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Mazda Repair/popping out of 5th gear, manual


Patriot Aussie wrote at 2013-01-13 08:24:56
John you have no idea. I was an automotive engineer and taught automotive engineering for about 20 years, total nearly 50 years in the profession.  The synchroniser ring has absolutely NOTHING to do with "holding" the the gears engaged.

Same with those that claim the detents hold the gears engaged,, untrue.  The detents only position the selector forks.  If the gears are worn and want to become disengaged the synchroniser ring and detents will never prevent it.

The helical cut gears (angle cut gears)  you mention always remain engaged, hence the modern gearbox is referred to as constant mess.  The engaging of the gears is performed by a synchroniser sleeve gear, never made from bronze, and the small dog clutch like teeth on the gear being selected.  If a gearbox is jumping out of gear it is most probably these parts which are worn.  However should a bearing be worn allowing shafts to be out of alignment, the bell housing and gearbox to engine bolts be loose these could also cause the gears and shafts to run out alignment and, hence jump out of gear.  

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John Campbell


I am an expert in body repair and restoration. This includes electrical and mechanical. I can also be coaxed into finding hard to locate parts for interesting marquees. I have a broad knowledge of automotive design and engineering that allows me to work on any make or model without digression.


Son in a father/son European and exotic restoration shop specializing in MG, Triumph, Jaguar, Austin Healy, and Morris. 12 years experience in field along with multiple show winning cars and caretaker to some of the finest European automobiles on the eastern seaboard. Already an expert in the automotive boards under cars-automotive and UK cars.

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