What do you think of this idea for power tilt/trim?

I can't find a used power tilt/trim unit for my 40hp that is within my price range. So what do you think of this setup:<br /><br />I get one of these 12 v trim tab hydraulic pumps (400psi, $187) <br /><br /> <br /><br />And one of these trim tab hydraulic cylinders (also rated 400psi, $57)<br /><br /> <br /><br />And I replace the manual tilt cylinder with the trim tab cylinder, hook it up to the trim tab pump, a few feet of wire and switches, and I should have a working brand new hydraulic power tilt/trim unit for my 40hp. <br /><br />I figure that the trim tab cylinder should be able to lift the 180lbs motor. At 400psi pressure and cylinders being about 1.5" bore that gives about 1.7 sq inches of area, or 680lbs of lifting force. Worse case two cylinders could be used (they should fit in the old manual cylinder location).<br /><br />The nice part about using these parts is they are all marine grade and should perform well on the water. To protect the investment and the outboard, the cylinders would be mounted with shear pins to break away easily if an obstruction (aka big rock) was struck at speed.<br /><br />What I like about this idea is: <br /><br />1. It seems like a lot less work than trying to fit an available used trim system from a different make or model outboard.<br />2. The parts are new so there are no used parts failure or life expectancy issues.<br /><br />3. The parts are marine quality so they will hold up better than using one of these linear actuators that I have been toying around with that weren't meant for marine use (165lbs thrust, 12v, $119) <br /><br />4. Shouldn't take much to mate the cylinders to the outboard. <br /><br />5. If those cylinders can hold trim tabs at an angle on a big boat against the resistance of water while going 40mph, then they should also be able to work as a motor trim system also.<br /><br />6. It is an all brand new system (warrantee!) for less than 2/3 the price of a used (buyer beware!) tilt/trim for the 40hp.<br /><br />So wadda think?<br /><br /><br />Edit:<br /><br />BTW, does anyone know what the stroke is on these big trim tab cylinders? The ones I show are replacements for Trim Master or Bennett Systems. Also, the collapsed dimension and diameter would be helpfull. <br /><br />Thanks!

Re: What do you think of this idea for power tilt/trim?

Hey Mark,<br /><br />I'm no mathmasurgeon, but don't you need to also add the thrust force in the calculations? I would think it would be some portion of pivot weight + the thrust force of the engine. I don't know, just asking.

Re: What do you think of this idea for power tilt/trim?

I really don't know. That's why I post this stuff here, I hope that someone will point out my flaws. Even if it doesn't have the power to act as a trim sysem while underway, it should still be able to perform the tilt function, right? <br /><br />I have been looking around and found other mini 12v pump systems by Oildyne (parker company) that run up to 3000psi. Need to find a retailer to get prices on their systems.<br /><br />Also found some of the merc cruiser power tilt/trim cylinders might work too. A bit bigger to handle the thrust of those big v8's. <br /><br />I think these area all single acting cylinders, meaning that the cylinder expands with pressure, but relies on the resistance to push them back. That might work OK for me too. Gravity and propeler thrust should work in my favor.

Re: What do you think of this idea for power tilt/trim?

Another consideration is that the trim pump you want to use have a valve. You need a way to lock the system or the thrust force will push the cylinder.

Re: What do you think of this idea for power tilt/trim?

Mark42, There is a difference between a trim tab hydraulic system and a trim/tilt setup. The trim tab hydraulics only push the tabs down. A spring pulls them back up. If you rig up the system you have described on your outboard, when you cut throttle, your motor may pop up, since there is no downward hydraulic pressure.<br />You may be able to get around this limitation, however,with proper operation of the motor.

Re: What do you think of this idea for power tilt/trim?

I'm not sure if it will work or not. I know that my 1989 J50 unit operates on much higher pressure than that pump and the cylinder is larger. I would try to calculate the force from the motor. A formula for that was mentioned in a post a few day ago I think (don't remember what forum though). You may find that the forward thrust of the motor is pretty high and then the angles the rams would be at may not hold the forces. The highest forces are when the motor is all the way down. It's much higher than just the motor weight because of the angles. Plus the stroke length of those units may not be enough. <br /><br />I don’t want to rain on your parade, but I just don’t think it’s going to work. I hope someone with some mechanical, hydraulic and/or structural experience comes along and adds input. I think it’s a pretty cool idea and hope that maybe you can get something figured out. Good luck!

Re: What do you think of this idea for power tilt/trim?

I would get a used unit on ebay, much cheaper and they are easyer to get during winther.

Re: What do you think of this idea for power tilt/trim?

I think you guys are right about the trim tab cylinder not being the right part. I did find a company that makes OEM tilt/trim motors and has a generic 12v motor/pump unit pushing about 3000 psi. Its reversable (I think). If I can find a generic aftermarket ram of the right size it should work same as the real thing. <br /><br />G Dane, the problem I have is that a used unit on ebay for the 40/50hp 1993 model is 1) hard to find. 2) usually sells for over $400. Plus there is that whole "used parts" issue of "how used is it?" Will it last one week, one season, or 5 seasons? If I could find one reasonably priced, I would snatch it up in a moment. But at $400 and up, I would rather spend my money on new equipment and know what i have.

Re: What do you think of this idea for power tilt/trim?

Often it is cheaper to get a blown motor to get it from. The twin looper 50 and 60 are identical to yours, and quite a bit of the 60 HP bite the dust as the output is high compared to CI. A used unit can be rebuild if neccesary, I agree in that 400$ is much to gamble with, at least in my budget.

Re: What do you think of this idea for power tilt/trim?

Outboard Non-repair. This is a no engines forum