Impeller – key vs pin to shaft

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  • johnny-infl


    Replies: 211
    Topics: 20
    #3454

    Currently converting a long shaft Johnson to a short shaft.
    While assembling the water pump, I noticed the replacement short drive shaft
    has a Round Pin vs Woodruff Key to hold the impeller. The pin is obviously
    smaller than the key. Is there a potential downfall of using the smaller pin
    in the larger key type impeller ? The impeller has a brass sleeve – not plastic.
    Or, should I take it to the machine shop and have a slot put in the shaft for the woodruff key ???

    The above photo is just for presentation only.


    dave-bernard

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 2014
    Topics: 30
    #30482

    never had a problem with either.


    1946zephyr


    Replies: 653
    Topics: 12
    #30483

    No problem. Just use the pin that’s on the shaft and continue using the waterpump as before. The impeller is going need changing, long before the pin will wear into it, anyhow. The fact that the sleeve on the impeller is brass is what’s important. The plastic sleeve impellers will need the woodruff key though, because the pin will dig in quicker. You can also get the pins, that have the flat sided heads on them, which will make your issue here a little closer to your liking. What kind of motor?


    johnny-infl


    Replies: 211
    Topics: 20
    #30486

    it is a newly gifted 1966 Johnson 33hp . . . with a long shaft.
    This is the one I have just refurbished the gear case. It is all sealed up
    now and just closed up the water pump with the pin in the short shaft…..
    got it all buttoned up and – – – – –
    oh wait – THERE’S MORE !!!!! I forgot to put in the new shaft seal
    that goes under the water pump 😳
    luckily, easy fix….. but, like Pappy said, the after market seals will always
    give you FITS !!! The metal case shaft hole was .002" too small so it had
    to be "wallered out" a little to fit. Nice smooth fit now.
    SO !!! Now, the lower unit is COMPLETELY refurbished !!! moving up this weekend
    to the powerhead and see what is going on there…… I am a complete NOVICE to
    working on my own outboards….. but, I have a manual, WITH pictures LOL LOL.
    so, if I can get spark in two cylinders and compression, there is no reason why
    this baby shouldn’t fire right up. Carb has been rebuilt and all that is left is to get
    a diaphragm for the fuel pump . . . or, another fuel pump if that one is not rebuildable.

    fun fun fun !!!


    frankr

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 6715
    Topics: 51
    #30490

    If you are comparing the round pin shaft (33hp) to a woodruff key shaft (40hp), the 40hp has a thicker impeller (taller). That means more friction and harder to turn. I guess the engineers felt it needed a stronger key to do it.


    1946zephyr


    Replies: 653
    Topics: 12
    #30514

    Yes, Frank makes a good point. The 40 has a taller impeller and the key is used typically on this application. The 33 would have a pin, since it has the thinner impeller.

    Those old 33’s are good tough old motors. Basically a "continuation" of the old clamshell 35 of the late ’50’s, but they have the sligthly updated fiberglass hood and lower compression heads.


    johnny-infl


    Replies: 211
    Topics: 20
    #30516

    thanks one and all . . . yes, it is the thinner body impeller.
    I had to drill a new hole for the pin as the existing hole came
    to the top of the impeller – now it is in the center. (I guess where it "should be"?)

    and since you mentioned the later style ’50s continuation, Now I am hoping that
    the RDS-20 hood will fit this RXE-14 . . . the RDS-20 is my favorite looking motor.


    1946zephyr


    Replies: 653
    Topics: 12
    #30533

    I believe the RXE has a different latching set up, than the RDS-20. Maybe modifications can be made though. 😉


    fleetwin

    US Member - 2 Years
    Replies: 4737
    Topics: 46
    #30683

    I dunno, I would be wary of using a smaller diameter pin in a impeller that is meant for a woodruff key. I’m not sure I am understanding everything you have explained. I would be wary of this situation and would research it more before putting the engine into service.
    I think you have said that the replacement short driveshaft has a pin for the impeller instead of the woodruff key, you also say that the diameter of the pin is smaller than the width of the original key. So, that would mean that the impeller fits loosely over the pin and can rock back and forth. Are you using OEM parts? The engine is a 1966 33hp, correct? I am also very concerned about hearing that you altered the gearcase housing in order to fit the new upper seal in place as well. Something does not sound right. Is the gearcase the original one that came with the engine?
    I looked in the 1966 parts book, and it shows a roll pin being used for the impeller: 300771 The short driveshaft is: 554314 The impeller number is:
    378891-775521 The upper seal number is: 302545-313284
    The 15" driveshaft is NLA, but the long driveshaft seems to supercede to an "shaft and key", I suspect the key is the woodruff key you are referring to. So, I am guessing that your original long driveshaft was the later style with the woodruff key, while your standard driveshaft that you found is the original pin style. I’m thinking there should be two different impellers used here depending on whether the key or pin was used, but the parts breakdown doesn’t seem to indicate that.
    I looked ahead in the parts book, all the 33hps up to 1970 show the same driveshaft/pin/impeller numbers. BUT, the 1971 40hp, that uses the 33hp style gearcase shows a woodruff key, but the same impeller part numbers. So, to me, something doesn’t add up here (probably me arithmetic skills). In any event, all these engines show the same impeller part number regardless of key or pin, so that makes me think that the diameter of the pin is the same as the width of the key. If not, then the original style impellers had a loose fit on the pins.
    Perhaps others with more experience on this model can weigh in.


    johnny-infl


    Replies: 211
    Topics: 20
    #30691

    Yes, it is the RXEL-14D motor – removed the 5" spacer to make it a RXE standard.
    the shorter lower shift rod fits well, I did not really "alter" the gear case, just made minor adjustments.
    I too am concerned about the looseness of the smaller pin in the larger key slot.
    There is no way to tell about any parts being original to the motor. BUT – the gear case part number for the 33 is the
    same for a 1960 RDS-22 40hp I am working on: 302520. But, the 33 parts book calls for 593514
    and the 40 parts book calls for: 377483. So anything is possible.
    When I search for part number 302520 it is not clear as to what it originally fit !!!!
    I thought of getting a larger diameter pin or grinding down a woodruff key to accept the impeller slot.
    I really hate modifying things that I have no control over nor an easy way to inspect later on down the road without disassembly.
    I will take the shaft to my machine shop tomorrow and have a slot ground for the correct woodruff key and be done with it.
    NObody likes being stranded on the water due to taking a shortcut on something mechanical.
    Other than that, everything is falling into place quite nicely !!
    Thanks Fleet – lots of great information there.

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