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 Post subject: Loose down track
 Post Posted: Mon Oct 26, 2009 1:09 pm 
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Loose down track seems to be a problem that pops up more and more now days. I was sitting here thinking of the possible causes. First, as it is later in the season, tracks may not be treating down there except for big races. Second Everyone is making more power every year and at lower RPMs. Third, There is a tendency to have higher stall speeds on Converters, putting it in the power curve more. Plus this allows the engine to gain a few RPM giving it some stored energy. Possibly enough to break traction and get it started. Fourth, I see a lot of guys running lower instant center values. This can make the spring choice much more important, especially for down track. You get way more weight transfer at the line than when you shift to second. With out the extra transfer a compressing spring could delay what transfer you get. Fifth, Higher HP cars usually have lower and forward centers of gravity. This makes it harder to transfer weight, especially at speed, where your torque vs wheel speed is less effective than on the line. Sixth, It just could be, it's time for some down force on the rear.
A couple year ago, I was helping a friend with a RED. He was getting wheel shake right after the shift. The simple fix for this was just a little more air in the tire and a more efficient wing. I think he went back to original air after the wing was made and adjusted right. He lost about 4 MPH but picked up ET, and more important for him better consistency and driveabillity.

What do you guys think?

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 Post subject: Re: Loose down track
 Post Posted: Mon Oct 26, 2009 4:52 pm 
 
Well that's the problem I'm having right now the car blows the tires of right at the shift and if you let off and then get back on it then it is like driving on ice.

I'm going to scale the car and check the four link to see were everything is set right now you cant drive the car.

Also i think the springs and shocks are junk or maybe way to much spring on it .


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 Post subject: Re: Loose down track
 Post Posted: Tue Oct 27, 2009 7:42 am 
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ron owens wrote:
Well that's the problem I'm having right now the car blows the tires of right at the shift and if you let off and then get back on it then it is like driving on ice.


Mine was the same way only the shocks were bottoming out and that made the rear suspension solid. Not good and yeah, it always felt like it was on ice. If you do a search on here I'll bet you'll find that I made that exact same statement back two years ago.

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 Post subject: Re: Loose down track
 Post Posted: Wed Oct 28, 2009 7:10 am 
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I was thinking on this bottoming out problem. First the instant centers play a large part in it. If 100% or above you have a very hard time bottoming out. If 50% to 70% it would induce squat and make it very easy. Don't confuse the percentage of anti squat that it don't need shocks and springs. It does. A bump or weight transfer will still compress suspension and it will rebound, just not as easy with higher percentages of anti squat. As you get higher you can get separation. This makes it very difficult to compress that same spring. A/S and springs are pardners in their tasks. You could even add the side wall stiffness into that work party. Then the shock modifies it.

Shocks are very complex things and I'm no shock guy, but what I do understand about them, I will share. Shocks dampen compression and separation by forcing fluid or gas threw orifices. Especially racing shocks have more than one or two orifices. You actually have several different rates of resistance on the same shock. A shock traveling along on a fairly smooth surface will be relatively stiff. If you hit a big bump It gets soft. Actually the faster the piston moves the less resistance there is initially and steadily stiffens. This is built into good shocks to control oscillation. As the piston moves it puts fluid or gas threw different ports that are connected to different size orifices. On some there is even a high pressure bleed off. So you can see depending on where the piston is at ride height can change the resistance of the whole shock throw. When you have adjusters on them. it is picking out the orifice or orifices to be used. So you can see how a shock could stop or help a spring bottom out. As far as what shocks are good, I don't know. I overheard a conversation at a dirt track, where a big time racer said he didn't care what brand shock he ran as long as they sponsored him. He would make them his shocks. Have you seen the price on the high end shocks? $3000.00, some used to build whole cars for that.

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 Post subject: Re: Loose down track
 Post Posted: Thu Oct 29, 2009 11:12 am 
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ron owens wrote:
Well that's the problem I'm having right now the car blows the tires of right at the shift and if you let off and then get back on it then it is like driving on ice.

I'm going to scale the car and check the four link to see were everything is set right now you cant drive the car.

Also i think the springs and shocks are junk or maybe way to much spring on it .


Ron what tires are on the rear ?

I just took my old gy's (tire shake at shift once in awhile) off my dragster put a new set of mt's on and they made a good car junk ! Put my old wore out hoosiers on it and problem solved.
I was ready to change shocks/springs and change suspension setup to make it hook down track glad I didnt. Maybe tires are old ?

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 Post subject: Re: Loose down track
 Post Posted: Thu Oct 29, 2009 11:41 am 
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Location: Benton, KY
I am just wondering if certain brands of tires don't work better on dragsters and door cars. I have a lot of friends that like Hoosier tires on dragsters , I tried them on my door car and did not like them. I bought a set of Mickey's because I got a hole in my goodyears at the nmra race and thats all that was available at the track. The Mickey's seemed to work good , but I broke the converter after 2 passes so I am not fully decided on them yet. I will give them a fair chance though , if not I will give them the boot =; .

I have only had one problem on the big end this year and I think it was mainly from the rainy weather we have had around this area causing the rubber to peel off the track.


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 Post subject: Re: Loose down track
 Post Posted: Thu Oct 29, 2009 12:10 pm 
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ky mustang wrote:
I am just wondering if certain brands of tires don't work better on dragsters and door cars. I have a lot of friends that like Hoosier tires on dragsters , I tried them on my door car and did not like them. I bought a set of Mickey's because I got a hole in my goodyears at the nmra race and thats all that was available at the track. The Mickey's seemed to work good , but I broke the converter after 2 passes so I am not fully decided on them yet. I will give them a fair chance though , if not I will give them the boot =; .

I have only had one problem on the big end this year and I think it was mainly from the rainy weather we have had around this area causing the rubber to peel off the track.


I agree, but also think its not just the dragster vs door car .. I think all cars react different to different tires.
The second thing I have noticed is this, you can buy 2 sets of the exact tires and they never seem to be the same on the car. I had actually tried the same mt tire I purchased earlier in the year ... it was nothing like the set I purchased.

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http://www.nyesautomotive.net
http://www.diamondracecars.com
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 Post subject: Re: Loose down track
 Post Posted: Thu Oct 29, 2009 2:44 pm 
 
Hammertime wrote:
ron owens wrote:
Well that's the problem I'm having right now the car blows the tires of right at the shift and if you let off and then get back on it then it is like driving on ice.

I'm going to scale the car and check the four link to see were everything is set right now you cant drive the car.

Also i think the springs and shocks are junk or maybe way to much spring on it .


Ron what tires are on the rear ?

I just took my old gy's (tire shake at shift once in awhile) off my dragster put a new set of mt's on and they made a good car junk ! Put my old wore out hoosiers on it and problem solved.
I was ready to change shocks/springs and change suspension setup to make it hook down track glad I didnt. Maybe tires are old ?


Dave they are Goodyear 14.5X32X15 D5 the guy said they was new with only a couple of weekends on them they look good but as i said before that don't mean much i haven't ran Goodyear's in a very long time i have Hoosiers on the nova and they didn't work good at all i have ran M/T's for years now always did a good job for me i also have a set of toyo's that don't have 20 runs on them but i don't know if i can get them on the car with the off set on these wheels


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 Post subject: Re: Loose down track
 Post Posted: Mon Nov 02, 2009 4:09 pm 
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Location: Benton, KY
I have to say I give the Mickey's a thumbs up . I bobbled the stage bulb and let go of the button to bump in one more bump and my safety on my delay box did not have time to reset on my last pass. It still had a 1.12 60' time just mashing the throttle. =; Got a bad red light though :-&


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