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Using Racetech to calculate my spring rates

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Ok I am 6'1" bout 200-210#'s and I'm trying to get some new springs. I will be racing on big tracks like Infineon and some track days at SM tracks. Race tech's calculator say for the SM I need .50kg front springs but only offer up to .46kg springs. Now if I input it as a RM250 it says I should use .47kg springs. So I was thinking I would get the .49kg RM250 springs and the preload would be good. Is this right? Is there any reason I should not do this? And for the rear I was thinking 6.0kg spring.

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Just look at the dimentions of the springs. +/- .5mm in ID/OD shouldn't make much of a differnace. +/- 5mm on length shouldn't matter either.

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I think you are on the right track.

I weigh 210+ and am running 6.4 in back and a 5.4 up front on ashphalt. I also am running shortened springs (11mm in back, 44mm in front) and therefore use slightly heavier springs. My springs are from Ohlins. You might want to contact Eibach in CA also for their offerings.

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when I bought springs I needed to go with eibach on one end and race tech on the other. I was told when I ordered that race tech's springs were made by eibach.

The idea of using springs from another bike is good but remember to take into account the weight of the bike. If race tech recommends .50, bear in mind that that is for a stock bike of the type you've specified. That rate is based on your weight added to that of the bike (100kg+140kg=240kg).

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I weigh 215 and went with the .50 fronts and 5.8 rear from Cannonracecraft. I switched the oil to 7.5 weight and it feels like a different bike...

Are you by chance in the AFM? I heard that the DRZ400sm is now legal in the 250 production class. I remember running 2:15's on mine at Bwillow, so it seems like they would be pretty competitive in that class...

Good luck if you are. I attend a few times a year and would love to see a DRZ out there representin'...

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Yes I am a AFM guy but I have a FCR on so it is not production legal, but I may run it for fun and pull off on the white flag lap. I would get protested with a quickness with it on there.

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I just had a bad experience with race tech.

I bought 1 stiffer than stock for the front. stock is 44 so I went to 46, when I got the 46 it was the same strength as the supposed stock 44, (tested on a jig, they measured the same with a 35 pound weight on it). I have 48 on order now. They make 50 and 52 as well. I'm going to 5.7 in the rear as well......hoping it is stiffer than stock I would go up one from whatever they recommend in the front. hope this help you:thumbsup:

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jfyi- I have .48 front and 5.7 rear with 7.5 home-brew fluid. totally new bike with the correct springs-no headshake, no wiggles, no front end washout, excellent ride in all conditions.

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