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 Post subject: Re: Shock sensor graph
 Post Posted: Fri May 01, 2009 11:20 pm 
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Beretta wrote:
Dennis I moved the front of the bottom bar down and right now im at 4" above the ground........And yes I can get a higher IC by moving the back of the bottom bar by just moving it down a hole......... =;


Barry how did the car react to this change, ie, did the short times pick up any?

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 Post subject: Re: Shock sensor graph
 Post Posted: Sat May 02, 2009 5:44 am 
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Ken, The short times did pick up some but the track got better and I was still leaning the carb out and then changed the rear gear to 4.56....But they did go from 1.25+ to a solid 1.23........Also it did run the same ET last week with the DA at 2500 that it did with 1500ish two weeks ago O:) ......

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 Post subject: Re: Shock sensor graph
 Post Posted: Sat May 02, 2009 7:10 pm 
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Beretta; your shock movement graph shows initial extension then traversing to compression. There are two ways it can traverse to compression, one is because of additional weight the other is because of tyre bounce. You need to correlate your G force to weight transfered and see which one is causeing the compression during the first few feet of track. I recon you have tyre bounce looking at your graph of shocker movement.


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 Post subject: Re: Shock sensor graph
 Post Posted: Sat May 02, 2009 7:25 pm 
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So how do I get some of that bounce out from the tires :-k :-k

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 Post subject: Re: Shock sensor graph
 Post Posted: Sat May 02, 2009 7:45 pm 
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Yeah and that would splain the tire spin early in the run also cuz iff'in that tire is bouncing then it's likely unloading too. I bet if you put a time line down that graph you'll see that the tire spin is happening at the same time that the shock is going haywire.

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 Post subject: Re: Shock sensor graph
 Post Posted: Sun May 03, 2009 10:38 am 
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I am just a rookie on this chassis tuning thing , but I had a similar problem like this with my car. Its hard to say exactly without seeing a video though. I ended up raising my bottom bar in the front and back and getting my ic closer to the a/s line.

I had talked with Bubstr and Billy and several others for sometime about my issues and I did not really deep down agree with what they were telling me to do , but I finally made the move and it helped big time. My car is 60' 1.12 -1.13 and my ic is a hair over 7" high. It don't sound right or in line with what you hear but it works and thats all that matters.


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 Post subject: Re: Shock sensor graph
 Post Posted: Sun May 03, 2009 11:45 am 
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Beretta wrote:
So how do I get some of that bounce out from the tires :-k :-k


I guess since the shock is suppose to control extension/compression movement then that would be what would do that.

I had an anti-roll bar poo-poo year before last where it flipped over backwards and I didn't know it. It bound the suspension up and believe it or not, that was the quickest short time I ever got out of that car (1.15). So making the suspension stiff (at least in my case) also made it hook harder. When I get my Afco's on the Camaro I'm going to keep tightning up on the rebound to see how it reacts to that as I think that is a key to hook. You have to have extension at the hit cuz the tire seperates from the body but what is killing mine is that once it goes down, then it wants to go back up, which judging from the graph your car seems to be doing also.

I've heard where the Pro Stockers run shocks that are controlled electrically and chage settings as the car goes down the track. I suspect that they have a very stiff setting at the hit, then soften them up as it gets down track. Anyone have any info on this and if so, is this correct?

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 Post subject: Re: Shock sensor graph
 Post Posted: Sun May 03, 2009 12:21 pm 
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I think what you have to identify is the compression caused from the tire recovering from the initial hit or from front end lift. If you don't have enough torque to keep the tire loaded until the car drives out of it ( tire wrinkle/wrap up ) it looks to me like the tire itself just bounces and unloads the car.


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 Post subject: Re: Shock sensor graph
 Post Posted: Sun May 03, 2009 5:02 pm 
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Tyre bounce; Big one that one. Firstly if the air pressure is on the low side the tyre flattens out too much. Running higher pressure reduces that and also reduces the movement of the IC during geometry change. You wont stop the first movement of the diff downward before the car moves. That action is going to happens no matter what. Soft springs allow the diff to move more than hard springs. The shocker wont stop the movement unless its really really hard. I suggest hard springs, 200 lbs to inch rate and 180LBs resistance at 21" shaft speed shockers. Shockers set on 50/50. Put the bottom bar horizontal to the ground and set the IC with the top bar. When you run hard springs and a flat bottom bar the IC stays at near the same position within the geometry of the chassis. Forget about the IC when its wheels up just look at it as within the chassis system. when the IC is stable in its position within the chassis the forces going through the linkage and the springs stay stable and therefore the body to diff distance doesn't move. That's the first stage of getting rid of tyre bounce, stop the body to diff bounce and do it with geometry not shocker dampening. You need the shocks to have movement for the down track bumps etc. Don't be scared to run a short IC, provided its stable it can be short and that shoves the tyre down for traction at launch.
There is a test you need to do, put the car on stands and take the springs off the car and hold the diff up with a jack. Put the diff at start line static ride height and undo the jam nuts on one of the top bars. Note how many turns and in what direction you have to turn the bar to get the threads to free up. What you doing is actually removing the preload most people wind into the bars. I dont know if you do it that way but maybe you do. It doesn't matter about that fact but then lift the diff up and down through its motion of travel and check the tightness of the threads at the extremes. If you have to adjust the bar in or out to free the threads then you have a binding problem within the geometry of the four link. Then you go get yourself some headache tablets and eat lots of banana's and sardines and try to figure out why its doing that and which way is it wrong. By setting the fourlink so that the binding is gone the car will go faster. Heaps faster actually.


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 Post subject: Re: Shock sensor graph
 Post Posted: Mon May 04, 2009 7:45 pm 
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So how did you do over the weekend Barry?

Was hoping to hear some feedback today. PM me if you'd rather.

Don

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 Post subject: Re: Shock sensor graph
 Post Posted: Mon May 04, 2009 8:21 pm 
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want-a-be wrote:
So how did you do over the weekend Barry?

Was hoping to hear some feedback today. PM me if you'd rather.

Don



No racing as we got rained out #-o

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 Post subject: Re: Shock sensor graph
 Post Posted: Mon May 04, 2009 9:03 pm 
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Bummer,...isn't dat suppose to be happening in early April... :-

Don

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 Post subject: Re: Shock sensor graph
 Post Posted: Tue May 05, 2009 12:10 am 
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want-a-be wrote:
Bummer,...isn't dat suppose to be happening in early April... :-

Don

Yeah, but it happened all over here too. Steve and Elkyman got rained out in BG, I got rained out in Clay City and the valley rained out. Those 3 tracks are about 200 miles apart. The valley was just running bikes this weekend so that really didn't affect me and clay city rained out over an hour before I planned on leaving, so no wasted trip for me. I did try to test at the valley Friday night and got rained on after 1 time shot.

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 Post subject: Re: Shock sensor graph
 Post Posted: Tue May 12, 2009 8:35 am 
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Ok guys here's the graph from this past weekend... :-k

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 Post subject: Re: Shock sensor graph
 Post Posted: Tue May 12, 2009 4:13 pm 
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Quote:
Ken, The short times did pick up some but the track got better and I was still leaning the carb out and then changed the rear gear to 4.56....But they did go from 1.25+ to a solid 1.23........Also it did run the same ET last week with the DA at 2500 that it did with 1500ish two weeks ago


The gear. ;-)


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