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Angle of the ladder bar is only a quick check, assuming every bar is located at the same point on the axle. The car only reacts to how far the pivot point (front bolt) is off the ground. You can change it by car height or bolt location. That's it. That's all there is. The higher the pivot the harder it hits the tire. The softer the spring the harder it hits the tire. More power (converter, engine gear ratio) hits the tire harder. The shock rebound controls the speed of the hit. The compression holds the tire down If it hits the tire to quick the rebound is too loose. If it bounces the car back up the compression is too tight. As for the front the same applies to rebound, compression and spring rate. The only other adjustment in the front is the amount of travel. More helps hit, less the opposite. C/G (weight distribution and height of that weight) keeps it from standing on the bumper. Higher and rearward will load it. Weight in the center is more tunable than at the ends. That's not always possible with a nose heavy car. Radials like to be hit pretty hard. Thus high bar pivot height. Adjusting how hard it hits and the amount of speed that the housing and front end move is the key. Try to slow the front, raise the rear bar and then adjust the rear housing speed with the rear rebound. Watch getting the rear compression to tight. when the side wall releases it'll blow the tires off. Good video is key. I watched my sons turbo car smash a 275 M/T pro so that the rim was within 1" of the pavement. Then rebound to original height. This happened with the car moving forward about 3". Obviously the rebound was WAY to loose. And we haven't even mentioned power management.
Doug
 

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Discussion Starter #63
Angle of the ladder bar is only a quick check, assuming every bar is located at the same point on the axle. The car only reacts to how far the pivot point (front bolt) is off the ground. You can change it by car height or bolt location. That's it. That's all there is. The higher the pivot the harder it hits the tire. The softer the spring the harder it hits the tire. More power (converter, engine gear ratio) hits the tire harder. The shock rebound controls the speed of the hit. The compression holds the tire down If it hits the tire to quick the rebound is too loose. If it bounces the car back up the compression is too tight. As for the front the same applies to rebound, compression and spring rate. The only other adjustment in the front is the amount of travel. More helps hit, less the opposite. C/G (weight distribution and height of that weight) keeps it from standing on the bumper. Higher and rearward will load it. Weight in the center is more tunable than at the ends. That's not always possible with a nose heavy car. Radials like to be hit pretty hard. Thus high bar pivot height. Adjusting how hard it hits and the amount of speed that the housing and front end move is the key. Try to slow the front, raise the rear bar and then adjust the rear housing speed with the rear rebound. Watch getting the rear compression to tight. when the side wall releases it'll blow the tires off. Good video is key. I watched my sons turbo car smash a 275 M/T pro so that the rim was within 1" of the pavement. Then rebound to original height. This happened with the car moving forward about 3". Obviously the rebound was WAY to loose. And we haven't even mentioned power management.
Doug
Thank you. A lot I've been thinking, just having trouble putting it into practice. I have some very good ideas to try this spring
 

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Radials or bias it takes some work to get there. My son and I run 2 completely different cars. His is a 3750lb turbo street car on Pro bracket radials with a trans brake. It has been 9.55 but do to only a roll bar it bracket races at 10.0 Mine is a foot brake index ladder bar car on 10.5x31 bias. It's been 9.00 but I slow it to run 9.25 index in N/SS. Mine will repeat mid 1.2x 60ft when its not backed off.
Doug
 

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This my ladder bar car.
I use QA 1 shocks front and rear. Mine was a disaster and I'd been everywhere, even here, looking for advice. The best advice came from here. What made it all come together was a 4 part video on shocks from Tim McAmis plus what I learned here. watch that video til your eyes bleed.

The video was from a track rental with some buddies. I count my shock setting from full soft, the softest setting (you can't turn it any more) being #1. The front shocks in this run at set at 10 compression, 13 extension. Rears 3 compression 12 extension. The wheelie bars have been raised so they are not part of the equation and the tire pressure is 11 lbs. The video shows the tire pressure is still low.

Now we are at fronts 10 compression, 15 extension, rears 2 compression 15 extension and we're at 12 pounds pressure with a Hoosier 260 tire.

What really caught my attention on the videos was 1. If you're drilling to sidewalls into the pavement you're likely cupping the tire. My video shows that. 2. Work the front shocks first. If those ain't right you never get the rears right. 3. Start your shock adjustments in the middle if you care. When making changes go two clicks soft on compression and two clicks stiff on extension and so on. Well that's three.

Listen, I'm not an instant expert here. There are guys here are way smarter than I am but, this has worked for me. What do you have to loose?

BTW, QA1 shocks ain't the best either.
 

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I was finally able to get to the track this weekend to test our new radial ladder bar combo. car specs in post#54

Car leaves on a plate with a 50 jet, then a fogger with a 36 jet is progressed with a leash.

First pass had to pedal when it went into a wheelstand because I forgot to tighten the front shocks. car went 1.21 to the sixty.

Change front ext from 4 off of full soft to 4 off full stiff and take 2 inches of travel out of the 4 that it had.

Next pass car left without picking the tire up and went 1.16 on just the 50 jet. That was the end of our night as something happened to high gear in the transmission.

I'll be posting a couple of videos to youtube shortly, one will be Go Pro footage of the rear shocks and tire hit.

Going to find out what's going on with high gear and try it again soon.

Rear shocks were set at
comp 15 from full stiff with 25 clicks
ext 20 from full stiff with 43 clicks
50lbs in the canisters
17 lbs in tires and ladder bars 3 degrees up in front compared to frame.
 

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Great ! Hopefully the second vids shows how much front suspension separation you got on that second pass as well as the action of the rear axle.
 

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ok trying to post a couple of videos straight to the thread.
 

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apparently not doing something right.
 

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Ok here's the video from the first pass when I forgot to tighten the front of the car.
 

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This is the second pass with the front shocks tightened and two inches of travel taken out. Sorry about the camera angle.
 

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Im having a problem uploading the under car video to youtube, as soon as I get it figured out I'll post it.
 

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As soon as we find out whats going on with the transmission we'll get back to the track and I'll post more videos and info.
 
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Discussion Starter #74
I'm surprised by the under car video how slowly it seems to separate. I assumed the tire would need to be hit faster than that!
 

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Don’t forget this is only leaving on a .50 pill in the plate with a fairly tight PTC converter. And it only had 650 psi of bottle pressure.
 

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Great video Gary. Have you done the math on the car to see how much anti squat you have in the car?
 

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No I haven’t Rob, I’m pulling the trans tomorrow then i’ll Take some measurements to find out what it is. I’m also going to add a couple more lights pointed right at the tire contact to get a better view of how much hit it’s getting.
 
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To the OP
The track you race at it's not the greatest for radial tires. Thursday nights were your best shot to test there. Any other day you'll chase shock settings and front end travel adjustments.
Gary is on point with ladder bar and shock settings. Very good advice coming from him.
 

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Discussion Starter #79
To the OP
The track you race at it's not the greatest for radial tires. Thursday nights were your best shot to test there. Any other day you'll chase shock settings and front end travel adjustments.
Gary is on point with ladder bar and shock settings. Very good advice coming from him.

Have we met? I do run at great lakes and try to get there on thursdays when they prep the track more. And I believe in what gary is saying and am currently changing my front crossmember
 

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Have we met? I do run at great lakes and try to get there on thursdays when they prep the track more. And I believe in what gary is saying and am currently changing my front crossmember
Not sure if we met before. I like to test at Dagrove on Thursday nights whenever possible. Another good track to go test at is at Cordova when they have their small tire race. They have test and tune lane open and the track is on kill for radial tires. I race and test with customers at, Byron, 41, RT66, Cordova and Dagrove.
My name is Jimmy Lopez
 
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