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Post by hotsports on Dec 1, 2009 9:01:10 GMT -7
hello everyone. new member here, first off my compliments on a fantastic forum. my son and i will be building his next derby car soon. he only races at the pack and district level. in 3 years of scouting he has made it to the district race all 3 years with his best finnish being 4th last year. this year will be his last so i am looking for some advise. a couple of questions, our rules state that all 4 wheels must remain flat on the track, will we be able to cant the wheels enough to make a rail rider and still have the wheels relatively flat when the car is on the track? next, in past cars we have split the weight placement, half in front and half behind the rear axle, this got us a com of 1" in front of the rear axle and a weight ratio of 4:1. my question is will concentrating the weight in one spot give us any increase in speed. thanks to everyone.  |
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Post by W Racing on Dec 1, 2009 10:23:59 GMT -7
hello everyone. new member here, first off my compliments on a fantastic forum. my son and i will be building his next derby car soon. he only races at the pack and district level. in 3 years of scouting he has made it to the district race all 3 years with his best finnish being 4th last year. this year will be his last so i am looking for some advise. a couple of questions, our rules state that all 4 wheels must remain flat on the track, will we be able to cant the wheels enough to make a rail rider and still have the wheels relatively flat when the car is on the track? next, in past cars we have split the weight placement, half in front and half behind the rear axle, this got us a com of 1" in front of the rear axle and a weight ratio of 4:1. my question is will concentrating the weight in one spot give us any increase in speed. thanks to everyone. I think you have too much wood on the car. I would try and get the added weight to 3.5 ounces or higher. It is OK to have weight in front and back of the rear axle. Just keep it grouped closely in both locations. Do not chase a COM. Place all the weight in together. Get the video 30 Years in 30 mins from JewkesEngineering or MB4hire. It will get you a very nice car design. "The Block" is a huge speed secret. this will get you alignment in shape. Narrow the front end of the car so that there is 1 3/4" between the front wheels. Axle and wheel prep is next. How is the four touching rule enforced? |
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Post by hotsports on Dec 1, 2009 11:07:40 GMT -7
thanks for the reply, as far as the rule enforcement the only thing i have seen done to check this is when the cars are checked in they are placed on a table to check dimensions, a quick check of the wheels and weigh in. if a car has canted wheels it obvious to the naked eye when the car is on the track? thanks again
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Post by Vodka Racing on Dec 1, 2009 17:15:59 GMT -7
thanks for the reply, as far as the rule enforcement the only thing i have seen done to check this is when the cars are checked in they are placed on a table to check dimensions, a quick check of the wheels and weigh in. if a car has canted wheels it obvious to the naked eye when the car is on the track? thanks again The standard cant recommended with the block is not noticable when the car is on all fours unless specifically looked for. Before and after the race when the car is parked off all fours, the cant is easily noticable. To uninformed eyes, it looks like the axles have been bent from an accident. |
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Post by W Racing on Dec 1, 2009 18:41:05 GMT -7
Correct me if I'm wrong but the longer gravity has to act on the weight the better so keep it towards the rear. Probably a stupid question but can you run razor wheels? They'll sit flat on the track. Good catch. I meant to say before and after the rear axle.... |
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Post by Shade Racing on Dec 1, 2009 19:21:41 GMT -7
HOW ABOUT LIGHTENED WHEELS LIKE 1grm.
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Post by W Racing on Dec 1, 2009 22:12:19 GMT -7
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Post by W Racing on Dec 1, 2009 22:54:05 GMT -7
thanks for the reply, as far as the rule enforcement the only thing i have seen done to check this is when the cars are checked in they are placed on a table to check dimensions, a quick check of the wheels and weigh in. if a car has canted wheels it obvious to the naked eye when the car is on the track? thanks again If you have BSA axles that are 0.087 in diameter and a 2.5 degree cant it may be possible to get the wheels to lat flat if you push them into the body... The thicker the axle and the steeper the cant the more chance they wil not lay flat... Keep the COM a litle under 1". Just dont let it go over 1". 3/4" is really nice. Then drill really accurate holes using The Block. At that point you almost cant go wrong . Use the 2010 wheels if allowed. Get the EDGE Pure stockers if allowed. Or even the super stockers if allowed. Axles are next. BSA axles require a lot of prep and if you need to use them spend a considerable amount of time getting them correct. Of course if you can use any axle then pick up the 91 GSAs as they are blazing fast. But know the rules. If you PM 2FAST4U he can get you setup... |
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Post by ACME Racing on Dec 2, 2009 6:37:08 GMT -7
Post your rules word for word and all of us can discuss what you can or can't do. Remember it's not what the rules say - it's what they don't say that can give you the EDGE.
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Post by hotsports on Dec 2, 2009 15:51:00 GMT -7
Correct me if I'm wrong but the longer gravity has to act on the weight the better so keep it towards the rear. Probably a stupid question but can you run razor wheels? They'll sit flat on the track. we can only use stock wheels, i will post our rules later tonight. thanks to everyone. |
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Post by speedie4u on Dec 2, 2009 16:29:21 GMT -7
I am curious to how the canting and RR on all four works.
I would enjoy hearing the process. It has taken me alot of hard work to try and get a 4 on the ground to rail ride and be fast
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Post by ACME Racing on Dec 2, 2009 16:48:53 GMT -7
I think I would still get that non dom wheel off the track paper thin. Then it would be possible that when they check by sight the wheel may be touching depending on the judge or table not being flat. Then make sure the dom wheel is highly polished with graphite since the whole width of the tread is going to scrub down the track. This is just a guess though.
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Post by hotsports on Dec 2, 2009 20:42:09 GMT -7
Post your rules word for word and all of us can discuss what you can or can't do. Remember it's not what the rules say - it's what they don't say that can give you the EDGE. here are the rules relative to the discussion as they are written. DIMENSIONS the minimum width between wheels shall be 1 3/4 inches. the use of the pre-cut axle locations in the official block is recommended. however, if the slots are not used, the following dimensions must be maintained: nominal wheelbase of 4 3/4 inches, 15/16 inch from one end of block to axle and 1 11/16 to the other end. WHEELS AND AXLES only official cub scout pinewood derby wheels and axles shall be used. axles may be polished only. wheels may be sanded to remove the mold projection on the tread only. this is the only wheel modification allowed. beveling or tapering of the wheels is prohibited. the entire portion of the wheel must remain flat except for the outermost edge that comes rounded from the factory casting. Lastly in bold letters THE PURCHASE OF MACHINED WHEELS AND POLISHED AXLES FROM OTHER SUPPLIERS IS SPECIFICALLY PROHIBITED. i was going to buy the stock straightened axles from this web sight that require polishing, bend but don't break the rules?? |
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Post by ACME Racing on Dec 2, 2009 20:58:08 GMT -7
It doesn't say you can't use the 2010 wheels. I would use the Jewkes 2010 pure stockers and BSA polished axles. It also says the wheel tread must remain flat. It doesn't say the tread has to be flat on the track. It doesn't say that all 4 wheels must touch the track either. I think you can run a BLOCK drilled canted three wheeled rail runner with Jewkes 2010 wheels and Jewkes BSA axles. That's what I see in your rules... You will kick butt!
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Post by W Racing on Dec 2, 2009 23:17:12 GMT -7
You can't cone the hubs it looks like....
The 2010 wheels are sweet. Risky to fix the outer hub...
I agree about the four wheels touching thing. Does not seem to be in there....
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