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Author Topic:   Stainless transom/engine hardware
SuburbanBoy posted 05-07-2002 09:21 AM ET (US)   Profile for SuburbanBoy   Send Email to SuburbanBoy  
There has been some recent discussion about mounting engines to transoms etc. Within this discussion are recommendations for stainless hardware. My experience with stainless hardware has been mixed.

I mounted my outboard to a jack plate on my 15' Striper. The jack plate was delivered with stainless bolts, and brass nylock nuts. This is what I used to attach the jack plate to the transom. I purchased stainless bolts and stainless nylock nuts at West Marine for my outboard to jack plate mounting. West Marine did not sell brass nylock nuts. This is where my troubles began. As I bolted the engine to the jack plate, I had problems with the stainless nylock nuts seizing to the stainless bolts. I had to cut the bolt/nut assembly off using a Moto tool with a cutoff wheel attachment. I purchased replacement stainless bolts from West Marine, and obtained standard (not nylock) brass nuts from a well-stocked local Ace hardware. I double nutted the stainless bolts, and have not had a problem since.

It would appear that the stainless bolt to stainless nylock nut galled and seized together. Keep this in mind when purchasing your mounting hardware and installing your engine.


lhg posted 05-07-2002 12:10 PM ET (US)     Profile for lhg    
Galling seems to be problem with course thread SS bolts and nylock nuts, for some reason unknown to me. But I have had the same problem.

New Mercury outboards come with 4" FINE thread 1/2" bolts, with brass nylock nuts, and galling is not a problem with those, also for some reason unknown to me. They are top quality hardware items, however.

My Mercury guys tell me that when they have to bolt an outboard or bracket on with regular course thread bolts, usually because a shorter length is required on brackets, they put some marine grease or anti-seize on the nut threads first. This solves the problem, but does not seem to cause the nut to loosen.

whalerron posted 05-07-2002 12:11 PM ET (US)     Profile for whalerron  Send Email to whalerron     
That is the one big issue when using stainless fasteners. Stainless will gall. The one thing that is supposed to minimize the galling is "aluminized" anti-sieze. The aluminized anti-sieze is usually grey in color...
JimU posted 05-10-2002 03:48 PM ET (US)     Profile for JimU  Send Email to JimU     
I've had the same problem. Solved it by double nutting and using loc-tite.
lhg posted 05-10-2002 05:04 PM ET (US)     Profile for lhg    
It has something to do with the nylock nuts. Anybody know why? The old solution of regular nut and lock washer also eliminates the problem, as does the anti-seize and marine grease.
Flipper posted 05-11-2002 12:06 AM ET (US)     Profile for Flipper  Send Email to Flipper     
I had the same thing happen when installing my jackplate, using the hardware supplied. I felt one of the bolts get 'prematurely tight',so I tried backing it off just for fun- it still seized right up.
Maybe stainless doesn't tap as cleanly as a harder, more brittle metal (like carbon steel)and if a small piece of metal gets dislodged in the thread, it's like a snowball effect-the loose metal cannot clear,so it dislodges other pieces until there's no room for movement.Maybe the softer metal of a brass nut doesn't let this chain reaction happen.
dangc78 posted 05-11-2002 06:16 PM ET (US)     Profile for dangc78  Send Email to dangc78     
I have come across the same problem with using stainless bolts and nylon lock washers. If you really wish to use these, use graphite as a lubricant. It helps a lot with assembly, but washes away after use so disassembly will always be a problem. Tubes of graphite are available at most hardware stores.
Ger posted 05-12-2002 04:17 PM ET (US)     Profile for Ger  Send Email to Ger     
Thread galling seems to be the most prevalent with fasteners made of stainless steel, aluminum, titanium, and other alloys which self-generate an oxide surface film for corrosion protection. During fastener tightening, as pressure builds between the contacting and sliding , thread surfaces, protective oxides are broken, possibly wiped off, and interface metal high points shear or lock together. This cumulative clogging-shearing-locking action causes increasing adhesion. In the extreme, galling leads to seizing - the actual freezing together of the threads. If tightening is continued, the fastener can be twisted off or its threads ripped out. --Industrial Fasteners Institute 6th Edition Handbook
Solution? Any lubricant or anti-seize

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