AndyCW

It seems that there is a balancing act of sorts between playability and realism. Where the individual builder attempts that balance is determined by many factors. I can think of a couple. target audience purpose of model time and patience of builder Can anybody else think of factors that influence playability vs. realism? v/r Andrew

It must really blow your mind when we see lego supercars with camber, caster, kingpin inclination, toe in, and camber curves through suspension cycle. Sometimes it is not enough of a challenge or "lulz" to just have suspension. The suspension itself needs to be as realistic as possible. Some people actually worry about getting the values of the above parameters correct instead of just incorporating the feature itself. v/r Andy

Supercars have suspensions because it makes them hande better and corner faster. Lego supercars have them because it makes them more realistic and provides a challenge to the builder.

Wow!!! I gues the increased voltage coupled with the buggy motors was too much. I am glad I am using 7.2 volts all of a sudden. This further goes to the need for redesigned 8t gears. They have redesigned all of the old spur gears recently, but the 8t has been left out.

I originally thought that the dimensions would not add up and it would look out of proportion. I want you to prove me wrong. The updates over the past week have been wondeful. Please continue. I drove a Hummer for many miles in Iraq and have "fond" memories of those vehicles. The differentials could be turned 90 degrees and this would free up space for those differential locks you were hoping for. It may also enabel a narrowing of the track width by two studs.

I have used the telescoping driveshafts to cope with the issue. The downside is that they provide another failure point. It takes a much closer tolerance on geometry to make fixed length driveshafts work with a triangulated four link. One of the key elements is to get the driveshaft equal in length to the links and parallel to the links. Adjusting caster angle by changing link geometry can also be used to fine tune the driveshaft length requirements. Do you have problems with the pinion gear trying to "walk up" the ring gear. The bearing surface is only 1 stud deep. On my 9:1 axles i had a double bearing on the pinion gear. One behind and one infront of the pinion gear. This put the pinion shaft in double shear when it tried to walk up the ring. This approach might reinforce your center section and make a repeat situation less damaging. I think that the GM 14 bolt axle uses a similiar pinion bearing structure. http://www.brickshelf.com/cgi-bin/gallery.cgi?i=5588763 I also think using the ball joint setup from 9398 is not as much fun. v/r Andy

Looks better. Can't wait to see it in action. I am currently away from home on business travel and don't have access to my Lego. I need to live vicariously through you guys during these trips.

My two buggy motor crawler could climb walls with unimog tires. My crawler was 9:1 and used 7.2 volts. It could spin the PP tires on occasion. According to Philo's page, on 7.2 volts the motors output about 7.5 Ncm of torque. We then multiply this by the 9:1 axles and we end up with 67.5 Ncm of torque at the wheels. 67.5 Ncm of torque was plenty for my crawler. You have somewhere north of 9.5 Ncm of torque at the motor because of your increased voltage. If you are looking for similiar torque at the wheels, then we take 67.5 and divide it by 9.5 and we arrive at an approximate gear ratio of 7.1:1. I am suggesting that you you can make do with less gearing and in doing so increase your wheel speed. One of the trial truck tips is to never gear the truck down more than you need. http://www.philohome.com/pfrec/pfcurves.htm v/r Andrew

I like the updated pictures and am planning something very similiar. Good luck. It is interesting to see the little ways that our vehicles differ. My crawlers share many of the same design elements and I see some points where you might run into issues further along. 1) The 7 stud beam on the axles between the lower link mounts can separate from the axle during abrupt maneuvers. 2) The servo may not have enough torque to handle larger wheels and obstacles. 3) Lower link mounts on chasis may create a point for the vehicle to get "hung up" on obstacles. 4) You can add caster angle by slightly changing the geometry of the links. This will help with the steering effort. 5) 9:1 axles + large tires works great on 7.2v, but you are running higher voltage. You may want to look into changing the axle ratios. Philo's page shows the difference in torque between 7.2 and 9+ volts. It looks like you will enjoy yourself creating this project. v/r Andy

I tried the same steering setup on one of my trucks, but it did not do too well. I was using the PP tires and the increased forces caused either the pitman arm or link to fail. It worked much better with the LPE front geometry, but I could not get that axle to stay together under load. The CV joints failed no matter how I reinforced the connection. I am planning on taking another stab at it later.

I like the cabinet full of drawers. Being a parent, I have to put mine away when I am not actively engaged with it. Setting the example and stuff. I gave my kids most of my older Lego. They now have the bricks that I had as a kid.

Just got back from the park and my first outdoor test of version two. It is not all "duckies and bunnies". There are a couple of issues, but the transmission and gear shift mechanism are not giving me any grief. 1)High gear (3:1) is a little too weak. It is only good for hard packed mostly level surfaces. It will travel along OK for sometime on rough surfaces, but the longer the motors are under this kind of duress they start to loose power. It must be something with the v2 receivers heating up and safety limiting. Low Gear(8.3:1) is great. I tried PP tires with the high gear and there simply isn't enough power to gather any speed. 2)Adjustable drive shafts fall apart over time when you pick up speed.(they casued some trouble on v1, but now it is worse) 3)Have some gears popping in the axles.(had this issue on v1) It managed a pretty wicked hill climb despite the less "grippy" tires. I may try a 5:1 version without a transmission and see if the power is adequate. So far it appears that v2 is not necessarily a leap forward from v1. More complex and interesting, but lacking in the performance department. Each gear interchange eats up some efficiency and this version has an extra set of geas over v1.

The top link mounts on the axle are 3 studs apart and on the bottom are 9 studs apart. The top link mounts on the chasis are seven studs apart and the bottom ones are 5 studs apart. There are five studs between the lower and upper links. This geometry is the same as I have used on all of my recent trial trucks. There is no caster angle change with suspension cycle and the caster is set to 0 degrees. You can adjust the mounting location of the upper links to create caster angle, but this hurts pinion angle. Here are a few pics of v2 that has the same link geometry and a vid of the gear shift mechanism. V2 will not be using PP tires, but will use unimog tires. It has enough power in high gear to drive through my grass. This should be enough to drive over any rough packed surface that is reasonably level. Low gear will spin the tires an rough pavement.

The 8880 hubs have ackerman capabilities and you can place the the upper control arms at an angle to provide other needed automotive geometries such as caster, toe in, and camber change with suspension cycle. Here are some quick pics from something I put together.

I am currently fine tuning version two with the gearbox. It is fully functional, but it is ugly. When I get it ready to present, I may make instructions. It shares so many of the same characteristics that one set of instructions may suffice for both models.

Brickshelf folder is now public here

I really like those U joints, but the wouldn't work with what I am doing right now. A couple of updates to the new version. Sariel's two speed gearbox is six studs across and needs one stud of travel to shift gears. This works really well with two buggy motors butted together because the outputs are seven studs apart. It fits really well in the chasis. I just needed to shorten the driveshafts. Low Gear 8.3:1 High Gear 3:1 For additional info on chasis construction is the bare chasis of the truck in the video on the turn table

I'm impressed.

I was somewhat worried that people would think that the video was sped up. I sped up the part on the turn table, but left everything else 1X speed. I just tried it with 12/20 gearing in the hubs for an overall of 5:1. I combined this with the unimog tires and it will stall the motors on medium obstacles. I want to try 3:1 overal and get a measure of capability. I am also looking at using a two speed transmission with 8.3:1 being low and 3:1 being high. 5:1 axles combined with the two speed transmission from Sariel. Packaging it in the current size chasis is going to be a challenge. It will end up being a King of the Hammers inspired vehicle. (both crawling and high speed) I need to get my hands on one of the proportional controllers to alleviate driveline jerk.

Pics as requested You can see the mangled eight tooth gear on the rear axle.

Interesting idea. Any idea how to also get the air out of the cylinders? The same approach might be usefull on a two stroke design, but you would need to build your own cylinder case. I think the barriers infront of you in this project are quite significant, but no one ever did anything new by sitting around a claiming that it was impossible.

I am using two of the rechargeable batteries to power the truck.

This is the problem we may have without even worrying about the camera.

Wow!! BEEFY

The combination of the newer receivers and the RC buggy motors is really outstanding. This thing produces more torque than my older setup with 15:1 gearing on the old receivers. The old setup would stall with PP tires on the smallest obstacles and this new setup with much less gearing will not stall the motors unless something obscene happens. Managed to mangle an eight tooth gear inside of the portal hub during a particular nasty hill climb that is not included in the video. I think the new axles from the 9398 will help the next set of eight tooth gears survive longer. The truck kind of reminds me of the arctic glacier trucks and with the unimog tires it still looks good. The steering servo was easily overwhelmed by the terrain, PP tires, and steering geometry. I tried the LPE power unimog front geometry and it performed much better, but the CV joints would pop apart at the hub under any stress. Still looking on how to make the better geometry trial truck strong. The body work is getting progressively better on each of my projects, but still remains my weakest area. The old setup is questions, concerns, comments