70979R Driveshaft Repair

Hi All,

I've recently inherited the old family boat and decided to pull the lower unit off to replace water pump just for piece of mind as I plan to use it a lot and venture 30nm out around the reefs here. It's a nice old motor, starts and runs like new. It's done bugger all hours for its age but found the condition of the lower unit to be not quite in the condition of the top half. The driveshaft was a little rusty and its actually quite pitted around the seal area at the bearing housing underneath the water pump. I wasn't expecting it to be anywhere near that bad of condition as we've always flushed it after use and near dirtied my pants when I saw the price of a new shaft. Has anybody repaired such damage on these shafts in the way of welding and machining back down or sleaving etc? I was always wondering what the difference is between 70973R and the 79R as when searching for parts the 73R is the only model number that comes up for the '79 70hp evinrude. I assume their must be no difference in parts?
Thanks for any advice.

Re: 70979R Driveshaft Repair

Not too sure if a speedi sleeve would work, depends if it will fit over the splines and the seal will tolerate one......they can be metal sprayed or welded but both would probably require machining down to undersize first before building back up and then machining to spec = costly.....have you looked around on ebay for replacement lower units/parts?

Check your model number again, i think you will find the "9" might actually be a "3".......

Re: 70979R Driveshaft Repair

Hi Mark,

Yea been trying to find a second hand shaft but no luck yet. I'll get the shaft out and take it to a machine shop and see what they can do. It'll still be cheaper than a new shaft. Just wasn't sure if anyone on here had successfully repaired one before.
Model number is definitely 79R not 73. Obviously not a popular model number.

Cheers.

Re: 70979R Driveshaft Repair

Gday Tim, you will be able to find it here listed in the "Evinrude recreational outboards 1913 - 1979" section......

http://www.skoterskroten.com/img/arsmodellstabell.pdf


It would be interesting to know what the diferences are if any......parts should be much the same.

Re: 70979R Driveshaft Repair

Yea I'm just awaiting the postman to deliver me the original service manual from home that came with the motor. According to the schematics there's no difference in part numbers. Must have just been a certain month or production batch.

Will let you know how I get on with the shaft repair. Welding won't be a problem as I know the airport welder here and he can do lots of cool stuff but I'm leaning towards the speedi sleeve if one is close enough to size.

Cheers

Re: 70979R Driveshaft Repair

To me there are few concerns with a speedi sleeve......

1. Whether it will fit over the splines (you might be okay here).
2. Will the seal tolerate one? (not quite sure here as the seals tend to be a fairly narrow profile).
3. The sleeve needs to be slid quite a distance down the shaft into position and because of the close fit any highspots or nicks will make this difficult.....you could smooth those out i guess.

Re: 70979R Driveshaft Repair

Well...Speedi Sleeve mission a success. So far!! Will it last?..time will tell. We actually speedi sleeve helicopter shafts at work that are an approved repair method.
I linished the shaft clean in the lathe and sized it up for a sleeve. The only sleeve available in that diameter wasn't deep enough to run both seals so I had to put 2 sleeves on it back to back (yes it is possible to put a sleeve on backwards even over the splines)!! Both seals now run on a sleeve and should hopefully be ok.