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Post by roosclan on Mar 10, 2009 1:46:07 GMT -6
My Webelo's car is a Warpspeed-inspired offset car using the standard wheelbase. We'll be running on a 42' Best Track for Pack and District (and if we can get the cars done in time, next Saturday's PWDR race!) So far the specs are: - lowered body with Pro Body Jig
- canted axles with RR tool
- 4.956oz (still need to add clear coat)
- 3-wheel rail rider with guide pin on non-dominant front wheel
- the COM is at 3/4" but...
- the weight on the front wheel is only .880 oz.
I just can't get any more on the front without increasing the COM. Hitting the 4oz. rear and 1oz front is proving to be elusive. Is this going to be a problem or should I abandon the COM and increase it to 7/8" to get the 1oz. on the front? The folks that set up the track do a really good job of it, so I don't expect rough joints to be an issue, and I can increase steer to more than the 2" in 4' I'm expecting to use for the 3/4" COM.
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khouse
Head in the Pine
Posts: 199
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Post by khouse on Mar 10, 2009 22:11:17 GMT -6
I wouldn't sweat it. No matter what you do only a run down the track will tell you what you need to know. Why are you trying so hard to hit 1 oz even on the front wheel? I didn't know there was a magic number for that? If so I'm in trouble. I just built a 7/16 COM super mod that has only .4oz on the front wheel.
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derbydominator
Head in the Pine
"Zero Gravity" PWDR Pro Modified
Posts: 146
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Post by derbydominator on Mar 10, 2009 22:58:12 GMT -6
Roosclan, The 80/20 4 oz to 1 oz. rule is only a suggestion I believe for most people on how much weight to shift to the back. I agree with Khouse in that I would not worry about how much weight is in front. You are working properly to manage the COM. Way impressed with the scale though, thousandths of an ounce!!!!!!! ?? That is unreal!!!
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derbydominator
Head in the Pine
"Zero Gravity" PWDR Pro Modified
Posts: 146
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Post by derbydominator on Mar 10, 2009 23:00:54 GMT -6
That's weird, The frowny face with the question marks was not intentional. Who knows what my computer is doing in the middle of the night now.
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khouse
Head in the Pine
Posts: 199
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Post by khouse on Mar 10, 2009 23:19:28 GMT -6
My cheap Harbor freight scale's not that accurate. But it was under $10.00.
Roosclan, Do your rear wheels gravitate out in both forward and reverse?
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Post by the woodbutcher on Mar 13, 2009 6:28:23 GMT -6
This is starting to make sense to me. If you get the COM to the 1" range that's what you would end up with. I guess I didn't consider checking the actual weight on the front wheel because I wan't to acheive the COM. The 2 directions have the same destination may be a better way of putting it. I am finishing up a car today for tomorrow's race and the COM is in the 1" range. 1 thing I did do, though, is I biased some of the weight to the DFW side. Seems like the right thing to do - right ? As for the scale, I use the elctronic scale from my tool kit designed for refrigeration tanks. Always felt it was pretty acurate. At a previous race it got me within a .10th . Not too bad. Now I use that car to 'zero' the scale. Oh, I've also used the postage meter at work.
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Post by roosclan on Mar 13, 2009 16:27:14 GMT -6
Roosclan, The 80/20 4 oz to 1 oz. rule is only a suggestion I believe for most people on how much weight to shift to the back. I agree with Khouse in that I would not worry about how much weight is in front. You are working properly to manage the COM. Way impressed with the scale though, thousandths of an ounce!!!!!!! ?? That is unreal!!! I bought it at winderby.com. It's quite nice and didn't cost much.
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Post by roosclan on Mar 13, 2009 16:55:11 GMT -6
My cheap Harbor freight scale's not that accurate. But it was under $10.00. Roosclan, Do your rear wheels gravitate out in both forward and reverse? Well, we don't have the wheels or axles ready to mount yet. I stuck them on to get the body balanced, but we still need to work on them. When they're put on, I'll make sure they migrate to the axles both ways. It'll give me an opportunity to teach the boys.
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