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  1. #1

    Default No forward drive

    Ok have ump modified car is wicked fast when is tacky but when it slicks off has no drive from center off chevelle clip lf spring 700 rf 600 Lr 200 16 inch rr 225 13 inch lift arm car spring behind 4 bar 48.6 cross 56.7 rear 57.3 lf side weight also have question about 4bar radius rods when looking from rear of car bars are inline with brackets when at full drop radius rods are to the left probably to left 3 inches on both sides just moved them does this effect load on rear tires used to be almost straight before moving also this car has very aggressive tie downs in front any help would be great

  2. #2
    Join Date
    Sep 2009
    Posts
    1,599

    Default

    Quote Originally Posted by eclipsegse View Post
    Ok have ump modified car is wicked fast when is tacky but when it slicks off has no drive from center off chevelle clip lf spring 700 rf 600 Lr 200 16 inch rr 225 13 inch lift arm car spring behind 4 bar 48.6 cross 56.7 rear 57.3 lf side weight also have question about 4bar radius rods when looking from rear of car bars are inline with brackets when at full drop radius rods are to the left probably to left 3 inches on both sides just moved them does this effect load on rear tires used to be almost straight before moving also this car has very aggressive tie downs in front any help would be great
    The first thing I notice is left side weight percentage is too high. Wouldn't want to be much over 54% with driver.

  3. #3
    Join Date
    Jul 2007
    Posts
    278

    Default

    you didn't list your wheel weights but your cross seems a bit low for slick and your left side seems high.
    looking from the back of the car we usually toe in the rs rods a little and opposite on the left. and you could bump up rf spring 50#...didn't mention your pull bar but we run the 700-2000 progressive..just some thoughts, good luck
    powerslave

  4. #4

    Default

    Has a lift arm with 300 in spring this is a rhulman car

  5. #5

    Default

    Don't know wheel weights off hand car turns anywhere u want just has no drive from center off doesn't matter where u put bars doesn't help run about 120 pounds Lr 1/4 inch of preload in lift arm

  6. #6

    Default

    This car runs a bump stop in rf car seems a little better if we put more shims in rf bump stop would taking rf rebound out and less tie down

  7. #7
    Join Date
    Sep 2009
    Posts
    1,599

    Default

    What does Brian recommend for left side weight percentage ?

  8. #8

    Default

    It's exactly where Brian wants it

  9. #9
    Join Date
    Jan 2014
    Posts
    253

    Default

    Something is fudged up here. 56 rear percentage....that car should have a ton of forward drive.

  10. #10

    Default

    Have tried everything on car and doesn't mKe a difference in the slick do u think taking tie down out of rf will help

  11. #11
    Join Date
    Jan 2014
    Posts
    253

    Default

    What's the rebound and compression of RF shock, and brand.

  12. #12

    Default

    It's a Penske it's like a 3.5/16

  13. #13
    Join Date
    Jan 2014
    Posts
    253

    Default

    16 being the rebound and 3.5 being the compression? That high of rebound wouldn't let the weight transfer back very quickly and would inhibit forward drive.

  14. #14
    Join Date
    Feb 2008
    Posts
    259

    Default

    Quote Originally Posted by dirtracr33 View Post
    you didn't list your wheel weights but your cross seems a bit low for slick and your left side seems high.
    looking from the back of the car we usually toe in the rs rods a little and opposite on the left. and you could bump up rf spring 50#...didn't mention your pull bar but we run the 700-2000 progressive..just some thoughts, good luck
    Here's his wheel weights:
    LF RF
    624 415

    LR RR
    751 610

  15. #15

    Default

    Those are pretty close

  16. #16
    Join Date
    Feb 2008
    Posts
    259

    Default

    Quote Originally Posted by speedbuggy View Post
    Here's his wheel weights:
    LF RF
    624 415

    LR RR
    751 610
    Whoops...

    For some reason, I was thinking you already said the car weighed 2400. Now I don't see that above anywhere. These weights are calculated for 2400 total weight with those percentages.

    If you know your actual total weight, I can adjust the wheel weights for that.

  17. #17

    Default

    2589 is total weight with driver

  18. #18
    Join Date
    Feb 2008
    Posts
    259

    Default

    Quote Originally Posted by eclipsegse View Post
    2589 is total weight with driver
    That makes the wheel weights:
    LF RF
    673 448

    LR RR
    810 658

  19. #19
    Join Date
    May 2007
    Location
    in a van down by the river
    Posts
    1,892

    Default

    ditch the huge RF tie-down and go with about half of that amount, and see if it improves. It should greatly
    I think there should be lifeguards in the genepool.

  20. #20
    Join Date
    Nov 2009
    Location
    Nevada
    Posts
    270

    Default

    I think your bars being 3 inches out of alignment may possibly be an issue. Are you sure the car is not to tight on entry, which will hurt exit on a slick track. Maybe go up another 30 lbs on bite, which will give more drive off and loosen entry also. Are you dropping tire pressures when the track is slick? Are you leading or trailing the left rear? And have you talked to your chassis builder about this specific problem? Just some thoughts. JMO

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