Mave
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| posted on 10/8/04 at 06:01 PM |
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Dedicated BEC chassis-design
I was wondering if someone had build a real dedicated BEC-Seven-chassis. With "dedicated" I mean that it is build using all the benefits
of the small engine, making the chassis useless for car engines. (such as making the tunnel a constant width, as you don't need space for the
gearbox).
As a consequence you could make the chassis tapered from the nose to the back-panel (like a Rush) without sacrificing space in the foot-well. This
will make the car lighter, as well as easier to construct.
The tunnel is only one example, I think there are more areas which might be worth a second look.
(I'm haven't even finished my "boat anchor Indy" yet, but am already investigating for the next project)
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bike_power
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| posted on 10/8/04 at 08:11 PM |
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You mention the Rush but this is the only BEC specific chassis I know about. The fuel tank is between the footwells as there's no gearbox in
there, it's L shaped to allow room for the propshaft.
The chassis is also lighter then the CEC chassis, with the camber compensation front suspension and the side intrusion bars, it's 7Kg lighter
than the CEC chassis without either of those additions.
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Guinness
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| posted on 10/8/04 at 08:42 PM |
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Good point. I'm surprised that only one of the manufacturers have made a specific BEC chassis yet.
Apart from the changes to the tunnel you mentioned, you could make the bonnet a good deal shorter / narrower?
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crbrlfrost
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| posted on 10/8/04 at 10:43 PM |
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Mine will look considerably like a typical locost, albeit a +4. The primary differences I make for the bike engine was that many tubes are lighter
gauge due to lower torque levels and I actually make the tunnel bigger with a constant section as I plan on putting the fuel tank there and I plan to
use the tunnel as the main torsion carrier.
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Mave
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| posted on 11/8/04 at 03:23 PM |
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The whole car can also be shorter right? Meaning what? Lighter weight, better steering (?), ......
Do mind the Ackermann-angles though...
The Rush MC chassis looks very good, and the place for the fuel tank is also neat. It's a shame it's not really locost.
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Jon Ison
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| posted on 11/8/04 at 03:30 PM |
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not sure id'e be too happy with a prop so close to the fuel tank, iv'e seen what an errant prop can do.....
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crbrlfrost
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| posted on 11/8/04 at 03:51 PM |
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That is an excellent point, and the same reason that I placed heavy duty steel hoops at either end and in the middle. Thought about going the rubber
bladder route, but couldn't find a descent way to make a custom one. Cheers!
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bike_power
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| posted on 11/8/04 at 08:40 PM |
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Yes, I suppose the Rush could be made at least 6" shorter, there's loads of room in front of the engine but it's fitted reasonably
far back in the chassis.
The way Dax fit the prop to the gearbox output shaft makes it far less likely to come loose. There are 16 pins that are bolted to a flange and each
pin locates in the dip in the sprocket. The other end bolts to a reverse box so can't move backwards or forwards. Even if the sprocket nut
comes loose the prop won't come off. I guess if you sheared the four high tensile bolts holding the prop to the reverse box you might have a
problem !
It's not locost, no, but then Peter Walker has put so much more effort and design into it than I could ever hope to do. The camber
compensation/anti-roll system for example is really effective.
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