Your thoughts/comments on these launches

Mopar Racers Forum

  1. Hot Metal

    Hot Metal '69 440 Cuda

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    1st time out with new combo, last week,I think I got a handle on whats going on but your thoughts to confirm or learn from gents.
    quick run down of car, 3836lbs race weight, 4.10's, mono's/caltracs 9-ways and 90/10's.
    720ftlbs@4400, 3600>4200 stall, bottom hole w/1.5 preload, shocks on 7 tight, 10x29 bias 16psi if guage correct, turning tyre on rim as not screwed yet.
    ran 10.74@124.7 1.51 60
    10.64@125 1.50 60
    10.56@125.83 1.50 60.
    Only interested in the hit, camera work not the best.
    I don't have any info on launch/shift/trap rpm, rooky driver, not me driving crew chief only.
    10.56 run

    10.64 run


     
    Last edited: Jul 17, 2020
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    • 360duster

      360duster Well-Known Member

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      hey, you got paint on your shoe :)

      you guys in UK are lucky to have a track available....i miss racing pretty much here in Germany.

      His burnouts are weak.....should have higher wheel speed (shifting?). Line Lock installed?

      I´d try to start from idle until i get a feeling for the car.

      last movie: rev limit while launching....still activated from burnout??? such thing installed?
       
      Last edited: Jul 17, 2020
    • Hot Metal

      Hot Metal '69 440 Cuda

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      The car has run in brkts for last 3yrs, it has all the things installed it needs, driver has gone a best of 12.5@105 with mild 440 prior, learning curve, first attempt with much more under hood.
       
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      • Oldmanmopar

        Oldmanmopar Going left turning right FABO Gold Member

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        Lower gears would be the first thing I would do. or cut weight. I had the same problem . To heavy for the gears I had and I had 456's car weighed 3650. Needed 488's shift light was set at 7900 which was max HP on dyno sheets. My car was still winding drive going through the traps with the gears we had. My biggest weight increase was the mild steel cage. We are going to use moly for the new car frame ties and all.
         
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        • mderoy340

          mderoy340 Well-Known Member

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          Rear tire is unloading on launch, you need to screw the beads down. I would then decrease extension and increase rebound.
           
        • Hot Metal

          Hot Metal '69 440 Cuda

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          ok so just had some feedback from my mate, only 3" of travel and shocks topping out, screws being done, gonna lower the car but getting adj fronts correct length the priority, so much to do so little time to do it in and track time but it will get better>>>
           
        • Hot Metal

          Hot Metal '69 440 Cuda

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          Max power on the motor is@ 5900, with verter slip its already (according to calcs) trapping@6400+...needs a better converter are my thoughts as 1 of the things.
           
        • justinp61

          justinp61 Well-Known Member

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          I'd try some more air in the slicks and/or tighten up the extension on the front shocks. It's wading the tire up on the hit then bouncing back up as drives over the tire. Air them up until it spins then adjust accordingly.

          This and $1.75 will buy you a cup of coffee in some places.
           
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          • crackedback

            crackedback FABO Gold Member FABO Gold Member

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            Ton of time in the front end. 3" of front extension if I'm reading that right is going to stress the chassis. Lowering the front might help along with cutting the UCA
            bump stop.

            I agree with more air in the rear tires. Watch the video at .25 speed and you will see the issues much easier.
             
          • Hot Metal

            Hot Metal '69 440 Cuda

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            I've watched the videos in slow mo countless times and have a handle on whats wrong but your suggestion of upping tyre pressure is worth trying, those 90/10's gotta go for some adjustable's to slow the front down, biggest issue, we'll try 18psi and see how that goes, getting into radial tyre pressures here but worth a shot. I can see where your going with lowering front end but its the rear we need to lower really I reckon, and we'll take a run@the verter just off idle and see rather than load it, may be running out of rear travel as well but thats easily sorted.
             
          • crackedback

            crackedback FABO Gold Member FABO Gold Member

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            JMO, the front is topping out, stopping rotation. That is not helping and causing the tire to unload. It doesn't have enough travel. If the car could easily hang the hoops, it's less of an issue.

            It's the teeter totter smacking the ground on one end. Kills any move/inertia.
             
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            • justinp61

              justinp61 Well-Known Member

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              So what do you think needs to be done?

              It's wadding up and driving over the tire, IMHO two ways to fix it, control the pitch rotation (shocks) and air pressure. If it takes 20 psi to keep it from driving over the tires what does it matter? Also a car that heavy should be running a stiff sidewall slick, other wise it will kill the sidewall in short order. I don't understand only 3" of travel in the front, it's not hard to get 5" of travel with stock torsion bars unless they are really jacked up. The 60' is way off, my Dart with a 340 ran 11.60 with a 1.52 60'.
               
            • Hot Metal

              Hot Metal '69 440 Cuda

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              So what do you think needs to be done?

              The same as what you guys have mentioned, I was looking perhaps for something I hadn't thought of or seen is why I asked. The tyre pressure thing is one that I hadn't really thought of doing so result so far.......thanks
               
            • Cudafever

              Cudafever Well-Known Member

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              Wow when this first posted, i commented on it but forgot to hit send:lol:
              don't think any more need to be said but here is a snap shot of the problem.
              Capture.PNG
              Nice ride by the way:thumbsup::thumbsup:
               
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              • toolmanmike

                toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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                You can hear it on the video. How much air are you running?
                 
              • Hot Metal

                Hot Metal '69 440 Cuda

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                We were running 16psi if his guage is accurate?.....against my thinking for a bias tyre but we'll go up until don't hook and adjust from there as suggested. Front adjustables are coming so that should help.......really should've had stiff walls from the off or radials, wasn't my call....yes that chirping sound is horrible.
                 
              • Cudafever

                Cudafever Well-Known Member

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                are you running tubes in your slicks?
                 
              • Hot Metal

                Hot Metal '69 440 Cuda

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                no tubes
                 
              • Hot Metal

                Hot Metal '69 440 Cuda

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                Well apparently I have to work with whats on the car now, he's not going to change anything for the rest of the season so I'm up against it, he reckons he's got 5" travel but he don't get that the rate of rise its whats wrong and we cannot alter that with those 90/10's. So with that front end the way it will stay I don't know quite how I'm going to get it to stop unloading the tyres, any suggestions welcome from you guys?...currently we have the bars in the lower hole with 1 flat preload either side, shocks were on 5 (no rebound on 9-ways) and the car doing what it is.
                Up the pressure to stop the tyre wadding is on, I guess all we can do is keep trying different preload/shock settings and not loading the converter as thats causing the car to rise further, running@the converter off idle will cause a harder hit so full stiff on ext. perhaps is the way to go.?
                 
                Last edited: Jul 19, 2020
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                • hotrod68

                  hotrod68 Well-Known Member

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                  I agree tire is wading up, had the same problem when i installed caltracs on my dart, more air in the rear tires cured it. Took me forever to figure that out!
                   
                • justinp61

                  justinp61 Well-Known Member

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                  Try a set of factory type of replacement shocks on the front and see what it does, surely someone has a set laying around he can try. It may not keep the front end up enough to stay hooked up but at least you'll be able to see if it's wading the tire up as much.

                  I'd try more air first, it's free. Also how many passes do the slicks have on them? If it's been wading them up for a while the sidewalls may be gone. If he's unwilling or unable to make changes this season he may just have to live with it.
                   
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                  • rumblefish360

                    rumblefish360 So close, yet so far away FABO Gold Member

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                    Nice catch/picture.
                     
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                    • Hot Metal

                      Hot Metal '69 440 Cuda

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                      Brand new slicks, 5 passes to date. We will deff try more air (I've got a better guage to use) and the std shocks idea (used) isn't bad, never thought of that, so it is what it is and we'll see where we go on the 1st Aug.
                       
                      Last edited: Jul 19, 2020
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                      • yellow rose

                        yellow rose Master Of Insanity

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                        Aren’t the 90/10 shocks adjustable? If so it has 80/20 and 70/30 settings which doesn’t mean much but you can at least slow the front end down a bit.

                        It’s damn near impossible to convince someone any shock that isn’t double adjustable is about worthless. Do guys go fast using them? Yes. But the assumption that’s a quick as it will go is a fallacy.

                        BTW, that’s the first I've heard that the 9 ways don’t adjust for rebound. If that’s true, then it would make more sense than what Calvert says on the phone, which is it changes bump and rebound at the same time. That makes no sense.
                         
                      • justinp61

                        justinp61 Well-Known Member

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                        Depends on the shock.

                        The way Calvert explained to me years ago was that the adjustment on the shocks is for the rebound but also makes small changes to compression. My Dart with the 408 went a bunch of 1.38 60' with them and CE three ways on the front so they can work but there isn't much adjustments for poor tracks.
                         
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