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Discussion Starter #1
checking and trying to adjust/set the IC and AS on my foxbody notch. Car is at race weight, tire pressures, fuel level, drivers weight in the seat, everything as it would be at the starting line. As with most cars I've seen, the drivers side sits about 1/2" lower than the pass side, this difference can be seen in the front mounting point heights of both the upper and lower control arms. It's enough difference that the DS values for IC and AS come out quite different than the values for the passenger side. Which side should I be targeting, or should I take an average, or what?

I do have adjustability with front coilovers, and different mounting points locations on the differential (Team Z unit), as well as shims or cut springs to adjust rear ride height.

ride height appearance or "coolness" are at the bottom of the priority list, "hook and book" are at the top.

I have scaled the car, and the numbers look okay as far as I can tell.
Car weighs 2951 at race weight, front to back bias is 55%/45%. front corner weights are within 15 pounds of each other. At the rear the DS is 45 pounds heavier than the pass side.
 

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I dont know if it is the "right" thing to do but on my car we try to get the ride height the same with me in the car, race ready.
 

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I should be easy to get the ride height the same
for the rear you need to adjust the front coil over this is how i do it on mine .(race trim weight with driver )
On my car i adjust the front so the rear is equal & my front is within 1/4``. your ARB will do that your car leaves straight no roll.
 

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Discussion Starter #7
okay, thanks. I set the car up level last night, used a little different method but it worked. I still use the thick poly rear spring insulators that go between the body and the tops of the rear springs, they are almost 1/2" thick so I removed the one on the pass side and it brought the right rear corner down almost dead even with the left rear. It also transversely brought the left front up slightly, everything is a lot more even, don't know if it's the correct approach but I have to try something. Going to stick the corner scales back under it in a little while to see if it through anything out of whack. I'm going testing tonight.
 

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checking and trying to adjust/set the IC and AS on my foxbody notch. Car is at race weight, tire pressures, fuel level, drivers weight in the seat, everything as it would be at the starting line. As with most cars I've seen, the drivers side sits about 1/2" lower than the pass side, this difference can be seen in the front mounting point heights of both the upper and lower control arms. It's enough difference that the DS values for IC and AS come out quite different than the values for the passenger side. Which side should I be targeting, or should I take an average, or what?

I do have adjustability with front coilovers, and different mounting points locations on the differential (Team Z unit), as well as shims or cut springs to adjust rear ride height.

ride height appearance or "coolness" are at the bottom of the priority list, "hook and book" are at the top.

I have scaled the car, and the numbers look okay as far as I can tell.
Car weighs 2951 at race weight, front to back bias is 55%/45%. front corner weights are within 15 pounds of each other. At the rear the DS is 45 pounds heavier than the pass side.
You wouldn't think it, but that can be a good thing. I do all the chassis/suspension set up and tuning on Mark and Dean Fisher's 91 Mustang and fought a car that would drift to the left for a long time.

The key in understanding how to make the car go straight is understanding what is actually happening when you let go of the trans brake. We've all seen the picture of the Mustang with the left front wheel about 3 feet off the ground at launch with the caption "no, your Honda can't do this".



Reality is, there is a lot of chassis flex going on in that picture, but it is also a great illustration of how misunderstood the application of torque to a chassis is.

People asume that because the left front comes up, torque is pulling the left front up. The reality is, the torque acts FIRST on the parts of the car with the least amount of weight (inertia) to overcome. The rear end in the car moves LONG before the rest of the car and HOW it moves it's what is most misunderstood.

People asume that the right rear of the chassis is being "rolled over" by the torque of the engine in the frame rails. That is a myth. What is ACTUALLY happening is the driveshaft torque is PUSHING the LEFT rear wheel DOWN, and PULLING the right rear UP into the fender well. Because the rearend only weighs a tiny percentage of the total weight of the car, and it is not "fixed" to the chassis, it "reacts" much more quickly than the chassis. The chassis does eventually join the "motion party", but it's WAY behind the rear end in the chain of movement.

This is what makes an anti roll bar a CRITICAL component of any drag car. The anti roll bar allows the suspension to continue to provide up and down movement, but locks the "roll" of the body, and the rear end motion together, where in the roll axis, they have no choice but to work together.

That said, even with the stiffest of anti-roll bars, there is still SOME variance in the load applied to the tires at launch. Normally there is some preloading of one side of the car or the other to counter the car wanting to go right or left.

I have always thought the only right way to set up a car was with the driver in the seat at race weight. What I have learned over time, is that the car is much closer to perfect when I set it up on the scales with driver in the car but the anti roll bar NOT connected. I will get the corner weights as close as I can, but focus more on the rear bias with the driver in the car and try to get the rear as even as I can.

Then after I'm done with that, the driver gets out of the car, and I attach the anti-roll bar completely neutral. I know what you are thinking: when the driver got out, the weights went all crazy and the car was sitting higher on the left than the right. You are correct. However, in practice, this has rarely failed me. In Mark and Dean's car, I just did this a few weeks ago and the first hit off the trailer, I was just a hair off, but it basically went just a tad right:

http://www.youtube.com/watch?v=SeHfyx3pirY

A quarter turn on the anti roll bar and even on a less than stellar track:

http://www.youtube.com/watch?v=ncQfxR4sWDg&feature=relmfu

Corner weights are not without value, but there's no need to get completely obcessed with having them exactly perfect. I've seen people go to some crazy extremes moving weight around trying to acheive the "perfect" corner weighting and then go and run the car and it look like it was in a zig-zag competition.
 

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Discussion Starter #9
Thanks. I went to the track last night with lackluster results, track conditions were probably the worst I've personally encountered. spinning and sliding anywhere and everywhere down the track. initially I had the car wanting to shoot to the left, I all but eliminated that finally with ARB adjustment. Every pass I had bad tire spin on launch, and had to "drive" the car all the way down the track, getting squirrely. I ended up with the strange 10 ways on full loose front and back to get down the track and the slicks down to 10 lbs cold. Everyone seemed to be fighting the track. I'm going to have to get to a decent track to iron this thing back out. I'll try to post up the best pass video of last night.
 

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Scott thank you for the read on suspension. I have been trying to figure it out also. You would think by now everyone knew what to do to make a car hook each and every time...
 

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Thanks. I went to the track last night with lackluster results, track conditions were probably the worst I've personally encountered. spinning and sliding anywhere and everywhere down the track. initially I had the car wanting to shoot to the left, I all but eliminated that finally with ARB adjustment. Every pass I had bad tire spin on launch, and had to "drive" the car all the way down the track, getting squirrely. I ended up with the strange 10 ways on full loose front and back to get down the track and the slicks down to 10 lbs cold. Everyone seemed to be fighting the track. I'm going to have to get to a decent track to iron this thing back out. I'll try to post up the best pass video of last night.
There's something to be said for being able to figure out how to get down a less than great track. It's good information to have down the road for a race. However, when you are at the bottom of the set up learning curve with a car, it just makes your job that much harder. If you've read any of my thread up in the sticky in this forum, you know that I basically wasted 72 passes and literally thousands of dollars chasing something that a killer prepped track would have told me right away. I learned more from the 5 passes I made on good surface than I did from all 72 of the previous passes combined.

Go to a really good hooking track. Write EVERYTHING you can think of down on paper, and ANYTHING you change, write it down. Also, video is your friend.

One more thing: I don't think I said it before, but don't get too crazy worrying about the A/S and I/C being a little different from side to side. As you already said, the car sits lower on the driver's side with the weight of the driver in the car. This is part of the reason why scale the car with the anti-roll bar NOT connected. When you get OUT of the car, the car will be closer to level and you will be hooking up the ARB with the car in that state. When the driver gets back in after hooking it up with no preload, the corner weights will be different, but you won't be chasing the ARB setting because the car will almost certainly not want to go left.

I'm glad I made that first post BEFORE you posted your results from yesterday. I'm guessing right about now some of what I've written here is clicking. When the car went left, it was because you had too much preload on the right rear. The right rear tire had too much bite. I'm curious as to how much you had to adjust shorten the right side ARB link (how many turns) to get it to go straight?

If you think about it, if you had left the ARB unhooked while you were scaling the car with the driver in the car, and then hooked it up (with no preload) after the driver got out, I'd just about bet good money the setting would be close to the same as you made at the track to get the car to go straight.
 

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Discussion Starter #13
Thanks again for posting Scott, I think I'm getting a better understanding. As far as the ARB adjustments I made, I can't supply a good answer as the first time I made an adjustment I couldn't remember which way to take it and went the wrong way.....made it worse, so the next adjustment I went quite away the other direction.....pretty much went til the pass side adjuster felt loose (as if you could just slide the bolt in without me in the car). I'm going to recheck everything as the car sits after getting back from the track.....didn't touch it yesterday. One problem I have is the best way to check if the rear diff is "square" in the car, what is a good accurate measure/reference point......I want to rule that out as a possible cause of the car wanting to not go straight.

I do intend to get to a better track, hopefully won't have to chase my tail so much. I'm still not sure where my shock and strut setting should be, or what to do with them based on track conditions, ie slick do this or sticky do that. I have the 10 way single adjustables, unfortunately double adjst aren't in the budget right now.
 

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Discussion Starter #14
One more thing: I don't think I said it before, but don't get too crazy worrying about the A/S and I/C being a little different from side to side. As you already said, the car sits lower on the driver's side with the weight of the driver in the car. This is part of the reason why scale the car with the anti-roll bar NOT connected. When you get OUT of the car, the car will be closer to level and you will be hooking up the ARB with the car in that state. When the driver gets back in after hooking it up with no preload, the corner weights will be different, but you won't be chasing the ARB setting because the car will almost certainly not want to go left.
That is a different approach to getting a baseline ARB setting, but I'll give it a shot, before I had everything at race weight with drivers weight in the seat and "then" hook up the ARB so the bolt would just slide in. With the driver OUT of the car the ARB would be "preloaded" or tight.......bolts not able to slide out.

I have had pretty good luck with set ups to this point, but it gets tougher as the car gets more power and over the winter I built in some more.
 

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That is a different approach to getting a baseline ARB setting, but I'll give it a shot, before I had everything at race weight with drivers weight in the seat and "then" hook up the ARB so the bolt would just slide in. With the driver OUT of the car the ARB would be "preloaded" or tight.......bolts not able to slide out.

I have had pretty good luck with set ups to this point, but it gets tougher as the car gets more power and over the winter I built in some more.
I think you will be pleasantly surprised with the result.
 
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