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I'm in the process of building my NIB Losi Jr.2 and I was wondering if anyone knows (I'm sure someone does!) why the LRM centre diff gear has the rather random looking square holes for the diff balls? It's puzzled me for a long time - I used to have an original JRX-2 a few years back - but until this forum, I've never had the opportunity to ask.

Was there any particular reason for it?

This is what I'm on about.

Im gonna take a stab at it and say its so there isnt that much area of contact of plastic touching balls but enough to keep them in there position. Picture a drilled hole, has 360 degrees of contact but a square only has 4 points

I think his query is not so much why square.. but why there is no order on which way the squares line up, they are turned every which way.

Chris

clm wrote:I think his query is not so much why square.. but why there is no order on which way the squares line up, they are turned every which way.

Chris

Thanks Chris - you got it!

I understand the square aspect for providing four points of contact for the diff balls (to hold them in place), the XX and XXX centre diff gears use the same square holes. It's how they are arranged around the circumference that puzzles me.....!

There must be a reason why the Losi's (Sr. & Jr.) designed it that way. Maybe Rich Trujillo can give us some insight???

As my father always explained to me....
"To make you ask WHY!"

Lol!

Cause they could never pass the hand an eye cooridination test!!! don
For real the square holes allow for movement of the balls to roll and not stick to one spot that way there is always a rolled surface an not to become flat in two areas.don

And it gives the grease a "pocket" as a reservoir

Remember RC Car Action from back then, how the text was never square on the page, but always went at some crazy angle? It was just the fashion back then.

slapshot1979 wrote:Im gonna take a stab at it and say its so there isnt that much area of contact of plastic touching balls but enough to keep them in there position. Picture a drilled hole, has 360 degrees of contact but a square only has 4 points

^^Along with this theory^^ - I guess by positioning the square holes differently you spread the load of the touching points on each ball across all the other ball in the diff i.e if you plotted the touching point of each square hole as you go round the gear, about one centre point, a circle would be plotted - this way the balls all track true in one arc as they rotate on the diff ring & minimise wear of the rubbing ball in the hole. I'm guessing whatever the intended effect it is very minimal, I didn't think the JRX2 diff was especially smooth - & I've not seen this arrangement on any other diff i've built... & i've built a few in my time!!

Strange, as this was something I wondered also when I built my first JRX2.

yes I did misunderstand the original question! oops.

Id bet we are all over thinking this. cheaper random production step??

and why isnt Gil.Jr a member here yet??