# What is a 'layshaft' in a manual trans.?

**URL:** <https://community.cartalk.com/t/what-is-a-layshaft-in-a-manual-trans/21102>\
**Category:** Maintenance/Repairs\
**Created:** [October 23, 2008, 2:58am UTC](https://community.cartalk.com/t/what-is-a-layshaft-in-a-manual-trans/21102 "2008-10-23T02:58:58Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![sigma693](https://avatars.discourse-cdn.com/v4/letter/s/6bbea6/32.png) [@sigma693](https://community.cartalk.com/u/sigma693)\
**Post date:** [October 23, 2008, 2:58am UTC](https://community.cartalk.com/t/what-is-a-layshaft-in-a-manual-trans/21102/1 "2008-10-23T02:58:58Z")

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A previous post suggested I might have a bad layshaft or layshaft bearing. My manual trans.-6 spd Nissan Frontier 30k mi. 2wd makes a whine in 1st thru 3rd gears while cruising 20 to 30mph but no whine in 4th thru 6th. I go to the dealer Friday to check it out. What is a gearbox layshaft?? Thanks.

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**Author:** ![ok4450](https://avatars.discourse-cdn.com/v4/letter/o/e9bcb4/32.png) [@ok4450](https://community.cartalk.com/u/ok4450)\
**Post date:** [October 23, 2008, 3:36am UTC](https://community.cartalk.com/t/what-is-a-layshaft-in-a-manual-trans/21102/2 "2008-10-23T03:36:03Z")

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A transmission has 2 main shafts inside of it; a mainshaft and a countershaft. The countershaft is sometimes called a layshaft.

Power is fed into the transmission through the mainshaft and fed out of the transmission by the countershaft.

I would think a countershaft problem, if it exists, would be present in all gears; not just the lower ones. A subtle whine in 1st or 2nd gear may also be normal as those 2 gears often have straighter cut gear teeth. Third gear and higher have gear teeth with more of a helical cut to them which allows them to run quieter.