Play in Volvo Penta Folding Prop

[jbmia]

Hey Folks,

I’ve had some vibration in my shaft I’m trying to solve and looking for some feedback. Running a 2GM20F with new mounts.. I put a dial indicator on the shaft and measured .1 inches if I recall correctly (engine off, by hand). Just hauled out and I’m currently working on pulling the shaft to bring the shaft and prop over to a shop to have them both evaluated, straightened, faced, etc. Replacing the dripless seal and cutlass bearing as well. I took this video of some play im seeing in the folding prop and thought I’d toss it up for thoughts and suggestions.

Is it possible the prop is out of balance, contributing to the vibration?

Would you say this is a normal amount of play solved with regreasing? Rebuild it, boring it out with new larger pins?

I’m inexperienced in this area so appreciate any guidance.

 

[jssailem]

There is always a little slop in those props as they age. The slop allows the blades to collapse when you move the prop into neutral. When you are running the prop, the force of the spinning shaft drives the blades out and to one side of the frame. The faster you go, the greater the force driving the prop blade to the outside of the spinning circle. Examine the pins for wear. I'd use the same pins again. Examine the blades for pin wear. That would give you an indication of the wear pattern. If the hole is elongated or the pins are worn, you may end up replacing the prop. Those are cast bronze pieces of metal. You will not be able to add metal to the blade, or the prop base, and a larger pin size will not likely be a solution. The pin size and the hole size were an engineered decision. There is likely not enough safety strength in the metal if you enlarge the pin and the home in which it fits. You may try and find the new tight-fitting blades are not functioning.

I'd go to a prop shop and examine the brand-new props to see the type of play in them.

A lot of vibration issues involve certain spinning rates of the shaft, engine and transmission. The cutlass bearing and the strut can also be an issue.

Good luck with your prop shaft visit.

 

[BigEasy]

Hey Folks,

I’ve had some vibration in my shaft I’m trying to solve and looking for some feedback.
Is it possible the prop is out of balance, contributing to the vibration?
Would you say this is a normal amount of play solved with regreasing? Rebuild it, boring it out with new larger pins?

I Rebuilt my Volvo prop last July. Had to replace the blades because of galvanic / stray current corrosion. I replaced the pins also & noted a tighter fit with the new pins & blades. I would try replacing the pins only (available from volvo) without reboring. (New blade set is $1800) The blades are supposed to be somewhat loose to allow opening & closing. I wasn’t able to remove the hub; however, I later determined that instead of trying to engage the arms of the puller on the forward edge of the prop hub, you should engage the arms in the prop shaft pin holes. I had to drill the set screws that capture the prop nut and remove them with an easy out. I didn’t realize that Volvo recommends removing the set screws periodically & lubricating with anti corrosive grease to prevent them from seizing. If your prop accumulated barnacles, that would cause some vibration. I doubt if the blades are out of balance if the symmetry appears normal (not bent / gouged). Be sure to mark exact location of each blade to facilitate reassembly. If there is still vibration after replacing cutlass bearing, shaft seal, prop pins, new mounts, & shaft checked & coupling faced, then I am guessing that there is an alignment problem with engine & shaft. Note: I used a Buck Algonquin plate type puller to remove the shaft coupling (worked well). Also, removed he shaft seal cooling water nipple fitting to inspect it. Cut the hose off the nipple & use vice grip pliers to unscrew fitting from frp shaft log. Try not to disturb fillet around base of nipple & you may get lucky & be able to reinstall by wrapping threads with plumbers teflon tape & a bit of sealant on the threads. That should allow easy removal for inspection in future. Sorry for lengthy reply; hope it helps.

 

[Ralph Johnstone]

I put a dial indicator on the shaft and measured .1 inches if I recall correctly (engine off, by hand).

Can you please explain what this means as related to alignment ? If radial, no big deal. If angular, ouch .

Did you do an alignment after you installed the new engine mounts ?

And the big question, do you know how to do an alignment ?

 

[colemj]

That's not too bad, but the holes in the blades are starting to wear. It isn't causing any alignment issues with the shaft, and unlikely at this stage to be causing significant vibration. You may hear it chattering in neutral idle, but once in gear centrifugal force locks the blades in the hub and they don't move like you are seeing. They usually don't start causing vibration until they wear enough that they skip teeth unfolding, and you are quite a ways from that point. I'd say that prop has a couple more years in it, but if it is causing vibration or not folding/unfolding easily, then it needs to be dealt with.

It is unlikely the pin is worn, as the stainless pin is more robust than the bronze prop. I've never seen a worn pin, but plenty of worn blade holes, and a couple of worn hub holes. Both the blades and the hubs can be easily bushed by any machinist. I'd bush the blades and see if that fixes the issue. I'm pretty sure it will, and the machinist will be able to immediately see if they are ovalled or too large for the pin. If the hub holes are also worn, then have them bushed, but that isn't usually the problem.

There is plenty of metal and strength in the blades and hub to add a bushing, and bushing the blades is a fairly common thing.

Mark

 

[colemj]

I put a dial indicator on the shaft and measured .1 inches if I recall correctly (engine off, by hand).

That is a lot. Are you sure the unit was inches and not thousandths?

Mark

 

[jbmia]

Huge thanks for all the replies.. these have all been super helpful so far. colemj, that's what I was thinking the prop shop might do with it.. I was just trying to get a sanity check on whether the thing is way way out or it's worth putting a few bucks into.. I'm headed over to FJ Propeller on Monday morning unless any S. Florida locals have another suggestion...

To a respond to a couple of the questions:

- Alignment... This was my first attempt, but I get the idea.. move the engine up/down, tilting forward/backward and side to side to attempt to get to .003 in or less between the transmission shaft couplings. I got pretty close, but I'm sure it was off by a little.. Of course there's also the shaft, shaft seal, shaft bearing and any inaccuracy there.. bottom line is I was just trying to get as close as I could, knowing I'd be hauling out soon and replacing those items, as well has having the shaft and prop looked oat.. full intention is to have a pro come in and perform an alignment for me. I want this thing running like a top and while I"m handy, I"m not a glutton for punishment either. The whole thing seems to be a sweaty fiddly frustrating experience..

- .1 inch on the dial indicator.. it's been awhile now, but I think I was getting 10 on this dial indicator... I'm not a machinist and haven't slept at a holiday inn express lately either so could possible be off.. it's a harbor freight one as well.. bottom line is there's a really good wobble in the shaft at all rpms that I want to get sorted out.

 

[Ralph Johnstone]

full intention is to have a pro come in and perform an alignment for me.

The whole thing seems to be a sweaty fiddly frustrating experience

Probably the best way to do it in the long run. It all depends on how much you value your time.

I notice you're using a dial micrometer which cannot possibly measure angular alignment any way you try. And angular alignment is the most exacting measurement required. Please read the attached manual and I'm afraid you'll come to the conclusion that what you've done so far is not ............... well, you'll see.

 

[jbmia]

Probably the best way to do it in the long run. It all depends on how much you value your time.

I notice you're using a dial micrometer which cannot possibly measure angular alignment any way you try. And angular alignment is the most exacting measurement required. Please read the attached manual and I'm afraid you'll come to the conclusion that what you've done so far is not ............... well, you'll see.

Thanks.... I was measuring prop shaft runout with the dial indicator... not alignment.. my understanding is that a feeler gauge is used to measure alignment at the coupling. Happy to be corrected if I"m wrong, but as I understand it, prop shaft runout can be a function of bad alignment, bent shaft, bad shaft bearing... anything else?

 

[dLj]

Huge thanks for all the replies.. these have all been super helpful so far. colemj, that's what I was thinking the prop shop might do with it.. I was just trying to get a sanity check on whether the thing is way way out or it's worth putting a few bucks into.. I'm headed over to FJ Propeller on Monday morning unless any S. Florida locals have another suggestion...

To a respond to a couple of the questions:

- Alignment... This was my first attempt, but I get the idea.. move the engine up/down, tilting forward/backward and side to side to attempt to get to .003 in or less between the transmission shaft couplings. I got pretty close, but I'm sure it was off by a little.. Of course there's also the shaft, shaft seal, shaft bearing and any inaccuracy there.. bottom line is I was just trying to get as close as I could, knowing I'd be hauling out soon and replacing those items, as well has having the shaft and prop looked oat.. full intention is to have a pro come in and perform an alignment for me. I want this thing running like a top and while I"m handy, I"m not a glutton for punishment either. The whole thing seems to be a sweaty fiddly frustrating experience..

- .1 inch on the dial indicator.. it's been awhile now, but I think I was getting 10 on this dial indicator... I'm not a machinist and haven't slept at a holiday inn express lately either so could possible be off.. it's a harbor freight one as well.. bottom line is there's a really good wobble in the shaft at all rpms that I want to get sorted out.

View attachment 230406

In reading that gauge, each small division is 0.001". When you get to the 10 on that dial you have moved 0.010". If your indicator needle ran all the way around the dial back to zero, then your little black dial hand on the upper left side would read 1 and you would have gone 0.100". Of course that's if you have set the device to zero to begin with. Currently, you are fully extended and the black needle is on the 9. That would be 0.100 before the entire gauge is set at zero. Not that you have to do that, you can set zero anywhere you want, and simply fine tune it by moving the face around.

So in your original post when you said your alignment was out by 0.100" - that would be a lot.

dj

 

[Ralph Johnstone]

anything else?

 

[jbmia]

View attachment 230428​

• No need to shout.
• That’s not a manual—it’s a how-to article. I read it last year when I was planning the motor mount replacement.
• This thread is about feedback on the play in my folding prop blades. If you don’t have anything constructive to add, please don’t post.
• The whole reason I mentioned taking the shaft and prop to the shop is to rule out “B” and “C” from the article, leaving only “A” as a possible cause.
• As for “A” (engine alignment), I’m in the middle of a standing rigging replacement, swapping all thru-hulls, grinding down a cast iron keel, coating it with Interprotect 2000, full bottom paint, removing old decals, full deck and topside wash/compound/wax, replacing the inverter, and adding a new house battery bank. So while I’d usually take on a DIY job like this, as I said earlier, I’m bringing in a pro for the alignment. I just want the damn thing to run smooth at this point.
• And again, in case there's still confusion — I wasn’t using the dial indicator to measure coupling face alignment. As I mentioned, I was checking shaft runout by hand-turning it. Just trying to confirm whether pulling the shaft for inspection made sense, to rule out “B” and “C” in the "article".

All that being said, any suggestions on the prop?

 

[Ralph Johnstone]

No need to shout.

I wasn't shouting, just clearing my throat. Touch of the flu, ya know ?

If you don’t have anything constructive to add, please don’t post.

• Just trying to confirm whether pulling the shaft for inspection made sense, to rule out “B” and “C” in the "article".

Absolutely right. Saves you an ocean of work rather than removing the rudder. The dial indicator IS the correct tool for that application.

My concern here is that not a lot of people fully understand angular (mis)alignment and that is the one (mis) that can really chew up your transmission. When doing that final tightening on those coupling bolts, you have no senseation as to how much POSSIBLE bending force you could be applying to the prop shaft and transmission shaft. Given a large uneven gap between those flange faces, the force would be enormous. And there's no way you want to risk those bolts coming apart so you are going to tighten them to the max. allowable torque which can only be achieved when the two faces are in 100% full contact. And that's why you read about so many people on this site replacing their transmission.

I think you had mentioned that the engine had received new mounts and I didn't know if the engine had been aligned afterwards. I know I replaced my rear starboard mount after I discovered the rubber was infused with fuel oil due to a leak. I thought I had marked out everything pretty well before starting but had one hell of a job doing a re-alignment after changing only one mount.

May I suggest you not put too many hours on your engine until you are sure of your alignment due to the new mounts ? New transmissions can be expensive.

 

[Tally Ho]

I think I would pull the prop and send it out for servicing. Hopefully the pins are a bit softer than the holes in the blades and body, so they wear, and you just need a new set of pins. If you are good with your hands and have some measuring tools (which you seem to have), maybe you can inspect and measure yourself and see if the pins are worn…then a new set of pins may (mostly) take care of your problem.

Greg