My cousin's 93 Top Gun used a front plate, rear engine plate and the ears on the transmission to the transom plate all secured. I didn't have to drill new mounts but had to r/r an engine twice in it, I did the same thing that was mentioned above by lil red to check the alignment during the reinstall. I liked the three points of contact for each engine/transmission even tho it was a pain in the ass to get everything mounted.

I also tossed all the galled up stainless bolts that came out of the mounts and switched to grade 5 bolts. 1) Because I couldn't find stainless bolts local and 2) you don't really need stainless bolts in freshwater, the coated grade 5/grade 8 are fine as far as I'm concerned for corrosion resistance and stronger than stainless.

Is there a spec on tolerance or is this just an adjust to feel? I align motor machine setups and we strive for less than 2 thou but you would need a horizontal plate in front to shim and adjust side to side. It's amazing how much movement you get just by torqing the bolts down

If you do use stainless dont use nylock nuts unless you have anti seize on the threads. When stainless locks up its a ***** snapping 1/2 or 9/16 bolts off down close to the bottom of the boat.

[QUOTE=BOATMAN302;4111176]If you do use stainless dont use nylock nuts unless you have anti seize on the threads. When stainless locks up its a ***** snapping 1/2 or 9/16 bolts off down close to the bottom of the boat.


I agree, the standard Grade SS bolts from 3/8-1/2" will last indefinitely with Nyloc nuts as long as you use a good lube each time on clean hardware. We have never had a failure with a lubed standard grade SS bolt with a ny-lok nut. Mercury sells a great anti-siege lubricant.
(Deleted grade 5-8)

Standard stainless bolts are about the same as grade 2 steel, only steel bolts are available in grades 2,5 and 8 that I'm aware of. Low carbon content of stainless prevents them from being available as hardened also.

Here is some more info from the Totally Stainless website.

Information on Stainless Steel
Stainless is a series of alloy steels which contain at least 12% chromium. Such steels will not rust when exposed to weather. The most common stainless steel is 304 which is an 18-8 alloy containing at least 18% chromium and 8% nickel. 304 is a non magnetic steel. The metric designation for 304 is A-2. Even more corrosion resistant alloys, such as 316, are available for some of our product line and are a good choice for high corrosion environments such as marine use. We carry medium strength hex and socket head cap screws made from strain hardened 316 in metric sizes. These fasteners have a strength designation of 80 and are approximately equivalent to metric 8.8 or a US grade 5. We have an extensive line of high strength stainless as strong as or stronger than US grade 8. The high strength bolts are made from age or precipitation hardened stainless and have a polished finish.

Stainless steel is superior to chrome plating because it won't crack or peel as it isn't a surface coating but the substance from which the fastener is made. Because stainless steel is softer than medium carbon steels (it only seems harder because it work-hardens) it tends to gall. Always use anti-Seize or a similar product on the threads.

That's good info, I'll look at their site. I was going off my local supply house and :
Stainless Steel
Stainless steel is an alloy of low carbon steel and chromium for enhanced corrosion characteristics. Stainless steel is highly corrosion resistant for the price and because the anti-corrosive properties are inherent to the metal, it will not lose this resistance if scratched during installation or use.

It is a common misconception that stainless steel is stronger than regular steel. In fact, due to the low carbon content, stainless steel cannot be hardened. Therefore when compared with regular steel it is slightly stronger than an un-hardened (grade 2) steel fastener but significantly weaker than hardened steel fasteners.

Stainless steel is also much less magnetic than regular steel fasteners though some grades will be slightly magnetic.

18-8 Stainless
18-8 refers to any stainless steel containing approximately 18% chromium and 8% nickel. This is the most common stainless designation for hardware. For information on 18-8 stainless steel material properties see our Material Grade Identification and Properties Chart.

Ive had this happen a few more time that I`d like , especially taking apart the drives, once it locks up forget it.. now I used some kind of lubricant before trying to tighten or loosen any stainless nylon nut.

[QUOTE=MILD THUNDER;4109393]I am redoing all my engine mounting. Whoever rigged my boat years ago, was an azz. The aluminum angle brackets were drilled like a hot chick on prom night. QUOTE]

I know exactly where you are coming from - mine didn't even line up. You should see the abortion they called tailpipes they gave me - if I told you what I paid you'd sh*t. I spent a lot of money unf*cking the mess I was given.

[QUOTE=yschmidt;4111448]That sucks. Mine worked ok for me, but wasnt right, so i wanna make it right. I think the alignment on a bravo setup, is more critical than on a ssm setup that has no gimbal bearing. Not to say it doesnt matter, Its just a little more forgiving. With a bravo if the alignment is off, the gimbal bearing wont last very long