prop moves on shaft-should it be tight?

Andrew, It may not be just tightening up the castle nut. I'd pull the prop and check to see if the props taper matches the shaft taper. The proper way to do this is to use "high spot" blue. It's typically used to check the contact area of the teeth of two gears such as the ring and pinion in the rear end of a car.

The tapers should match within about .002" front to back. If the taper is bad, then valve grinding compound is used to lap in the taper.

How long has it been this way? It could also be that the prop was never installed properly ether. It's the taper that transmits 80% of the HP and torque to the prop so do check the key too. Never oil a taper. the taper fit is why we need a puller to remove the prop!

jbear wrote: Sure do enjoy your posts and knowledge Pete. john

He really is a fountain of knowledge. I can't tell you how many times I learn something new from Pete's posts - even after almost 50 years of messing around with boats.

OM45GE wrote: jbear wrote: Sure do enjoy your posts and knowledge Pete. john He really is a fountain of knowledge. I can't tell you how many times I learn something new from Pete's posts - even after almost 50 years of messing around with boats.

Guys thanks for the compliment. It's really appreciated but trust me that there are many times when I need help too and that will never end. We all help each other.

8122pbrainard wrote: Andrew, It may not be just tightening up the castle nut. I'd pull the prop and check to see if the props taper matches the shaft taper. The proper way to do this is to use "high spot" blue. It's typically used to check the contact area of the teeth of two gears such as the ring and pinion in the rear end of a car. The tapers should match within about .002" front to back. If the taper is bad, then valve grinding compound is used to lap in the taper. How long has it been this way? It could also be that the prop was never installed properly ether. It's the taper that transmits 80% of the HP and torque to the prop so do check the key too. Never oil a taper. the taper fit is why we need a puller to remove the prop!

thanks for that. not sure how long to be honest, only just noticed it. dont remember it being like that last time I looked as couple of months back. there always seems to be something which needs looking at!

you don't have to lap it in unless it's really out of wack. Just remove the keyway slide the prop on as far as it will go onto the shaft then mark the shaft on the back side of the prop, then remove it, install the key way, install the prop tighten it down then verify that the mark is even or gone once you tighten the castel nut.

The store was out of High Spot Blue or equivelant. I didn't check with that. I put on lapping compound and made revolutions for a couple of minutes, cleaned up, and reinstalled.

I bent my beloved 540 in Aug. (I ran it 3+ years) I hit a piece of firewood floating. I sent to ACME and decided to also have them take off .5 inch diameter to help with clearance.

"Ain't" got it right since...

My old Fed 12x14 runs fine...makes me think shaft OK. I am still getting a lot of vibration in my ski mirror between 15-25mph with the 540.

I have been working with Jim Thelen at ACME. They have been great. They checked the prop a second time and sent it back. He is questioning the install and recommended using the lapping. He said sometimes you just don't get a good join of prop and shaft.

I hope we didn't create "frankenstien" with cutting the diameter down.

I think there is documentation on this forum that people have tested the 540 on older Tiques and Mustangs and had uncorrectable minor vibration.

So now, I don't know which way to throw money... (advice appreciated)

A. $90hr to have the dealer mechanics check everything out. (shaft, alignment, prop install, strut and bushing)
B. Try to work out something with ACME on trying a 1210 or another prop.
C. Give up on the 540 and buy a less aggressive OJ (~$300).
D. Give up and stay with the old Fed 12x14 (naa..not after feeling the 540 holeshot)

I would hate to give up on it. The performance is just too good.

Thanks all.

The ground paste did look even when I looked at the shaft and prop. The only place it wasn't touching the prop taper was at the tail end close to the nut where the diameter is smallest. I did notice a straight line the full length of the taper that might be high or low. I will check again.

I ran the 540 (13'') out of the box for 3+ years without vibration. So far, the diameter trim seems like a mistake.

I will check again for the key/no key placement on the shaft.

In the back of my mind, I am thinking by the time I pull it 80+ miles both ways and pay 90hr, I could just as easy get in a shiney new OJ 12x13.   I want to get the mechanics to check everyhing...but I also know the 90hr labor doesn't always buy you superior service.

Thanks!

Here are some pictures of the mark down the middle. Notice the rest of the surface shows smooth contact (lightly sanded look). I can't tell if this is a high or low point.

Do you think this is enough to cause problems?

Also, notice the area closest to the nut does't make contact...

The prop was on there good. It was tight. I will try the key test next.

Thanks all.

h20loo wrote: eric lavine wrote: He helped build Noahs Ark Maybe not build it but DEFINITELY HELPED RESTORE TO ORIGINAL!!!

Pete is also a very flashy dresser...know he could also give out some tips on how we could all look our best.

john

Randall,
Out of curiosity, I printed out your pictures and brought them in this morning to show one of out tool makers the bore finish. The first think he said, was that it sure looks like they had their feeds and speeds wrong when they machined that taper! The RMS should be better than that on a CNC. He continued on to say that the finish needed to produce a decent taper fit should include a secondary grinding or reaming. Without that, it's defiantly the reason for the lapping recommendation. Without the high spot and just looking at the pictures, he said the closest guess to a contact area is 60%. I have to agree with the % figure.

Lap it in some more like I said and try it out. I however don't feel it will cure your vibration issue.

What's the prop shaft look like?

Randall, Probably wouldn't hurt to check the shaft for straightness. I have a feeling that's not what is causing the vibration especially since the Federal prop runs good. It just may be the harmonics with the Acme which has changed since it was cut down. I don't feel it's your rudder ether.

When I asked about the shaft, I was asking about the taper on it.