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View Full Version : Tohatsu 40c lower unit rebuild



San Felipe Bob
05-16-2007, 11:12 AM
My Hatsu 40c Lower unit is in need of a rebuild (seals and bearings).
Is this doable with normal tools?
It looks simple enough , However.....????
Any tips?

Thanks
SFB

San Felipe Bob
05-17-2007, 01:08 PM
Looking for gears......

SFB

Boatnut
05-17-2007, 04:58 PM
Pretty technical area you are diving into there. It is absolutley critical that the pinion gear and foreward gear mesh with the correct clearence. This is achieved by shims. You will need a workshop manual if you don't already have one and it is a process of blueing teeth, assembly, rotate a few turns, pull apart and inspecting for correct contact area on the teeth. Shims are changed and the process repeated until the correct alignment is achieved. It is impossible to say what thickness shims will be required thru a forum due to the nature of the machining tolerances of the gearbox housing. I would suggest if you have not done this before and you know an outboard mechanic, ask them to walk you thru it, if not it may well be worth the few bucks you will spend in the long run to have it assembled by an experienced mechanic. IMHO. I hope this helps and, PLEASE anyone, correct me if i'm wrong.
P.S. You probably already know this but, absolute cleanliness is also critical while assemling a gearbox, bearings and cones must be changed as a set and you may require special tools to remove and install cones, if there is evidence that a bearing cone has spun in the housing then the housing wil need to be replaced, also replace prop shaft if it is bent, be careful with new bearings, if you drop one on the floor it is buggered. All O rings MUST be renewed as does the clutch pin retaining spring. Again i hope this helps
Regards Boatnut:)