Help Please...

[MSM546]

Just a quick question...

i recently bought some ball bearings and need to replace the standard bearings in my 3-speed gearbox (Scania R470)

i have used instant cement to glue two bearings, one either side, to a plastic part and wanted to know if there is any way of getting them off

(n.b. the bearings are glued to part J7)

[gozone]

As far as i recall, the 2 bushings that are glued in according to the manual are not supposed to be replaced with ball bearings. (At least i believe that is what the manual says, so take a look. )

[TamiyaDan]

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[MSM546]

OK thanks, so ill just leave them ones as they are

I see where it says dont replace them but ive heard somewhere else that it doesn't matter if you replace them or not

is this true???

[TWINSET]

Ball bearings are for rotating parts like axles

For slide applications (gear changers, shocks etc) the bushings are better as they're softer than the material sliding through them, so the eventual wear is on the (replaceable) bushing, not the rod.

If you replace a brass/bronze insert with a steel bearing, you risk wearing out the rod

There's also a chance the kit bushing is impregnated with oil, which'll help stop it wrecking the shaft too

[TamiyaDan]

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[MSM546]

So I should leave them 2 bushings where they are but replace all the other ones???

[TamiyaDan]

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[MSM546]

thanks for the help guys

[MadInventor]

The bushes also help to keep the slider rotating at the same speed as the shaft it is running on, which aids with a smooth gear change. Ballraces will allow the part to slow it's rotation much faster when not connected to either of the drive gears through the dog clutches.