Anyone have any problems with this part?

[dandexter]

I'm currently building a truck with a very similar suspension, steering and driving system as the 8466 4x4 Off Roader.

However i'm having trouble with the x873cx1 part. I'v narrowed it down to this part from testing, without them attached it works fine.

As you see in the video link below, I can only get one side to drive at once.

http://www.youtube.com/watch?v=5Q_CT8WiEbE&feature=youtu.be

If I have one x873cx1 part on each side the same thing still happens as in this video. Hold the left and right works, and vice versa. Hold neither and one will randomly spin, and the other spin very slowly/or not.

I really have no idea what is causing this to happen/how to fix it. Might have something to do with the differential?

The only way I have thought of fixing this is to use one motor per wheel.

Note, the section i'm building is just to test if the construction method would work (clearly something doesn't) and how much weight it can move. So I can find the best gear ratio.

[DLuders]

Did you try lubricating the Lego steering elements with Mineral Oil? It seems that the friction of the differential is almost as great as the friction inside the rightmost steering element. If you place wheels on the parts and "load" them onto the ground, does the same thing happen?

[dandexter]

I don't have any mineral oil, so I can't try that. I gave it a go with wheels, it works a bit better but still not great. They both spin, however the right wheel runs much better then the left one does.

I'll give gearing it down a shot, which i'll probably need to do anyway for the truck to work properly once finished. I was just wanting to see how much weight it could move with the higher gear ratio first.

[Paul Boratko]

You are not going to get the power to be distributed evenly with the wheels off of the ground... One side is almost always going to be favored based on which hub is looser...

When you vehicle's wheels are grounded, everything will correct itself...

[KopMaister]

ehm.... do you use a diferensial between them? if so it's only natural if you hold the axle/car(or whatever) above ground. try holding it against the ground so that the power can transfer equaly on the ground.

[nicjasno]

Go ahead and lubricate lego with mineral oil... if you want to ruin your parts....

you lubricate with silcon based lubricants (preferable a spray lube), which is also clean and does lego parts good.

The acids in the mineral oil destroy plastics.

Also, i don't see a problem in your video. Unless you have a locking/limited slip diff, this behaviour is normal.

[allanp]

As others have said it's not really a problem with what you have built. But it is a flaw in the design of the hub itself. There is far too much friction between the CV ball and socket which saps alot of power from the motor.

[dandexter]

Thanks for the replies, I didn't realize it was normal. At least I can stop wasting time re-design it to stop that happening.

Never really played around with motors before.