Help on Ladder bar car

[altune]

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

[Tod74]

I'd put a powerglide in it.

[cepx111]

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

[altune]

Forgot to mention, yes we put a powerglide in it.
I think first is 1.9 or something like that.
Al

[promod45]

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

[us7race]

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.

[altune]

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.

[us7race]

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.

[TopspeedLowet]

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.

[TopspeedLowet]

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.

[dparker]

What topspeed said will work in setup. In my experiences, when you go with alot more HP engine your car will have a tendency to go right. Due to striking the tires harder. Usually you need more preload. If thats the case then shorting the passenger side adjuster bar a bit will a add a little preload. I'm basing this on the fact that your car was going straight with the other engine.

[TopspeedLowet]

What topspeed said will work in setup. In my experiences, when you go with alot more HP engine your car will have a tendency to go right. Due to striking the tires harder. Usually you need more preload. If thats the case then shorting the passenger side adjuster bar a bit will a add a little preload. I'm basing this on the fact that your car was going straight with the other engine.
Actually Dparker, a high powered car will go left, not right. The turning condition he has is no doubt, due to the rear pointing that way or random preload, old tires, shocks with unequal adjustment etc. He said that they just made an adjustment in the squareness of the diff in his first entry prior to testing the new engine, that fact may have eluded your prognosis. When you make real power in a door car like 1200 or so you will find that negative preload is your friend. I have a car that I built and drive that needs no preload at all, in fact I use 1/2 flat negative to keep from going left. But I'm only running My crap in a door car at 7.62 ET at 187.22 MPH for what it is worth.

[dparker]

Sound like you running faster than we are. Fastest in our crew is 7.90s. But not one of us has been able to get away with less than 50lb more on the right rear and 70lb more on the left front. On scales mine is 65lb heavier right rear and 90lb heavier left front.

[TopspeedLowet]

[quote="dparker"]Sound like you running faster than we are. Fastest in our crew is 7.90s. But not one of us has been able to get away with less than 50lb more on the right rear and 70lb more on the left front. On scales mine is 65lb heavier right rear and 90lb heavier left front
[/quote

The right rear does not need to be heavier than the left ever. I have 494# on RR and 557# LR but the left front is heavier than the right by 54#

[TopspeedLowet]

To add detail to the scale report I just gave, that car has an anti roll bar and a 4 link. When the tires feel the 920# of torque the preload is a bit of a joke to the rod ends and causes binding in the suspension which will cause major traction loss at that moment of bind. This is why I am big on getting the correct instant center on a given combination to avoid using mechanical bind (Pre load) and excessive pinion angles to get off the line. The less pre load you use the better the car or dragster will behave on the big end and under deceleration. The bind condition is constant and you are crutching the suspension for the first 10' and have to deal with it all the way down the track. If you look at any Pro stock car scale report it will be the same or very similar to mine with the RR lighter than the left.

[dparker]

What topspeed said will work in setup. In my experiences, when you go with alot more HP engine your car will have a tendency to go right. Due to striking the tires harder. Usually you need more preload. If thats the case then shorting the passenger side adjuster bar a bit will a add a little preload. I'm basing this on the fact that your car was going straight with the other engine.
Actually Dparker, a high powered car will go left, not right. The turning condition he has is no doubt, due to the rear pointing that way or random preload, old tires, shocks with unequal adjustment etc. He said that they just made an adjustment in the squareness of the diff in his first entry prior to testing the new engine, that fact may have eluded your prognosis. When you make real power in a door car like 1200 or so you will find that negative preload is your friend. I have a car that I built and drive that needs no preload at all, in fact I use 1/2 flat negative to keep from going left. But I'm only running My crap in a door car at 7.62 ET at 187.22 MPH for what it is worth.

I really don't see what your saying. I've used Ed With edvancedengines concept over the years and In my experiences have not had any problems. Not to say I'm disagreeing with you. But this is what Ed has on his chassis post....

What happens when Torque hits Rear End from Driveline;
Know and understand that anytime torque is applied that your left rear tire will be trying to push down and your right rear tire will be trying to rise looking from the rear of car. All cars in any kind of racing or activity will exhibit this twisting motion if there is any form of friction coefficient existing between the tire rolling surface and the ground/track/road. The tendency will still be there to twist the rear with torque even with no tires or wheels. It is when you start to hook that it really shows up.

If your rear end was not attached with brackets, when the drive shaft rotates in the counter-clockwise movement (looking from rear of car), the entire rear end assembly would rotate counter-clockwise like a propeller if it were suspended in the air and had room to move. The drive shaft rotates in the direction that engine torque is applied to it. Even attached with bars and suspension it still wants to rotate.

Always keep in mind that As greater torque is applied the rotational force will be greater so as power increases the car will want to pull to the right, which we counteract by suspension preloading in adjustments. If doing any bar preloading do know that even only 1/2 turn is an extreme adjustment from neutral load position. We usually preload bars in increments of portions of a nut flat when we are close. 1/2 of a flat can make a car go straight that was trying to veer to the right. Too much bar preload will pull us to the left and quickly can get us into the wall.

[TopspeedLowet]

What topspeed said will work in setup. In my experiences, when you go with alot more HP engine your car will have a tendency to go right. Due to striking the tires harder. Usually you need more preload. If thats the case then shorting the passenger side adjuster bar a bit will a add a little preload. I'm basing this on the fact that your car was going straight with the other engine.
Actually Dparker, a high powered car will go left, not right. The turning condition he has is no doubt, due to the rear pointing that way or random preload, old tires, shocks with unequal adjustment etc. He said that they just made an adjustment in the squareness of the diff in his first entry prior to testing the new engine, that fact may have eluded your prognosis. When you make real power in a door car like 1200 or so you will find that negative preload is your friend. I have a car that I built and drive that needs no preload at all, in fact I use 1/2 flat negative to keep from going left. But I'm only running My crap in a door car at 7.62 ET at 187.22 MPH for what it is worth.

I really don't see what your saying. I've used Ed With edvancedengines concept over the years and In my experiences have not had any problems. Not to say I'm disagreeing with you. But this is what Ed has on his chassis post....

What happens when Torque hits Rear End from Driveline;
Know and understand that anytime torque is applied that your left rear tire will be trying to push down and your right rear tire will be trying to rise looking from the rear of car. All cars in any kind of racing or activity will exhibit this twisting motion if there is any form of friction coefficient existing between the tire rolling surface and the ground/track/road. The tendency will still be there to twist the rear with torque even with no tires or wheels. It is when you start to hook that it really shows up.

If your rear end was not attached with brackets, when the drive shaft rotates in the counter-clockwise movement (looking from rear of car), the entire rear end assembly would rotate counter-clockwise like a propeller if it were suspended in the air and had room to move. The drive shaft rotates in the direction that engine torque is applied to it. Even attached with bars and suspension it still wants to rotate.

Always keep in mind that As greater torque is applied the rotational force will be greater so as power increases the car will want to pull to the right, which we counteract by suspension preloading in adjustments. If doing any bar preloading do know that even only 1/2 turn is an extreme adjustment from neutral load position. We usually preload bars in increments of portions of a nut flat when we are close. 1/2 of a flat can make a car go straight that was trying to veer to the right. Too much bar preload will pull us to the left and quickly can get us into the wall.
well Dparker,My pointing out that a high powered car WILL go lift pretained to a HIGH powered car, Like pro mod and pro stock and the like. This blog info does not address the set ups in high powered cars. I can not and do not disagree with the basic info in this snippit you cut and pasted off the net for general info. But in a car that is neutral on preload and goes left needs NEGATIVE preload and that is a common need in high powered cars reguardless of what this guy posted and now you posted. This info ASSUMES that the differental is square and all suspension mounts are square and correct which is why I went on with the explination of how to check that on his car prior to giving a bunch of random advice that likely does not apply. I don't like to hear (racers) mechanically say that if she goes right it need more pre load because they don't know any other way to correct or locate the likely true culpret, and will not likely fix the problem. You can pre load to your hearts content on your own stuff because you probably know your own car well, but I personally do not recomend to someone needing advice on there suspension, to preload prior to determining where the set up is in the first place weather it is square, plunb etc. This is why I try to explore the entire combination as apposed to plagerizing someone else's log book. I don't want to send a guy or gal in to the wall or wreck there car with vague canned advice that jumps over the 20 steps that are required to do the task accurately.
Good luck to you all and enjoy the read
:)

[dparker]

Your exactly right, sometimes I think as it would pertain to my car. Kinda what I would do is mine were doing the same thing. Its always better to ask a few questions before giving advice. Your right, getting everything straight should be done first. But a 2x3 9sec. ladder bar car just reacts different to changes than a 7sec all round tube prostock chassis.
You ready to sponsor me one of those chassis? I promise to put it in the winners circle...

[TopspeedLowet]

Your exactly right, sometimes I think as it would pertain to my car. Kinda what I would do is mine were doing the same thing. Its always better to ask a few questions before giving advice. Your right, getting everything straight should be done first. But a 2x3 9sec. ladder bar car just reacts different to changes than a 7sec all round tube prostock chassis.
You ready to sponsor me one of those chassis? I promise to put it in the winners circle...
I wish I had the Jack to throw your way buddy. I have only been building a few sets of headders so far this winter. No full fab cars to help my bottom line this season :(
Thanks for the reply though, I appreciate your commentary and friendly comments on this site. Sorry I can not float you a new chassis to play with.
I hope to have more work next year to help my program finance's as well.
I hope every one here is able to get through the season safely with there budgets they have, that is why I believe getting good advice is so important lately.
Thanks again Dparker for your thought provoking comments
Bruce

[altune]

Thanks for all the comments pertaining to this problem. I have a better idea as to what is happening on the car now. I just need to spend some time tweaking it. Spring preload, preload on the ladder, etc.
Damn power always causes problems. ( or the lack there of )
I'll keep you posted on progress.
Thanks
Al

[br1984]

altune i have a 2/3 chassis vega does the same thang mine goes to thr right every time unless i can kept the wheels down mines my not be right but i ended up with preload and right shock ajusted abought 1 1/2 inches higher on the shock has done good like that like i say my not be right but it works good luck

[BillyShope]

Actually Dparker, a high powered car will go left, not right. The turning condition he has is no doubt, due to the rear pointing that way or random preload, old tires, shocks with unequal adjustment etc. He said that they just made an adjustment in the squareness of the diff in his first entry prior to testing the new engine, that fact may have eluded your prognosis. When you make real power in a door car like 1200 or so you will find that negative preload is your friend. I have a car that I built and drive that needs no preload at all, in fact I use 1/2 flat negative to keep from going left. But I'm only running My crap in a door car at 7.62 ET at 187.22 MPH for what it is worth.
This going left on launch business was discussed in the pro mod forum a few months ago.

Yes, a high powered door car will veer left on launch, and, yes, negative preload (adding static load to the left rear) will straighten it out.

But, we have to consider both transient and steady state effects. On launch, a good portion of the reaction to the driveshaft torque goes to the front end, where it does a good bit of twisting. When that left front fender pops into the air, that corner of the car acquires some inertia. To slow its upward flight, increased loading appears at the right rear tire. The result is that veering to the left. (Actually, the whole front end acquires a rotating inertia, but it's easier to think of that left front corner by itself.)

This is, however, only a transient effect. After the car has twisted as much as its going to twist, steady state effects take over. As we know, the driveshaft torque tends to unload the right rear. So, for the rest of the run down the strip, that negative preload is helping the driveshaft torque to cause unequal rear tire loading. And, unequal loading of a tire pair results in a loss of traction performance.

What's a fella gonna do? With negative preload, performance is lost and, with positive preload, the leftward turn is worse. (Actually, enough positive preload will fix the problem, but we're talking hundreds of pounds difference between right rear and left rear.)

A reasonable approach is to somehow cancel that torque which is twisting the front end. There are various ways of doing this, almost all of which involve some form of asymmetric rear suspension setup. For instance, the problem goes away when different antisquat values are used for left and right sides of a 4link. With the proper ratio, the car can have equal rear tire loadings statically and maintain that equality throughout the run. And, since the rear tires remain equally loaded, that means the fronts also remain equally loaded.

I cover a few of the possibilities at my site:
http://home.earthlink.net/~whshope
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