Care and Feeding of the 55H Lower Unit

[Yellowjacket]

I've just bought a 402 (35ss) that I will eventually be fitting a 500 powerhead onto. The tower is fine, and the lower unit has been rebuilt.

Before I start using it, I was thinking that I should get some tutoring on how to maintain it.

I am interested in learning how long I can expect to run it between rebuilds?

What tends to wear out and at what intervals?

Replacement parts? I know a lot of technology has passed under the bridge since these units were first designed. Are there better seals and lubricants available now or is the old stuff (like lubriplate) still the best?

Brinkman said in his pamflet that he said never to install a roller bearing in the rear cover instead of using the original setup, does anybody know why?

Brinkman talked about using a method of injecting lube past the seal (with the caveat that once you start doing it you are going to have to do it every time you use it). Any comments on this procedure? Seems like you it could extend the overhaul period with this technique.

Would like to get a discussion started so that I can learn what to do and not to do before I mess it up.

[modhydro]

Merc gearboxes

I always recommend opening up a new purchase since you have no idea of the previous maintenance it has had. The stuff is being reproduced now and big thanks to those who have done that for us. On the flip side, if you take care of what you have, you should be fine and not need to buy new parts.

I don't remember Harry talking about not putting in rollers so I'm not sure what you mean there. I use needles with retainer rings on all of the gearcases that I do. They have higher rpm and load ratings. They also keep the needles from skewing in the housing and leading to the shaft sliding on locked needles rather than rolling. Another note on bearings is that if you go to the trouble to check the parts out, replace them. They are cheap in the big picture.

What he was talking about is a cone greasing tool. They allow you to give the cone bearings a shot of grease after a days running. This forces out any water that finds its way in there and keeps the bearings working as bearings so you don't score the propshaft. They are simple to use and do a great job.

One trick that Harry showed me was stoning off the sharp edges of the gear teeth. It can be done in a short time with a good hard stone. A new gear usually has an edge so sharp that it will scrape your fingernail. Just stone it until it slides smoothly and you are done. This helps keep you from having a hard sharp edge that acts somewhat like a squeegee, shearing the oil off of the mating geartooth. This is another thing that I do on every box I put together. You can physically feel the difference after this treatment.

Another trick worth mentioning is using some copper based never-seize on the prop gear during final assembly. I just put it on the prop gear so that you can't see the teeth any more. This helps with the break in of the gears and gets everyting acclimated to each other. It will also help with seal and bearing life. Another benefit is that it will be in solution in the oil and help with lubricity by having a dissimilar metal between the teeth. I'm pretty sure that all of the gears we run are technically impossible from the engineering side as far as tooth size vs loading. We need to give them every benefit that we can to prolong life.

Check gear oil often. Be sure to pump it full to eliminate any water after a day's running. Be especially diligent here when putting it away for an extended time. It always amazes me how many get junked from a lack of simple maintenance. Take care of it and it will take care of you!

One last item that comes to mind as I'm typing this is that I recommend to all my customers is to break in the gearcase. The usual response is a kind of surprised "what??" When you think about it though, the gearcase is the weakest link in most of our engines. It simply makes sense to run one in for a while to get everything happy with itself. I just run one on a cart with a test wheel for a while.

I'm sure I will think of some stuff to add later. Hope this helps.

Steve Roskowski

[pops67g]

Virtually everything Steve has said is spot on. With a little care the Merc gearcase will give great service. Even though nothing seems to be wrong they should be torn apart at regular intervals and checked out. I have 24 years (with the original gears!!!) on my 44xs gearcase and I expect a few more.

[proprider]

Crunchy!!

Hey Steve, you forgot to mention about the "crunchy" feel/noise the copper base never-sieze is prior to break-in. I'll never forget that feeling when I first turned mine over after recieving it from you. Totally went away a few minutes after break in. Quite sure I gained a few more gray hairs that day, plus you got a good laugh out of it.

Just thought I'd mention it.

[trident]

D Gearcase

Virtually everything Steve has said is spot on. With a little care the Merc gearcase will give great service. Even though nothing seems to be wrong they should be torn apart at regular intervals and checked out. I have 24 years (with the original gears!!!) on my 44xs gearcase and I expect a few more.

Check the shear pin hole... if it has a sharp edge, chamfer it.

Grease the cone bearings every running session. Be sure to use a waterproof grease (I use Lubrimatic Marine Corrosion Control grease. Dark green, doesn't wash out. Available in 1# can or small gun cartridge) As you pump one or two pumps in, the gun will 'firm up' and a drop or two of water will come out the case inlet. Done.

Grease and oil are cheaper than parts.

Jerry

[Yellowjacket]

Recommened lubricants

What is the "best" lube to use for the gearcase?

How often should I check lube in the gearcase?

How long (in hours or races) should I expect to run it before the seals start to leak and let water into the gearcase? Do you assume that once the seal on the gearcase starts to leak, that the seal in the tailcone is starting to leak at the same time?

Assuming I have new seals on the tailcone bearing, how long do those last? I saw in Brinkman's book, that once you start to inject lube past the rear seal, you have to do it every time you use it. If that's the case I'd like to run it for a reasonable time and then start to do that procedure after the seals start to allow water into the bearing.

If you inject lube past the rear tailcone bearing seal, where is the old lube going, into the water pump? If so, is that a bad thing in that you are putting gear lube into the water jackets and will that mess up your coolling later?

Sorry for all the questions, but I've got a lot to learn and I'm sure this has all been common knowledge for a long time but us nubies gotta learn and I've found in life that there are no dumb questions....

[modhydro]

Gearcase lube

I run 90wt synthetic oil in mine. That and the never-seize has never let me down.

I give it a few pumps every time I run it just to be sure it is full and clean (no water)

I give the tailcone a pump with the grease gun after every day's running. It only takes a tiny bit. Like Jerry said it only takes a little bit. You will see a little water come out of the inlet hole. There is very little volume inside the tailcone as the bulk is taken up by the bearings.

With experience and watching for the water to come out, you will get to the point of not getting extra grease into the impeller. If a little does, it won't hurt a thing and may in fact help save your impeller if you are one of the guys who dry fires up on the bank with everything dry.

I'd say these are all good questions and may help save yourself or others from aggrivation down the road.

Steve

[Guest]

Quicksilver lube tool

I have one new A,B, and C unit and one D lube tools for sale. These are the last two I have. They have O rings on the back side to keep the lube going in the right direction. The cost of the tool is $85 including shipping.

Alan

[bh/]

...I don't remember Harry talking about not putting in rollers so I'm not sure what you mean there...Steve Roskowski

-that did seem curious , so here is what he wrote;
"The 1950 foot, A-B or D , had a solid bronze bushing tail cone. You should NOT install roller bearings in these solid one piece cones."
Harry does not elaborate, but I wonder if there is room for a caged roller,
and how do rollers like rolling around with beads of water about???
He obviously favors the later needles with cone greaser,
even twice a day, if your heats are split by a break.

[ddalton]

Doesn't the tailcone seal have to be installed backwards for grease tool to work?

[Guest]

Tailcone tool

The tool is very thin at the contact point of the seal and will slip under it. If you have the seal in backwards it will allow water to be drawn in.

Alan

[ddalton]

Always thought the backwards seal thing was wrong!!!!

[Yellowjacket]

I also have a question, one of the clamp screws is messed up.

One of the clamp screws is bent. Not much, it will clamp about a half an inch in and then it binds up. I can see by turning it that the screw is bent just a bit, and I don't want to mess up the threads by forcing it.

Should I:

A.) do the right thing, grind off the bottom of the screw, get the pad off, and the screw will wind right out, get another clamp screw and replace the screw.

B.) can I bend it straight after clamping it on something or do I risk doing more damage trying to straighten it.

I can't be the only person who has ever had one of these with a bent clamping screw.