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So you think a lower IC would be better? I've talked to Jerry Bickle and he was the one that got it where its at. It use to stick the tire then spin, this was as good as I could get it in current set up. They do make a newer version Hoosier 33x15x15 that works pretty well with no shake. I'm pretty local to Hoosier and they had given me some test tires when developing the new one its a much stiffer sidewall than there old version.
I'm pretty sure Mr. Bickel knows way more than I ever will when it comes to setting your car up. Anti-squat close to 100% hits the tires harder than lower AS numbers. That is a good thing.
Reducing front tire weight all the way through the launch is tougher to do.
If you had that video so you could play it frame by frame in front of him, he could probably give you 3-4 things to adjust to improve how your hot rod launches.

You need to stiffen the rebound on the shocks in the rear (assuming you have double adjustables) if the tires look like they are "chattering" which can lead to spinning. I'm assuming it will do this even at or before 60' sometimes?
This^^.
I tuned up my little 4 link program so Extension (Rebound) damping is 4 times more than compression damping. It made a big positive change from .1 second to .3 seconds and reduced front tire weight.
Adding front travel also helps a bunch. It took more "fiddling" to finally get some weight on the wheelie bars so it could be possible to hang the front end depending on how much adjustment is in the bar mounting holes.
In general, to lighten the front, which maximizes rear tire force, one needs to move the IC forward and up but like above, I will defer to experts in the field.

Just for shiggles, measure the distance from the ground to the center of the cam, or as best as you can estimate. A CG height estimate is a fundamental dimension that one should know for all this stuff.
 

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Discussion Starter #22
I'm pretty sure Mr. Bickel knows way more than I ever will when it comes to setting your car up. Anti-squat close to 100% hits the tires harder than lower AS numbers. That is a good thing.
Reducing front tire weight all the way through the launch is tougher to do.
If you had that video so you could play it frame by frame in front of him, he could probably give you 3-4 things to adjust to improve how your hot rod launches.


This^^.
I tuned up my little 4 link program so Extension (Rebound) damping is 4 times more than compression damping. It made a big positive change from .1 second to .3 seconds and reduced front tire weight.
Adding front travel also helps a bunch. It took more "fiddling" to finally get some weight on the wheelie bars so it could be possible to hang the front end depending on how much adjustment is in the bar mounting holes.
In general, to lighten the front, which maximizes rear tire force, one needs to move the IC forward and up but like above, I will defer to experts in the field.

Just for shiggles, measure the distance from the ground to the center of the cam, or as best as you can estimate. A CG height estimate is a fundamental dimension that one should know for all this stuff.
Thanks for the input, and I'm sure you are right if I got him some video it would get more changes. I was just fighting weight transfer especially on crappy surfaces. Once I get it back together with reduced weight up front it will be tuning time again. I'm hoping I wont need to hit the tire so hard to get good transfer. I appreciate the help.
 

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What sucks even more is we both spent a bunch of dough this winter, and they may never run the points series :(


.
 
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I'm hoping they can get some racing in so they can run their big events and make some dough!!!
I know the points events don't make any dough, so they will be bumped for the money making events.
I don't blame them one bit for that.
I will be happy if we can make some T & T nights at this point!!!

We don't want the track to fold, that's for sure.

.
 

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Discussion Starter #26
.

I'm hoping they can get some racing in so they can run their big events and make some dough!!!
I know the points events don't make any dough, so they will be bumped for the money making events.
I don't blame them one bit for that.
I will be happy if we can make some T & T nights at this point!!!

We don't want the track to fold, that's for sure.

.
The big $ race is probably on the chopping block. I was really looking forward to that one. Fingers crossed it can be ran but mid May is really pushing it I would think.
 

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Discussion Starter #27
Is 10" spread to little for the rear of 4 link bars? My adjustments are course so not a lot of useable settings without moving the entire bar some times. My front bracket holes are 1 1/8" apart and rears are 1" . I checked my bars and the IC is actually only about 47" out and 7.15 up roughly 91% AS. Rear split now is 11" front is 7. If I drop the top rear the split would be 10" rear 7" front the IC would be 57" out 7 up 73% AS. If I raise the top front the split would be 11 rear and 8 1/8" front and IC would be 66 out 6.85 up and 62% AS. Thoughts on best place to start?
 

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some interesting reads:
 

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Discussion Starter #29 (Edited)
Good read. I'm a little confused about some of it. “The farther forward you move the IC, the lower it must be,” The farther back you move the IC, the higher it must be.” This is confusing to me. Further forward already lowers % ant squat then you lower the IC and it makes the anti squat even less.
After that read I'm more confused than ever I think. Maybe I'll just hire it done.:oops:
 

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I am not an expert, but here are some thoughts. 47" I feel is too short for bias tires. The 57" & 7" looks promising to me. I actually like the top bar close to the housing. Anyone else feel the same?
 

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Good read. I'm a little confused about some of it. “The farther forward you move the IC, the lower it must be,” The farther back you move the IC, the higher it must be.” This is confusing to me. Further forward already lowers % ant squat then you lower the IC and it makes the anti squat even less.
After that read I'm more confused than ever I think. Maybe I'll just hire it done.:oops:
I think the author of the article screwed that statement up. To stay on the neutral line, or any constant AS % line, if the IC moves forward, it needs to move up. (if it's not one of the outlier examples of putting the IC way out and below ground level.)
Then the discussion of the Patrick Budd is easier to follow but still could take a ton of track time to finally get dialed in.

What all of the articles avoid is recommending a starting point. Currently, you have measured above 90% AS which is probably a good thing. According to Jerry, you're a bit short on IC length which makes for a quick reaction but not a lot of bite after the hit. Your symptoms are that the tire gets hit hard and then the tires lose bite (not enough weight transfer), sometimes shake, and then after the front comes down it shits and gits. You mentioned Jerry suggested 58 and 7 for an IC. This would soften the hit but keep bite longer. Adding a bunch of extension damping could fill in the tire bite "dip" and then losing 110lbs off the front makes your car happy.

Here is what your car seems to act like on the left and what it could do with a big swing in IC but not a lot of change in AS %. Basically, you can see the IC change to 77 and 11 which gives an AS change from 97% to 102% (dynamic). Added a bunch of extension damping, raised the CG 1/2 inch, and loosened up the front end. Rear tire load never droops and maxes out at your car's current weight. Now, if you were to get this type of response and then you added 50HP and dropped 110lbs, it would hit the wheelie bars pretty good and maybe cause new 60 foot issues. :) This program is $79 and Bickel's book is $59 which is way cheaper than 4 days at the track, throwing wrenches, swearing at the dog and not having fun.
71983
71984


This one is really close to your original numbers: it's 58 and 8 with AS% of 104. Took a bunch of droop out of the fronts, now it's 3", still let the front come up, took 110lbs off the front and had to tighten the compression a bit in the rear. If you look close, it likes that 110lbs put in the trunk. Leaving the 110lbs out of the trunk, it only takes a little tweaking to the front to make it behave.
71985
 

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Discussion Starter #32
I think the author of the article screwed that statement up. To stay on the neutral line, or any constant AS % line, if the IC moves forward, it needs to move up. (if it's not one of the outlier examples of putting the IC way out and below ground level.)
Then the discussion of the Patrick Budd is easier to follow but still could take a ton of track time to finally get dialed in.

What all of the articles avoid is recommending a starting point. Currently, you have measured above 90% AS which is probably a good thing. According to Jerry, you're a bit short on IC length which makes for a quick reaction but not a lot of bite after the hit. Your symptoms are that the tire gets hit hard and then the tires lose bite (not enough weight transfer), sometimes shake, and then after the front comes down it shits and gits. You mentioned Jerry suggested 58 and 7 for an IC. This would soften the hit but keep bite longer. Adding a bunch of extension damping could fill in the tire bite "dip" and then losing 110lbs makes your car happy.
View attachment 71982 View attachment 71981
I was thinking 57 and 7 would be good starting point but the one article says try to get IC as close to AS as possible. If I did that I could get a setting at 56 and 9.75 97% AS but never see anyone saying there IC is 10 up. This would require lowering the rear of the car 1/2" to get that IC
 

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I have both JB's book and his 4-link wizard Pro program. The book recommends a basic start setting of between 50" to 60" IC and an IC height between 3" and 7" for up to 1300hp, trans brake type car. With limited info and assumptions, I ran the numbers you gave and a good base line start is 54" IC length with a 5 5/8" IC up height. To get these, it helps to have the computer program as it shows you all the various numbers very easily and quickly so you can figure which on fits your needs. I tried drawing them with my CAD program but it was time consuming and the program gave me ideas for bar settings and ride heights that I hadn't even considered. He doesn't give "anti-squat" much consideration as he believes it's not that critical. JB is one very sharp hombre and has the championships to prove it. Hope this helps.
 

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If you go to 57" IC, your IC heights will be around 5 5/8" to 7 5/8" (depending on your hole spacing, etc.) which will give you anti-squats of about 62% and 84% respectively in case you want the anti-squat values. I'd be happy to plot them for you if you give me much more information (hole spacing, measurements, etc.).
 

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Discussion Starter #35
If you go to 57" IC, your IC heights will be around 5 5/8" to 7 5/8" (depending on your hole spacing, etc.) which will give you anti-squats of about 62% and 84% respectively in case you want the anti-squat values. I'd be happy to plot them for you if you give me much more information (hole spacing, measurements, etc.).
I may order those but in the mean time here are some measurements.
Bottom rear hole is 7.75" above the ground and has 3 holes 1" apart and has 2 more holes set back that split them. The bottom top hole in on the rear is 17.5 from the ground and has 3 holes 1" apart. The front lower hole is 6.375" above the ground and has 4 holes 1.125 apart. The lower top front hole is 12" above the ground and has 5 holes that are 1.125" apart. Bottom bar is 18.25: long and top is 16.25" long.
Not sure if these will help or not.
 

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Discussion Starter #36
I think the author of the article screwed that statement up. To stay on the neutral line, or any constant AS % line, if the IC moves forward, it needs to move up. (if it's not one of the outlier examples of putting the IC way out and below ground level.)
Then the discussion of the Patrick Budd is easier to follow but still could take a ton of track time to finally get dialed in.

What all of the articles avoid is recommending a starting point. Currently, you have measured above 90% AS which is probably a good thing. According to Jerry, you're a bit short on IC length which makes for a quick reaction but not a lot of bite after the hit. Your symptoms are that the tire gets hit hard and then the tires lose bite (not enough weight transfer), sometimes shake, and then after the front comes down it shits and gits. You mentioned Jerry suggested 58 and 7 for an IC. This would soften the hit but keep bite longer. Adding a bunch of extension damping could fill in the tire bite "dip" and then losing 110lbs off the front makes your car happy.

Here is what your car seems to act like on the left and what it could do with a big swing in IC but not a lot of change in AS %. Basically, you can see the IC change to 77 and 11 which gives an AS change from 97% to 102% (dynamic). Added a bunch of extension damping, raised the CG 1/2 inch, and loosened up the front end. Rear tire load never droops and maxes out at your car's current weight. Now, if you were to get this type of response and then you added 50HP and dropped 110lbs, it would hit the wheelie bars pretty good and maybe cause new 60 foot issues. :) This program is $79 and Bickel's book is $59 which is way cheaper than 4 days at the track, throwing wrenches, swearing at the dog and not having fun.
View attachment 71983 View attachment 71984

This one is really close to your original numbers: it's 58 and 8 with AS% of 104. Took a bunch of droop out of the fronts, now it's 3", still let the front come up, took 110lbs off the front and had to tighten the compression a bit in the rear. If you look close, it likes that 110lbs put in the trunk. Leaving the 110lbs out of the trunk, it only takes a little tweaking to the front to make it behave.
View attachment 71985
Thanks for this, I'm not sure how I didn't see this when you posted it.
 

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I believe that JB's Chassis Performance book and 4-link Wizard program are must haves. I also have Dave Morgan's Door Slammers book (outdated and too theoretical and too little "base lining info), Rick Jones Quarter-Max Chassis Tuning Guide book (again, too little "base lining info") and every other article I could find on drag race chassis suspensions (some totally wrong). There are other software IC plotting programs but what I liked about JB's is that it shows you a recommended starting or base line area. The book also give you lots of info (shock settings, rear wing angle, pinion angle, wheelie bar settings, pre-load settings, etc.) for a starting point. That was really important for me as I had no clue where to start. He also talks about down track performance issues and how a good starting line set up might be a handful down track or while stopping the car. Well worth the cost of the book and software.

What is your wheel base, center line height of your rear axle housing from the ground (race ready) and the center of your camshaft height (race ready - I'll use that as your theoretical vertical center of gravity). How much engine setback?
 

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Assuming your camshaft centerline is 18", Bickel's program suggests: Bottom front in hole #2, upper front in hole #3, Axle bracket bottom hole # 2, Upper axles bracket hole #3. This will give you an IC length of 56.4", IC height of 6.36, Anti-squat of 67.3%, and lower bar angle of -2 degrees. All of these numbers put you right in the middle of the recommended ballpark. All hole numbers are from bottom up.
 
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