ARXD

Yes I know, found out the hard way :) I gear it up (higher RPM) on the expense of torque (safer that way)

the pic is just a test model - not the real RC car. I am building 4x4, nothing crazy - just for fun around the house. at the moment the RC car drive fine with one XL motor, and I was wondering if it will perform better with 2 XL motors. It is a lot of fun pushing the limits, so I was also wondering if I can make a 2x4 to 4x4 gear box, and in the 2x4 state, gear it up slightly... yes I know I am pushing it, but like I said, that is the fun part :)

Your opinion please! 2 XL motors must be better then 1 XL right? so, on RC car, which configuration will perform better? A. Hard-Coupling 2 XL motors on rear axle (rear only) OR B. one XL for each axle (rear and front) ??? My guess is B, but I didn't had the chance to test it out yet, and I'm wondering if anyone ever tried it. Thanks.

2 speed gear box!? and what's up with the elastic bands?! that is new... I wonder what's is for... The blue pins really ruining it for me... why not in black!? What is that new crawler in the background? another new set!? edit* YES it is - 42055 !!!! nice :)

If this car will come in white, I will buy it in a heartbeat!!! This set in white will be perfect as a set donor for my custom MOCs :)

WOW Amazing!!! so much details!!!

I will buy this part even if it is not made by LTG, perfect in any way.

What about 3D printing for that damaged gear?

YES, I HAVE , but with old motors styles, not the PF ones.

I have that book, this is the BEST book on LEGO Technic on the market!

It is not that hard, just follow these steps: 1. Find the right angles, (from rear axle canter) 2. Follow this design for steering: 3. Measure \ test the angle.

Yes, this is a real issue. All motors has some differences in tolerances and spec PLUS it's own footprint of wear and tear (How it was used/played history) No motor is exactly the same, and when you coupled motors you need to take that to account, especially large motors (XL or RC) Hope it's helps.

They are not equivalent. In hard Coupling, one motor is attached directly to the second motor, any speed variation will put strain on both motors. In adders, any difference between speed inputs will be equalized by the system of the differential’s inner gears. The output will be driven by the sum of the inputs’ torques and the average of their speeds.

YES and NO It depend HOW you do it, "Hard-Coupling" is a simple solution, this is good for M or L Motors, but can be harmful for motors with heavy load/torque The safest way is to use Adders, but that also add friction, wight and take space in a design adder makes use of a differential in order to equalize the differences between two (or more) inputs and to drive a single output. I like to build powerful designs so for safety I always use adders.

Well, I was experimenting last night with the 2 XL Motors on a very basic experimental vehicle, - Empty and with heavy wight on it. and here is what I have found so far: - Two XL Motors are always better the one XL motors, that extra torque is significant. - Reduction Gear Box for two XL motors is NOT what I need for my next creation! In 1:1.4 ratio test, Motor connected directly to rear differential (20T to 28T differential) the motors are VERY POWERFUL and VERY SLOW, this is great for constructions models like my old Bulldozer or for a 4x4 Crawler, BUT not suited for my next RC FATH (Fun Around The House) model. In 1.19:1 ratio test, Motor pass through 1.6 Multiplier gear box to rear differential (20T to 12T, 20T to 28T differential) The experimental vehicle drive in fair speed and still have a A LOT of torque to spare! I will continue to experiment in the next few days, coming up: 1.985:1 Multiplier gear box, (20T to 12T, 20T to 12T, 20T to 28T differential) 2.143:1 Multiplier gear box, (36T to 12T, 20T to 28T differential) And for the fun of it , I will also try: 6.429:1 Multiplier gear box, (36T to 12T, 36T to 12T, 20T to 28T differential) - I will video-tape this one :) I really want a good gear box, possibly with "Gear Adder", witch will also open up others Multiplier gear box ratio like 1:1, 1.98:1, and 2.78:1 Will updated as I progress. *edit: I have uploaded a video of my testing last night for your amusement (and some pics of the experimental vehicle) My Experimental Vehicle:

I am going to try to couple 2 XL together, that will give me twice the torque with the same RPM (using Adder differential) For high speed, I will use the extra torque to gear it up to 2.7:1 = ~400 RPM at 10.5 N.cm For low speed, I will use the extra torque to gear it down to :1:2.7 = ~52.5 RPM at 80.5 N.cm

Sorry, I can't see that link, It was removed. Thank you very much for your post, it was VERY helpful.

Anyone else?

I have the Motorized Bulldozer (8275), so I got two XL motors, two M Motors and remote. I wish to build RC car (I got all the right parts from other sets), but I don't have L motors or a Servo motor. I plan to build 2 speed transmission: first gear for crawling (high torque - low speed) , second gear for fun speed around the house (low torque - High speed) 1. Should I buy a servo motor, or one of the M motor that I already have can do the Job? 2. L motor (that I don't have) vs XL Motor to power the wheels? what is the advantage that L motor has over XL motor beside size? (if any) Don't want to spend a ton of money on unnecessary parts. Thanks.

Last night I took apart the 42029 and the 8275 (Motorized Bulldozer), as I plan to build a Motorized 4x4 version of the 8297 (will try in red) I never really liked that Bulldozer, too heavy for my kids to play with and use so many good pieces... The pickup truck - design wise, is a disgrace (V6 instead V8, rear independent suspension - really!? Hideous front... week frame... I can go on and on) but I did got it for it's pieces so nothing to complain here I guess. What can I say, my daughter (age 5) was very upset, 2 of her favorite model are now gone! I did promise her that I will build a lighter version of that Bulldozer (plan to build 42028, light and functional) and a new SUV out of that red pickup truck... so I will bite the bullet and order the wheels from Bricklink, All is left to do is play the waiting game... with a impatience 5 year old daughter :) (we will play with the SUV with the pickup wheels until the big wheel arrived) Thank you all the the pics!

Yes, I am a member of Bricklink (for a long time now) and that is where I buy most of the custom pieces that I need. I live in Canada, and it is the shipping cost that sometimes kills me... A $5 package from Hong Kong can sometimes cost up or over $50 in shipping... no fun.

Oh man... I'm screwed! this is a gigantic difference, And they are VERY pricey to by individually.... (around the $10 each ?) I guess I will have to scale the model down somehow...

That will be great if I knew how to use LDD... but I am going to try it out - Thank you very much for the link! Real pictures are still welcome!

Hi. I have missed the boat on 8297 (Off-Roader) when it was out, and now I wish to build it for my kids to play with (my 5 year old daughter love to play with my Technic collection) I downloaded the instructions and I have ALL the pieces (and some) EXCEPT the wheels. I plan to sacrifice my 42029 (Customized Pick up Truck) and build a red version (4x4) of the 8297, but my concern is that the 42029 wheels (R38) that I have will be too small for the 8297 (R44)? not sure. Can anyone PLEASE post a pic of the 42029 beside 8297, or even better a pic of 8297 with 42029 wheels? Thanks.

This is the perfect Arctic Turtle! (not Racer) Amazing body design! now I want one too!