What Prop for my Suzuki DF20A?

[Martin]

@PeterM that makes sense and fits with my gut feeling of “being in the wrong gear”. It’s like pulling off in second in a low power car.

And pulling up a hill in top gear..!!

Martin

[ChrisParish]

Look what arrived this morning!

[harrison]

Ooooh! Nice.

[ChrisParish]

Once the grease arrives (tomorrow, I hope) I will get it installed.

[Martin]

Awesome...
fingers crossed it has the desired effect... there’ll be no catching you on the hole shot

Martin

[ChrisParish]

So I tried to fit the prop today.
Bad news. It doesn’t fit.
The spline count is correct but the length of the hub is wrong - the new one is far too short.

You can clearly see the splines protruding beyond the hub

The old one (on the right) vs the new one (on the left)

What is annoying is that I used the Solas prop finder and ordered the correct model (according to them). There is a fitting kit but it doesn’t include a suitable spacer.

I am very annoyed here. I will have to contact SteelDevelopments on Monday and see if I can get them to take it back.

[Martin]

Sorry to hear that pal, bit crappy.
I believe they have to take it back Chris .
14day distance selling regulations to notify intent, 14 days to return.

The device fitting error is not your fault as you used their tool to confirm fitment.

Martin

[ChrisParish]

Update:

I contacted Steel Developments and they were exceedingly helpful. The lady on the phone told me that there is a nut-end spacer available and when I asked how much it is she said "I was just going to put it in the post to you"; that's my kind of price.

The nut-end spacer arrived today I got the engine out and it fits perfectly now. The spacer goes between the prop and the castle nut and is splined to fit the shaft.

When I took the nut off the shaft the first time I was surprised by how lose it felt. Well, not so much lose as just not tight. I checked and the correct torque is 16nm, which is 11ft-lbs for those of you who work in old money. In other words, not a lot. I refitted the prop by holding the bare socket in my hand and turning it until it was as tight as I could get it and then I nipped it round to the next available hole.

I am looking forward to getting out and seeing what the performance is like now!

All in all the service from Steel Developments was superb and I would highly recommend them.

[Froglet]

That's interesting. My engine has something that looks just like that, but in brass. It's listed as a thrust holder and sits on the shaft between the prop and gearbox, rather than between prop and nut.

The first time I went to remove my prop I found the nut completely loose. The only thing keeping it on was the split pin. I guess the previous owner either never checked or didn't care.

I have two service manuals that I "thought" covered my 25hp 2 stroke, but one, the Mariner one, says torque prop nut to 75Nm while the other, the Tohatsu manual, says 25Nm. That first value seems crazy tight. That's like an axle nut on a 100hp motorcycle. So I go with the Tohatsu value which I think is much more realistic.

[ChrisParish]

My engine has that thrust washer, but it now also has this nut-end spacer which goes on the other end and is t shown on the exploded diagram - I presume because it is a part manufactured by Solas to that their props fit a wider range of engines.

75nm! That’s mental. I think someone got their maths wrong when converting from ft-lbs!