Blakbird

I just got back from Germany. Between Munich and Salzburg on the autobahn I stopped at a rest area for fuel and they had small Technic sets by the cash register.

In Europe you do not need to go to such specialized stores to find Technic like you do in the USA. In Germany, you can buy Technic at roadside gas stations.

I'm not sure if LEGO is cheaper in the Netherlands, but based on sales of my instructions I can say that there appear to be more active Technic fans in the Netherlands than anywhere else. From that point of view, it makes sense that Technic parts would be more prevalent and therefore cheaper there. I don't think you would find the same true of "other" LEGO parts.

I don't agree with your assessment of the Defender, but it sounds like you have already made your decision. If you feel like there is something wrong with the Defender then build the Mustang.

No, that would be virtually impossible. And it wouldn't be an improvement. The Mustang is 5 speed + reverse, but the Defender also has high/low range and a 2wd/4wd selector built into the gearbox. It needs to be the way it is.

I see the disconnect now. The illustration below shows why you can't put them in from the same side (the red arrows require rotation one direction and the green arrows require rotation in the other direction at the same time). But you are suggesting installing the output gears from opposite sides of the cage. This would be possible with the old diffs but the new diff only allows insertion of the output gears from one side. Allanp's thought about the interference of the crown gear teeth might also be a problem with the oldest diff. The following picture from Dikkie Klijn's tow truck instructions is why I was so adamant about the impossibility, since it is physically the same as a differential. What you see here cannot be assembled because both black gears need to be installed from the top. The only way to put it together is to take all the Technic bricks off, align all the gears, and then lower the whole assembly onto the chassis.

I've got both, so I can appreciate that recommendation, but these things cost a mint to build. Choosing one is a sensible thing to do. However this thread has clearly demonstrated that there is no obvious advantage to either. It comes down to personal preference, and only you can answer that.

Try it and you will see. The only way to assemble it is to bend the parts. Read your sentence again and think about it carefully. You can't insert both output gears at the same time because they require the spider gears to rotate in opposite directions. That doesn't work. You can't do step 2 because to slide the side gears in, the spider gears need to turn the same direction even though they normally spin opposite directions. The direction they need to rotate to put the gear on the right is the opposite direction they need to rotate to put the gear on the left. It can't be done unless you push so hard that the teeth skip. It can be done with only one spider gear because you can rotate the output gears while you translate them. With two spider gears, this is impossible. You DO need a differential. The pins on the diff housing which hold the spider gears are what make it impossible. I've already tried it lots of times in the past. You can force the 4th gear in on a Technic diff only because there is no guide pin. With 2 guide pins, it can't be done.

Right! It is theoretically impossible to assemble. However, allanp's design can be assembled because the spider axis is inserted externally after the gears are in place.

I don't have the link handy, but I explained all the forces in detail at the time (I analyze gear systems for a living). Just think of it like this: the spider gear transfers load between the two output sides of the diff. Imagine that the input was locked and you turn one of the outputs. The other output should spin the opposite direction right? If there is no guide pin for the spider gear, the spider gear just gets ejected from the diff. You can try this easily enough by installing the spider gear in the unpinned side of an old diff. No gear can transfer load between teeth without a bearing support on the axis, it just doesn't balance. On the other hand, the diff proposed by allanp has two spider gears and actually does have increased strength because both are guided. Edit: Found it! Here is an old diagram I did to show the basic forces on a gear. This particular load case shows a torque introduced at the axle being reacted by a single tooth. You can see the additional bearing reactions at the axle (Bx and By). This is why it is so important to have good lateral support for your gear designs. A differential spider gear does not transmit any torque (T=0) because it is free to spin on its axle. A simplified free body diagram (ignoring radial forces) looks like this. You can see that the force at the central bearing is twice the tangential force at the tooth. If there were no bearing, then no load can be transmitted through the gear (F must be zero). In the LEGO example provided earlier in the thread, the only reason the second spider gear does not fall out is that the first spider gear is keeping the output gears indexed. For bonus points, can anyone guess why LEGO didn't just make two spider gear guide pins in their original differential? There is a good reason!

I remember seeing this at BrickCon and talking to you a bit about it, but I don't think I fully appreciated what it does until now. It is hard to demonstrate without a lot of space!

This topic has come up before. Adding the 4th gear to the diff makes no structural difference whatsoever. In order for it to strengthen the differential, the 4th gear needs to be guided on a pin in the differential housing (like the 3rd gear). The 4th gear carries zero load.

Personally, I can't wait to build these little models. I was really impressed not only by the 853 mini model itself, but by the artistry behind the instructions. You can see in the sample cover page that the instructions have been designed to look just like the old Expert Builder instructions. This is not limited to the cover page. All the way through, the page layout and rendering style are very nostalgic.

The same reason people buy MegaBloks. They are cheaper and if you are not an expert, you don't understand what the difference is. When I was 16 years old, I got a job and was saving up my money for a really nice stereo system that cost about $1500. My grandmother bought me a stereo system for my birthday from a discount store for about $50. She did not understand what the difference was because they looked about the same to her. I did not have the heart to tell her that what she bought was garbage, so I just kept it until I could afford the one I wanted. I bet most Chinese copy sets are bought by grandparents.....

I find them both to be marvelous, and different in many ways, I don't think you will be disappointed either way. Your decision should probably be based simply on which type of vehicle appeals to you more. The Land Rover has more functions with high/low range transfer case and 2wd/4wd selector.

I didn't have any clue how to route the wires either, and the way I did it is almost certainly not optimal. That's why the instructions have a big disclaimer on them stating that the routing is up the builder. I'd recommend building the fenders which attach below the cabin before deciding anything because it closes up some of that space you are referring to. I didn't find any way to completely hide the wires..

Correct. The relative initial phase of the cranks is relevant to the output. The theoretical number of possibilities is infinite.

Yes, I'm sure. If you don't like the new wheels then just send to me and I'll use them.

Actually, if you search you will find several of them. Sariel attempted one but gave up due to structural concerns. My favorite is from Holger Matthes.

Welcome to the forum. Apparently you can buy the cargo plane in the middle of the Atlantic even though we still can't buy it in North America!

The new wheels are shinier and have more holes than the old wheels, but there is no functional difference. I actually prefer the new ones. They will work just fine with your Defender 110.

You know we're getting close when I have the renders done......

Don't worry too much about the exact lengths and connections. The key is to connect all 4 extend ports together and all 4 retract ports together.

These pictures show the difference between the wheels in the original model and the newly available yellow wheels. Both use the Unimog tires which are different than the balloon tires M_longer used in 2009. I'm not actually sure the new wheels are an improvement. They are too open compared with the real thing. That would indeed be epic. If only I had an LDraw model of that truck and trailer........

Yes, that would be nice. Actually, the instructions already use the Unimog tires. However, the yellow wheels were not available so that could be an update. M_longer should be be proud, especially since this model was first posted years ago and is finally getting the attention it deserves.