Spur gear chassis cut out's

[T17]

Hi All

I've been looking at the TLR 22-4 and the Schumacher Cat K1 Aero as possibles to get back into the sport.

The one thing that surprises me in both cars is the chassis seems to have a cut out for the spur gear (well the cat does not so sure about the 22-4 - some photos appear to show this). Surely this is exposed to harm or dirt egress.

Any experiences/thoughts. Is this a problem?

Thanks

[mattr]

Pretty sure the K1 has a recess, not a cut out.

[racingdwarf]

yer not sure on K1 but doubt it would, the 22-4 is all sealed

[JohnM]

Sometimes on cars that aren't sealed like a 22-4, it's better to have a cut out under the spur gear as there is less chance that a stone will jam in & buggier the spur gear up, instead it gets pushed out of the hole.

On my old Yokomo BX, the rear diff is quite open, but it would stay cleaner for longer like that then when I sealed it up a bit, the dirt would collect instead of passing through.

[simonrhart]

I remember the Yokomo YZ10 Dogfighter (the one without the slipper clutch) had an open diff front and rear too. Never had a problem with it even on stone riddled dirt tracks.

Simon

[T17]

I queried the chassis spur hole with Schumacher and got this response from none other than Tom Cockerill himself in respect of the Cat K1 Aero:

The Spur gear does have a hole in the chassis beneath it. However, I’ve never seen this allow any damage to occur to the spur gear. On the flip side of the hole, it can also be said to allow debris out that would otherwise have got stuck between the gear and chassis. The reality of it is spur gears are normally only damaged from 1 of 2 things, the motor moving or sand grains getting in the teeth of the spur gear. No matter how well sealed a spur gear is, sand will always find a way in, as it happens on 2wd’s which a fully enclosed gear cover!

[simonrhart]

My Kyosho Lazer suffers with that problem of sand grains getting stuck in the spur gear, this then damages the pinion gear. However the Losi 22-4 is completely closed - out of the 3 times I have raced it, I have never seen any grain of sand get into the spur gear and the drive train is completely clear of debris.

Also on the 22-4, the motor is screwed to a plate in order to set the gear mesh. This plate reduces the likely hood of debris from entering the drive train via motor vents - I think this is the problem he refers to with 2wd cars, debris can easily enter.

Cheers
Simon