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 Originally Posted by TeamGRT12x
Weight jacks do not put pre load on springs. Where did you come up with that?
When you turn a weight jack the spring is either getting shorter(more preload) or getting taller(less preload) It may not be a great term to use but i believe this is what he was trying to say.
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If you are talking about my post, maybe the term is not what you use, but if you take your coil over adjuster and crank it down to shorten, or put more pre load on the spring, you should see the wheel weight number go up...period
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The spring doesn't get taller or shorter. The chassis changes ride heights, which changes wheel weights. The only way a spring is going to compress more is by putting much more weight on it than it currently has. Why do you think when you put 5 rounds in the right front, the chassis height raises on that corner? If what you think is true, the ride height would drop.
Curious that we spend more time congratulating people who have succeeded than encouraging people who have not.
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So let me ask you, if the shock is extended all the way out and you keep cranking down on the adjuster what do you think happens...The installed height of the spring does get shorter. Granted, when the car is at ride height and you screw down the adjuster you are altering ride height, but there will come a point when the shock is fully extended and then you are compressing the spring
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If your shock is fully extended, then you need to work in that area of the car. Are we really having this conversation? This is race car scaling basics. If that was the case, you'd need to change spring rates all the time.
Curious that we spend more time congratulating people who have succeeded than encouraging people who have not.
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I agree... If your shock is fully exteneded, you have a very different set of problems to worry about. GRT is correct. Weight jacks do not add preload to a spring. When one end of the spring is on a movable part (control arm) you are not compressing the spring and adding pre load, you are simply adding static weight.
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Originally Posted by TeamGRT12x
The spring doesn't get taller or shorter. The chassis changes ride heights, which changes wheel weights. The only way a spring is going to compress more is by putting much more weight on it than it currently has. Why do you think when you put 5 rounds in the right front, the chassis height raises on that corner? If what you think is true, the ride height would drop.
When I crank down on my rf or lr wt jack bolt that puts more weight on that corner and in turn makes that spring shorter...
Not sure why your in this argument, your not helping anyone get faster or smarter thats for darn sure. If you want to argue for arguement sake go to the gossip section.
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When we put "wedge" in a car we go around the car maintaining our R/H's. For this to occur something is compressing and something is lengthening. IE the spring so therefore the spring is getting shorter/longer or in SJ's term getting some "preload"
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Originally Posted by powerslide
When we put "wedge" in a car we go around the car maintaining our R/H's. For this to occur something is compressing and something is lengthening. IE the spring so therefore the spring is getting shorter/longer or in SJ's term getting some "preload"
Absolutely right.
If they didnt get shorter with weight added and taller with weight taken away we would never be able to change the wedge without changing the ride heights a bunch. This is something most guys dont understand when scaling a car.If you screw a half inch into a spring, it usually doesnt raise the car a half inch, because the spring is compressing some when weight is being added to it. The corners straight forward and straight acroos will get higher because of weight coming off those springs.That is why you have to check all 4 corners when making an adjustment to one spring.
Last edited by HEAVY DUTY; 04-06-2012 at 12:45 PM.
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Ok. Changed my ride heights a little. Moved the fuel cell to the lr more. Lf shock was extended all the way(moved the mount down) and had the lr spring slider catching on the birdcage. Got her right on the scales now. Went to practice and turned 3rd quickest time on record and I've been out of a car for 4 yrs( not to toot my own horn. Lol) thanks for suggesting the 90lbs in the seat. That was a lot easier than me getting in and out of the car since I'm such a small guy. Thanks for all the help!!!!!!!!!!!!
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Originally Posted by crateracer16
Ok. Changed my ride heights a little. Moved the fuel cell to the lr more. Lf shock was extended all the way(moved the mount down) and had the lr spring slider catching on the birdcage. Got her right on the scales now. Went to practice and turned 3rd quickest time on record and I've been out of a car for 4 yrs( not to toot my own horn. Lol) thanks for suggesting the 90lbs in the seat. That was a lot easier than me getting in and out of the car since I'm such a small guy. Thanks for all the help!!!!!!!!!!!!
I do all my scaling minus driver. Its a lot easier.
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Ya. I never had enough weight to make up for my body weight difference cuz my setup sheet is setup for a 210 driver. but it was a LOT easier being out of the car! Thanks again guys
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Jeff,
Trying to help someone not make a mistake. I have never in my life heard of someone say that when you crank on a weight jack, you are making the spring taller or shorter. It's such a minute amount that it isn't to be worried about. If you are worried, you better carry quite a few springs.
When does the JNJ Stock Car come out? I noticed you had it for sale???
Curious that we spend more time congratulating people who have succeeded than encouraging people who have not.
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Originally Posted by crateracer16
Ya. I never had enough weight to make up for my body weight difference cuz my setup sheet is setup for a 210 driver. but it was a LOT easier being out of the car! Thanks again guys
In that case I would scale with the 210 in then remove it and write down your bite, left, rear and total and scale to those numbers from then on and adjust from those numbers etc.
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As fast as you are i would leave the car alone and get used to driving it. You did write down all your setup numbers, didn't you? Continue scaling the same way you did it the last time as it sounds like you are right on on the setup.JMO
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Originally Posted by TeamGRT12x
Jeff,
Trying to help someone not make a mistake. I have never in my life heard of someone say that when you crank on a weight jack, you are making the spring taller or shorter. It's such a minute amount that it isn't to be worried about. If you are worried, you better carry quite a few springs.
When does the JNJ Stock Car come out? I noticed you had it for sale???
I havent bolted a single part on it. Everything I have is for sale always. I would like to quit or at least cut my racing down to 20 nights approx this summer. I am down to only 2 motors 1 imca 1 USRA and parts for most of another of each, this is the lowest in hard parts Ive been in years. The IMCA USRA differences really suck for me.
I think if I could sell the purple car. I have a very hard time working in my shop when the weather is as nice as its been lately and I got an awful lot more satisfaction hearing about the hobby I built race at Beatrice than I ever thought I would.
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Scale
Originally Posted by crateracer16
Ok. I missed the first race tonight because I couldn't get the scales to come out right. I just got this car too. 04 bms mod. 4 bar. Springs are rf 750 of 650 or 175 rr 225. Lr shock in front spring behind rr is coil over in front. No matter what we did the rr was always heavier by at least 100 lbs. I just can not get any wedge in the car. We've gone over everything 10 times tonight and we can't find an issue. Nothing is touching or binding anywhere. We even went as far as pulling lower a arms to check jacking bolts and plates for a bind. Everything looks like it should. Measured the chassis and it is square(thought it may have been bent) I weigh 290lbs and thought I would have too much wedge but no. We put the car on 2 different scales and the same outcome. Someone told me you are supposed to pull the lr axle out to scale. I didn't do that but would it cause this headache? Any suggestions. I would like to go to a practice session on weds but want the car to be close on the scales. Thanks
Listen to lm14 he has got it right. 1. set all your ride as directed by the manufacture. 2. see , what you got and go from there, in your case I would do as lm14 said,put 3turns in the right front and take 3 out of the left front, go to the rear and put 4 to 6 rounds in the left rear and take out the same on the right rear, car will sit just like it did when you set it earlier. this should put left rear in the car and you can work from there as needed. always scale the car with your poundage in the seat, this is how you race the car, so scale it the same way you race it. It is that simple. Leave the shocks hooked up, pull bar in and hooked up. This works for me every time, and make sure you check for binding, it will throw your car off every time. Hope you got something out of this and some of us here are ready to help and I hope through this forum you get the help you need to have the fun that all of us out there are having now. See ya on the track! Good luck.
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We did a lot of what lm14 suggested along with modd55 and it got us running quick. Thanks!!!!
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You can also take anything HEAVY DUTY has to say to the bank, as he has built National Championship mods and actually understands what these things are doing and why. Some of these guys...well they just confuse people
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Jeez...I never meant that in the real world that you would have a shock fully extended, I just replied when someone said that you NEVER could shorten a spring by cranking down on a coilover adjustment...I was taking it to the absurd to prove that yes you can...Have fun with this discussion as I will just go back to racing our DLM...LOL Some people take themselves sooo seriously..LOL
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