some results from my offroad bcg testing
Posted: Thu Mar 11, 2004 7:12 pm
well, over the past few months i've been refining my designs using information i've gathered while testing on every type of terrain i could find. along the way i've learnt a few hints and tips for the prospective micro offroader out there! 
terrain
i've found the best driving surface to be even concrete followed by smooth hardpack dirt.worst surface would definately be mud, followed by loose dry sand. i haven't had a full on session in mud yet, but i'm guessing the cars would just spin the wheels til it's buried to the axles and pretty much destroy all moving parts! the odd time i've had mud on any parts it's fouled things up. concrete with some sand scattered over it is fun for some cool drifting and circle work (roll over an anthill and hit boost! hehe
). the most important thing to remember when choosing your driving surface is SCALE. look at the surface and scale it up to 1:1, would a 1:1 4wd manage? driving over a surface strewn with rocks the size of the wheels isn't going to work. although i've done this but you're constantly flipping. also take into account the fact that bits don't have propo control. get any car, drop it on the sand and put your foot to the floor, you'll end up with a fountain of sand and a bogged car. 2 speeds help with this and zz se's are even better.
wheels and tyres
i've found the small lego wheels to be the best. mainly because i have them but also because they have a bigger footprint. unfortunately larger and wider wheels are not so great offroad with bits or enertecs as the steering spring isn't up to the job. as a result the steering is almost useless offroad but plenty good on the concrete. i cut new tread into the tyres to aid grip, lego tyres are a hard compound rubber (doesn't help that most of mine are over 20 years old!) i've ordered some new ones as i think they're softer now. trim the front tyres or the chassis to accomodate the steering.
chassis
different brands have their good and bad points. tomy's are well made and smooth running, the axles are easily removed but don't have as much front suspension travel as an lxx. their looser fitting knuckles are more reliable in dusty conditions.
lxx's have more precise fitting knuckles, .5 mm more front suspension travel than a tomy, are cheap and have slightly stronger steering. but they're poorly assembled and axle changes are difficult.
enertecs have powerful steering and track neatly, have a space for 2 1/3AAA batts requiring minimal modding, nice wide 7.1:1 gears, quality products. they require modding on the steering to get any decent susp travel, axles aren't removable.
steering springs need a little tightening or add another to keep it straight but too much and it won't turn at all.
batteries
nicads seem to have the most punch and nimh's have more capacity and weigh less. i always go a dual cell as raw power is what you really need most in difficult terrain.
motors and gears
on the concrete it's pretty much anything goes, but offroad you need bottom end grunt! i find speed is a disadvantage so i go for motors that are torqey such as tomy 1.6's. the low range gearset (blue, 12:1) is great with a faster motors or the medium gears (orange, 9.86:1) with a 1.6. faster gearsets may not work as well anywhere other than concrete.
pcb's
my super favourite is a mosfet modded lxx 2 speed with the extra channels for lights. fets are a vast improvement over the stock trannies and the 2 speeds give you more control.
shells
hummers are my fave, but flat looking sports car shells look suprisingly good on an offroad chassis! and it will be less likely to roll than a taller shell. and don't go using your most prized shell without expecting it to get scratched to buggery! concrete grinds the paint off in no time! i usually raise the shell and do a little modding to accomodate the steering and suspension.
lubricant
i use powdered graphite on all moving parts and it works well. it's dry so it won't attract dirt and dust like a wet lube. you can just scrape some dust off a greylead pencil lead if you don't have a bottle of it. i'd rather use no lube than oil for offroading as the dirt and oil would just turn into a very efficient grinding paste and the pinions die quicker as it is.
hopefully this helps some of you to avoid some of the mistakes i've made along the way. there's heaps of pics in my webshots gallery http://community.webshots.com/user/bettykphoto-date that may help explain things better, but if you have any questions fire away!
terrain
i've found the best driving surface to be even concrete followed by smooth hardpack dirt.worst surface would definately be mud, followed by loose dry sand. i haven't had a full on session in mud yet, but i'm guessing the cars would just spin the wheels til it's buried to the axles and pretty much destroy all moving parts! the odd time i've had mud on any parts it's fouled things up. concrete with some sand scattered over it is fun for some cool drifting and circle work (roll over an anthill and hit boost! hehe
). the most important thing to remember when choosing your driving surface is SCALE. look at the surface and scale it up to 1:1, would a 1:1 4wd manage? driving over a surface strewn with rocks the size of the wheels isn't going to work. although i've done this but you're constantly flipping. also take into account the fact that bits don't have propo control. get any car, drop it on the sand and put your foot to the floor, you'll end up with a fountain of sand and a bogged car. 2 speeds help with this and zz se's are even better.wheels and tyres
i've found the small lego wheels to be the best. mainly because i have them but also because they have a bigger footprint. unfortunately larger and wider wheels are not so great offroad with bits or enertecs as the steering spring isn't up to the job. as a result the steering is almost useless offroad but plenty good on the concrete. i cut new tread into the tyres to aid grip, lego tyres are a hard compound rubber (doesn't help that most of mine are over 20 years old!) i've ordered some new ones as i think they're softer now. trim the front tyres or the chassis to accomodate the steering.
chassis
different brands have their good and bad points. tomy's are well made and smooth running, the axles are easily removed but don't have as much front suspension travel as an lxx. their looser fitting knuckles are more reliable in dusty conditions.
lxx's have more precise fitting knuckles, .5 mm more front suspension travel than a tomy, are cheap and have slightly stronger steering. but they're poorly assembled and axle changes are difficult.
enertecs have powerful steering and track neatly, have a space for 2 1/3AAA batts requiring minimal modding, nice wide 7.1:1 gears, quality products. they require modding on the steering to get any decent susp travel, axles aren't removable.
steering springs need a little tightening or add another to keep it straight but too much and it won't turn at all.
batteries
nicads seem to have the most punch and nimh's have more capacity and weigh less. i always go a dual cell as raw power is what you really need most in difficult terrain.
motors and gears
on the concrete it's pretty much anything goes, but offroad you need bottom end grunt! i find speed is a disadvantage so i go for motors that are torqey such as tomy 1.6's. the low range gearset (blue, 12:1) is great with a faster motors or the medium gears (orange, 9.86:1) with a 1.6. faster gearsets may not work as well anywhere other than concrete.
pcb's
my super favourite is a mosfet modded lxx 2 speed with the extra channels for lights. fets are a vast improvement over the stock trannies and the 2 speeds give you more control.
shells
hummers are my fave, but flat looking sports car shells look suprisingly good on an offroad chassis! and it will be less likely to roll than a taller shell. and don't go using your most prized shell without expecting it to get scratched to buggery! concrete grinds the paint off in no time! i usually raise the shell and do a little modding to accomodate the steering and suspension.
lubricant
i use powdered graphite on all moving parts and it works well. it's dry so it won't attract dirt and dust like a wet lube. you can just scrape some dust off a greylead pencil lead if you don't have a bottle of it. i'd rather use no lube than oil for offroading as the dirt and oil would just turn into a very efficient grinding paste and the pinions die quicker as it is.
hopefully this helps some of you to avoid some of the mistakes i've made along the way. there's heaps of pics in my webshots gallery http://community.webshots.com/user/bettykphoto-date that may help explain things better, but if you have any questions fire away!
