Help needed with technic 4x4 crawler 9398

[joshbear]

Hi

pls can anyone help. My 10 year old has been building the 4X4 crawler. he loves a challenge and has go to the point where the chassis is built the motors and wheels are on and the remote built. So he tested it to find the front and back wheels were working against each other. I've had a look at the instructions but I am hoping there is an easy fix as opposed to starting again. the motors look like they have been fitted correctly so not sure where he has gone wrong.

any help very much appreciated.

Thanks

Josh

[Edwin Korstanje]

Your problems are the diff's, one off it is in opposit direction.

[dhc6twinotter]

Your problems are the diff's, one off it is in opposit direction.

What he said.

[DLuders]

Yes, the two Technic Differentials (with those small tan gears inside of them) should look like this orientation:

Edited November 18, 2012 by DLuders

[Jim]

That's funny (kind of), because Lego purposely placed a bush in the frame, so that you can't make a mistake (unless you misplace the bush). Building a previous 4x4 model, I encountered the same problem, so I was aware of this. Guess they need to make it even more clear for kids (or adults for that matter).

[le60head]

i dont think it could've been any clearer. Hope this turns out to be the problem! Good luck!

[Jim]

i dont think it could've been any clearer. Hope this turns out to be the problem! Good luck!

It's pretty clear, although you can still place the bush on the wrong side. An extra alert where both diffs are shown (one image with correct placement, one image with incorrect placement) would be a nice addition. Just to avoid this problem.

[Lipko]

I consider myself experienced in Technic building, I built the 8880 when I was nine without error. Yet, A month ago I built the Unimog with the central differential in the opposite direction. Luckily I checked early if the gears are running smoothly so I didn't have to rebuild much. Otherwise I would have thrown it out of the window...

And when I was about ten, after rebuilding the 8880 at least 20 times, I made the same mistake with the differentials. Broke the car into half...

*denies his anger management problems

Edited November 19, 2012 by Lipko

[Jim]

*denies his anger management problems

[allanp]

I made this mistake once building the 8868 when I was 8, never forgot to make sure the differencials are in the right way, which came in handy for 8880 when I was 9.

[FuzzyBallz]

Good pointers on the 4x4 crawler and the unimog, I have both in boxes. Gonna be a helluva build when I get to it.

Speaking of making mistakes, when I built the 8043 a few months back, after the model is complete and I was testing out the remote control, the gear shifting wasn't as smooth as I like it to be (The red switch on the model, that lets you change between the scoop arm and the movement of the excavator and spinning of the cab). I'm considering taking the whole thing apart and rebuilding it.

Edited November 20, 2012 by FuzzyBallz

[Jim]

Good pointers on the 4x4 crawler and the unimog, I have both in boxes. Gonna be a helluva build when I get to it.

Speaking of making mistakes, when I built the 8043 a few months back, after the model is complete and I was testing out the remote control, the gear shifting wasn't as smooth as I like it to be (The red switch on the model, that lets you change between the scoop arm and the movement of the excavator and spinning of the cab). I'm considering taking the whole thing apart and rebuilding it.

If I can remember correctly, I had the same problem. It does work, but it could work better/smoother. Maybe it's just like that.

If you have the parts, you can think about making the Ultimate 8043. This model has more motors (and some other improvements), so there's no need to switch between functions. I have built it and it really turns the 8043 into an ultimate machine.

http://www.jurgenste...r.com/8043.html

Edited November 20, 2012 by Gekke Ted

[Bigfoot]

Good pointers on the 4x4 crawler and the unimog, I have both in boxes. Gonna be a helluva build when I get to it.

Speaking of making mistakes, when I built the 8043 a few months back, after the model is complete and I was testing out the remote control, the gear shifting wasn't as smooth as I like it to be (The red switch on the model, that lets you change between the scoop arm and the movement of the excavator and spinning of the cab). I'm considering taking the whole thing apart and rebuilding it.

Could you replace the axle joiner under the diving ring with a smooth joiner? Also the smooth joiner has two flat sides and two round sides.

[jhirst613]

Can anyone please offer any further advice in how to make resolve the problem. My 6year old son has assembled his 4x4 crawler and the wheels drive in opposite directions also. I note the comments on the differentials but do not understand how to resolve the problem. I would really appreciate any help anyone can provide to describe or show how to resolve this problem as he is upset not to be able to play with his Xmas toy and I dont understand how to help him at this stage?

[Robert M]

All you need to do is switch one of the differentials around. Take the axle off, dissasemble and rebuild with the differential in the other way round and this will solve it. On the unimog, this happened to me, but because it happened, it meant that the engine didn't turn, and only with my dads knowledge did I find out why, the differentials.

[me00rjb]

Can anyone please offer any further advice in how to make resolve the problem. My 6year old son has assembled his 4x4 crawler and the wheels drive in opposite directions also. I note the comments on the differentials but do not understand how to resolve the problem. I would really appreciate any help anyone can provide to describe or show how to resolve this problem as he is upset not to be able to play with his Xmas toy and I dont understand how to help him at this stage?

The differentials in the axles need to have the larger diameter portion on the same side, as per the picture above. It sounds like your son has fitted one of them in the opposite orientation. One of the axles will need to be dismantled, the differential removed and refitted the correct way around.

The differential is this part:

http://www.bricklink...tem.asp?P=62821

If both differentials are the same way around currently, then something else must be assembled incorrectly.

Hope that helps,

Richard.

[Robert M]

I don't think it would be possible for it to be any other issue than the differentials other than the wires in the motor have been put the opposite way round. If both differentials as the same way currently, I would talk to Lego about your Motors.