prop wobble on shaft

[Drkrieger]

I have a pro boat MG 29" with an aftermarket flex shaft, and a Grim racer 42x55 prop. I have recently sharpened and balanced the prop. I am going to de-tongue it soon. This gave me a bit extra RPM and speed.

The problem I have noticed is the prop seems rough at the dog notches, not straight. It seems like maybe the notches are not deep enough. And it is strange that the notches are almost rounded on opposing sides. So the prop when on the shaft and dogs, has a bit of movement back and forth near the lock nut. I am sure this is throwing off the balance. Is it normal for Grim props to be so rough?? and what can i do to center out the prop when i lock it down??

Any help would be appreciated.

[rol243]

can you use a small file to file out the recess cuts so both are abit deaper and square ?

[NativePaul]

The shallow dogs are no problem, you can file them further out or not, as they are square edged you don't need much engagement at all to stop it slipping.

Being able to move it back and forth near the prop nut sounds like it is another matter though, I only have a few ABC props ( I believer ABC make props for Grimracer) and 2 off them are bored significantly over 3/16, the dog stops them wobbling around at the front but near the nut there is maybe .5mm play. On mine there is enough gap to wrap the stub shaft in tape and put the prop over that to reduce the wobble, but I already bent a shaft before I noticed and did that, and while the performance is better than the Octuras I am used to, the sloppy centre really put me off, and I am not sure that I would buy any more. Is that the issue you are having, I am not sure from your post?

[Drkrieger]

I suppose I can. But is that just gonna make the looseness worse? If I file off the excess metal in the notches, it will sit flat,but, may create a wobble at the dog side..

The other thing i noticed is the stock metal version from pro boat is very tight on a 3/16" drill bit. But the Grim prop is quite loose on it. Do i just have a bad prop?

[Drkrieger]

The shallow dogs are no problem, you can file them further out or not, as they are square edged you don't need much engagement at all to stop it slipping.

Being able to move it back and forth near the prop nut sounds like it is another matter though, I only have a few ABC props ( I believer ABC make props for Grimracer) and 2 off them are bored significantly over 3/16, the dog stops them wobbling around at the front but near the nut there is maybe .5mm play. On mine there is enough gap to wrap the stub shaft in tape and put the prop over that to reduce the wobble, but I already bent a shaft before I noticed and did that, and while the performance is better than the Octuras I am used to, the sloppy centre really put me off, and I am not sure that I would buy any more. Is that the issue you are having, I am not sure from your post?

Yes. that is the issue. I will try to file the dog notches, and a wrap of tape may do the trick.

On a side note, should there be a bit of play at the strut where the shaft exits?

[Erroneous]

Yes. that is the issue. I will try to file the dog notches, and a wrap of tape may do the trick.

On a side note, should there be a bit of play at the strut where the shaft exits?

Yes. You need to leave about 1/8"-3/16" gap from the dog hub to the strut. But if you mean play as in the shaft is loose inside the bushing no, it should be snug. OSE sells upgrade struts that are pretty tight for 10-15 runs.

[urbs00007]

The shallow dogs are no problem, you can file them further out or not, as they are square edged you don't need much engagement at all to stop it slipping.

Being able to move it back and forth near the prop nut sounds like it is another matter though, I only have a few ABC props ( I believer ABC make props for Grimracer) and 2 off them are bored significantly over 3/16, the dog stops them wobbling around at the front but near the nut there is maybe .5mm play. On mine there is enough gap to wrap the stub shaft in tape and put the prop over that to reduce the wobble, but I already bent a shaft before I noticed and did that, and while the performance is better than the Octuras I am used to, the sloppy centre really put me off, and I am not sure that I would buy any more. Is that the issue you are having, I am not sure from your post?

my grimm props are the same. over-bored. will not buy grimm any more. my abc props are fine however. and I knew abc made grimm props. go figure. the rudders that they sell , you know the cheap ones, have sloppy bushings. so i buy speedmaster. I don't understand why they can't use better fit shaft to bushings. they lost me as a customer. just sounding off a little. lol.