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Loosing grip after launch
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DRR Pro
posted
Hey guys just wondering a direction here. Car is pretty consistent just wondering the best coarse of action to get rid of this spin/hop.

Car is 6.30 door car hooking good of the get then Looses grip .25 after launch. Shock are compression is pretty loose 2 or 3 from full loose. Extension is about mid way.

This message has been edited. Last edited by: Bob Payton,


--------------------
Bob Payton
S/P, T/D, S/C, TOP
309Z, 393, 3093, 8X93


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Posts: 1990 | Location: Michigan | Registered: November 14, 2001Reply With QuoteReport This Post
DRR Pro
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Maybe include some car specifics.
Cu in / HP
Weight with driver
Rear diff gear
Rear tire size / brand
Adjustable front shocks?
Obviously a Glide. What planetary gear?
4-link or Ladder bar?
Wheels up launch?

I like the stall rpm.
 
Posts: 2500 | Location: 53056 | Registered: December 30, 2009Reply With QuoteReport This Post
DRR Pro
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468 bbc, launch is 3800, 4 link, tires are mt 32x14s, 4.88 gear. 2750 with driver. Front struts are old as dirt not adjustable. Doesn't pick front end on launch. Rear adjustable shocks. 1.80 pg.


--------------------
Bob Payton
S/P, T/D, S/C, TOP
309Z, 393, 3093, 8X93


www.apdracing.com
www.diamondracecars.com
www.callies.com
 
Posts: 1990 | Location: Michigan | Registered: November 14, 2001Reply With QuoteReport This Post
DRR Pro
Picture of rusty
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what is the light blue line


honesty is the best policy,insanity is a better deffense
1.036, 6.16@ 224

 
Posts: 1421 | Location: texas | Registered: February 17, 2006Reply With QuoteReport This Post
DRR Pro
Picture of rusty
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does it have a wheelie bar


honesty is the best policy,insanity is a better deffense
1.036, 6.16@ 224

 
Posts: 1421 | Location: texas | Registered: February 17, 2006Reply With QuoteReport This Post
DRR Top Comp
Picture of Curly1
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I would highly recommend getting a good slow motion video of the car launching. What you are looking for is how much the tire is flattening and if it is bouncing up. Also how much the body is separating at the hit.
I have an idea what it needs but with out a good video it is just a guess. One possibility is too low of air pressure and rear shocks not right allowing tire to wrap up, flatten and then unwrap bouncing up (spin). May be as simple as more air or may require tire change. May be able to control it by changing four link settings. There is an issue and it is spinning now you need to find out why. Video.


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-a type of Cognitive bias where people with little expertise or ability assume they have superior expertise or ability. This overestimation occurs as a result of the fact that they do not have enough knowledge to know they don't have enough knowledge.

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Posts: 4061 | Location: United States of Texas | Registered: April 02, 2011Reply With QuoteReport This Post
DRR Pro
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How much air in rear tires?
 
Posts: 2500 | Location: 53056 | Registered: December 30, 2009Reply With QuoteReport This Post



DRR Pro
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Light blue line is 02. Tires are are 7 5psi and brand new. To me it looks like a shock change just not sure which way to go.


--------------------
Bob Payton
S/P, T/D, S/C, TOP
309Z, 393, 3093, 8X93


www.apdracing.com
www.diamondracecars.com
www.callies.com
 
Posts: 1990 | Location: Michigan | Registered: November 14, 2001Reply With QuoteReport This Post
DRR Pro
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Rear tires need more air imho. Consider starting at 10 psi and work up in 1/2 increments to no more than 12 psi.

You should / might be able to feel the tire running over itself in the launch now.
 
Posts: 2500 | Location: 53056 | Registered: December 30, 2009Reply With QuoteReport This Post
DRR Pro
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I have video. It will just take a bit to download. Hmm didnt think 7.5 was that far off. I could try it .


--------------------
Bob Payton
S/P, T/D, S/C, TOP
309Z, 393, 3093, 8X93


www.apdracing.com
www.diamondracecars.com
www.callies.com
 
Posts: 1990 | Location: Michigan | Registered: November 14, 2001Reply With QuoteReport This Post
DRR Pro
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Are these MT 3074 or 3074S ? The 3074S are stiffwall.
 
Posts: 2500 | Location: 53056 | Registered: December 30, 2009Reply With QuoteReport This Post
DRR Sportsman
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quote:
Originally posted by Bob Payton:
I have video. It will just take a bit to download. Hmm didnt think 7.5 was that far off. I could try it .


We've run the 3074 and 3074s both a 9lbs. 2850lbs Cutlass going 9.60s


Denis LeBlanc

 
Posts: 475 | Location: Manchester, NH | Registered: February 03, 2006Reply With QuoteReport This Post
DRR Pro
posted Hide Post
30751 mt


--------------------
Bob Payton
S/P, T/D, S/C, TOP
309Z, 393, 3093, 8X93


www.apdracing.com
www.diamondracecars.com
www.callies.com
 
Posts: 1990 | Location: Michigan | Registered: November 14, 2001Reply With QuoteReport This Post
DRR S/Pro
Picture of Big Steve
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quote:
Originally posted by Bob Payton:
. Front struts are old as dirt not adjustable. Doesn't pick front end on launch. 1.80 pg.


I think you may have answered your own question.....
 
Posts: 2448 | Location: Moving back to the door side | Registered: April 30, 2010Reply With QuoteReport This Post



DRR Pro
posted Hide Post
quote:
Originally posted by Big Steve:
quote:
Originally posted by Bob Payton:
. Front struts are old as dirt not adjustable. Doesn't pick front end on launch. 1.80 pg.


I think you may have answered your own question.....


Its on the list to be changed but there are plenty of good cars that leave wheels down. I will mess with air pressure and see where that gets me.


--------------------
Bob Payton
S/P, T/D, S/C, TOP
309Z, 393, 3093, 8X93


www.apdracing.com
www.diamondracecars.com
www.callies.com
 
Posts: 1990 | Location: Michigan | Registered: November 14, 2001Reply With QuoteReport This Post
DRR Pro
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At 103 circumference try 10 psi, make one run and look at your DA. This should show if tire pressure is possibly part of the problem.

Here’s a 2840# car with 32x14 stiffwall (Hoosier 103” RO) at 10.5 psi. Leaves wheels down (street struts) and runs 6.0 /6.2/ 6.4 depending on gear leaving in and ignition tune up. This run was 6.25

6.25 Run
 
Posts: 2500 | Location: 53056 | Registered: December 30, 2009Reply With QuoteReport This Post
DRR Sportsman
Picture of Mark Yeager
posted Hide Post
quote:
Originally posted by Big Steve:
quote:
Originally posted by Bob Payton:
. Front struts are old as dirt not adjustable. Doesn't pick front end on launch. 1.80 pg.


I think you may have answered your own question.....


This^^
My car did the same thing, I loosened the front struts and it fixed it. Front suspension is often overlooked....


Mark Yeager
 
Posts: 1383 | Location: Hollister,CA | Registered: April 06, 2004Reply With QuoteReport This Post
DRR Pro
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OK still trying to get the run from last weekend but this was a pass last year at the end of the year. Only thing different now is the slicks are brand new.

https://www.youtube.com/watch?v=ys5X88s5__Y

The car has struts on it not but I think they are some street setup non adjustable. I am working with Strange to try and identify them.


--------------------
Bob Payton
S/P, T/D, S/C, TOP
309Z, 393, 3093, 8X93


www.apdracing.com
www.diamondracecars.com
www.callies.com
 
Posts: 1990 | Location: Michigan | Registered: November 14, 2001Reply With QuoteReport This Post
DRR Trophy
Picture of NC3x58
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To me it looks like it hits really hard and can't keep it planted.. If what I was told a few years ago that the Extension is the "hit" and compression keeps it planted, you should try loosening the extension and then tightening the compression. I don't think it would be tire pressure, they look like they have the right amount of wrinkle.


Nick Craig

1971 Camaro Split Bumper
376ci LS3
 
Posts: 410 | Location: Ohio | Registered: December 28, 2013Reply With QuoteReport This Post
DRR Pro
Picture of RacerVX54
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I vote for new struts. Looks way to tight. doesn't stay tranfered.


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Brian Martin
Martin Racing
5.66 @121.55
 
Posts: 1405 | Location: Va.Beach .Va | Registered: August 03, 2005Reply With QuoteReport This Post
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