustment would help. I ordered new Aftco double adjustable and the car came back with consistency and better 60’ times.

Re: A Ladder Bar Hole Tuning/Adjustment
 

What is the left and right rear wheel weight?