Anti squat

Posted By: Ohio Joe

Anti squat - 01/27/15 11:18 PM

How valuable is anti squat % compared to IC height and length. I have been using a instant center calculator and can get a bunch of numbers and by plotting my current settings I believe I was WAY off. Please don't laugh, anti squat is 33.35%,IC length is 102" and IC height is 5.44 " . Car 60 ' times are usually around 1.35 , and has ran as fast as 9.83. I came up with one plot that come out A/S- 97.51 ICL- 61.40 and ICH at 9.75. It just seems to stay close to 100% AS and to keep the IC less than 62" my ICH is going to be above 9" . Question is , where to start . Thanks

Posted By: MR_P_BODY

Re: Anti squat - 01/28/15 12:18 AM

Quote:

How valuable is anti squat % compared to IC height and length. I have been using a instant center calculator and can get a bunch of numbers and by plotting my current settings I believe I was WAY off. Please don't laugh, anti squat is 33.35%,IC length is 102" and IC height is 5.44 " . Car 60 ' times are usually around 1.35 , and has ran as fast as 9.83. I came up with one plot that come out A/S- 97.51 ICL- 61.40 and ICH at 9.75. It just seems to stay close to 100% AS and to keep the IC less than 62" my ICH is going to be above 9" . Question is , where to start . Thanks

Anti squat is important... that will dictate the
movement of the rear... dont feel bad about the long
IC.. you can get away with it IF you run a -anti squat
but the torque dictates where you want the IC... usually
with big power you want about 55"-75" based on power
and try to keep a zero or - anti squat(you wont see
the body move much)... as you go out farther on the
IC you will raise the anti squat to follow the line
EDIT
with the long IC and above the anti squat you will
tend to wheel stand.... think of where you are lifting..
in front of the CG you tend to lift the front.. near
the CG you tend to lift the whole car(weight wise)..
then if the IC is too short (behind the CG) you tend
to lift just the rear

Posted By: Ohio Joe

Re: Anti squat - 01/28/15 12:40 AM

Thanks for answering Mr P Body, guess I'm just a little leary of making to big of a change.

Attached picture 8409989-image.jpg

Posted By: MR_P_BODY

Re: Anti squat - 01/28/15 12:56 AM

Quote:

Thanks for answering Mr P Body, guess I'm just a little leary of making to big of a change.

If you have a 4 link program your gonna find that you
will end up with maybe 6 settings that work well..
and that will be with different IC lengths and where
you are on the anti squat line (whether you want more
hit or less and if it stands up to much)... in my
pic in my sig here its up.. great for pics.. this
other pic is how I normally launch.. this is a 1.19 60'..
mine doesnt change much in the 60' except for the height..
and it does set down smoothly

Posted By: Ohio Joe

Re: Anti squat - 01/28/15 01:10 AM

My brother got a video of the same pass as the picture was taken. The car carries the wheels no higher than what they are in the pic but suddenly drops them about 15 to 20 feet out. Really don't know if it's just running out of power or it's my suspension set up. Thanks again for your help.

Posted By: MR_P_BODY

Re: Anti squat - 01/28/15 01:18 AM

Quote:

My brother got a video of the same pass as the picture was taken. The car carries the wheels no higher than what they are in the pic but suddenly drops them about 15 to 20 feet out. Really don't know if it's just running out of power or it's my suspension set up. Thanks again for your help.

Its probably the chassis set up... it might be just
the shock settings.. do you mess with them much
EDIT
and mainly the fronts(travel and stiffness on extension)

Posted By: MR_P_BODY

Re: Anti squat - 01/28/15 01:30 AM

Quote:

My brother got a video of the same pass as the picture was taken. The car carries the wheels no higher than what they are in the pic but suddenly drops them about 15 to 20 feet out. Really don't know if it's just running out of power or it's my suspension set up. Thanks again for your help.

What are the numbers on a normal run

Posted By: Ohio Joe

Re: Anti squat - 01/28/15 01:39 AM

Strange struts on the frt set as loose as we can get them. Afco da's on rear. When we make adjustments to the shocks in the rear it shows up in the 60' times. I must say my son and I are not real happy with the struts. Thinking about having them revalved.

If I remember the 60' time on that run in the pic was 1.32 and that was the best it has ever done . That weekend every pass was in the mid 9.80s .

Posted By: MR_P_BODY

Re: Anti squat - 01/28/15 02:59 AM

Quote:

Strange struts on the frt set as loose as we can get them. Afco da's on rear. When we make adjustments to the shocks in the rear it shows up in the 60' times. I must say my son and I are not real happy with the struts. Thinking about having them revalved.

If I remember the 60' time on that run in the pic was 1.32 and that was the best it has ever done . That weekend every pass was in the mid 9.80s .

It might want the shorter IC... thats the thing with
cars... nothing is the same... my setting wouldnt
most likely work for you... just start trying but
move the IC back to about the CG point.. it will
most likely like it just behind the CG... testing
is the only way

Posted By: Ohio Joe

Re: Anti squat - 01/28/15 03:12 AM

Thanks again Mr P Body, think I will go with the setup I posted above.

Posted By: CMcAllister

Re: Anti squat - 01/28/15 10:55 PM

Not interested in causing a train wreck so I will just add this.

For a long time, I have not paid attention to ICs or anti-squat numbers. I am only concerned with geometry; upper and lower bar angles, front and rear spread and height, percentage of rear spread above and below the axle centerline, etc. These are the things that determine what happens when torque is applied to the pinion.

I've seen old 4 link brackets with the holes in the wrong locations, front brackets in the wrong place, things that make it impossible to put the bars where they need to be. Sometimes it's not as simple as moving a bar or making a shock adjustment.

Torque and stroke matter. Effective low gear ratio matters, as does many other factors. Shocks and spring rates are more important than most would think.

Once a base line is established, the car will tell you what adjustments it wants once you get it to the track.

Posted By: Ohio Joe

Re: Anti squat - 01/29/15 12:08 AM

Thanks for the reply, just looking for suggestings because I believe that there is more left in the car and I want to get the most out of it. I can tell u that the bottom bar is 2.5 degrees down and the upper is 9.8 degrees down. It has an 11.5 inch spred in the rear and 8 inch spred in frt. Plotting it out puts the IC at 102 inches out. The motor sits back in the car and the weights are 1320 lbs in the frt and 1430 in the rear. 727 trans and 4.88 gear with a 470 ci low deck. Thanks for your time.

Posted By: dvw

Re: Anti squat - 01/29/15 01:29 AM

If I'm wrong on this I'd like an explanation. My feeling is if the car is up on the tire w/o excessive spin and chassis/housing movement, a suspension change isn't going to make it go any quicker. I think power has a way bigger influence on 60 ft that most people think. Whether it be gear, converter, engine or a combination of any of the three.
Doug

Posted By: Joes66dart

Re: Anti squat - 01/29/15 02:00 AM

I say leave it alone. The car goes rounds and is very consistant!

Posted By: Ohio Joe

Re: Anti squat - 01/29/15 02:11 AM

I can tell u from just making adjustments to the shocks and struts we have seen changes in 60' times, that makes-me think that changing the IC could make a difference . Just trying to get the most out of the old rat racer!!! Thanks for your reply.

Posted By: Duner

Re: Anti squat - 01/29/15 02:13 AM

Quote:

If I'm wrong on this I'd like an explanation. My feeling is if the car is up on the tire w/o excessive spin and chassis/housing movement, a suspension change isn't going to make it go any quicker. I think power has a way bigger influence on 60 ft that most people think. Whether it be gear, converter, engine or a combination of any of the three.
Doug

That "IF" thing gets me every time.

Posted By: CMcAllister

Re: Anti squat - 01/29/15 08:45 PM

I wondered the same thing a long time ago. There is an awful lot of things happening from the time the driveshaft starts to turn until the front tires break the 60' beam. Making it all happen as efficiently as possible is the trick.

Posted By: MR_P_BODY

Re: Anti squat - 01/30/15 12:51 AM

Quote:

If I'm wrong on this I'd like an explanation. My feeling is if the car is up on the tire w/o excessive spin and chassis/housing movement, a suspension change isn't going to make it go any quicker. I think power has a way bigger influence on 60 ft that most people think. Whether it be gear, converter, engine or a combination of any of the three.
Doug

It is the whole package... I have some good video
of my car with some slippage(controlled) to get up on
the tire.. and I have some other settings that it
gets up on the tire(again controlled slippage).. on
my car it just lifts the front higher with the same
60' numbers... but with it up higher I get more wind
under the car and tends to show up in the 330'...
but I have to make sure whether its the fronts or
rears hitting the 60' lights.. but usually its easy
to see by the numbers

Posted By: Ohio Joe

Re: Anti squat - 01/30/15 02:28 AM

The thing that got me started on this is the new converter we put in. It knocked a tenth out of the 60' time. It also caused use to change our shock settings that also affected the 60' times. That just raised more questions for me about the IC. My son thinks I should just leave it alone but ..... I can't . Thanks guys.

Posted By: CMcAllister

Re: Anti squat - 01/30/15 03:01 AM

Quote:

The thing that got me started on this is the new converter we put in. It knocked a tenth out of the 60' time. It also caused use to change our shock settings that also affected the 60' times. That just raised more questions for me about the IC. My son thinks I should just leave it alone but ..... I can't . Thanks guys.

Don't. That's how you learn. The good part is it doesn't cost anything but some time and you can always change it back. Try the top bar at about 12 or 13 degrees and the bottom bar about 1 or 1 1/2 down. Shock adjustments will likely be needed after any change. With 52 percent on the rear tires and almost 12:1 effective low gear, the suspension won't need to be very aggressive.

Video it at 30 or 60 frames/second if you can and play it back a frame or 2 at a time. That's when you begin to see what's really happening.

Posted By: ADakotaRTGuy

Re: Anti squat - 01/30/15 04:10 AM

Does he want to lower his AS because it is lifting to much?

I had issues getting good traction and the AS was only at 8.8% so I adjusted it to go to a 106%. Now mine was a traction issue. So would it be better to find a good middle ground?

Before

After

Posted By: dvw

Re: Anti squat - 01/30/15 04:33 AM

No reason not to experiment. I've had may ladder bars in every hole and shocks all over. That being said I've picked up maybe .05 in 60 ft in 2 years of testing.
Doug