Increasing MC-1 trim range

[Cresco750]

Hi
I would like to increase the amount of 'in' trim range on my MC1, ie get the leg to tuck in more to get increased nose down force. Currently, at full down trim the leg is still in an almost vertical position. The trim rams appear to be going to their normal position, ie stopping at the paint line on the ram itself, which I can only assume it has done since new?
The transom is almost vertical, so any angle beyond the vertical of the leg would have to be coming from the trim of the leg.
When trimming full down the trim pump can be heard to start labouring when the rams hit the end of travel, as I expect it would.
There is a small amount of play in the rams when full down, ie the leg can me physically pulled up and down half an inch or so (about 1/4" in the rams). Would this indicate that they need to be bled?

My question is; in relation to the transom plate, how many degrees of 'in' trim should / could I expect in an MC1 leg? Is this range adjustable? If the rams weren't bled properly, would this have an impact on trim range?


The boat is fairly new to me, and so I don't know whether this is the way it has always been, or whether its as a result of me installing new trim position senders, or other?

Cheers

 

[Don S]

Re: Increasing MC-1 trim range

The transom is almost vertical,

There is your problems, it's all designed for transoms between 10? and 16?. A quarter of an inch is not going to be of any help.
Your engine must be really nose down in the boat with an almost vertical transom, that is also going to be a problem.

 

[Cresco750]

Re: Increasing MC-1 trim range

Thanks Don. Well it sounds like I just have to be content with trimming with the trim tabs? You mention that it is a problem having the engine nose down in the boat; why is this?

 

[Don S]

Re: Increasing MC-1 trim range

Oil level for one. You will probably get aerated oil from the crankshaft hitting it in the front of the engine, and will probable have running issues when the lifters get soft from the aerated oil. You may also have issues with the carbs fuel level since the engine will now be about 12? or 13? nose down.
Water ingestion from the exhaust.

 

[Cresco750]

Re: Increasing MC-1 trim range



Ok, hopefully I have managed to successfully attach a photo of my transom and drive? As the photo clearly shows I was a little over zealous when i stated that my transom was vertical! Clearly it isnt . The drive is pictured fully down / in, which when i look at other drives around the park seems to be a little short of where it should be?
Thoughts?

 

[Bondo]

Re: Increasing MC-1 trim range

View attachment 176718

Ok, hopefully I have managed to successfully attach a photo of my transom and drive? As the photo clearly shows I was a little over zealous when i stated that my transom was vertical! Clearly it isnt . The drive is pictured fully down / in, which when i look at other drives around the park seems to be a little short of where it should be?
Thoughts?

Ayuh,.... Donno if it matters, 'n donno if it's the issue,... But,....

Those are Not the original trim rams...

The original rams woulda had both of the trim lines attached at the leading end of the ram, not with the 2 different length trim lines...

 

[Don S]

Re: Increasing MC-1 trim range

Disconnect the rams from the drive and see if the drive will go down any further. The 228 drive lists both internal and external lines on the trim rams, unless your have a 77 model.
It does look like the rams are not fully down.

 

[Bt Doctur]

Re: Increasing MC-1 trim range

They look like Alpha ones mounted upside down

 

[Don S]

Re: Increasing MC-1 trim range

They look ok as far as the lines go, but I can't really find a picture showing a MC-1 drive all the way down to see how much of the trim cylinder ram is showing when full down.

Can you post a serial number for the drive or a boat year?

 

[achris]

Re: Increasing MC-1 trim range

Those rams do look like they are not all the way in. I was trying to find a spec on the length of the ram when all the way in, but couldn't find it. Did the external line rams have an option to put spacers in them to reduce the DOWN range?

 

[oldsub86]

Re: Increasing MC-1 trim range

Not sure the drive is all the way down in this photo but looks more tilted than the photo posted by OP.

 

[achris]

Re: Increasing MC-1 trim range

Oldsub86, Any chance you could trim your drive all the way in, then measure from the centre of the front and rear anchor points and post it here?

 

[Cresco750]

Re: Increasing MC-1 trim range

Ok, so the plot thickens! Serial number of my drive is 5968201. Best I can tell is from around 1982? I wonder why it would have odd-ball rams? The whole setup has done less than 300hrs from new, so its unlikely that they would have been replaced because the old ones wore out.
Oldsub; that drive of yours in the photo does appear to be trimmed in further than mine. I would be very greatful if you could possibly measure the distance of ram centers some time, and I shall do the same as soon as I get a chance.

Don, I will also try your suggestion.

Cheers.

 

[achris]

Re: Increasing MC-1 trim range

Those rams aren't 'oddball', they are the normal EXTERNAL RETURN LINE rams issued in that era.

Chris......

 

[Don S]

Re: Increasing MC-1 trim range

Chris, I don't have a clue if they had down stops for them, couldn't imagine why.

Cresco, I think since oldsub has internal line type cylinders and you have external, a measurement from trim pin center to trim pin center may be a better measurement.
The overall could be the same but the internal line cylinder could have a longer cylinder, but shorter rod. Which would give you a false reading.

 

[Cresco750]

Re: Increasing MC-1 trim range

Hi Don. Agreed. I will try and take a photo with the rams removed tonight after work.

Cheers

 

[oldsub86]

Re: Increasing MC-1 trim range

Oldsub86, Any chance you could trim your drive all the way in, then measure from the centre of the front and rear anchor points and post it here?

Unfortunately, not any time soon. The boat is 175 miles away and it is minus 22 here tonight. I won't likely see the boat again until mid-April at the earliest.

 

[ziggy]

Re: Increasing MC-1 trim range

fwiw.
distance between the end of the ram and the cc of the anchor pin on mine is 5''. + or - a little. i put my rams all the way in for storage and remove my drive. sometimes the rams will extend by them selves over the winter. as of right now. both look about the same and may not have moved much. port side is 5'', starboard is a little more, maybe 5.5''. the op's rams don't look as far retracted as mine.
my rams have 4 hydraulic lines going to them. all at the ft. of the ram. not like the op's. my drive is a '75 mc-1.

 

[Don S]

Re: Increasing MC-1 trim range

If you can Ziggy, measure from center line of the trim pins. Being a different cylinder, they could be different lengths.
See reply #15 above.

 

[ziggy]

Re: Increasing MC-1 trim range

measure from center line of the trim pins.

if i understand correct. from the cc of the ft pin to the cc of the aft pin. length is 19 1/8'' + or - half inch depending on which side i measure. imho. my port trim ram is looks fully retracted.