Gearbox Lash

While stripping my primary in expectation of receiving a CNW starter kit, I noticed what seems to be excessive lash at the gearbox input shaft. With the gearbox in 1st gear, I have about 15 degrees of rotational lash and about 30 degrees in the other gears. Can't find any specs for this. Am I in trouble?

Yakatak said:

With the gearbox in 1st gear, I have about 15 degrees of rotational lash and about 30 degrees in the other gears. Can't find any specs for this. Am I in trouble?

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I don't think so as it sounds like the normal amount of dog backlash.

Drain the oil and see if there are metal flakes in it. Otherwise you probably do not have a problem. The hardened surface on the gears can spall, but that usually does not happen unless trhe gearbox has been run without oil.

acotrel said:

Drain the oil and see if there are metal flakes in it. Otherwise you probably do not have a problem. The hardened surface on the gears can spall, but that usually does not happen unless trhe gearbox has been run without oil.

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....or you ride it hard

"15 and 30 degrees of rotational lash" is far more likely to be the normal dog backlash than a problem with the gear teeth due to the dogs being considerably shorter than the recesses with which they engage so there is a considerable lash between 'drive' and 'overrun'.



1st gear lash is less because, unlike other gears, the (layshaft 2nd gear) dogs are more peg-shaped and engage with circular holes in layshaft 1st.

Love it when I can ask a question and get an education,. Thanks L.A.B..