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Maximum length of Power Trim XD cylinder at full up/out position

delVincent

delVincent

Member
I have a 1993 Chaparral 180 SL Limited with a Mercruiser 3.0, Alpha 1, Generation 2 power train. This power train includes XD hydraulic cylinders for the Power Trim.

My SELOC manual gives a maximum UP/OUT cylinder dimension of 20.750 inches (520 mm) as illustrated in the attached image from page 14-9.

Is the dimension for the XD cylinders larger than 20.750 inches? If so does anyone know the value or where I can find it? The sender and switch are not positioned correctly so I can't use my trim gage yet.

I just got the boat a few weeks ago. I have the carb adjusted now, air filter and plugs cleaned, and all remnants of old fuel gone and only use ethanol-free gas. The boat runs well but speed and handling is really sensitive to trim so I want to get the trim gage calibrated.
 

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  • Length of cylinder given in manual at max up-out position.jpg
    Length of cylinder given in manual at max up-out position.jpg
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Ok, since I don't know how long you've owned this boat (or any other MerCruiser powered boat with a correctly functioning trim system) I'm going to give a brief overview.

The system operates with a trim up/down toggle switch if you have a Mercury/Quicksilver branded remote. The trim range of an Alpha drive is 21 degrees from full down until the unit should stop with the trim up toggle switch. (Pre alpha units had a 15 degree range but operated the same). At that point you move to the "trailer button" located lower down the control handle & the drive goes full up.

That being said, later controls (if I recall correctly) had a toggle switch with 2 up positions. Push gently & up it goes until the limit is reached. Press harder & it goes all the way up.

Earlier controls had 3 rubber buttons & even earlier boats had a 3 button trim control panel on the dash.

The theory behind the trim limit is so the engine isn't overtrimmed at high power because the 2 flanges of the gimbal ring would be exceeded & the entire drive could break off.

Now to your question:
Put drive full down & operate the trim up until it stops. The cylinders should only extend maybe 3" (truthfully I'm guessing at that dimension). The exact dimension is 20 3/4" from center of mounting hole to center of mounting hole.The trim limit switch located on the left side of drive can be adjusted within its mounting slots to achieve this dimension. The pump will turn off. The switch isn't tremendously consistsnt. Try it a few times after you've made an adjustment. Don't concern yourself it it varies plus or minus a bit, just try to get it as close as possible.

Full trim up (whether trailer button or 2 position toggle switch) will run until cylinders fully extend & you hear the pump sound change. Pump will continue to run until you release the switch or it overheats.
 
Great explanation. Thank you for the quick reply. I have a question about the maximum down position.

The manual refers to a stop pin at the maximum down position- "Be sure the drive trim is fully IN and it is resting against the stop pin."

Where is a stop pin? I think my cylinders are bottomed as you can see in my PDF attachment with three images. The center-to-center distance on the cylinder at this position is 17.375 inches.

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A black metal object on a red surface AI-generated content may be incorrect.
A motor on a boat AI-generated content may be incorrect.
 

Attachments

  • 071525-01 delVincent- Drive at maximum down position based on hydraulic cylinders stopping here.pdf
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There is no stop anything on trim cylinders. The travel is determined by the internals of the trim ram assembly.

There is nothing else to know. There is nothing you can see and nothing you can do to change any of it unless you install something on the ram to limit the down like a plastic piece that would clip on the ram.
Measurements dont matter with regards to full travel in or out.
 
delVincent said:
Great explanation. Thank you for the quick reply. I have a question about the maximum down position.

The manual refers to a stop pin at the maximum down position- "Be sure the drive trim is fully IN and it is resting against the stop pin."

Where is a stop pin? I think my cylinders are bottomed as you can see in my PDF attachment with three images. The center-to-center distance on the cylinder at this position is 17.375 inches.

.View attachment 35655View attachment 35656
Click to expand...
ditch the seloc manual and get mercruiser manual 14 for alpha gen 2 drives. Seloc is pretty notorious for bunk info.

As mentioined the dimension is for where to set the trim limit switch which is different from trim sender for gauge
 
Dieter said:
ditch the seloc manual and get mercruiser manual 14 for alpha gen 2 drives. Seloc is pretty notorious for bunk info.

As mentioined the dimension is for where to set the trim limit switch which is different from trim sender for gauge
Click to expand...
Did I miss his intention? It read as if he was measuring travel up and travel down...
 
I attached pictures of the drive when it stops. I don't see a stop pin that is stopping the rotation. Is the stop pin reference inaccurate? Is the cylinder bottomed at this location in the pictures? This is for the down maximum, not the UP maximum for the limit on the port side.
 
Thanks Mark. I think i am going with that position for my down reference. I will set the two switches now. I may have some questions on the one on the starboard side that gives feedback to my dashboard gage.

Thanks everyone for the input. I was up to 39 mph at 3,900 RPM last weekend. We were bouncing pretty high on the wake of other boats so i didn’t want to give any more throttle.
 
kghost said:
Did I miss his intention? It read as if he was measuring travel up and travel down...
Click to expand...
no I was just pointing out how the Seloc manual was sending him down a rabbit hole, as there is no pin.

If I recall the measurement of trim limit switch is the extension length of the cylinder ram has nothing to do with upper or lower limit which unless you have the limits in the cylinders (like used when you have an extended swim platform) they are when trim stops full up or full down.

Unlike some OEM manuals the merc ones are excellent such that if you have good mechanical skills you can do the repairs.

to the OP set the limit at the 20.75" length and go boating. Hopefully the sender/limit switch if replaced are OEM. I made the mistake of getting a sierra set and the sender has never worked right...
 
I will try to calibrate the OEM sensor today. So I should zero the dial on the dashboard by rotating the sensor at the down position of the outdrive, correct?
 
Yes but because of voltage differences from engine off to running you will probably notice a slight variation in actual use.
 
Both limit switch and sender calibrated to spec.

Thank you all for the help.

On to the next task while fitting in time using the boat.
 

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  • 20250716_145249_exported_20.jpg
    20250716_145249_exported_20.jpg
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