gear ratio question

[fishtails4beer]

my out drive se #is A349804 my boat is a 1985 imperial vtc230 my problem is my upper gears are tore up and need replaced the teeth are 24-24 from reading on the net that ratio is for inline 6cyl my engine is a v6 205 hp should i go with 17-19? and the bell housing se number doesnt match the drive so it probl has been switched.will all the bearings need replaced? or is that what caused the gear to break a tooth? thanks im clueless, im pondering on doing it myself ? scott

[Technical Support]

Most likely someone changed the drive at some point. If it is propped correctly now, and you change to the 17/19, then you will have to reprop it. 17/19 is most likely the correct gear set though.

Both gear sets use the same bearings, although if the gear has failed you will want to change all of the bearings because they most likely had metal running through them.

As far as changing them yourself, you really need the proper shimming tools to get the gears shimmed correctly, plus there are some other special tools required to get the job done. I imagine you could spend 3-400 dollars for the tools pretty quickly.

Tech Support

[fishtails4beer]

out drive

i will probly be buying the upper from you guys soon i tore a part mine today it doesnt look to difficult there was about .025 shim behind the drive gear.the face of the bearring race behind the drive gear got beat up, my casting got marred up a little as well. i had the upper re-sealed right before all this happend , oil was dripping out around the shift rod, i think the guy did faulty work and charged me 350.00 to do it.i am a machinist so measuring shim and slop isnt a problem i have the seloc book as wellwill my lower unit fit properly to your upper? thanx any advice will help im in dayton ohio.. scott oh one more thing the bottom drive gear had a busted tooth that i believe is what ripped everthing up .. why do the gears break??

[Technical Support]

The gears break from hitting something, or fatigue. Everytime the tooth has a load on it it flexes, it can only do that so many times before it fails depending on the load.

Tech Support

[onplane]

Scott,
Perhaps your drive was changed out to a 1.62 from a previous owner due to a failure of the original. It was probably a really good deal on a used one and just re-propped at a low price. Now if you stay at the current ratio you will most likely be under propped with a lower pitch and lower speed. Whay type of boat is it, cuddy or bow rider. Are you quick on plane or do you struggle and how is your top end speed and are you making WOT. If you were to re-gear to 1.81, sure you would have to reprop but it would most likely work to your advantage with a higher pitch prop with better results. Most boat shops have a try before you buy program. So if you are unhappy with the pitch and the prop is not damaged they will let you try another. The damage to your current drive could be a number of things, most common are lack of lubrication, improper istallation, water intrusion, or most likely severe impact, and if it was used you will never know.
My advice, and mine only, would be to purchase a complete drive, upper and lower. If you attmept to rebuild your own you are looking at at least $1000.00 in tooling, and then parts $(?), and most costly your time. You would have to expect to have to assemple, measure, disassemble, reshim, and reassemble, measure and disassemble several times, and hope that you got it right. For the price that S.E. charges do you really think it would be worth rebuilding your own?
Good luck with what ever you deside,
Scott

[fishtails4beer]

to onplane

thank you for the advice. my upper drive has 1.65 stamped on the side of it. the gears measure 3.125 in dia. 24 -24 teeth,the boat actually planed out fast but speed was hard to get 28 mph top end, i did have a 19 pitch prop on there, i just had a 21 rebooted i will probly buy the 1.84 upper drive next week when i get some cash. thanks for all the info i like this forum

[onplane]

Hi there Scott,
Your drive is a 1.65 but is now to be considdered a 1.62 since Mercury changed them several years ago in an attempt to make stronger gears. By going to the 1.81 you will be able to use an aggressively propped pitch with a really nice high end that will scare off the weak! And yes you are right, this is a really good forum, with Tech Support and others that can pitch in, only good can come of it.

Take care,
Scott