I have 454 mags and have the two drive trim buttons on the dash and just installed the throttle mount single switch with the diodes in place. Button works fine, drives go up and down.

Question: The starboard drive trims up and down quicker than the port drive and I still have to go back to the dash buttons to even out. What causes this effect and is there any way of correcting it??

Thanks in advance for your advice!!!

mine do the same thing

same here, always have to adjust each one....

its a law ..

just think how much fun trips are. maybe someday merc will sell trim pumps in matched pairs or put a rating on them.

there was some disscussion about this subject a while back .... I think it concluded that you could have one pump ......to serve both Trim and Tabs ....didnt seem to be overly complicated ....bet you would still have different travel rates though ....there was even a guy that had an idea about preset posistion on tabs and drives .... #1 all down #2 favorite #2 all up ..... I'll see if I can find it ....Mike

It's normal. Both my twin engine boats do the same thing.

Your correct, they would still travel at different rates..

I design hydraulic fixtures all the time and no matter how you plumb them the cylinders will always travel at different rates. There are just too many factors (the friction of the seals for instance) from one drive to the other to get them perfectly in sync. you may be able to get them very close but never perfect. The only way I could see you getting the perfectly in sync would be to use a ball screw and a servo motor, which really wouldn't be that hard.

I've heard different thicknesses of oil will cause it too.

I have the same problem as-well. I have never tried this but I believe you could slow down the fast pump with hyd. flow controls on both hyd. lines at the pump. You just need to remember they are free flowing in one direction and metered in the other. The rule is, you meter out of your cylinder back to your reservoir. Your controlling your back flow or velocity in how fast your cylinder can dump it's oil back to the tank. This in turn controls your tabs. It probability won't be prefect like a servo but it be closer then before without much work. Any good place that sells hyd. fittings should be able to help with the selection of appropriate fittings and there sizes with the in line flow controls as part of the piping. Propwash.