DSR88
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« on: March 07, 2010, 09:45:49 AM » |
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For those of you that scale there car, I am just wondering what would be a good front to rear % number ? Like a stock body car or an alt or comp coupe exc. This would be a Bonneville or El Mirage question.
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krusty
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« Reply #1 on: March 07, 2010, 11:00:16 AM » |
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We race a rear-engined modified roadster at 3400#,currently 60% rear, 40% front with fuel and driver. The first thing we do at the Salt is put the car on the scales with the driver and check corner weights and ride heights (compare to set up in shop) after the 2200 miles "shakeout" trip from NCarolina. This also allows us to zero the shock pots for the data system. Some people look at us like we're nuts, but we've been doing racecars - road racing and oval track - this way for so long that I'd feel like I cheated the checklist if we didn't do it on the Salt. I have heard that shorter wheelbase cars like you mention want closer to 50/50, but you need to balance adding downforce and drag vs grip at the rear wheels. Trevor Harris once told me to exhaust all avenues of balancing a car mechanically first, then apply aerodynamic aids once you were out of mechanical solutions. I've followed this for the last 20+ years. I would start out at 55rear/45 front and rebalance as handling dictated; I hope that others here with more experience with your class vehicle will provide more proven solutions. vic
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DSR88
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« Reply #2 on: March 07, 2010, 11:24:25 AM » |
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Very good info,I was out in the shop scaling my open wheel modified and though did would be a good question. We run a comp coupe and we did scale our car on the salt in aug only because we ran out of time at the shop but you bring up a good point about doing it every time to to towing.That will go on our ck list now. Maybe we will get some more input on this.
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bvillercr
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« Reply #3 on: March 07, 2010, 11:55:14 AM » |
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What is your current % and are you spinning your tires in high gear currently?
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maguromic
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« Reply #4 on: March 07, 2010, 11:56:43 AM » |
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I don’t know why more people don’t scale there cars on the salt for the exact reasons that Krusty mentioned. Trevor Harris once told me to exhaust all avenues of balancing a car mechanically first, then apply aerodynamic aids once you were out of mechanical solutions. I've followed this for the last 20+ years. Its like deja vu Trevor Harris recently told me the same thing. He is consulting on our chassis, and those are some words of wisdom from one of the iconic chassis designers in racing. Tony
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DSR88
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« Reply #5 on: March 07, 2010, 12:16:53 PM » |
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Hey Troy, Not have a problem in high gear,Just kinda looking the lower gears.I really was just wondering what other people were doing lust to come up with some sort of baseline. I think that is a good way to keep up with you car. Just think I you run your car for a couple of years and you have a suspension part froze up you would see it on scales.
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bvillercr
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« Reply #6 on: March 07, 2010, 12:22:58 PM » |
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We have some slippage in 1st and 2nd gear, 3rd and 4th is not a problem. Once we put taller gears in we shouldn't have as much slipping in the lower gears. We are 65% rear, and DO NOT SPIN OUR TIRES IN HIGH GEAR.  . Good luck this year. 
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jl222
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« Reply #7 on: March 07, 2010, 01:12:11 PM » |
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We have some slippage in 1st and 2nd gear, 3rd and 4th is not a problem. Once we put taller gears in we shouldn't have as much slipping in the lower gears. We are 65% rear, and DO NOT SPIN OUR TIRES IN HIGH GEAR.  . Good luck this year.  Or 3rd gear  JL222
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SPARKY
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« Reply #8 on: March 07, 2010, 06:06:19 PM » |
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I run a rear eng Lakester that is set up mor like a rear eng roadster--I run 1/3 F 2/3 R with a SWAG slight bias on the RR and LF to offset eng and Drive line tq.
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Cajun Kid
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« Reply #9 on: March 07, 2010, 06:23:05 PM » |
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Yes we scale the cars too.
The Vicky is 50/50 empty,,, add me and 8 gallons of gas and it's 52% Rear...48% front.
We plan on the Stude to be very close to that balance as a starting point. With the longer wheelbase,, may put 1 to 2 % more out back if need a bit more traction.
Charles
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ECTA Record Holder Maxton E/CBFALT, E/CBGALT, E/CGALT, E/CFALT, A/CGALT, C/CGALT, D/CGALT, C/CBGALT, B/CBGALT, C/CFALT OHIO C/CGALT LTA Record Holder A/CBFALT, B/CBFALT, C/CBFALT, C/CFALT, E/CGALT, E/CFALT Fastest Standing Mile at Ohio 195.51mph Fastest Standing Mile at Maxton 191.006mph Fastest Standing 1.5 Mile at Loring 188.31mph http://s261.photobucket.com/albums/ii43/cajunkid5690/Blog www.venablerodsandracing.comemail venableracing@gmail.com
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DSR88
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« Reply #10 on: March 07, 2010, 06:26:42 PM » |
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I was wondering if any one aloud for enging TQ. Do you think that a spolier or a wing would over come that at high speed? That is a good point.
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DSR88
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« Reply #11 on: March 07, 2010, 06:41:27 PM » |
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A stude was the first car I ran on the salt as a c/gc, I had a great idea take all the ballest out and I could pick up the four mph I need to hit the 200mph mark.Not knowing any better that is how I got into the spin-out club!!!!!!Triped the 3 mile light with the back bumber @186. At that time I didn't even know what scales were. Good luck with your new car.Stude's are cool.
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John Burk
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« Reply #12 on: March 07, 2010, 10:30:45 PM » |
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My front drive streamliner is a static 90/10 , at speed 90/20 .
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saltfever
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« Reply #13 on: March 07, 2010, 10:53:38 PM » |
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 . . . 90/20 is more than 100%. Not sure I follow your thinking, John. . Are you adding downforce? And how are you applying it to the rear and not the front?
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