Gear and engine bed/supports

[Darren Kinvig]

Working through a re-power. Two part question..
Using a ZF68IV gear and a 6bta 315 H.P. engine. The mounts for both the gear and the engine line up almost dead center of boat Stringers. I need to drop my gear down into the stringer. This means that I need to cut into the top of the stringer about 2″ deep. The total depth of the stringer is 7″ and 4″ wide. My first instinct is to box the stringer with aluminum, bolting a welded box through the stringer to mitigate any strength lost from cutting into the stringer. I would like to hear any other suggestions on how to set the gear down to the proper level when the mounts are hitting center of stringer.
The second part to this question is: Do you actually use the rear engine mounts on the engine? Or do you put two isolating mounts onto the gear bracket?

Topic

[Tony Athens]

Darren,

I see two very viable solutions here………………Send me those pics and more, direct——————-.jpg attachments–Not embedded in the emails or they go into the round file ……………… Add a few more too.. Lay you camera in the bilge, both ends, and shoot a pic so I can see under the engine and gear.

But before anything can really be done, the engine/gear ( or just the gear) needs to be in very close to feeler gauge alignment..

How “hands-on” are you? What exact boat– all specs??

Tony

[Darren Kinvig]

Gear and engine supports

Thanks for everyone spending the time to give feedback to questions I have

I have added some pictures to the text .

First picture shows the gear bracket. It lands in center of the stringer below. There isn’t enough room between the bracket and the stringer to put in the isolator.

Second picture shows the depth at which the stringer would need to be cut out at the top to get the isolator to fit between the bracket and an attachment point. 2″-3″ down from the top. stringer is 7″ deep.
My concern was not wanting to cut into the top of any stringer for fear of jeopardizing strength. I thought it could be boxed and bolted through stringer with aluminum material. lots of labor. has anyone done something like this? opinions….

The third and fourth pictures show how far out from the gear the isolator would need to be moved to be on the outside of the stringer. (11 inches..) I could then bolt an aluminum mounting bracket through the stringer. More conventional. I would need to make new gear brackets. How thick of material and what kind of material would I need in order to span 11 inches from the gear. seems this needs to be pretty heavy material. Steel? thoughts . Thanks

[Tony Athens]

Some really good pics showing the issue may yield some other solutions

[donald roth]

Sounds like you’ve really no choice about cutting the stringers.
Hopefully there’s plenty of meat left below.
The rear mounts should ideally be on the transmission, putting them as close as possible to the torque output location.
Sometimes cutting out stringer requires additional reinforcement, but we can’t see what’s going on with your situation. Pictures?

[Gene Fuller]

I know nothing about your boat or that particular gear.

However, my overwhelming first choice would be to try to find or fabricate different gear mounts that would fit.

Cutting stringers under the engine is not a typically recommended practice.

[Author]

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