Limiting trim tab retraction

[C_Spray]

Is it possible to install a spacer of some sort on the back face of the piston inside the ram, or does everyone just put some sort of sleeve on the shaft? It seems to me that, either way, you have to take the ram apart, which is not a problem, as they are off of the boat right now.

[MOBILEMERCMAN]

Fountain used to install them on the 29's. It is a piece of nylon or delran tube about the diameter of the cylinder bored and split. Its length will determine how far the rod can retract.

Since it is split it can be installed easily with out any dis- assembly. Place in position and screw the split pieces together.

[DAREDEVIL]

Fountain used to install them on the 29's. It is a piece of nylon or delran tube about the diameter of the cylinder bored and split. Its length will determine how far the rod can retract.

Since it is split it can be installed easily with out any dis- assembly. Place in position and screw the split pieces together.

:iagree:

[C_Spray]

Interesting. The tabs on my Formula are restricted, but there is no external collar. There must be something on the inside. Anyone had their rams apart? It looks like all you need is a spanner wrench to unwind the plug in the end..

[Knot 4 Me]

Fountain used to install them on the 29's. It is a piece of nylon or delran tube about the diameter of the cylinder bored and split. Its length will determine how far the rod can retract.

Since it is split it can be installed easily with out any dis- assembly. Place in position and screw the split pieces together.Sunsation did something similar on their Dominators. If memory serves, they were one piece and snapped onto the tab rod.

[Sydwayz]

Mercury sells a plastic snap on limiter that goes INSIDE the trim ram on the Bravo drive trim rams. I don't know about the trim tabs, but it would not be hard to make.

[C_Spray]

I'll blast them apart and have a look.

Just one more job for "the list".... :rolleyes:

[mr weazelle]

Chuck;
On my 29' fountain, they are correct. It is mounted external on the shaft itself. I can get you pictures if you need!

[Chris]

Whatever you use, it has to be a material that can stand years in total immersion of hydraulic oil. Oil is oil, plastic is made from oil. You have to do some research to be certain that the plastic you're using is going to last. If it disintegrates it'll probably damage your pumps.

There are grades of UHMW polyethylene you can use. I know for certain that any grade of aluminum will work. If all you have is a drill press, a piece of UHMW rod from McMaster Carr will do the job. If you have access to machinery, I'd just make it out of aluminum. Remember, one end of the piston/rod assembly comes off. If the piston is welded, the trunnion is screwed on. Possibly pinned. If you're going to disassemble, you might as well throw $5 worth of seals in them. And you don't have to make a split sleeve. Just a tube.. I would definitely put something the largest diameter I could find. The gland is made to have the top-out load distributed across it's face. If you slide a piece of thin-wall tube, your force will be as far away from its restrictionas possible. That's the gland's thread. It probably won't take long to fatigue that part.

[MOBILEMERCMAN]

Chuck;
On my 29' fountain, they are correct. It is mounted external on the shaft itself. I can get you pictures if you need!

Share a pic with these guys.

They are simple and clean. I see no reason to make it more complicated than it is.

[mr weazelle]

I took a few pictures. Hopefully this helps. I can get dimensions if needed.

[C_Spray]

I took a few pictures. Hopefully this helps. I can get dimensions if needed.That's a great solution if you want to be able to adjust it without dismantling things.

Since I'm planning to make my restriction permanent, I took the ram apart (easy with a 1/4" pin spanner wrench) and had a look. There is a 5/16" bolt that holds the piston on, so I just machined up a piece of aluminum 1-1/4" OD x 3/4" long x 5/16" through-drilled. I counterbored it 1/2" deep to minimize the loss of thread engagement, and it worked perfectly. Once I take a few measurements, I'll fine-tune the length so that the tab only retracts about 2 degrees above level, and I'll be done.

Very, very simple as it turns out...

[C_Spray]

Well, in the end, I made even taller (1") spacers to go on the retraction end of the piston, and bored the old 3/4" spacers out to use as extension limiters. Now the tabs only go about 1-1/2" above the bottom of the boat, and about 3" below. Before, the travel was ridiculous. This whole project will give me much finer resolution on my LED position indicators.