Jackplate help??

[100333624]

I just picked up a used CMC jackplate 5.5" setback, its manual not hydraulic. Got a good deal on it so thought I'd give it a shot since I'm fooling around with engine height and propping. As dumb as this may sound, I can't seem to figure out which is the correct way to mount it?? Which part is on the boat transom, and which on the motor end?? Which way is the rightside up?? I can see marks on the one side of it from the guys motor, but it seems as though all the way up makes no difference in engine height?? Unless I'm not seeing this correctly. Can someone help shed some light on this please? I can't seem to find an installation manual for this thing either?

 

[jbcurt00]

Just get the manual from CMC
http://www.cmcmarineproducts.com/resources/instruction-sheets

 

[fhhuber]

Big long vertical slots typically go to the transom.

 

[gm280]

As jack plates go, they are usually setup to allow height above the top of the transom. So which ever way allows that additional extra height is the correct way to mount it on the transom. As for the side that bolts to the engine, I would mount the widest section to the transom and the narrowest side to the engine. That way you have a lot of transom support for the jack plate. JMHO!

 

[100333624]

No Title

Hey guys thanks for the help! I got it all sand blasted and shes nice and clean. I think I got it all figured out, how it works and how it mounts. But I have one minor issues now, cant seem to figure out how the nuts go on the shaft? There are 4 nuts and 2 washers left, so are they supposed to be doubled up like I have it in the photo? That seems to be the only way it makes sense but it adds some height in there with 2 nuts, not sure if my hydraulic steering piston will be in the way of adjusting the jackplate height?

jbcurt00: The manual is for a different model, it seems mine is an older obsolete model. Though the manual helped me identify which side goes where, it still didn't help me figure out how it works properly.

fhhuber: Yes you are correct, according to the manual posted above (which is for a different model) shows the BIG side of the bracket to the motor and the smaller one (with vertical slots) to the transom. I thought it would have been the other way around as the bigger section I figured would go against the transom to add strength, of course I was wrong on that one....

gm280: Thanks for the suggestion, yes it would seem it only works one way and i think I got it figured out. I was hoping the bigger side was against the transom but thats not the case with this model and I can't turn it over because it won't work that way as it seems to work with "gravity" and the weight of the motor. If flipped the other way it will be upside down, and the weight of the motor will have no effect on moving it up or down.

 

[fhhuber]

You need double nuts above and below the cross-member to be able to lock the jack plate height.

Initially loosen all nuts and move the "spares several threads away from the ones nearest the crossmember.

Use the 2 closest to the cross-member to adjust the height.. Tighten them up. There may be a torque spec here... At least tight enough that you might feel confident without the "spare" nuts.

then using a wrench to hold the nut below the cross-member, bring the lower "spare" nut up and TORQUE it tight. (should be a torque spec for that... if not, reference a torque table such as: http://www.engineersedge.com/torque_table_sae.htm )

Then repeat for the upper nuts.

Once the height is adjusted... then you tighten and torque the side bolts which are what actually hold the jackplate together.

some manual jack-plates it won't matter which way is up... Yours might be one. If that is the case, you can put the adjustment to the bottom so its out of the way of the steering and throttle cables.

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When torquing by the tables... use the WEAKEST metal involved for determining the spec. If a SS bolt is threaded into aluminum use the correct aluminum spec. If not sure of the grade of aluminum... use caution, because what is appropriate for T-4 will strip out the weaker alloys. Using the spec for the stronger metal will guarantee you break the weaker metal.

 

[gm280]

100333624, with that type of jack plate you could remove the threaded rod and four nuts totally and still have adjustments. Some folks put a piece of wood under the engine and then loosen up the side bolts and use the trim of the motor to move the engine up or down and then tighten the side bolts. But this takes place on the dry ground not in the water. I used the trailer jack to move the engine up and then tightened the side bolts. Once you have it dialed in, there will be no more need for any adjustment rod and nuts. JMHO!