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  1. #1
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    Default Scale vs smasher

    We were told by our last car owner to put 60 lbs more load on the rr. What will that look like on scales?

  2. #2
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    May 2007
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    Quote Originally Posted by ZERO25 View Post
    We were told by our last car owner to put 60 lbs more load on the rr. What will that look like on scales?
    Depends on the motion ratio of the RR suspension. Could be about anything scale number wise depending on car and what you have on there.

    Easiest way to do what he says is (assuming he was talking ride and dynamic load - just a 60# increase everywhere) is to just divide the spring to the measurement and compress the spring that much more at ride height.

    Example 225# RR spring. 60# / 225 spring = .26"

    Spring is compressed to 10.625" at ride height so add rounds until that measurement becomes .26 less at 10.365"

    PS 60# isn't much of a change, IMO

  3. #3
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    Oct 2017
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    I agree with billet i have had drivers tell me they can feel 25-30# in the rr but just because they could tell their was a change doesn't necessarily mean their was any significant change on the stopwatch. When we want to want to get a definitive change from a car we typically change 100-150# on the rr

  4. #4
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    Jul 2014
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    May I ask what he is trying to accomplish? I see ~25#/turn on @ ride height on MY 225 spring, no rubbers and Integra Shock threads..FWIW
    Last edited by CCHIEF; 04-21-2020 at 07:15 AM.

  5. #5
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    In my prior days before smashers, 110-150 lbs of lr bite was common. Whats a ballpark for todays setups?

  6. #6
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    Jul 2014
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    What car/engine....and (springs just curious). I can only provide #'s for Rocket Blue front car.

  7. #7
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    May 2007
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    Batavia, OH
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    Quote Originally Posted by ZERO25 View Post
    In my prior days before smashers, 110-150 lbs of lr bite was common. Whats a ballpark for todays setups?
    I think it varies a lot by mfg. I've seen anything from 180# LR to 40# rr
    Droop isn't the problem.

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  8. #8
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    May 2009
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    Use builders baseline. They canít make a setup baseline for each car and set of rules etc. After that once your care is decent you can take advantage of all your rules and fudge ride heights etc once you roll it back on scales after you smash springs and make changes you can end up way different then baseline statically but your dynamic can be virtually the same as your baseline but you will be taking advantage of a lot of other things.

  9. #9
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    I'm going to play devil's advocate here. Which dynamic? We typically pick a point or two. There are a whole bunch of them in between. Some will be the same, some won't.
    Droop isn't the problem.

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  10. #10
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    Nov 2014
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    Quote Originally Posted by MasterSbilt_Racer View Post
    I'm going to play devil's advocate here. Which dynamic? We typically pick a point or two. There are a whole bunch of them in between. Some will be the same, some won't.
    Exactly. A 225 rf spring at 2000 @4" has a hell of alot different graph than any stack that ends at 2000

  11. #11
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    Jul 2014
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    Dynamically...Toss in a bump spring, spring rubber/s or stop to muddy the water....and amount of rebound in shock where it has you hovering dynamically and spring pushing back depending on quantity and quality of them, available surface traction......clear as mud! Take good notes and data!---------------- To original post... simply.... more RR load, less LR bite from where you were on scales, but more than that going on.
    Last edited by CCHIEF; 04-22-2020 at 08:14 AM.

  12. #12
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    Feb 2013
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    You guys not scaling your car and checking your static weight on your rear wheels let me know how that 100 rr heavy works in the slick..

  13. #13
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    Dec 2012
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    100rr heavy in the slick will most likely end up in the inner wall or infield frequently.

  14. #14
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    Quote Originally Posted by crownman25 View Post
    You guys not scaling your car and checking your static weight on your rear wheels let me know how that 100 rr heavy works in the slick..
    Ummmmm, the guy we bought the car from runs 60, and he's a regional terror!

  15. #15
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    Quote Originally Posted by crownman25 View Post
    You guys not scaling your car and checking your static weight on your rear wheels let me know how that 100 rr heavy works in the slick..
    You clearly don't understand how any of this works. And no body here said anything about being 100# heavier on the rr statically. The op asked about adding 60# he did not state what he was starting from he just asked what the effects of the change would be

  16. #16
    Join Date
    Nov 2007
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    Static wedge numbers mean very little.

    Dynamic numbers are what really matters.

    Scale numbers tell you left and rear percentage for setup purposes.

    Reading dynamic numbers is impossible on scales, but a spring smasher can give insight.

    Then there is aero numbers to add even more confusion.

  17. #17
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    May 2010
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    Quote Originally Posted by 95shaw View Post
    Static wedge numbers mean very little.

    Dynamic numbers are what really matters.

    Scale numbers tell you left and rear percentage for setup purposes.

    Reading dynamic numbers is impossible on scales, but a spring smasher can give insight.

    Then there is aero numbers to add even more confusion.
    I would argue that both Scale and Smasher (which are by no means "dynamic") numbers are important. There are maybe 2 or 3 people in our entire sport capable of actually closely calculating dynamic wedge, taking into consideration all of the non elastic movement of weight. Even then, what good are those exact numbers really? For our purposes, BOTH static and "smasher dynamic" wedge are important because all we are looking at is the relative difference. If I scale the car out with a 50lbs of "bite" then adjust the C/O nuts to give me 150lbs of bite, I will undeniably have more wedge than I did before (on track). Likewise, if I change from a 200/400 stack with a bumpstop to a 300 lb spring with no stop (RF), I will also also have more wedge. Do these smash numbers or scale numbers closely approximate any numbers that the tires are seeing on the track? No. But the relative difference between the changes are relevant and useful for tuning.

  18. #18
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    Oct 2017
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    Quote Originally Posted by Austin34471 View Post
    I would argue that both Scale and Smasher (which are by no means "dynamic") numbers are important. There are maybe 2 or 3 people in our entire sport capable of actually closely calculating dynamic wedge, taking into consideration all of the non elastic movement of weight. Even then, what good are those exact numbers really? For our purposes, BOTH static and "smasher dynamic" wedge are important because all we are looking at is the relative difference. If I scale the car out with a 50lbs of "bite" then adjust the C/O nuts to give me 150lbs of bite, I will undeniably have more wedge than I did before (on track). Likewise, if I change from a 200/400 stack with a bumpstop to a 300 lb spring with no stop (RF), I will also also have more wedge. Do these smash numbers or scale numbers closely approximate any numbers that the tires are seeing on the track? No. But the relative difference between the changes are relevant and useful for tuning.
    Your absolutley correct but with all the manipulation of ride heights and use of staged spring combinations. It pretty much makes static scale numbers completely useless for anything other than setting front end geometry, percentages and rear differential lateral location. You can crank all the static lr you want into my car but it will have virtually no effect anywhere but possibly on a slow restart. Our if the driver has to turn right abruptly at the end of the straight away to avoid somthing but we don't really setup for those sorts of things

  19. #19
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    Quote Originally Posted by Jking24 View Post
    Your absolutley correct but with all the manipulation of ride heights and use of staged spring combinations. It pretty much makes static scale numbers completely useless for anything other than setting front end geometry, percentages and rear differential lateral location. You can crank all the static lr you want into my car but it will have virtually no effect anywhere but possibly on a slow restart. Our if the driver has to turn right abruptly at the end of the straight away to avoid somthing but we don't really setup for those sorts of things
    It's possible to completely decouple ride height load from load at a point on the track, but that isn't the case for most people, on most locations on their car
    Droop isn't the problem.

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  20. #20
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    Feb 2013
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    You can do things many diff ways.i prefer just scaling and no trick springs ..i have found that this weeks newest speed trick never works...it depends on where you race the big rr spring soft lr or stacked works great some places it sucks..some tracks like a stiffer lr than rr spring. You just got to have a feel for what the car needs..im not saying stacked bump stop on rear doesnt work or proggressive this is where the smashing comes in... But they aint no way in hell im leavin the shop without knowing what my rear wheel weights are...i have won races 100 heavy rr on a single leaf car and 150 heavy on lr on a 4bar flat and rr heavy some tracks diff conditions..

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