Guidance on rear axels of AROCS 3345 6x4 tipper reuck

[AEC_Steve]

This is my first model build and I am so glad I started with a Tamiya - wonderful quality and engineering!

So far I have built up to the rear axels but would like a little guidance on them. 

 

The differentials were initially very stiff but soon eased off with some manual turning and they are now perfectly smooth in operation. However now assembled in the axel housings I find the drive from the prop shaft very tight indeed and although I have checked assembly carefully and lubrication (of course) it is still very stiff when turning the input shaft by hand and it feels extremely notchy as I can feel the teeth meshing between the bevel gears and the ring gear. The rear most axel is not too bad but the front is much worse as the ring gear has also to drive the small output bevel gear. It feels to me as if the gears are too deeply meshed and are interfering with each other rather than running sweetly

My question is, should it be like this initially and will it bed in after a little running? Is there anything I can do to ease things?   Any advice would be very welcome!

[Tamiyabigstuff]

I've built quite a few of these and they should be quite easy to turn by hand.

If you run it with the gears tight to turn by hand they will probably wear and overheat.

Easiest thing to do is take it all apart and carefully reassemble - chances are there has been a minor assembly error or there might be something in there which shouldn't be which is causing the gears to bind - maybe a chip of plastic trapped in the gears. Also check bearings are fully seated.

Best to use ball bearings in the axles & gearbox rather than the plain bearings which come with the kit - it will run much smoother and give longer run times on the battery.

[AEC_Steve]

Thanks for that good advice. I will completely dismantle the rear end and start again. I didn't think it was right - you have confirmed that! Thanks also for the suggestion about ball bearings - I will certainly use those in the reassembly. Fortunately I have not yet started on the gear box so that can be built with them from the start!