lower drive shaft concern

[ziggy]

a mercruiser 1 drive, listed in my sig.

i have some wear patterns at the top of the splines of my drive shaft. i don't know what has caused them.

the wear i'm talking about is on the outside edge of the end of the drive shaft splines. is this something i should be concerned about? ya can feel the disturbed metal with your finger...

 

[ziggy]

Re: 1 drive lower unit, drive shaft concern

Re: 1 drive lower unit, drive shaft concern

so no one sees anything unusual about these wear patterns? they just seemed to be a shade rough and looked like parts are wearing against ea. other...

 

[chiefalen]

Re: lower drive shaft concern

Ziggy how long that shaft been in use??

 

[ziggy]

Re: lower drive shaft concern

how long that shaft been in use??

since sept.. 06 by me. i think that's the year i got it. maybe a hundred hrs a season in '07, 08, is my guess (no hour meter). sat for 15 years in a airplane hanger aledgedly prior to that. don't know before that.. sounded like the po didn't use it much towards the end... as far as i can see. it's the original drive..

 

[JustJason]

Re: lower drive shaft concern

have you ever been working on the upper? Sorta looks like (and this is just a WAG) the vertical shaft in the upper may be hopping around a bit. Alot of people miss setting bearing preload on the vertical shaft, its done with shimming behind the race in the top cap then installing the cap then spinning it over.
I say alot of people miss it because the process for that isn't the clearest in the old manuals.

 

[ziggy]

Re: lower drive shaft concern

have you ever been working on the upper?

interesting idea.... yes. i did a new yoke + brgs. and ft. seal spring of 08. best i know. i did it right, yes, i reshimmed the drive gears. but no, i didn't do anything to the vertical shaft in the upper nor the shims under the top cap that has the brg with shims under it..

 

[ziggy]

Re: lower drive shaft concern

so here's the mating pic. looking up inside the drivin gear...

so i can assume that the outside of the perimeter of the drive shaft is contacting. what is it contacting. the inside of the vertical drive shaft in the upper? same circles. should i be concerned? is jason's wag guess in the ball park? guess i woulda thought that the preload pin sat inside the hole and that the drive shaft never made contact. i still don't see since the shaft is splined together, how these types of marks can occur...

am i being concerned over nothing. just put it back together and move on?

here's my wag. my preload pin has moved down or wore down. allowing the contact to start to occur. don't think i'd wanna know what the cure for that is... anyone got any ideas?

 

[JustJason]

Re: lower drive shaft concern

ahhh... now that i see the other side of things i formally retract my initial WAG and i'll offer a new WAG.

Quite simply.... the driveshaft is to high. But I think you know that already. Now why is it to high???? Could be a couple reasons.
Have a look at the parts breakdown.

http://www.mercruiserparts.com/Show...03&bnbr=90&bdesc=GEAR+HOUSING(Driveshaft)+-+R

When you build the drive the first thing you need to do is set gear height. Its done by using the shim gauge and adding or subtracting shims under the needle bearing (#9 in the pic... but they don't show you the shims in the parts breakdown)
Then you need to set the rolling torque on bearing #21. Thats a tapered roller bearing and all tapered bearings need to be set correctly to function correctly. If the bearing is set to tight, it will want to lift,(before it grinds) and it will overcome the ability of the preload spring (#16) to hold everything down correctly.
There is some normal up and down movement on the driveshaft when you have the lower unit sitting up on a bench. It's how much it moves when it's all together that makes the difference. Because of the way the gears are cut and how they push against eachother, the driveshaft wants to shoot up out of the drive when the boat is underway. It is the job of the preload pin/spring to keep it down in place.

So getting down to your problem.... and depending on the tools that you have. I'd probably start by checking the backlash, if the backlash is good then you know your gear height is good. you'll need a dial indicator and the Mercury flag to do it. If that checks out then i'd check the rolling TQ on the upper bearing. If that checks out i'd replace the pin and spring in the driveshaft.... but don't ask me how to do that... i've never had to. In fact I haven't been inside an "R" drive aside from a water pump in a while.

If you ever wondered what the difference is between an "R" drive (same thing basically as a #1...) and an "MR" drive... which is the same as an alpha 1.... its all in how they handle the upper bearging preload and how they deal with locking down that driveshaft. They do it a bit differenty and they do it without that preload pin.

 

[starsnstripers]

Re: lower drive shaft concern

Hey Zig, I see a small (dot) in the upper where the preload pin rests. Is that worn (concave) ? If so it may be taking the tolerance away from the preload and allowing the shaft to ride up and touch the surface. Looks like some filings in the greese around the preload pin too. Hard to tell from here. check it out.

 

[ziggy]

Re: lower drive shaft concern

i formally retract my initial WAG and i'll offer a new WAG

that funny.

well, i'm at a loss as to what to do.
i don't have a dial indicator nor a flag, nor a dial indicator inch lb torque wrench. i have no mercruiser tools at all for the lower.
i suppose one option could be to take it to the mercruiser dealer and see if he'd feel them out.
or
buy some tools, though i'd bet that before i was done. i'd have more invested in tools than the other option. that being just R&R it with a sei lower. which i suppose is the best option. specially since i'd loose the preload pin and get the better design of gear interaction in the lower...
i suppose if it realy has lost it's tolerance in the lower. when it goes it'd go out with a bang.... that don't sound good.
the crux of my problem is lack of funds this year. really sucks having lost my tax relief and child support (boy turned 19 and moved out) all in a year that the economy is failing... grrr.
any opinions on just running it... or any other ideas too..

sns, kinda hard to get yer finger up in that hole. but any grease that i did remove, i felt no metal shavings. one thing i did find was the wrong grease still in place from when i didn't have any mercruiser spline grease... i used molycote grease that's black so maybe that's why the deception in the pic... don't know about the covcave hole where the preload pin rides. i've only seen 2 1 drives. both have had the preload pin covex. i thought it was that way in design... the preload pin does move with much resistance. a very loaded up pin for sure (heavy spring)..

 

[starsnstripers]

Re: lower drive shaft concern

Well Zig, I guess knowone has come accross such a thing before! ha! I'm going to be taking two 1 drives apart shortly to do the pumps and pressure tests. I'll inspect the preload pins and seats and the area around the shaft spline to see what they look like. I'll try to remember to take a pic of them for ya to compare yours to. I'd say where you filed the burrs off, grease her up and run er'. If it's going to be a problem then you'll find out if it pops out of gear at some point, but i think it will last the season. Check er' again next off season and see if it's any worse or?

 

[starsnstripers]

Re: lower drive shaft concern

I was looking at it again Zig and i'm thinking someone befor you may have had trouble lining up the splinse and bang bang banged it to get it lined up. So it made the marks on it and you didn't notice it when you had it apart before. I'd shine it up with some emry cloth so it's nice and shiny/smooth and put drive together gently, Next season you'll know.

 

[achris]

Re: lower drive shaft concern

Hi Ziggy,

I've had a look at the photos and unless you've cleaned all the grease, I'd say it's short some lub. The other thing I alway check when I split a I drive is that the pre-load pin isn't siezed. Just give it a tap with a hammer, it should just bounce. If it does, all is good.

Cheers,

Chris.........

 

[ziggy]

Re: lower drive shaft concern

i've not cleaned inside the drive shaft in the upper. i did clean the lower driveshaft. yes, inside the upper driveshaft came apart looking clean like that...
i don't think i put much lub on the end of the shaft when i greased it. mostly on the splines. some on the end, but not much.
yes the preload pin moves

are you saying that if i grease it up and the preload pin moves, ya think nothing is out of the ordinary?

 

[Bondo]

Re: lower drive shaft concern

are you saying that if i grease it up and the preload pin moves, ya think nothing is out of the ordinary?

Ayuh,..

It appears to me that it mighta been put together alittle Dry,...
Put the Grease to it,+ Go Boatin'......

 

[ziggy]

Re: lower drive shaft concern

well, i was ambivalent as for what to do. lack of tools..
in the end. what i did was took the waterpump base off. i'd not done that and wanted to see the drive shaft at the seals anyways. i'd say it had a little wear. so was disappointed to see that. then i used method one in the book and set it up like i'd be taking a backlash reading. since i don't have the proper tools, all i could do was see how much play it had. i figured any discernible play was probably to much. best i could see spec is .010"-.012". not much. i had discernible play.
i did talk to the dealer and he would have let me use his personal tools, but i just couldn't come to it. borrowing a real marine techs personal tools. what a great guy for offering. i probably should have went and borrowed them tomorrow. instead, i put the waterpump back on, greased up the driveshaft spines with spline greaser real good and put it back together. it's pressure testing now. so far, held 12psi for 3 hours. just turned it a half hour ago, still holding.. assuming it holds vac. too. i'm gonna fill it up and be done with that and on to the next thing.. hope it was just a lack of grease thing..

 

[JustJason]

Re: lower drive shaft concern

i did talk to the dealer and he would have let me use his personal tools, but i just couldn't come to it. borrowing a real marine techs personal tools. what a great guy for offering.

That is mighty big of the guy. Nothing personal here at all Ziggy, but I would never even think about loaning somebody a special tool. Maybe if the guy left a cash deposit at more than the tool is worth.... but then only maybe.
Talk to the dealer and ask him if you can talk to a tech. Ask if the tech lives nearby and offer him 50-100 bucks for him to swing by after his work and check it out for you.

 

[achris]

Re: lower drive shaft concern

i figured any discernible play was probably to much. best i could see spec is .010"-.012". not much. i had discernible play.

Glad to hear it. 10 thou is quite a lot (but correct) and you should definitely feel it. I'll take a photo of the tool later and post it, with the appropriate dimensions. If you have access to a good TIG welder you can make your own. or go to a parts shop and buy for $13 the tool. 91-53459.

Chris...........