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So how do I make one of these fit my 870C?



It looks like I need a special collet, has anyone fitted one before of have any ideas?

Thanks.

Extra bearing?

It's more the issue of keeping it on the shaft that's the problem as the original retaining collet is hex shaped to key into the standard spur gear, I should have used a photo from the other side.

they just fit on the output shaft with the one way bearing no? The hex was to key the spur to the pulley, which is molded together or something on those gears isn't it? then you use an E clip to keep it from coming off? Ill have to go check out one of my cars....

EDIT::
I checked one of my cars just now. There are parts installed as follows:

e clip>>clear rubber tube>>flgd bearing(4x8?)>>spur/oneway brg>>unflgd bearing (4x8?)>>washer ~2mm thick, 5mm ID.

So there are three bearings total that install in the gear. seems to be nice and smooth, I would probably check belt alignment and adjust the rubber fuel line and last washer thickness to keep the belt running true.

What's the point of a one way spur?

Thanks for that, any chance of a picture?

The original hex isn't molded to the spur it just keys into it then attaches to the layshaft via a grub screw, my layshaft doesn't have a place to attach an e clip, just a flat for the grub screw.

85Edinger wrote:What's the point of a one way spur?

I'll have to leave that to the handling gurus to explain, it allows the front wheels to run freely if they over speed the rears on landings etc.

I'm sure there are other factors, as my 870C is destined for the track I bought it for resilience as it has a metal gear.

We used 2 - 4mm x 8mm flanged bearings & this aluminum collet found with the Yokomo one-way and an e-clip to hold it on.

Aaron

That's the sort of thing I was thinking I might have to try and put together, thank you for the photos

yeah, mine is almost identical except I have a hard rubber spacer instead of the collar. Syngery are you sure you don't have a relief cut for an e-clip? if not, you could use a 4mm collar with setscrew, and then a spacer as needed to fill the gap.

jwscab wrote: Syngery are you sure you don't have a relief cut for an e-clip?

Hmmm I'm going to have to double check

My bad on further inspection I do have an e clip relief as shown in the photo so that will make the job easier.

Thanks to you all for the guidance.

The one-way spur works like any other one-way: it allows the front wheels to run free. The rear wheels are full time driven as the pulley is fixed on the spur. But the center axle can freewheel fwd in the spur so the front wheels can turn faster when needed; for example while the rear tires balloon.

It's funny how many one-ways you could put on those models:
There are after market axles that have one way bearings in the wheel hubs.
Then there are aftermarket one-way units that replace the front diff
Next up are the one way center pulleys for the front belt
And finally here's this one-way spur.

Personally I think the first solution was the most efficient and the last the least, but reliability is a different story.
The first was the most efficient as it has the least friction