Lower unit swap

[samtech]

How much trouble is there to removing lower unit and transferring the insides to another housing. Like I mentioned before, foot has crack in it. Shopped internet and found just the casing for 1989 evinrude. If this is fesiable, I quess this would be the time to replace whatever needs to be replaced. Any info would be greatly appreciated. Thanks

 

[brim_buster]

Re: Lower unit swap

no hard at all just get you a service manual.

 

[samtech]

Re: Lower unit swap

Just ordered manual. Thanks

 

[Chris1956]

Re: Lower unit swap

Not sure about Johnnyrudes, but Merc gearcases require gears to be shimmed for proper meshing. You might look for this procedure and see if you can source shims.

 

[racerone]

Re: Lower unit swap

OMC gearcases are precision made.----Gears are specified with exacting mounting dimensions.----------The pinion gear is shimmed to the driveshaft.------So if you are switching internal parts from one gearcase to another there is no additional shimming required.

 

[samtech]

Re: Lower unit swap

Thanks for info. Is there a kit to I need to purchase to reinstall in new casing, i.e. gaskets, seals, etc.?

 

[Faztbullet]

Re: Lower unit swap

Only buy it if has been checked for alignment with OMC gearcase alignment tool. These cases are bad about warping and gcausing gear failures. I have thrown in scrap pile housings that look almost bad new but was warped.

 

[daselbee]

Re: Lower unit swap

Uhhhh...I think you will find it is a bit harder than described above. Pulling the bearing carrier is difficult without the proper tools. I am assuming you have the tool, but it can still be very stubborn, and often requires oxy/acetylene heat to break it loose. Also, without a driveshaft splined holding socket, you will not get the pinion nut torqued properly. Then there is the problem of actually holding the pinion nut (so you can torque it) without the special tool.

Shimming the driveshaft gets you started with a "stake in the ground" fixed dimension. Then the other shims are selected using various methods, dial indicators, etc., and those shims are what adjust gear backlash, propshaft end play, etc. The only place that this variance can come from considering you are re-using all your internal parts.....is the case machining tolerances. And you are swapping cases....

So,.....it will be a crap shoot....you may get it close enough.....

Don't get me wrong....I would do EXACTLY what you are doing if it were mine. You should study up a bit on gearcase shimming, and specifically, the different ways to check gear backlash....

There is a guy in Interlochen, MI, his name is Joe Eby, and he has some informative videos on Youtube regarding shimming. Problem is, he doesn't do a V6....this is a V6 right?

 

[daselbee]

Re: Lower unit swap

I am not sure on your model....I think I am correct that there is a huge snap ring down in the case that requires a huge snap ring plier to get it out and re-install....then there's that.....

 

[oldboat1]

Re: Lower unit swap

Some Chrysler gearcases require shimming too, like the Mercs. These must not be "precision gearcases" (reminds me of an old joke about getting Rolls Royce to replace a broken spring....). Anyway, why not explore spot welding the gearcase crack? Probably should take it to an outboard repair shop and let them take a look at it to see what to do next.

 

[racerone]

Re: Lower unit swap

The driveshaft / pinion / and thrust bearing are shimmed as a unit.-------If swapping existing parts to an identical part # gearcase there is no other shimming required.

 

[daselbee]

Re: Lower unit swap

You know, I am going to back off a bit on what I just posted. Looking over the 1989 V6 gearcase parts, I really don't see any shims other than the driveshaft shims. So I will revise it and say that the shimming should not be an issue.
The driveshaft is shimmed with the upper DS bearing carrier: that part is crucial to the correct shimming of the driveshaft.

And there appears to be two huge snap rings....those are always tough.

 

[daselbee]

Re: Lower unit swap

Racer corrected me while I was looking over the parts.

Off this exact subject, but still on gearcases and shimming....you guys should see an Evinrude 70 hp 4 stroke gearcase...
Nightmare of shims....driveshaft shim, forward gear shim, reverse gear shim, thrust washers of different thicknesses...
Each shim kit has about 10 choices...all have to be measured and fitted to the gearcase...

 

[samtech]

Re: Lower unit swap

Well, you guys have just about talked me into spot welding. Doesn't the lower unit have to come off to weld? Guess it would be easier to remove and clean up before welding, leaving everything else where it is.

 

[oldboat1]

Re: Lower unit swap

If you have a local shop, and the boat and motor sit on a trailer, you could pull it over so they can have a look-see. If it can be fixed, you can take off the lower unit and leave it. Find out if anything else is required, but if gearcase disassembly is required, I would leave that up to the shop. See what they say. It's a precision instrument, and leave anything but the grunt work up to the shop.

 

[samtech]

Re: Lower unit swap

Thanks for reply. I'm going to take it to shop. I just do not want to deal with it.

 

[Chris1956]

Re: Lower unit swap

Does SEI make a replacement gearcase for that motor? Might be good if the welding idea doesn't work.

 

[racerone]

Re: Lower unit swap

Agreed those EVINRUDE 4 strokes are a nightmare to shim.------Have a brand new 140 hp gearcase that I need to install all the parts from a cracked housing.----Keep putting it off for later.-------But those gearcases are really a SUZUKI design and it just is not the same as old time OMC engineering.---Old time quality beats new junk every time.

 

[daselbee]

Re: Lower unit swap

Racer, I have the shim gauge bars and shimming tool if you need assistance.

SEI....that brings up an important point....

The two piece DS gearcase he has .....the upper driveshaft is normally held in with a small spring steel clip down in the guts of the gearcase. You can actually use a slide hammer and yank the upper driveshaft out, allowing quick exchange of the upper driveshaft. It bends/distorts the clip, and all you have to do is slide the upper back in. It does not lock in place anymore tho. You have to disassemble the gearcase to fix the bent steel clip.

Now, here is the thing....SEI doesn't ship their gearcases with a driveshaft. Even the old one-piece driveshaft applications now come from SEI as a two-piece design and NO upper driveshaft or shift shaft is included.

How the heck do they expect a customer to install that upper driveshaft? A shop yes, but a weekend warrior that just wants a bolt up LU, no fuss....

 

[oldboat1]

Re: Lower unit swap

geez. definitely not the stuff for a retired weekend warrior either. (man's got to know his limits....)