AndyCW

Pictures will allow us to better help. The forces created on crawlers cause the the Lego components to deform. It is critical that bracing and cross bracing is integrated into the design to prevent this. This same concept applies to full scale crawlers. The axles and gear trains are reinforced with aftermarket parts to withstand the forces created. Stock vehicle parts on a crawler would break rather quickly. The deformation can actually cause the gears to be damaged. I have a cup full of broken gears from this very thing. v/r Andrew

The portal hub is not a mandatory thing for Hummers. 8880 wheels and hubs + unimog tires could suffice for the below HMMWV version. http://www.oshkoshdefense.com/products/21/hmmwv-with-tak-4supregsup-suspension Hope to see more. v/r Andy

The control arm mounting locations on the spindle are 5 studs apart on the 8880 parts and only 3 studs apart on the 8070 parts. This allows us to set up caster, camber, and camber curve more easily. Because the distance from the pivot point to the steering linkage is longer on the 8880 hub, you need a rack that can travel further to achieve the same steering lock. I really like the combination of these hubs, wheels, and tires. I have tried some stuff with them in the past. I am excited to see your progress.

Good luck. This forum is an invaluable resource and without many of us would be dead in the water with regards to ideas. I usually build two versions of a vehicle and develop the design in leap frog steps. This way I can verify if my newer version is indeed an improvement. I then disassemble the loser of the two models and build the next iteration.

Welcome to the forum and good luck with your project. On to your questions. It is not the batteries that are in the battery packs that matter as much as the battery packs themselves. The battery packs have a built in current limiter of sorts and so do the IR receivers. The PF motors are designed for the most part not to exceed the strength of the lego components and with this in mind they do not put out an enormous amount of power. Six large motors would require 4 IR receivers and 4 battery backs to power them at their full potential. You may as well go with 8 large motors, because they would require the same battery and rx support. The problem in my eyes is that as you scale up power, you also scale up weight and the increased weight ussually ofsets the majority of the gains. The overwhelming majority of fast and agile MOCs on here are fairly small in size. You should check out this webpage. It details the properties of the different Lego motors. This can be used to help make educated decisions. http://www.philohome.com/ The best Lego motor with regards to power output is the RC Buggy motor. It is motor number 5292 on Philo's website. It requires one rx and one battery pack per motor to allow it to "breath". v/r Andy

Thats the biggest tumbler that I have seen. What is the overall gear ratio?

Your video made me laugh and it demonstrated your truck very well.

WOW! Amazing performance. Maybe it is time I put my RC motors away and start using my XL motors again. It looks wide, but that makes it stable.

I have never seen one IRL, but wow that kind of machine must work circles around other standard loaders. It is a wonder that this design is not more common.

I really like studless and hardly ever pull out my old studded technic building parts. I think it is better today than it has been in some time. Hopefully the trend continues and it keeps getting better every year. If this happens today will not be seen as a "golden age". Today will only be seen as a golden age is if Lego goes downhill from here and that is not something any of us want.

You might want to try the grey springs before you jump on the yellows. You want just enough spring to hold it up and upright without inhibiting articulation.

Wow! That low gear is really low with 2XL motors. 5:1 on 2XLs is about right. It seems as though your second gear should become your low and your new second gear should become somewhere in the neighborhood of 4.2:1. Disclaimer: I don't know the Hispalug rules for TT and all of my experience comes from building cralwers. This most certainly has some influence on any advice I may provide. I suppose with a large enough body, the gear ratio may begin to make more sense.

You might have it geared down too much. What are its current two gear ratios?

If you are looking for excellent pieces and a build that educates, then 8069. If you are looking for a part collection with which to build future vehicles, then 9395. If you want a lot of red panels, then 9394.

I really like this scale of vehicle and should probably do one of my own.

Those are the newer tan axles in the portal hubs. This is my current technique to try to locate the 8t gear. The new 8t gear should make this solution even better or obsolete. I also use that part on the pinion shafts of the axles. The increased "bearing" surface hopefully helps. The tires I got off of RC4WD's website. I was thinking about putting 2.2 tires on the 8448 wheels, because they have a better offset to work with portal hubs. v/r Andy

Just uploaded a large number of pictures to imageshack. Here are some highlights. Bottom view of front axle Top view of front axle w/ steering motor removed The remainder of the pictures are available at http://imageshack.us/user/andycw I used my cell phone camera. So..... the quality may not be the best. Enjoy.

The brown 12t gears in the axles so far have held together. I did have one of my old grey 12t spider gears shatter, but that was after there was some wheel hop trying to climb a carpeted obstacle in the house. The loss of all traction and then the sudden reaplication of that traction caused an "impact load" on the gear and it turned itself into a bunch of little pieces. Wheel hop is what usually break pieces during full scale off roading. I have pictures and will be uploding them shortly.

To the best of my knowledge, the tires are very similar to the Ansman ones. Pics will be forthcoming. In the meantime, what specifically would you like to see?

My newest project is inspired by the American King of the Hammers style of off road racing. It is not strictly crawling and is also not strictly desert racing a la the Baja 1000. The vehicles need to be dual purpose. They need to crawl over some pretty unpleasant obstacles and also go all out on open terrain. You can even overtake other competitors during the race. I think this style of Lego vehicle can combine all that has been learned about trial truck and crawlers and combine them. I was most inspired by the appearance of the vehicle at the 1:40 mark in the following video. My KOH truck has the following -2 RC buggy motors -2 V2 IR receivers -2 LiPo rechargeable batteries -2 speed transmission from Sariel http://sariel.pl/201...utput-selector/ -Front and Rear Differential Locks from Sariel http://sariel.pl/201...ferential-lock/ -Auto valve inspired from TechnicBricks w/ onboard compressor -RC4WD Rock Crusher H/T 1.9 tires -Triangulated four links front and rear -telescoping drive shafts -9:1 axles -PF Med steering 5:1 with 8t on rack and Ackerman geometry I am currently mulling over Sariel's newer servo actuated three speed transmission. Initial tests showed that two RC Buggy motors had no trouble back driving the servo and so now I need to figure out how to overcome this shortcoming. The two speeds in the current transmission are not that far apart and with its weight the low gear was not low enough on some obstacles. These problems ought to be corrected by the update to a three speed, but it will take some more work to get there. I tried this transmission http://sariel.pl/201...linear-gearbox/ but the space between low and high was too great without a middle gear to bridge the spread. I am not sold on the benefit versus cost analysis of the locking axles as opposed to axles that contain a spool. I ended up compromising myself and breaking a cardinal rule of not altering parts. The front axle has a 2.5 stud axle and a 3.5 stud axle in it to achieve the track width I wanted. This could be alleviated if I had gone to a 2 stud wider front axle, but I didn't want to change the proportions that much. I don't have many other relevant pictures yet, but I will provide what people ask for. Comments, Questions, Concerns, or any advice is greatly appreciated. v/r Andy

Thank you all for being more observant than I am. I'll see if I can get a bag of the newer style gear.

Does anybody know if the new 8t gear has a different part number? Could we call Lego and get a bag of them? I managed to do this with the portal hubs from the Unimog long before the set was available. I have not seen this part on Bricklink yet. I am tired of watching my 8t gears died miserable deaths in the portal hubs. Sometimes the corners of the teeth round off when the gear slides into the recesses of the adjoining beams. This new version looks like this will no longer be a problem. It also looks as though each individual tooth will be stronger due to the increased mass.

Thanks. Hope to see more from you in the the future.

I have a friend who owns a Mosquito helicopter. It could be an inspiration for a chasis to put your rotor head into. I also doubt it has ever been done before.

That vehicle looks capable. Those tires look identical to the ones I picked up for my next project. How much do they change the performance over lego brand tires?