Only a low 1.7 but the launch but sure is pretty

 

Last years launch, no slicks

 

AWESOME!

 

Sweet pic, wish i had one of mine like that...whats done to your suspension?

 

What slicks are you running? Good lookin pic

 

1.7's are not bad at all. However it looks to me like you car is squatting to much in the rear and you can do even better. You might want to look into another torque arm to change your instant center. The rear should actually raise a little from the stock position when things are right. This is what I'm looking into.

 

Tony, What was the tire pressure set at on the 1.7 60'?

 

I wanted to say all that this morning when I first read the post but had to get off to work.

Way too much squat. The tires are digging in (good) but it's pulling the back end of the car down too much which actually means you're still not getting the best traction. There's only a couple of things you can do to correct it.

Adjustable rear shocks on a firm setting
Heavier spring rate rear springs may help a bit but it probably won't be noticable when you consider just how much force is pushing them down.
Adjustable suspension. You need to raise the IC of the suspension. Not really possible with stock suspension. What you would have to do is move the front mount point of the torque arm a little higher.
I'm not sure how much of a change a pinion angle adjustment would do.

You want just enough squat for weight transfer. Too much and energy is used to pull the back of the car down. Anti squat or seperation is when the rear of the car starts to ride up when the tires are digging in. Too much and the tires can unload. It takes some fine tuning to get a perfect suspension launch.

 

now thats a launch pic. my best 60` was 1.69 and never squatted like that. awesome.

 

Like others have said, Get rid of the squat and it will 60ft even better.

 

Your right 10.90streetcar, getting rid of the squat will make your 60ft better but not all cars are setup to do that. The whole theory for getting traction for those that may not know is when you use a slick you want all of the 'off the line' force or initial shock to be absorbed into the slick, which means have the chassis and suspension stiff just like u can see with that blue car 10.90streetcar posted, however if the force is greater than the tire can hold (as in the case with my car) you must compensate by letting some of the suspension absorb the shock. If i set my suspension up stiffer (6th or 7th setting on 12 way adjustable QA1s) it will spin on the line (1.60-1.65 60ft.) however if i go one or two clicks looser to the #5 setting i can cut 1.51-1.54 60fts depending on the track surface. with my transmission (th400) and gearing (4.10s) the car hits pretty hard off the line, which i'm sure Tony89GTAs car is the same, not to mention he's using a 26" slick which is even more a disadvantage off the line, so he's doing the right thing by giving the suspension the shock car looks good man

 

tony89gta very nice take off.

im just wondering about the t-56 410's setup, how is it on the highway and stuff?

as i have 410's, and im putting in a t-56 i would just like to know

 

That blue car( My Car) has the QA1s set on the 3rd softest setting. Anti Squat is all about IC.

 

Wow so many replies, thanks guys

Suspension details are boxed LCA with polly bushings, LCA relocation brakes set at lowest setting, Spohn t-56 torque arm and crossmember and just have the stock springs and shocks. My slicks are a M/T 26-8.5/16 with like 11-13 psi in them. Also the track is unpreped it that means anything to you guys.

Not sure what I'am going to do to improve the suspension since it still is a street car for the most part with a week rear but I'am going to look into what some of you said and see if i can work on some of the simple stuff.

roughskinjrz, 4.10's are a perfict match for the t-56 i think, the rpms at about 60 mph are at 2000 rpm's in 6th.

 

lol nice pic but there is one more thing wrong. That dude in the background isnt looking at the car! He is all millitary about it! yea yea.. its his job sure sure..

 

Hmm interesting.. mine are set on 5 and it squats much more than that..?? IC?? Are you running a torque arm suspension or ladder bar? OR are you meaning 3 from the positve side? i'm going up from the negative side 5 clicks..

 

3 clicks up from the negative (softest) setting. Its a torque Arm. Stock springs.

 

Looking great Tony!

 

You’ve totally missed the point in tuning a rear suspension in this post.

It has almost nothing to do with stiffness. If you get the instant center/anti squat right the suspension geometry should push the rear tires down hard enough that you could make a pass without any rear springs installed on the car, assuming that you had something rigged to hold the car up on the line and catch it at the end.

And yes, if you apply too much force to the rear tire it will grab and then bounce when the tire cannot absorb any more power, at which point it will loose traction.

You use spring and swaybar stiffness/preload to adjust how the chassis reacts to the weight transfer, and shocks adjusts how fast it reacts.

 

I've just been doing some research for finding the best setting for my ladder bars and have discovered a couple of things. My current setting has the suspension at 91% anti-squat. That's why my suspension doesn't squat or lift when I launch. More than 100% will raise the rear end and hit the tires harder. Lower than 100% will cause the car to squat and hit the tires softer. My highest setting for the ladder bars will give me 129%. If you look at 10.90's picture above with the wheels high in the air, he has a high anti-squat. The rear tires are away from the body as the body is rising up and the tires are being forced downwards.

Since the instant center with ladder bars only has a couple of choices, I can move mine around to change the anti-squat percentage. A torque arm suspension has no adjustments however moving the rear of the LCA around can also do changes. You say you have the relocation brakets already and have the bars in the lowest holes. Right now I'd suggest moving them up at least one hole and try again.

With the torque arm/LCA suspension it's sort of like a 4 link system. When you change the position of the LCA, you move the IC around slightly.

 

Basically, yes, but in real life it’s not that simple… (is anything that simple IRL?), because of shock dampening, spring rates, vehicle corner weights and front suspension reaction you could get rise at lower antisquat numbers and squat at higher ones.

I’m curious, how did you get such accurate antisquat numbers?

Yep, most likely, but it’s also hard to tell from a passenger side shot. There used to be a video of one of the local guys with a blown, 4th gen TA and I believe a GW TA setup that REALLY showed this well, you could clearly see the rear suspension reacting and rising as he came off the line… I’ll see if I can find it, if it even still exists (it’s probably 5 years ago now)

LCA brackets (I really think that most need a 1” down position, instead of just the 2” and 3” available on most brackets, but that’s another story) and TA front pivot location change the instant center on an f-body. With stock pieces it’s hard to change, but there is enough slop in the front TA bushing to move it around about 1”

 

Huh, I don’t believe that I actually found it (at least I think that this is the video I was thinking about, I’d suggest that you right click and save so you can see it full screen

 

It took a lot of searching to find what I was looking for. There is no real ladder bar charts but there's lots for 4 links. You can download a free 4-link spreadsheet from http://www.xtreme4x4tv.com/news.aspx?iid=5023 The author's home page is http://mysite.verizon.net/triaged/

Put in all the proper numbers and it can become a ladder bar system. The front point for the top and rear bar are at the same height. Lots of other measurments are required. The only ones I don't have as accurate are the front and rear unsprung weights.

 

Interesting. Guessing at the unsprung mass.

Front I'm going to say 200 pounds. That will be tires, rims, tubular a-arms, springs. Plus spindles, rotors calipers etc.

Rear I'm going to guess at 500 pounds. How much does a Ford 9" with the smaller brake drums weigh? Springs, tires and rims.

That puts my current setting at 99% anti-squat. No wonder it's so hard for me to pull the wheels. My highest setting can give me 139%. If the car could hook up on a 10.5 tire, it would shoot me to the moon.

So even with a rough guess at the unsprung weight, it still looks like I need to move my ladder bars up one more hole to help weight transfer with my very nose heavy car.

 

Oops. Way over on the weight guessing.

Ford 9"
Housing = 39 pounds
28 spline axles = 18 pounds each. My aftermarket 31's guess high at 25 each.
Drum brake assemblies 26 pounds each
Third member = 68 pounds. Assuming this is also with the gears? My spool is light so I'll say 65 pounds for mine.
Race rims and slicks guess at 35 pounds each

39
25
25
26
26
65
35
35
= 276. Add in a few extras like springs, oil, brake lines etc and I'll round it up to 300 pounds. I'm sure the front unsprung weight is also much lighter.

Having all the proper numbers or at least as close to possible is what you need for many calculations. Just like everything else. Garbage in/garbage out