mercruiser lower unit

[sarantis]

Hello every body!
does anybody know if when rebuilding the lower unit of a mercruiser #1-R the gears need matching (by using new shims) like the gears of the stern drive or I just put back the old ones?

 

[Don S]

Re: mercruiser lower unit

Not sure what you mean about "like the gears of the stern drive "? The lower IS the lower part of the stern drive, and yes the gears need to be shimmed properly to get the correct gear contact and backlash dimensions. However, it takes special tools to do that. Here's a link to the Mercruiser manual for the lower.

http://www.boatfix.com/merc/Servmanl/6/6C3R3.PDF

 

[FreeBeeTony]

Re: mercruiser lower unit

I know Don S isn't going to like this but............I replaced the gears in my lower unit once and just put the original shims back in............seemed to work fine. I probably put close to 100hrs on it before I sold the boat.

 

[sarantis]

Re: mercruiser lower unit

Thanks both of you despite of your disagreement.DON S with this manual you saved me a lot of money and time.this is what i wat trying to find three weeks now since i started the service of the lower unit!
Anyway,the manual reports that if you don't change internal parts of the lower unit(gears,saft,bearings,etc.),you don't need to change the shims.However a measurement with the special tool for the height of the saft and the backlashes of the forward and reverse gear is suggested and what i intend to do (if the special tool has a logic price,up to 35 euros here in Greece).
thanks again

 

[Don S]

Re: mercruiser lower unit

When I hear the words "Rebuilding" I am assuming a minimum of new bearings and possibly some new gears. If all you were doing is resealing the drive and keeping all the old bearings and gears, then YES. The old shims should work just fine.
As far as FBT's 100 hours using different bearings and gears....... No biggy at 100 hours, you can take a new drive and throw all the shims away and it will last that long......... it's when you are looking for 1000 hours or more, that the shimming and bearing preloads really shows up and things aren't excessivly worn or stressed..

 

[sarantis]

Re: mercruiser lower unit

You are right Don S.Sorry for not explaining so well but my native language is Greek.
anyway my problem was shifting forwards/backwards and i wanted to secure that the shiftcrank at the lower unit is ok. Anyway i found it wounded.
As about your reply to FBT, it sounds scientific!

 

[Don S]

Re: mercruiser lower unit

What was your problem when shifting?

It helps when you just say what your problem actually is than trying to ask how to fix something that may not actually be the problem.

Language problems can usually be a problem, but eventually we usually end up with a solution to the problem...... Just takes a little longer.

 

[sarantis]

Re: mercruiser lower unit

Don S give me some time to find the terminology to describe my problem properly.I dont want to confuse you since I appreciate a lot your insant and accurate advices.
Thanks
Sarantis
Egio,Greece

 

[sarantis]

Re: mercruiser lower unit

Well Don S ,my problem was that when puting the reverse gear it hold it for a sec or less and then it returned to neutral. It keeps the reverse only if when puting it i speed up.I 've been told that it s probably a matter of adjustment from the special nut at the place of engine.but since the lower unit was never opened i wanted to check everything inside it and clean and reseal it.So I found the the shift crank to be worn.its body which is round has formed a small edge.The clutch looks good.In adition i think that the part at the upper unit that engages with the shift shaft of the lower unit looks worn but i intend to examine it after finishing with the lower unit.
That was my problem Don S!

 

[qystan]

Re: mercruiser lower unit

Sarantis,

Your problem is in the adjustment of the shift cable. The pull travel to put it fully into reverse gear is not enough. Assuming the cable adjustment is correct, move the adjustable stud position upwards. see the diagram on the lower right of page 2A-28.

Would be best to start from the beginning. Read Installing Shift Cables. 2A-18 of the manual describing the installation and adjustment of the shift cables. While the book describes the process, it will get you close. I find that it needs a bit of fine tuning by adjusting the lower shift cable brass barrel half a turn each time and testing.

Since you are touching the shift cable, incorrect adjustment and resut in engine stalling. Read this for more http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=36;gtid=1035571

 

[Don S]

Re: mercruiser lower unit

If it used to shift ok, and now it doesn't go into one gear fully, you need a new lower shift cable.
They just don't go out of adjustment, they wear out internally.
The inner core of the cable wears a groove in the outer part of the cable. At that point, there is too much internal movement in the cable (Slop in the cable) to reach both forward and reverse.

 

[sarantis]

Re: mercruiser lower unit

Thank you guys,with all that information I m sure I ll solve my problem.If somebody could give me an adress to download the service manual Qystan is talking about I would be gratefull.

 

[Haut Medoc]

Re: mercruiser lower unit

http://www.boatfix.com/merc/Servmanl/6/6covr3.pdf.....

 

[sarantis]

Re: mercruiser lower unit

Thanks Haut.I feel so obliged and I would want very much to help all of you in return but since I am a beginner I can help you only with relative to electronics problems and ps2/xbox hacking!

 

[sarantis]

Re: mercruiser lower unit

i haven't finished the service yet but just to inform you after good cleaning and new seals and shift saft bushing now i can easily turn the shift shaft by hand.(previously it turned only by using a wrench)

 

[I/O WALDO]

Re: mercruiser lower unit

The ol binding shift shaft syndrome,Bet you found the problem!Opa!